Challenges & Solutions 

for the 21st Century

Applications Across Land, Air, and Sea

Challenges & Solutions 

for the 21st Century

Volume 7, Issue No. 4
Report Documentation Page Form Approved

OMB No. 0704-0188

Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and

maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information,

including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington

VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it

does not display a currently valid OMB control number.

1. REPORT DATE

2012 2. REPORT TYPE

3. DATES COVERED

 00-00-2012 to 00-00-2012 

4. TITLE AND SUBTITLE

Leading Edge. Volume 7, Issue Number 4

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S) 5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Naval Surface Warfare Center, Dahlgren Division,Corporate

Communications, C6,6149 Welsh Road, Suite 

239,Dahlgren,VA,22448-5130

8. PERFORMING ORGANIZATION

REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)

11. SPONSOR/MONITOR’S REPORT 

NUMBER(S)

12. DISTRIBUTION/AVAILABILITY STATEMENT

Approved for public release; distribution unlimited

13. SUPPLEMENTARY NOTES

14. ABSTRACT

15. SUBJECT TERMS

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 

ABSTRACT

Same as

Report (SAR)

18. NUMBER

OF PAGES

102

19a. NAME OF

RESPONSIBLE PERSON

a. REPORT

unclassified

b. ABSTRACT

unclassified

c. THIS PAGE

unclassified

Standard Form 298 (Rev. 8-98)

Prescribed by ANSI Std Z39-18 
1

Table of Contents Directed Energy 

3 Leading Edge Directed-Energy RDT&E

Captain Michael H. Smith

4 Directed-Energy Topics in This Issue

Mr. Dale Sisson

Past, Present, and Future

6 Naval Directed-Energy Weapons — 

No Longer a Future Weapon Concept

David C. Stoudt

12 Historical Overview of Directed-Energy Work at Dahlgren

Stuart Moran

26 History of Laser Weapon Research

Melissa Olson

36 Laser Weapon System (LaWS) Adjunct to the Close-In 

Weapon System (CIWS)

Robin Staton and Robert Pawlak

RDT&E, Acquisition, and Warfare Management

44 The Acquisition Challenge Associated With Directed-Energy RDT&E

Mike Kotzian

Technology, Modeling, and Assessment

50 The Basics of Electric Weapons and Pulsed-Power Technologies

Stuart Moran

58 Solid Modeling of Directed-Energy Systems

Joseph F. Sharrow

64 A Fundamental Key to Next-Generation Directed-Energy Systems

Directed Energy Division, Electromagnetic and Sensor Systems Department

70 Active Denial Array

Randy Woods and Matthew Ketner

74 Directed Energy in the Military Environment

LT Leedjia Svec, Jeremy Beer, and Dave Freeman

High-Power Microwave

78 Directed Energy Using High-Power Microwave Technology

Jacob Walker and Matthew McQuage

High-Energy Laser

82 Laser Counter Rocket, Artillery, and Mortar (C-RAM) Efforts

Michael Libeau

Nonlethal Capabilities

86 Multifrequency Radio-Frequency (RF) Vehicle Stopper

Stephen A. Merryman

92 High-Power Electrical Vehicle-Stopping Systems

Jordan Chaparro and Melanie Everton

96 Nonlethal Small-Vessel Stopping With High-Power 

Microwave Technology

Jacob Walker

Volume 7, Issue No. 4
2

Naval Surface Warfare Center, Dahlgren Division (NSWCDD)

Captain Michael H. Smith, Commander

Carl R. Siel, Jr., Technical Director

David C. Stoudt, Distinguished Engineer for Directed Energy (ST) and

NAVSEA Technical Warrant for Directed Energy and Electric Weapon Systems

Janice Miller, Corporate Communications Director (Acting)

Steve Zehring, Managing Editor

Margie Stevens, Production Coordinator

Patrice Waits, Editor & Layout

Clement Bryant, Layout Design & Graphic Artist

Kellie Yeatman, Graphic Artist

Trey Hamlet, Graphic Artist/3-D Modeling

Electromagnetic & Sensor Systems

Dale Sisson, Head, Q Department

Brandy Anderson, Graphic Artist/Cover Design

NSWCDD

Jordan Chaparro

Melanie Everton

Matthew Ketner

Michael Libeau

Matthew McQuage

Stephen A. Merryman

Stuart Moran

Melissa Olson

Robert Pawlak

Joseph F. Sharrow

Robin Staton

Jacob Walker

Randy Woods

Defense Acquisition University

Mike Kotzian

Naval Medical Research Unit – San Antonio

Jeremy Beer

Dave Freeman

LT Leedjia Svec

The Leading Edge magazine is produced by the Naval Surface Warfare Center, Dahlgren, 

Virginia. The purpose of the publication is to showcase technical excellence across the Warfare 

Centers and promote a broader awareness of the breadth and depth of knowledge and support 

available to the Navy and DoD.

Address all correspondence to Corporate Communications, C6

Email: dlgr_nswc_c6@navy.mil; or write to

Commander

Naval Surface Warfare Center, Dahlgren Division

Corporate Communications, C6

6149 Welsh Road, Suite 239 

Dahlgren, VA 22448-5130

NSWCDD/MP-09/34

Approved for public release; distribution is unlimited.

2
3

Introduction

Leading Edge Directed-Energy RDT&E

Dahlgren first launched research and development efforts devoted to harnessing the power of electromagnetic energy over 

40 years ago. From early work with voltage multipliers and pulsepowered technology, to today’s high-energy lasers and high-power microwave technologies, the Naval Surface Warfare Center, 

Dahlgren Division (NSWCDD) has led, and continues to lead, 

cutting-edge directed-energy research, development, testing, and 

evaluation. Our commitment in this area only grows stronger—

evidenced by our chartering of the Directed Energy Warfare Office (DEWO)—in order to provide increased focus on warfighting 

applications of these technologies.

Today’s military forces face a wide array of challenges in diverse operating environments around the world. Directed energy offers unique and flexible options to address today’s challenges, 

as traditional kinetic weapons are often of limited value in peacekeeping missions and in urban environments, where restricted 

rules of engagement typify the norm. Kinetic weapons can also be 

more costly or ineffective to employ against asymmetric threats. 

The Chief of Naval Operations (CNO) recently placed added emphasis on directed energy and on expanding the range of directed-energy capabilities. In response, scientists and engineers at 

NSWCDD are actively developing prototype systems in a number of areas that you will read about in this issue—areas that have 

been successfully demonstrated and tested in our Navy laboratories and ranges.

In this issue of The Leading Edge magazine, you will trace the 

rich history of directed-energy work at Dahlgren, gain insight into 

directed-energy weapons already fielded or being readied for the 

field, and learn about prototypes that show real promise for providing incredibly effective offensive and defensive directed-energy solutions. For example, scientists and engineers at NSWCDD 

are leading the way toward realizing small, lightweight radio frequency (RF) transmitters using high-power, solid-state switching 

amplifiers for the development of counter-improvised explosive 

device detection and neutralization systems. You will also learn 

about diverse applications of directed-energy technology—such 

as research and testing of laser glare devices and laser eye protection—and have the opportunity to gain a better understanding of 

the Department of Defense (DoD) acquisition framework and the 

challenge of maintaining cost and schedule estimates while delivering weapons systems that are critical to the warfighter.

From lasers to high-power electrical vehicle-stopping systems, 

I am sure you will be fascinated and, along with me, be impressed 

with the advancements our scientists, engineers, and technical 

staff are achieving in the directed-energy arena to support of our 

men and women in uniform.

Captain Michael H. Smith, USN

Commander, NSWCDD
4

Welcome to our Directed Energy issue of the Leading Edge

magazine. This issue represents the third in a trilogy of issues 

covering the truly fascinating and incredibly challenging area 

of naval warfare in the operational electromagnetic environment. In our first issue, we covered the full range of operational 

and readiness implications when operating in the electromagnetic environment. Then, in our second issue, we highlighted 

the complexities and dynamics of providing relevant and effective sensors and radars to our warfighters. Now, we focus on 

directed energy and relate how the Naval Sea Systems Command (NAVSEA) Warfare Centers, and the Naval Surface Warfare Center, Dahlgren Division’s (NSWCDD’s), in particular, 

are working on state-of-the-art directed-energy weapons capabilities for the warfighter.

In this issue, we first look back to the early years, decades 

ago, when directed-energy weapons research began. We examine the history of directed energy, and we cover significant discoveries and achievements made by NAVSEA Warfare Center 

scientists and engineers, and others in the scientific community. We then relate information about several of our current directed-energy initiatives, and about how we’re working hard to 

solve some of the most complex technical challenges associated with directed-energy weapons. We highlight how others in 

the Navy, such as the Naval Medical Research Unit in San Antonio, Texas, are also conducting research into directed energy and how our forces can better protect themselves from the 

effects of directed energy. We show how directed energy can 

be employed in a variety of offensive and defensive, lethal and 

nonlethal situations. We explain how directed-energy weapons 

work and how they can be employed in various environments 

against a wide range of situations. Lastly, we look forward as we 

provide technical and strategic leadership for the efficient and 

effective development, acquisition, and fielding of directed-energy systems for the warfighter.

So, if you want to learn about what the NAVSEA Warfare 

Centers and others in the Navy are doing in the area of directedenergy weapons, look no further than this issue of the Leading 

Edge magazine. I’m confident that you will be impressed by the 

progress made in this most important technology field.

Dale Sisson

Head, Electromagnetic and 

Sensor Systems Department 

NSWCDD Dahlgren, Virginia

Directed-Energy Topics in This Issue 
5
6

Directed Energy

Past, Present, and Future

Naval Directed-Energy Weapons — 

No Longer A Future Weapon Concept

By David C. Stoudt

Directed-energy weapon (DEW) technologies typically take the form of highenergy lasers (HELs), high-power microwaves (HPMs), and charged-particle beams. 

This article focuses on the first two technology areas, as they have reached the point of 

being ready for operational testing and evaluation, and in some cases, operational use 

on the battlefield. DEWs have been popularized in science-fiction writings for over a 

hundred years. The Department of Defense (DoD) has been investing in their development since the 1970s. This article will not go into technical depth regarding the various 

directed-energy (DE)-related efforts currently underway in the Navy, but rather, it will 

overview DE areas under development and relate recent Navy leadership activity. Other articles in this issue of The Leading Edge magazine will provide the reader with much 

greater technical and programmatic details on various DE efforts.

High-Energy Laser Weapons

HEL weapon systems have been envisioned for a great many years, to include being referred to as Martian “Heat Ray” weapons in H.G. Wells’ epic novel The War of the 

Worlds, originally published in 1898. In reality, a high-average-power laser weapon system is very similar to a “heat ray”, or even a blow torch. During the early years of DoD 

investments in DE technology, the Navy led the development of HEL with the creation 

of the world’s first megawatt-class, continuous-wave, Mid-Infrared Advanced Chemical Laser (MIRACL), located at White Sands Missile Range (WSMR). Roughly 80 years 

after the work of H.G. Wells, the U.S. Navy tested the MIRACL laser and ultimately 

used that laser system to engage static and aerial targets in the desert of WSMR in the 

following years. While that laser proved to be the wrong choice for the Surface Navy’s 

self-defense mission, it did spawn work by the Air Force on the Airborne Laser (ABL), 

and the Army on the Tactical High-Energy Laser (THEL). In 2000 and 2001, the THEL 

successfully shot down 28 supersonic Katyusha artillery rockets and 5 artillery shells. 

Dr. Stoudt is the Distinguished Engineer for Directed Energy (ST) 

and the NAVSEA Technical Warrant for Directed Energy and Electric 

Weapon Systems.
7

Naval Directed-Energy Weapons — 

No Longer A Future Weapon Concept

In 2010, the ABL successfully engaged and destroyed tactical ballistic missiles during the boost 

phase of their flight. All three of these laser systems—the MIRACL, the ABL, and the THEL—

are chemical lasers that utilize toxic chemicals 

and operate in less than optimal wavelengths that 

make them a poor choice for most naval applications. The MIRACL is shown in Figure 1.

Recent advances in solid-state lasers, to include fiber lasers, have moved these electric lasers to the forefront of the Department’s research 

and development (R&D) for near-term HEL applications in the services. The Navy has particular 

interest in electric lasers, to include the free-electron laser (FEL), for shipboard self-defense and 

force protection applications. The speed-of-light 

delivery of HEL energy can defeat the high-g maneuvers of newly developed foreign antiship 

cruise missiles (ASCMs). Thus, the Office of Naval 

Research (ONR) started an FEL Innovative Naval 

Prototype (INP) program in FY10, with a goal of 

reaching the output power of 100 kW. The eventual goal of the FEL program is to reach the multimegawatt power level with wavelength selectivity. 

The Naval Sea Systems Command (NAVSEA) Directed Energy and Electric Weapons Program 

Office (PMS 405) has been actively developing a 

fiber laser-based Laser Weapon System (LaWS) 

that could be a retrofit to augment the current capabilities of the Close-In Weapon System (CIWS) 

currently deployed on many surface combatants. 

The Naval Surface Warfare Center, Dahlgren Division (NSWCDD), is the Technical Direction 

Agent and lead system integrator for PMS 405 on 

the LaWS program. The Naval Air Systems Command (NAVAIR) has interest in compact, solidstate HEL systems for aircraft self-protect and 

air-to-ground engagements, and will be starting a 

Figure 1. Mid-Infrared Advanced Chemical Laser (MIRACL)
8

Directed Energy

Past, Present, and Future

Figure 2. Laser Weapon System (LaWS)

fiber laser-based ONR Future Naval Capability effort in FY12. LaWS is shown in Figure 2.

High-Power Microwave Weapons

Like lasers, microwave weapons have been fantasized about ever since the invention of microwave 

power generators. In fact, in 1932 it was generally 

recognized by the British government that bombers, ostensibly German bombers, would be able to 

penetrate British air space and bomb its civilian 

population and infrastructures. In 1934, the Air 

Ministry initially asked Robert Watson-Watt, of 

the National Physical Laboratory, if he could build 

a “death ray” that could kill enemy pilots or detonate bombs while they are still on the planes of enemy aircraft. Such a “death ray” had been proposed 

to the Air Ministry by Harry Gindell-Mathews 

10  years earlier in 1924. Watson-Watt, a former 

meteorologist who had become an expert on radio signals, suggested that energy reflected from an 

aircraft could be used to locate it. His experiments 

were successful and RADAR (radio detection and 

ranging), a name coined by the U.S. Navy in 1940, 

was born. While RADAR is not a DEW in the way 

they are thought of today, its roots can clearly be 

traced to the military’s desire for such capabilities.

The Navy’s HPM, or high-power radio-frequency (RF) systems, have been progressively increasing 

in power density to the point where it is now feasible to integrate the technology into weapon systems 

for deployment. While initial HPM applications 

suffered from their inability to obtain militarily 

useful outcomes, either due to technology limitations, difficult concept of operations (CONOPS), 

or inherent robustness of potential target systems, 

many feasible military applications for using HPM 
9

Naval Directed-Energy Weapons — 

No Longer A Future Weapon Concept

Figure 3. Multifrequency RF Vehicle-Stopper (RFVS) System

devices have surfaced over recent years to include 

nonlethal, antipersonnel weapons and nonkinetic, 

antimateriel weapons. While these concepts offer unique capabilities to the warfighter due to the 

nonkinetic effects they generate, other warfighting 

concepts—such as stopping vehicles, or countering 

hidden roadside bombs or improvised explosive devices (IEDs)—are difficult to achieve by any other 

means. The multifrequency Radio-Frequency Vehicle Stopper (RFVS) system is shown in Figure 3.

In addition, the difficulty in overcoming the 

propagation losses associated with HPM has driven some concepts into platforms such as unmanned aerial vehicles (UAVs) or cruise missiles 

that deliver the HPM device to the target for a 

close-in engagement. Over the past 10 years, fieldtestable prototypes have been developed to demonstrate the operational utility of these concepts, 

and in some cases, those prototypes have or will 

be deployed operationally to support our troops in 

theater. It is only through the hard work and perseverance of the Naval Research Enterprise (NRE), as 

well as other DoD laboratories, that concepts that 

were once only laboratory curiosities are now making their way onto the battlefield and contributing 

to the fight.

Foreign Directed-Energy Weapon 

(DEW) Development

While the United States has been very active in 

this warfighting area, significant foreign DEW development also has elevated the need for the Navy 

to afford these threats a higher priority. This can be 

done either by incorporating the necessary DEW 

countermeasures into weapon systems, platforms, 

and critical infrastructures, or by adapting the 

CONOPS and tactics, techniques, and procedures 

(TTPs) employed by our armed forces to properly account for those foreign DEW systems. Materiel developers need to understand how this threat 
10

Directed Energy

Past, Present, and Future

is evolving and properly address it during the design of their systems. They also need to address DE 

in the development of their system threat assessments. There has been movement on the HPM side 

to modify existing military standards, such as MIL 

STD 4641

 and others, to now include information 

on potential HPM threats. For example, in the HEL 

arena, work has been accomplished in the development of protective measures for eyes; however, this 

threat needs to be considered during the system 

development process. It is well known that building in countermeasures is much cheaper during 

the initial development of a system, vice trying to 

retrofit systems with countermeasures once a new 

threat is on the battlefield. As analysts evaluate the 

foreign development of DE technologies, and the 

trends become clearer, it is the responsibility of the 

acquisition community to take this threat into consideration and ensure that weapon systems, platforms, and infrastructures will be available and 

at full capability when needed. By accounting for 

foreign threat developments, assessing blue force 

susceptibilities and vulnerabilities, and adopting 

appropriate measures to negate or counter these 

threats, naval forces will avoid technological surprise on the battlefield in the future.

Requirements

The DE programs briefly mentioned in this 

article, and covered more deeply in this and other publications, offer warfighters unique capabilities not currently found in their arsenal. The 

continuing problem, however, is matching those 

unique capabilities to vetted operational requirements. The DE technical community has made 

great strides in helping the operational community understand the capabilities of DE weapons and 

their potential military effects on targets. The lack 

of formal requirements, however, has yielded more 

of a technology push—rather than an operational 

pull—of various DE capabilities. Progress has been 

made, but more effort is required if DE capabilities 

are to be developed and transitioned between science and technology (S&T), and formal programs 

of record. Notwithstanding, the current outlook 

and trends are positive.

A Resurgence of Navy Interest in 

Directed Energy

The Navy’s interest in DEWs for future maritime operations has increased in recent years due 

to a number of weapons development successes. 

Recognizing the importance and value of DEWs, 

NAVSEA reestablished the Navy Directed Energy Weapons Program Office (PMS 405) in 2004. 

Accordingly, PMS 405 was designated as the point 

of contact for matters related to DE and electric 

weapon systems (EWS) development and acquisition initiation for NAVSEA, and for matters 

being coordinated with other federal agencies and 

military services. PMS 405’s mission is to transition technology from the laboratory to prototype/ 

advanced development/testing for operational development and use.2, 3

The Navy also established its first formal executive position for DE (ST-level), the Navy’s Distinguished Engineer/Scientist for Directed Energy, 

at NSWCDD in August 2004. Following the establishment of this position, NAVSEA then formally established a Technical Authority Warrant 

for Directed Energy and Electric Weapon Systems 

(DE&EWS)—Surface Ships in July 2008. The scope 

of the warrant includes the transition of S&T development to weapon system development of lethal and nonlethal capabilities associated with the 

DE&EWS for Surface Ships.4

 This included, but 

was not limited to, the following:

•	 Laser Weapon Systems

◆ High-Energy Lasers

◆ Solid-State Lasers

◆ Free-Electron Lasers

◆ Femtosecond Ultrashort Pulse Lasers

◆ Laser-Induced Plasma Channel

◆ Lethality/Vulnerability

•	 Electromagnetic Rail Gun Weapon System

•	 High-Power Microwave

◆ Active Denial System

◆ Laser-Guided Energy

•	 Maritime Directed Energy Test Center

•	 Electromagnetic Launch of Weapons (excluding the Electromagnetic Aircraft Launch 

System (EMALS))

Then, within the NAVSEA Warfare Center Enterprise, Warfare Center leadership established two 

technical capabilities (TCs): an NSWCDD TC for 

DE systems research, development, test, and evaluation (RDT&E); and a Naval Surface Warfare Center, Port Hueneme Division (NSWCPHD) TC for 

in-service engineering, test and evaluation (T&E), 

and integrated logistics support to DE systems. 

NSWCDD leads all S&T and RDT&E for the development and weaponization of DE systems for surface, air, and ground environments. It also leads the 

development of offensive and defensive DE technologies needed to characterize and exploit vulnerabilities, provide weapons, and protect against attack. 

NSWCDD provides the technologies, devices, and 

systems designed to create or control electromagnetic energy used to cause persistent disruption or 

permanent damage by attacking target materials, 
11

Naval Directed-Energy Weapons — 

No Longer A Future Weapon Concept

electronics, optics, antennas, sensors, arrays, and 

personnel, including nonlethal applications. NSWCPHD provides in-service engineering, T&E, and 

integrated logistics support to DE systems throughout the system life cycle.

The Navy further demonstrated increased 

interest in DE when Assistant Secretary of the 

Navy (Research, Development & Acquisition 

(ASN(RDA)) designated NAVAIR offensive and 

defensive leads for naval aviation DE activities:

•	 Program Executive Officer for Unmanned 

Aviation and Strike Weapons (PEO(U&W)), 

assigned as the offensive DE lead for naval 

aviation

•	 PEO for Tactical Aircraft Programs (T), assigned as the defensive lead for naval aviation

Concerning future initiatives, the Chief of Naval Operations (CNO) tasked the Strategic Studies 

Group (SSG) to examine a topic entitled “Maritime Operations in the Age of Hypersonic and Directed-Energy Weapons.”5

 The intent of the study 

was to provide Navy leadership with an understanding of where DE technologies and weapons 

are today and how they might influence future 

maritime operations. The theme of the study was 

completed during FY10, the results of which discuss many DE concepts, as well as tactics for the 

employment of DE capabilities. The study’s findings are currently under review and consideration 

by senior Navy leadership.

Conclusion

While H.G. Wells’ The War of the Worlds novel and television programs like Star Trek popularized the notion of using DE for weapons in years 

past, today— through persistent DEW RDT&E—

Navy leadership is realizing the great potential that 

DEWs offer naval warfighters and homeland defenders. The scientific and technical advances the 

Navy has made in HEL and HPM in recent years 

have been nothing short of extraordinary. Moreover, future technological and engineering advances undoubtedly will result in profound differences 

in our nation’s future warfighting capabilities. Naval DEWs, therefore, are no longer just a future 

weapon concept...they are here today.

References

1. Department of Defense Interface Standard, Electromagnetic Environmental Effects—Requirements for Systems, MIL-STD-464, 18 

March 1997.

2. NAVSEA Notice 5400, Ser 09B/240, Subject: Establishment of the 

Navy Directed Energy Weapons Program Office (PMS 405), dated 4 January 2002.

3. NAVSEA Instruction 5400.101, Ser SEA 06/058, Subject: Directed Energy and Electric Weapons Program Office (PMS 405) Charter, dated 21 July 2004.

4. NAVSEANOTE 5400 Ser 09B/240 of 4 January 2002 and 

NAVSEAINST 5400.101 Ser SEA 06/058 of 21 July 2004.

5. Letter from the CNO tasking the SSG XXIX Theme—”Maritime 

Operations in the Age of Hypersonic and Directed-Energy Weapons,” dated 23 September 2009.
12

Directed Energy

Past, Present, and Future

Historical Overview of 

Directed-Energy Work at Dahlgren

By Stuart Moran

In 1962, the United States set off a megaton nuclear weapon 250 miles above the 

Pacific. The blast caused a large imbalance of electrons in the upper atmosphere that 

interacted with the Earth’s magnetic field to create oscillating electric fields over a large 

area of the Pacific. These fields were strong enough to damage electronics in Hawaii, a 

thousand miles away, and clearly demonstrated the effects of an electromagnetic pulse 

(EMP). It didn’t take long for the military to begin considering ways to create such 

pulses without using nuclear weapons.

In the late 1960s, the Special Applications Branch at the Naval Weapons Laboratory 

at Dahlgren began studying ways to generate high-power oscillating electric fields that 

could be used as a weapon to damage enemy electronics. These devices were basically 

high-power versions of the old spark-gap transmitters used in the early days of radio. 

To construct a device that could produce nuclear EMP-like fields, stored electrical energy was converted to radio-frequency (RF) energy that could be radiated from an antenna through the atmosphere to a target. These devices typically would store energy in 

a high-voltage capacitor and release the energy quickly using a spark-gap switch. This 

would then drive oscillating currents on an antenna, causing it to radiate. To achieve 

field strengths of thousands of volts per meter, typical of a nuclear EMP, devices operating at hundreds of thousands of volts or more were needed.

A number of radiating devices were studied in the early 1970s. Most belonged to a 

class of devices called Hertzian oscillators. A capacitor is charged to high voltage, the 

switch is closed, and current flows in the circuit, causing the stored energy to oscillate between the electric field of the capacitor and the magnetic field of the inductor. 

To charge the capacitor to extremely high voltages, a step-up transformer of some type 

must be used. One of the fastest voltage multipliers, the Marx generator, was frequently used. The losses from internal resistance and external radiation damp the oscillating waveform, typically after a few cycles. The radiated pulses are, therefore, short in 

time and broad in frequency content.1

 A simple diagram of the inductance-capacitance 

oscillator (L-C oscillator) is shown in Figure 1.

Single-Pulse Burnout Devices 

Many types of Hertzian devices were designed, constructed, and tested at Dahlgren during the 1970s. The transmission-line oscillator, or cavity oscillator, used a quarter-wavelength 
13

Historical Overview of 

Directed-Energy Work at Dahlgren

coaxial pipe, which was switched at one end, to create 

the oscillating waveform. A frozen wave generator, 

a different type, had quarter-wave sections of cable 

that were charged plus and minus to create a twocycle waveform “frozen” in the cable. All sections 

were simultaneously switched, causing the wave to 

travel to an antenna. A special folded design was developed so one switch could be used, eliminating 

the multiswitch synchronization problem. A Ross 

circuit used a square wave pulse, which traveled 

down cable “tees,” creating reflections, which were 

timed to create several RF cycles. In the Travetron, 

the turn-on time of a series of spark-gap switches was incorporated as a designed delay, creating 

reflections through a series of gaps to produce the 

waveform. This design allowed higher frequencies. 

All of these devices were designed, built, and tested to determine power and frequency capabilities, 

as well as efficiency.

Scientists and engineers at Dahlgren built and 

tested versions of Hertzian oscillators operating up 

to half a million volts. These devices powered relatively simple monopole or dipole antennas that 

could produce very high electric fields at hundreds of meters. In the early 1970s, a special outdoor field-measurement range was constructed. 

It housed high-voltage systems in underground 

trailers that fed antennas above ground on a specially-built, 100-m-long ground plane that was 

constructed for testing and field measurements. A 

picture of the ground place in a fielded measurement range is shown in Figure 2. Field probes were 

even carried aboard helicopters to make measurements above ground effects, as shown in Figure 3.

Other types of devices to produce pulses were 

constructed, too. Vector inversion generators used 

spiral-wound capacitive plates to generate high 

voltages without transformers.2, 3

 The Landecker 

ring used a paddle-wheel arrangement of capacitors and inductors charged in parallel and discharged in series. The circular arrangement was 

designed so the entire system would radiate as a 

magnetic dipole, thus forming its own antenna.4

Switch timing was critical, and Dahlgren engineers 

attempted to verify reports that Landecker developed a specific type that brought all capacitor leads 

into a single-center spark gap.

Scientists and engineers also looked at devices 

that used explosives to generate the electrical energy 

needed. These included explosive flux compressors 

of several types, which generated fields and then explosively squeezed the fields between conductors to 

amplify the peak power. In the early 1970s, a large 

(70-ft clear zone) anechoic chamber was constructed at Dahlgren with an explosive chamber in one 

end. Explosives would be set off in the chamber to 

drive various types of flux compressor schemes that 

would generate electrical pulses fed into an oscillator 

and antenna in the anechoic chamber. Pulse parameters and field strengths could be measured. Impedance-matching networks, matching transformers, 

and methods of improving efficiency were studied. 

Tests were performed at Dahlgren and at Los Alamos using large antennas suspended from balloons.5

In other schemes, piezoelectric devices were developed, which could be compressed hydraulically and 

then quickly released to produce high voltages. The 

concept was to use explosives to generate the high 

Figure 1. Inductance-Capacitance Oscillator (L-C Oscillator) Diagram
14

Directed Energy

Past, Present, and Future

Figure 2. Field Measurement Range

Figure 3. Airborne Electric Field Measurements
15

Historical Overview of 

Directed-Energy Work at Dahlgren

pressures. Ferroelectric and ferromagnetic transducers driven by explosives were also tested.6

Special Effects Warhead 

(SEW) Program

In 1973, Dahlgren began the SEW Program to 

look at the feasibility of “burning out” enemy radar 

and missile systems using single-shot, very highpeak-power EMPs. The program looked at the 

feasibility of constructing an electromagnetic warhead that could disable electronics beyond a normal hard-kill explosive range as far as a mile away. 

The program was funded at several million dollars 

a year through most of the 1970s.

A major thrust of the SEW Program was to 

better understand the effects of high fields on military electronics. Little information was available 

on the vulnerability of foreign or U.S. electronics, 

particularly entire systems. A trailer-based RF impulse system, employing a Marx-driven L-C oscillator charged at two million volts, was constructed 

at Dahlgren. This Transportable Oscillating Pulser 

System (TOPS) was connected to a large boundedwave structure that produced uniform fields over a 

region large enough to place an entire radar or missile system. The electric field emitted from the throat 

of this system was so high that a special bag of highvoltage gas was needed until the radiating structure 

became large enough to transition to the normal atmosphere. A picture of TOPS is shown in Figure 4.

Since many important target systems were not 

available for testing, much of the vulnerability information was obtained from U.S. electronics, and 

estimates were then made for foreign systems. In 

addition to the tests done at Dahlgren, pulsers were 

also constructed in mobile trailers that could be 

transported to other sites for testing against simulated or actual targets. The Mobile Oscillating Pulser System (MOPS) was an example that was carried 

to test sites, such as China Lake, to perform tests 

against radars and simulated foreign systems.

A key requirement for the SEW Program was 

to demonstrate enforceable target vulnerability, 

which means that a high percentage of the time a 

large percentage of the targets are affected. One important finding was the broad difference between 

an electromagnetic safety concern—where a 1 percent vulnerability was far too great—and a weapon concern—where a 10 percent vulnerability was 

not good enough. The field strengths between the 

safety requirements and weapon requirements often were many orders of magnitude apart.

The SEW Program looked at many types of 

electronic component vulnerability, subsystem 

vulnerability, and complete system vulnerability. 

As a result, energy tables for burnout effects were 

developed. Subsequently, Dahlgren performed numerous field tests against radar and communications systems between 1973 and 1978, and funded 

component and subsystem testing on missiles.

Figure 4. Transportable Oscillating Pulser System (TOPS)
16

Directed Energy

Past, Present, and Future

Repetitive Systems for 

Electronic Warfare 

The electric fields required to damage military 

electronics in the 1970s often were very high, and 

ranges typically were limited. As a spinoff of programs trying to damage targets with a single pulse, 

some of these devices were reduced in size and 

power, and operated in a repetitive mode to generate noise pulses for the purpose of electronically jamming target systems. In 1976, the Naval Air 

Systems Command (NAVAIR) began the Electromagnetic Countermeasures Program to study the 

application of high-repetition-rate Hertzian devices for use as noise jammers. The initial targets were 

low-frequency radars.

In late 1976, Dahlgren performed effectiveness 

tests against various radars using helicopter-mounted Hertzian jammers. These devices were able to 

screen incoming target aircraft at useful ranges. The 

concept of a forward-launched rocket to deliver a 

parachute-suspended Hertzian jammer also was investigated. Dahlgren teamed with engineers at China Lake to study packaging concepts of utilizing an 

extended 5-inch Zuni rocket as a forward-fired delivery vehicle. A prototype is shown in Figure 5.

Similar Hertzian devices were considered for 

use as communications and data-link jammers. 

Several antenna deployment schemes were developed, and by fall 1978, successful ground launches 

had been performed in which the deployment sequence and jammer operation were demonstrated. 

The name Zuni Expendable Pulsed-Power Oscillator (ZEPPO) was given to the project. Dahlgren 

teamed with the Naval Avionics Center (NAC) to 

build the systems. By 1980, China Lake fired the 

first air-launched prototypes at both low and high 

altitudes. Devices, batteries, spark gaps, and antennas continued to be developed, and new targets—

such as spread-spectrum systems—were tested. 

Other delivery systems besides rockets were also 

considered.

The Pulsed Power 

Technology Program 

Large directed-energy weapons (DEWs) often required megawatts or gigawatts of peak power, 

so methods of supplying and modifying this power were needed. As Dahlgren became involved in a 

broad range of DEW systems, one attribute became 

more and more obvious: the size, weight, and cost of 

a directed-energy (DE) system were dominated by 

the pulsed-power technologies needed to drive the 

system, not by the source device itself. Consequently, more effort began to be devoted to the power-delivery technologies needed for many of the weapon 

concepts. Pulsed-power components enabled energy to be stored over long periods of time (seconds) 

and released very quickly (nanoseconds) to obtain 

a billion times increase in peak power.

Dahlgren hosted a pulsed-power systems 

symposium and workshop in 1976 and helped 

initiate the International Pulsed Power Conferences, which began in 1977 and continues today 

under the Institute of Electrical and Electronics Engineers (IEEE). As Dahlgren’s involvement 

with systems design increased, it became apparent 

that new technologies were needed in the primepower and pulsed-power area to support a variety of new concepts. Dahlgren urged the Navy to 

initiate a Pulsed Power Technology Program to 

develop power sources, energy storage systems, 

high-power switches, and power conditioning systems needed for a variety of future weapons. This 

program was initiated in 1978 and was originally 

funded by NAVAIR and then by the Directed Energy Program Office (PMS 405) in the early 1980s. 

In addition to the Pulsed Power Technology Program, PMS 405 also began funding free-electron 

lasers (FELs), chemical lasers, high-power microwaves (HPMs), and charged-particle beams 

(CPBs). The Pulsed Power Technology Program at 

Dahlgren, in turn, funded many areas of research, 

both internal and external, over the next 10 years. 

Dahlgren served as the focal point for the Navy’s 

science and technology (S&T) in pulsed power 

and funded many universities, government laboratories, and commercial companies under the 

Pulsed Power Technology Program. Figure 5. ZEPPO Payload
17

Historical Overview of 

Directed-Energy Work at Dahlgren

To provide large amounts of electrical prime 

power, new types of rotating machines were studied, including flywheels, conventional alternators, 

homopolar generators, rotary flux compressors, 

and compensated pulsed alternators. These machines attempted to produce fast, high-power pulses using special materials to reduce losses, eddy 

currents, and mechanical stresses. MHD generators were developed using rocket-motor propellant 

that could be started and stopped. In the mid1980s, a full-scale hybrid (solid fuel/liquid oxidizer) combustor was fabricated and tested at 10 MW, 

achieving world records for power-to-weight ratio and conductivity. By 1980, new types of energy 

storage systems were studied, including inductive 

storage and advanced capacitors using new types 

of insulating materials and geometries. During the 

late 1980s, programs such as the Mile-Run Capacitor Program reduced the capacitor size by a factor of 10 through better synthesis of polymer films.

Beginning with internal independent research 

funds, Dahlgren developed liquid dielectric materials based on water/glycol mixtures at low temperatures. These water-capacitor devices could 

hold energy for orders-of-magnitude longer time 

periods than ever before, allowing pulseforming 

lines to be constructed that could be charged directly from rotating machines. Dahlgren scientists developed a world-record high-voltage water 

capacitor that could hold pulses for milliseconds 

and became internationally recognized experts in 

water breakdown.7, 8

High-power fast switching was another important area of research. Dahlgren funded companies 

to develop new types of multistage thyratrons that 

could operate at very high voltages. By the early 

1980s, multistage thyratrons capable of operating 

at over 200 kV, 40 kA with 20 nsec risetimes were 

demonstrated. Vacuum switches, ignitrons, plasma pinch switches, pseudospark switches, backlighted thyratrons, and e-beam switches all were 

studied, as well as a variety of spark-gap switches. 

Higher power solid-state switches were developed, 

too, using new geometries and substrate material. Superconducting coils were considered, both 

for energy storage and as opening switches. Dahlgren engineers developed exploding-wire opening 

switches, and several types of plasma pinch switches were funded. They also worked on stacked cable 

pulsers. Additionally, concepts for electromagnetic armor were developed. These systems used 

high-density capacitors to blunt penetrators. Inductive energy storage—which could be far denser 

than capacitors—was studied, including methods 

of generating the seed current and the problematic 

high-voltage opening switch. Opening switches—

which were needed for inductive energy store systems—were studied, as well as magnetic switches, 

which used saturating magnetic material to sharpen pulses. Magnetic switches operating at 10 kHz 

were demonstrated by 1983.9

In 1985, Dahlgren used internal funds to upgrade a facility to provide controls, diagnostics, and 

200 kW of average power at 50 kV to accommodate 

testing of new switches and water-based capacitors. 

This facility could control the power with a vacuum-tube pulser and could generate over a million 

volts with a rep-rated Marx generator. The facility 

was used to:

•	 Develop water-dielectric energy storage, reprated spark gaps, and pseudospark switches.

•	 Test a variety of switches developed by contractors, such as back-lighted thyratrons.10, 11

A picture of one system being tested—a water pulseforming line and spark-gap switch—is shown in 

Figure 6. 

Dahlgren concentrated in-house switching efforts in spark gaps. New types of gases were studied, as well as electrode materials, gas-flows, switch 

geometries, and triggering techniques to produce 

high-repetition-rate switches for electronic warfare, as well as particle-beam weapons.12 Dahlgren 

scientists and engineers demonstrated 100-μs recovery of spark-gap switches after handling kilojoules of energy at hundreds of kilovolts, a world 

record.13 The High Energy 2-Pulse System for fast 

recovery experiment is shown in Figure 7.

In 1986, Dahlgren ran a workshop on highpower switching for Navy tactical and Department of Defense (DoD) strategic applications and 

became involved with numerous DoD working 

groups on electromagnetic propulsion, high-power diagnostics, advanced energy conversion, power modulators, and pulsed power. Spark gaps were 

investigated to create underwater noise for submarines. Dahlgren also led four North Atlantic Treaty 

Organization (NATO) Advanced Study Institutes 

in Europe and the UK on various pulsed-power topics. International assessments of key pulsedpower technologies were also performed. 

Particle-Beam Weapons 

Particle-beam weapons were a major focus of 

DE work during the 1970s and 1980s. A CPB weapon takes subatomic particles, generally electrons, 

and accelerates them to near the speed of light before sending them toward a target. These fast electrons penetrate deeply into most materials, so they 

are difficult to counter. The high-current electron 

beam was to be accelerated by an induction-type 
18

Directed Energy

Past, Present, and Future

Figure 6. A Water Pulse-Forming Line and Spark-Gap Switch Test

Figure 7. High Energy 2-Pulse System
19

Historical Overview of 

Directed-Energy Work at Dahlgren

accelerator, repetitively pulsed. High electronbeam currents (kiloamps) and a hole-boring series 

of pulses were anticipated to create a stable, longrange beam. Since the beam was capable of penetrating quickly and deeply into any target material, 

it had the potential to damage electronics and set 

off explosives before salvage fuzing could occur. 

The beam was predicted to be all-weather and essentially countermeasure-proof. Even a near miss 

could cause substantial damage from high fields 

and X-rays produced by the deceleration of electrons as they hit air molecules near the target. The 

CPB concept is shown in Figure 8.

Scientists and engineers from Dahlgren worked 

on the pulsed-power technologies needed to drive 

these machines beginning in 1980, and it became 

a major focus of the Pulsed Power Technology 

Program.14 The White Oak Laboratory developed 

beam-steering concepts and looked at material interactions. By 1989, the program investigated:

•	 Propagation

•	 Compact Recirculating Accelerators

•	 Pointing and Tracking

•	 Prime Power

•	 Material Interaction

•	 Fratricide

For a compact shipboard system, recirculating 

accelerators were needed to make multiple passes 

of the electron beam past the accelerating cavities. 

This required a high-power, fast recovery switch, 

which Dahlgren began working on in 1988. Using 

patented hydrogen switches and special triggering 

techniques—efforts that had begun with internal 

research funds—Dahlgren demonstrated sparkgap switches, the only technology that could meet 

the current, voltage, and recovery requirements at 

that time.15 The High-Voltage 5-Pulse System experiment is shown in Figure 9.

During these technology efforts, significant 

advances were achieved in all aspects of the program. These included:

•	 Generating high-current, high-energy beams 

(although still below weapons parameters)

•	 Demonstrating a 360o turn in a high-current 

beam

•	 Propagating a single pulse through the air

•	 Demonstrating beam steering on a small scale 

•	 Performing target interaction measurements

Multipulse, long-range propagation was never 

demonstrated. A comprehensive tri-service summary called the Net Technical Assessment for CPB 

was sponsored by the Defense Advanced Research 

Projects Agency (DARPA) in 1987 to describe the 

accomplishments of the program. The report said 

compact accelerators were the most pressing technology need. As a result, most funding was directed toward this topic. Funding was stopped in 

the early 1990s, however, due to the high expense, 

stretched timelines, and changes in the threat.

Pulsed Power and 

Electromagnetic Launchers 

During the 1980s, the Army and Air Force 

looked at short-range electromagnetic weapons 

to penetrate stronger armor with higher velocities. The Navy worked on concepts for a weapon 

that could be mounted on ships to intercept missile 

systems at line-of-sight distances. The Navy—then 

the biggest user of space systems—was also interested in studies showing that small satellites could 

Figure 8. Charged-Particle Beam (CPB) Concept
20

Directed Energy

Past, Present, and Future

be electromagnetically launched into low Earth orbit for the fraction of the cost for a normal launch.

Through the 1980s, electric guns were funded 

by independent research and independent exploratory development programs at Dahlgren, studying electric gun concepts for both rail guns and 

electrothermal (ET) guns. Kinetic energy weapons 

were also investigated as part of the Pulsed Power 

Technology Program. Under these programs, pure 

electric launchers were developed and tested at 

Dahlgren, including ones that self-formed projectiles.16–18 Also studied were ET guns that used the 

discharge of electrical energy at the gun breech to 

generate a plasma jet. This plasma jet heated a lowmolecular-weight working fluid, such as water, to 

produce a heated gas that accelerated the projectile 

to higher velocities than conventional explosives. 

The Electrothermal-Chemical (ETC) Gun concept augmented the electrical energy generating 

the plasma jet with a chemical reaction. A 127mm 

ETC gun was investigated, and a 60mm ETC gun 

was tested at Dahlgren, with the ability to fire short 

bursts at a rate of 100 rounds per minute.19

Early Dahlgren work on electromagnetic 

launchers—along with capacitor development and 

switch advances from the Pulsed Power Technology Program—allowed Dahlgren to provide the 

Navy with detailed conceptual designs in the late 

1990s for near-term, long-range rail guns based on 

capacitor energy store. These efforts helped support the decision to begin a long-range rail-gun 

program at Dahlgren that continues today, resulting in world-record achievements. Capital investment funds were used to construct a high-energy 

facility in 2005 to test pulsed-power components 

and module designs for use in electromagnetic launcher programs. An early electromagnetic 

launcher is shown in Figure 10.

High-Energy Lasers (HELs)

In general, megawatts of continuous laser 

power are required to kill hard targets at long ranges. Laser technologies that can produce this much 

power are very limited. The Navy was a leader in 

developing powerful chemical lasers in the 1970s 

and 80s. These lasers burned chemical reactants to 

Figure 9. High-Voltage 5-Pulse System Experiment
21

Historical Overview of 

Directed-Energy Work at Dahlgren

generate the excited states for lasing, thus reducing the need for large amounts of electrical power. The Navy built an entire HEL system, including 

the Mid-Infrared Advanced Chemical Laser 

(MIRACL) and the Sea-Lite beam director. By 

1990, this building-sized system demonstrated 

shooting boosters, missiles in flight, and supersonic vehicles. However, the system had drawbacks 

because it:

•	 Used hazardous, expensive chemicals

•	 Had propagation problems at the midinfrared wavelength

•	 Was large in size and high in cost 

FELs require electron accelerators similar to 

CPB weapons, so they also are large and complex. 

However, they can be designed to operate at optimum wavelengths and scale nicely to higher powers. The Strategic Defense Initiative began working 

on FELs in the late 1980s, funding the advanced 

test accelerator at LLNL, originally developed for 

CPBs. FELs were also studied under the Strategic 

Defense Initiative Organization (SDIO) to be used 

as an antisatellite weapon. These lasers went from 

milliwatts to watts under SDIO, and then to kilowatts more recently with work at the Thomas Jefferson National Accelerator Facility in Virginia. 

Space-based lasers and relay mirror systems were 

studied under SDIO funding, too, including the 

development of the Advanced Beam Control System for beam steering, beam control, rapid optical 

retargeting, and self-alignment.

Dahlgren engineers concentrated its internal 

laser efforts on medium-power soft-kill weapons. 

They performed tests against sensors and cameras, and investigated damage thresholds. In the 

late 1980s, Dahlgren engineers worked with optical augmentation to locate enemy optics for targeting and on green laser dazzlers for defense against 

small-boat attack. There were efforts to harden 

electro-optical equipment, including sights and 

night-vision systems for the Marines, and laser 

eye-protection filters for goggles and binoculars. 

Laser systems were also investigated for remotely 

cutting holes and wires to disable electronics. Lethality work continued under funding from the 

Joint Technology Office for High-Energy Lasers to 

look at alternative wavelengths and pulse shapes in 

addition to modern target materials.20

Dahlgren scientists continued to investigate laser-damage thresholds for materials, components, and subsystems for a variety of laser 

technologies. Near the start of the 21st century, 

Figure 10. Early Electromagnetic Launcher at Dahlgren
22

Directed Energy

Past, Present, and Future

commercial lasers based on pumping optical fibers with semiconductor lasers became common 

and more powerful. Dahlgren purchased the Navy’s largest collection of fiber lasers in 2004 and 

began investigating ways to combine multiple 

beams into a laser weapon. These lasers have very 

high efficiencies, above 20 percent, and the fiberoptic output reduces the requirement for complex 

optical paths. In 2008, Dahlgren engineers demonstrated a laser capability to ignite spinning mortar rounds, and in 2009, engineers demonstrated 

the capability of fiber lasers in a shoot down of soft 

targets at China Lake, California.

Resurgence of Directed Energy 

With the fall of the Soviet Union and a greatly 

altered threat, DoD funding (particularly technology funding) experienced an overall decline in the 

late 1980s and early 1990s. This caused Navy managers to emphasize near-term, lower risk, evolutionary concepts. The Pulsed Power Technology 

Program and the Navy’s Charged Particle Beam 

Program both came to an end. Investigations into 

HPM weapons declined as the difficulty of burnout of military electronics—particularly analog 

components—became apparent. Problems with 

propagation and cost caused the Navy to greatly 

reduce efforts on chemical lasers. With the cancellation of major programs, Dahlgren used internal 

funding in 1990 to keep a core technical capability together, which was necessary for the Center to 

remain in the mainstream of tactical DE and its 

associated technologies. Efforts continued in water breakdown, testing of contractor-developed 

pulsed-power components, and electric guns. 

New talent and technologies from universities 

were brought in to jump-start new projects. Tunable waveform generators using unique semiconductor materials were developed. These used bulk 

semiconductor material, fabricated in-house, that 

could be used as a fast switch controlled by laser 

light for both on and off operation. This allowed 

faster repetition rates and better triggering than 

could be done with small spark gaps, as well as 

the ability to create specific waveforms.21 “Green” 

technologies were also investigated using nonthermal plasmas and spark-gap shock waves for 

cleaning and pollution reduction.22 New types of 

particle detectors and magnetic field sensors were 

developed, and new methods of infrastructure 

protection were investigated.23 Soft-kill weapons, 

both optical and HPM, continued to be studied. 

Short-pulse jamming of spread-spectrum systems 

was investigated, as well as beat-wave coupling 

and special waveforms.24

A number of trends led to a resurgence of 

DEWs by the end of the 20th century. The DoD 

trend in using digital electronics and off-the-shelf 

commercial technologies increased dramatically. 

The pace of change in electronics and computers 

changed rapidly, too. Most of these new electronic 

systems had never been tested for vulnerability, and 

there was a question of how much they would increase military vulnerability to RF or HPM attack. 

The reduced emphasis on nuclear EMP shielding 

meant more military electronics were not as well 

protected from RF attack. Consequently, interest 

in protecting U.S. military and civilian infrastructure increased, including systems in foreign countries. Moreover, with the increasing reliance on 

civilian infrastructure, such as power, communications, and emergency and industrial systems—all 

of which were controlled by digital electronics—

the potential that an adversary could attack infrastructure systems to affect or divert military 

operations became an increasing concern. Following several major terrorist attacks during this time 

period, there was also concern about the impact of 

an RF attack on airport towers, financial systems, 

alarm systems, and industrial plants. Human factors—such as a state of confusion experienced by 

humans—also played an important part in determining the overall effects of an RF attack.

The asymmetric threat—where large numbers 

of cheap weapons in a swarm attack could overrun 

a few sophisticated weapons—caused more concern. As the asymmetric threat to the surface Navy 

pushed the limits of conventional defensive systems, DE—with it speed-of-light propagation, softkill potential, and cheap rounds—offered tactical 

advantages, either as an adjunct to conventional systems or as stand-alone systems. Additionally, 

there was an increased emphasis on nonlethal, precise accuracy and graduated effects that could be 

used. Moreover, the idea that future battles would 

be fought together with civilians and friendly forces on the battlefield increased the importance of 

low collateral damage and antimateriel attacks.

The Joint Program Office for Special Technology Countermeasures (JPO/STC), located at Dahlgren, began efforts concerning the vulnerability of 

new digital systems to RF attack. The program also 

established a DoD-wide database of vulnerability 

data, source designs, and RF-effects information—

bringing together much of the information collected by the services over the years. The program 

looked at the protection of modern digital infrastructure systems and funded a facility constructed 

in 1992 to test large-scale electromagnetic vulnerabilities to various methods of attack.
23

Historical Overview of 

Directed-Energy Work at Dahlgren

In the late 1990s and early 2000s, Dahlgren 

initiated programs regarding the potential for RF 

attack using nonkinetic disruption, with minimal collateral damage. Capital investment funds 

were used to construct a test facility for this effort in 1998. Dahlgren developed RF payloads 

for remotely piloted vehicles and demonstrated their effectiveness in field tests in 1999, and in 

similar tests in 2007. The successful completion 

of Project Guillotine was DoD’s first demonstration of this type of HPM technology. As the need 

for statistical vulnerability to commercial digital 

systems became apparent, Dahlgren constructed instrumented test facilities in 1999 and 2002. 

Two multistory buildings could be reconfigured 

to reflect different types of building construction 

and electromagnetic shielding. Large complexes of electronics, computer networks, server systems, telephone systems, security systems, and 

various types of digital industrial controls could 

be assembled, instrumented and exposed to attack from an external device or technique. This 

program-funded complex—called the Maginot 

Open Air Test Site (MOATS) facility—continues 

to be used to test target systems, as well as a variety 

of RF weapon technologies developed internally and by external and international organizations. A picture of the MOATS facility is shown in 

Figure 11.

As the need for additional DE laboratory space 

and testing capabilities became apparent, Dahlgren applied for military construction funds, and 

in 2008, constructed the Naval Directed Energy 

Center (NDEC), with access to Dahlgren’s overwater test range. Other construction funds were 

used to construct a remote facility at the Pumpkin 

Neck Explosive Test Range to serve as a laser backstop and measurement facility, as well as an explosive-test staging area. These facilities already have 

been used to develop and test fiber lasers against 

modern threat targets. Construction is currently 

underway to build an expansion of the NDEC and 

a 120-m laser test laboratory building using an existing tunnel structure. This collection of facilities 

represents very important capabilities to develop 

and test future DE systems.

Conclusion 

For over 40 years, the Naval Surface Warfare 

Center, Dahlgren Division (NSWCDD) has been 

a leader in developing DE devices, pulsed-power systems, and electric weapons. Its people have 

contributed many publications and patents, and 

set world records. DEWs tend to be complex and 

technically challenging to build. Regardless, these 

weapons offer important, powerful advantages, 

such as:

•	 Deep Magazines

•	 Cheap Rounds

•	 Fast Targeting

•	 Variable Lethality

•	 Pinpoint Targeting

As a result of NSWCDD’s leadership, persistent 

scientific initiatives, and leading-edge engineering 

Figure 11. MOATS Facility Undergoing Testing with an RF Weapon (on right)
24

Directed Energy

Past, Present, and Future

over the years, naval warfighters will increasingly find themselves turning to DEWs when dealing 

with situations spanning the spectrum of conflict.

References

1. Moran, S.L., “High Repetition Rate L-C Oscillator,” IEEE Transactions on Electron Devices, Vol. ED-26 No. 10, October 1979. 

2. Fitch, R.A. and Howell, V.T.S., “Novel Principle of Transient HighVoltage Generation,” Proceedings IEEE, Vol. III, April 1964. 

3. Ramrus, A. and Rose F., “High-Voltage Spiral Generators,” 1st International Pulsed Power Conference, Lubbock Texas, pIIIC9, November 1976.

4. Landecker, K.; Skatterbol, L.V. and Gowdie, D.R., “Single Spark Ring 

Transmitter,” Proc. IEEE, Vol. 59, No. 7, July 1971, pp. 1082–1090.

5. Erickson, D.J.; Fowler, C.M. and Caird, R., EM Radiation from an 

Explosive Generator System Coupled to a Large Antenna, Los Alamos Scientific Laboratory Report M-6-258, March 1978.

6. Fowler C.M. and Brooks, M.L., Explosive Flux Compression Devices Project, ARPA Order No. 2161, Semiannual Technical Report, 

1 March 1972–31 August 1972.

7. Zahn, M.; Ohki, Y.; Fenneman, D.; Gripshover, R. and Gehman, V., “Dielectric Properties of Water and Water/Glycol Mixtures 

for Use in Pulsed Power System Design,” Proceedings of the IEEE, 

September 1986, pp. 1182–1221.

8. Gehman, Jr., V.H.; Gripshover, R.J.; Berger, T.L.; Bowen, S.P. and Zia, 

R.K.P., “Effects of Filtration on the Impulse Breakdown Strength of 

High-Purity Water,” IEEE 1995 Tenth International Pulsed Power 

Conference, Albuquerque, New Mexico, 10–13 July 1995. 

9. Moran, S.L., Pulsed-Power Technology Program: Accomplishments 

in Switching, NAVSWC Tech Note TN-89-259, 1990.

10. Berger, T.L.; Gehman, Jr., V.H.; Lindberg, D.D. and Gripshover, 

R.J., “A 2.5 Gigawatt Liquid Dielectric Coaxial Pulse Forming 

Line,” Proceedings of the 6th IEEE International Pulsed Power Conference, Arlington, Virginia, 29–30 June and 1 July 1987.

11. Bernardes, J.S., “A High Power Fast Response Switch Testing System,” 7th IEEE Pulsed Power Conference, June 1989. 

12. Moran, S.L. and Hutcherson, R.K., High-PRF High-Current Switch, 

U.S. Patent No. 4,912,396, 27 March 1990.

13. Moran, S.L. and Hardesty, L.H., “High-Repetition-Rate Hydrogen 

Spark Gap,” IEEE Transactions on Electron Devices, Vol. 38, No.4, 

April 1991. 

14. Rose, M.F. and Huddleston, C.M., Pulsed Power and Directed Energy Technology, 10th Anniversary Technical Symposium, NSWC 

MP 84-560, October 1984.

15. Moran, S.L., “Hydrogen Spark Gap for High-Repetition-Rate 

Compact Accelerators,” NSWCDD Technical Digest, NSWCDD/

MP-92/104, September 1992, pp. 126–139.

16. Bernardes, J.S. and Merryman, S.,“Parameter Analysis of a 

Single Stage Induction Mass Driver,” Proceedings of the Fifth 

IEEE Pulsed Power Conference, Arlington, Virginia, June 1985, 

pp. 552–555.

17. Bernardes, J.S., “Muzzle Velocity Control with Electrothermal 

Guns,” Proceedings First Navy Independent Research/Independent 

Exploratory Development Symposium, Laurel, Maryland, June 

1988, Vol. 2, pp. 123–131.

18. Bernardes, J. S., “Focusing Induction Accelerator,” Proceedings of 

the Sixth IEEE Pulsed Power Conference, Arlington, Virginia, June 

1987, pp. 735–738. 

19. Bernardes, J.S., Sliding Breech-Block for Repetitive Electronic Ignition, Patent Number: 5,233,902, 10 August 1993. 

20. Kim, H.S. et al., “Effects of Chopping Laser Penetration of Metal 

Targets,” Applied Physics Letters, 55 (8), 21 August 1989. 

21. Stoudt, D.C. and Schoenbach, K.H., “The Electrical Characteristics of Semi-Insulating GaAs for High-Power Switches,” 7th IEEE 

Pulsed Power Conference Proceedings, June 1989. 

22. Grothaus, M.G. et. al., “Gaseous Effluent Treatment using a Pulsed 

Corona Discharge,” Proceedings of 10th IEEE Pulsed Power Conference, Albuquerque, New Mexico, July 1995.

23. Gripshover, R.J. et. al., Power Frequency Magnetic Field Detection 

Systems, Patent No. 6,483,309, 19 November 2002. 

24. Spread Spectrum Countermeasures Final Report, E-Systems, Inc., 

Melpar Division under NSWC contract # N68786-82-C-0109.
25

Historical Overview of 

Directed-Energy Work at Dahlgren

NAVSEA Warfare Centers
26

Directed Energy

Past, Present, and Future

History of Laser Weapon Research

By Melissa Olson

The idea of using light as a weapon can be traced back to Hippocrates, commander of the Greek forces in 212 B.C. His forces supposedly set fire to the sails of the Roman 

fleet by focusing sunlight with mirrors. Weapons systems based on lasers and “ray guns,” 

long a staple of science fiction, have captured the imagination of people everywhere. But 

with steady progress toward the development of lasers in the last 40 years, viable, stateof-the-art laser weapon systems have now become a reality.

The production of lasers in the modern scientific world is fairly new. The first laser 

was developed in the 1960s and represented the beginning of a drastic change in how 

the military viewed warfare. The late 1970s and 1980s, too, marked a busy time period for developing lasers into possible weapon systems. All branches of the military and 

industry were striving to master high power levels, beam control, and adaptive optics. 

In 1999, the Department of Defense (DoD) formally recognized lasers as future weapons and began research and development (R&D). In 2000, the Joint Technology Office 

for High Energy Lasers was formed to bring all laser technologies together to develop a 

complete laser weapon system that could be used by the warfighter.

Electromagnetic Spectrum

The electromagnetic spectrum contains all the types of electromagnetic energy, including radio waves, microwaves, infrared, visible light, ultraviolet, and gamma rays. 

Laser is an acronym for “light amplification by stimulated emission of radiation.” Light, 

therefore, is a type of electromagnetic radiation. Light is made up of tiny packets of energy called photons. The amount of energy is what determines the wavelength. Lasers 

are usually infrared (1 mm to 750 nm) and visible light (750- to 400-nm wavelength). 

Microwaves are mostly high-frequency radio waves (millimeters to centimeters), with 

wavelengths 10,000 times longer than lasers. Diffraction of any electromagnetic radiation beam is based on the wavelength and aperture size. For the same aperture size, lasers diffract 10,000 times less than microwaves. This allows the beam to reach farther 

ranges while maintaining a small spot size of concentrated energy on the target. Lasers 

are preferred in specific scenarios because of minimal diffraction. The electromagnetic 

spectrum is shown in Figure 1.

Laser Fundamentals

The quantum mechanical idea of stimulated emission of light was discovered by 

Albert Einstein in 1917 and is one of the fundamental ideas behind the laser. Einstein 
27

History of Laser Weapon Research

theorized that when a photon interacts with an 

atom or molecule in an excited state, two photons 

are produced when the atom or molecule leaves the 

excited state. Population inversion occurs when the 

atoms or molecules are in the excited state. In order 

for molecules to come out of the normal “ground” 

state, a source of power must be introduced to the 

system energizing the atoms to the excited state. 

When many photons are passed through many excited atoms, more and more photons are produced. 

The photons are contained and reflected back and 

forth in a cavity, with mirrors usually on each end. 

The mirror on the output end is only partially reflective, allowing some photons to leak through, 

creating the laser beam.

The difference between an everyday light bulb 

and the light of a laser is temporal and spatial coherence. In a light bulb, the light emits photons 

equally in all directions. The light is random, out of 

phase, and multiwavelength. A laser emits coherent light, so photons travel in identical direction 

and phase. A laser is also monochromatic, i.e., light 

of one wavelength. Another significant difference 

is that laser light is highly collimated, which means 

the laser beam can travel long distances with minimum spreading.

The laser gain medium through which the photons travel to become amplified or magnified can 

vary. The source of power used to excite the medium, achieving population inversion, can be the result of a chemical reaction, an electric discharge, 

a flash lamp, another laser, or some other excitation mechanism. The type of the lasing medium 

determines the type of laser. The three categories 

in which lasers are usually classified are chemical, 

gas, and solid state. A laser can also be continuous 

wave (CW) or pulsed. Each type of laser produces a 

specific wavelength of radiation. It is important to 

note that different wavelengths of radiation interact with the atmosphere differently. A laser beam is 

either scattered or absorbed by air molecules, water 

vapor, or dust. Longer wavelengths scatter less and 

are absorbed more than shorter wavelengths; our 

sky is blue because the shorter blue wavelengths 

of light are scattered more than the longer wavelengths.1

 Gamma rays are so highly absorbed that 

they cannot propagate more than a few feet in the 

air. Thus, some laser wavelengths are scattered or 

absorbed more than others. This makes laser wavelengths with minimum absorption better for use 

as directed-energy weapons since they propagate 

through the atmosphere better than others. For example, the carbon-dioxide (CO2

) laser is strongly 

absorbed by water vapor, so any use near the ocean 

will be negatively affected. Near-infrared and infrared lasers have shorter wavelengths with negligible 

absorbance. The optimal laser choice, therefore, 

would be a wavelength-tunable laser that could 

vary depending on the atmospheric conditions, 

such as the free-electron laser (FEL).

Lasers have affected almost every type of modern technology. Most laser technologies use low 

Figure 1. Electromagnetic Spectrum
28

Directed Energy

Past, Present, and Future

powers and were mastered very quickly. They are 

used in many everyday appliances, such as scanning/inventory devices, surgery/medicine, hair removal, presentation pointers, law enforcement, 

ranging and sighting devices, welding applications, 

and much more. Using a laser as a weapon has 

many advantages. For example, a laser:

•	 Is unaffected by gravity

•	 Causes minimal collateral damage

•	 Travels at the speed of light

•	 Can precisely reach far distances

•	 Is capable of causing a specific, 

predetermined amount of damage to targets

The theory behind these capabilities makes the 

laser weapon a prime choice in multiple engagement scenarios. However, developing lasers with 

higher powers to use as a weapon has proven more 

difficult than first considered.

Military Laser History 

and Laser Types

Generally, a laser weapon is any laser used 

against the enemy with more than 50 kW to megawatts of power. This is much greater power than 

commercial lasers. Accordingly, they have greater 

support needs, including:

•	 Environmental and personnel safety

•	 Mirror coatings

•	 Chilling requirements

•	 Power requirements

•	 Laser fuel storage

•	 Alignment and tracking requirements

In 1960, the very first laser (a ruby laser) was 

built, producing minimal power. This event was 

followed by many other laser technology developments. The first chemical laser, hydrogen fluoride 

(HF), was built in 1965, producing 1 kW. It was 

then that DoD became interested in researching 

and developing a more powerful laser for weapon applications. Subsequently, in 1968, the Defense 

Advanced Research Projects Agency (DARPA) 

Baseline Demonstration Laser produced 100 kW, 

and the Navy-ARPA Chemical Laser (NACL) produced 250 kW in 1975. The very first laser is depicted in Figure 2.

Solid-State Lasers (SSLs)

An SSL uses a solid lasing medium, such as a 

rod made up of glass or crystal, or a gem, like the 

ruby laser. Along with the rod or host material is 

an active material, such as chromium, neodymium, erbium, holmium, or titanium. Chromium is 

the active material used in ruby lasers. Neodymium is the active material in the most widespread 

applications. A flash lamp, arc lamp, or another laser carries out the optical cavity pumping to 

achieve population inversion and stimulate the laser beam. The Neodymium Yttrium-aluminum 

garnet (Nd:YAG) laser is a popular SSL. It operates at a 1064.5-nm wavelength and can be pulsed 

wave or CW. A great advantage of these lasers is 

that the wavelength and pulse duration can be varied considerably.1

 The power level can reach up to 

megawatts when using Q-switching to achieve 

Figure 2. First Ruby Laser Developed in 1960 by Research Physicist Theodore H. Maiman

Power

Supply

Switch

Ruby Crystal

Components of the First Ruby Laser

100% Reflective Mirror Quartz Flash Tube

Polished Aluminum 

Reflecting Cylinder

95% Reflective Mirror Laser Beam
29

History of Laser Weapon Research

short pulse lengths. The various interactions with 

the laser and different crystalline materials can 

double the electromagnetic frequency, which will 

halve the wavelength, bringing the laser beam into 

the visible range, 532 nm (green). The wavelength 

can be further divided down three or four times, 

making this laser range from the near-infrared to 

the ultraviolet wavelength. These lasers are commonly used for rangefinders and target designators. Other advantages of these lasers are that they 

can be made very small, rugged, cheap, and battery-powered. Characteristics of SSLs are shown 

in Table 1.

Chemical Lasers

A chemical laser uses chemical reaction to create population inversion in the lasing medium. One 

example is the Mid-Infrared Advanced Chemical 

Laser (MIRACL) developed in the mid-1980s. The 

MIRACL is a continuous-wave, mid-infrared (3.8-

μ) laser. Its operation is similar to a rocket engine in 

which a fuel (ethylene, C2H4) is burned with an oxidizer (nitrogen trifluoride, NF3).2

 Free, excited fluorine atoms are among the combustion products. 

Just downstream from the combustor, deuterium 

and helium are injected into the exhaust. Deuterium (U) combines with the excited fluorine to create excited deuterium fluoride (DF) molecules, 

while the helium stabilizes the reaction and controls the temperature.2

 The laser’s resonator mirrors are wrapped around the excited exhaust gas, 

and optical energy is extracted. The cavity is actively cooled and can be run until the fuel supply is exhausted. The laser’s megawatt-class output power 

can be varied over a wide range by altering the fuel 

flow rates and mixture. The laser beam in the resonator is approximately 21-cm high and 3-cm wide. 

Beam-shaping optics are used to produce a 14- × 

14-cm (5.5- × 5.5-inch) square, which is then propagated through the rest of the beam train. Diagnostics for evaluating the beam shape, absolute power, 

and intensity profile are used on each firing of the 

laser. The beam can be directed to a number of different test areas or to the SEA LITE beam director.2

The DF Chemical Laser (MIRACL) and the Sea Lite 

Beam are shown in Figure 3.

The laser and beam director were integrated 

in the mid-1980s at the Army’s High Energy Laser Systems Test Facility (HELSTF) at White Sands 

Missile Range, New Mexico. Following integration, 

extensive tests were conducted in the areas of:

•	 High-power optical components and beampath conditioning

•	 Beam-control techniques

•	 High-power propagation

•	 Target damage and vulnerability

•	 Target lethality3

Tests supported by the MIRACL included:

•	 The high-power dynamic with flying drone 

(BQM-34)

•	 Conventional defense initiative with flying 

drone

•	 High-velocity target test with Vandal 

Missile

•	 High-altitude target tests with flying drone

•	 Missile and plume tests using the 1.5-m 

aperture

•	 Radiometrically calibrated images and 

spectral radiometry

These successful tests are what made many believe that MIRACL was the first and only successful laser weapon system developed by the Navy 

prior to the Navy Laser Weapon System (LaWS).3

Gas Lasers

Gas lasers are a type of chemical laser that uses a 

pure gas or gas mixture to produce a beam. The typical gas laser contains a tube with mirrors on each 

end. One end transmits the beam out of the cavity. Most gas lasers use electron-collision pumping, 

with electric current passing through the gas. Some 

use optical pumping with flash lamps. The helium 
30

Directed Energy

Past, Present, and Future

neon (HeNe) laser is a very well-known gas laser. It 

produces a bright red, continuous beam of low power. It is used for many applications such as scanning, 

alignment, measurement, and stabilization devices. 

University students use them in optical training laboratories. Many larger lasers contain a HeNe inside 

the beam path, as well to verify beam alignment. 

HeNe lasers are fairly cheap and very rugged. They 

can work continuously for thousands of hours.

CO2

 lasers are in the gas family. These lasers 

were the earliest, truly high-power lasers and have 

been among the most crucial lasers used in R&D 

for high-energy laser (HEL) weapons. In industry, 

the more powerful CO2

 lasers are used for welding, drilling, and cutting. There are many different 

types of CO2

 lasers that vary in pumping design. 

CO2

 lasers work by burning a hydrocarbon fuel 

(like kerosene or methane) in oxygen or nitrous 

oxide. The hot gas flows through a comb of nozzles, expands quickly, and achieves population 

inversion. The gas then flows through an optical 

resonator at supersonic speeds, resulting in stimulated emission and a laser beam.4

CO2 lasers have been researched for use as 

nonlethal weapons. The wavelength produced by a 

CO2

 laser is also absorbed by glass. For example, 

the beam does not penetrate a windshield. Thus, 

shooting a CO2

 laser at a vehicle’s windshield could 

deter a threat by damaging the windshield or by 

causing a dazzling effect to reduce the visibility of 

the driver, while not reaching the driver at all.

The gas dynamic laser (GDL) is a CO2

 laser based on differences in relaxation velocities 

of molecular vibrational states. The laser medium’s gas has properties such that an energetically 

lower vibrational state relaxes faster than a higher vibrational state; thus, a population inversion is 

achieved in a particular time. A GDL is shown in 

Figure 4. Characteristics of chemical and gas lasers 

are identified in Table 2.

Fiber Lasers

Modern fiber lasers are considered SSLs. They 

are powered by electricity, making them highly 

mobile and supportable on the battlefield. Fiber lasers use optical fibers as the gain media. In most 

cases, the gain medium is a fiber doped with rare 

earth elements—such as erbium (Er3+), neodymium (Nd3+), ytterbium (Yb3+), thulium (Tm3+), 

or praseodymium (Pr3+)—and one or several laser 

diodes are used for pumping. Optical fibers have 

been used in industry, specifically for telecommunications to transport information via light. With 

developing technology, optical fibers have become 

high-energy, powerful laser energy sources. Fiber 

lasers have proven to have much benefit over traditional SSLs. They are rugged and do not require 

a clean room to operate or maintain, as most other laser systems do. They also are extremely efficient; however, they cannot operate well in all 

weather conditions. One example is the IPG CW 

fiber lasers, which produce moderate beam quality, causing damage to materials and components 

through thermal heating and burn-through. The 

Naval Surface Warfare Center, Dahlgren Division 

(NSWCDD) purchased eight commercially available 5.5-kW IPG lasers, where two multimode 

(seven fibers) lasers are housed per cabinet. This 

type of laser is easy to mount due to the flexible fibers. The IPG CW Fiber Laser is shown in Figure 5.

Miscellaneous Lasers

There are other types of lasers that do not necessarily fit into the chemical or solid-state categories. These include semiconductor lasers, used in:

•	 Television	 •	 Radios

•	 CD Players	 •	 Telecommunications

•	 Dye Lasers	 •	 Medicine

•	 Spectroscopy	 •	 Astronomy

There also are the FELs mentioned previously. The FEL is a completely different breed of laser. 

Figure 3. DF Chemical Laser (MIRACL) and Sea Lite Beam

DF Chemical Laser (MIRACL) Sea Lite Beam
31

History of Laser Weapon Research

Figure 4. A laser engineer inspects a gas dynamic laser after installation 

aboard an NKC-135 airborne laser laboratory.

Figure 5. IPG CW Fiber Laser System
32

Directed Energy

Past, Present, and Future

bed and was used to provide the first demonstrated 

kill of an operational missile in 1978.

Alpha HF—Built for Strategic Defense Initiative 

(SDI) Space-Based Laser (SBL)

Alpha, an HF laser, was the baseline technology 

for the SBL readiness demonstration (SBLRD). In 

1991, the Alpha laser demonstrated megawatt-class 

power levels similar to MIRACL, but in a low-pressure, space operation environment. Alpha demonstrated that multimegawatt, space-compatible 

lasers can be built and operated. 

Tactical High-Energy Laser (THEL)

The THEL is a DF chemical laser developed 

by the Army. In 2000 and 2001, THEL shot down 

28 Katyusha artillery rockets and 5 artillery shells. 

On 4 November 2002, THEL shot down an incoming artillery shell and a mobile version successfully 

completed testing. Subsequently, during a test conducted on 24 August 2004, the system successfully 

shot down multiple mortar rounds. These tests represented actual mortar threat scenarios in which 

both single mortar rounds and salvo were tested 

and intercepted. A photograph of THEL is shown 

in Figure 6.

Advanced Tactical Laser (ATL)

The ATL uses a closed-cycle, chemical oxygen-iodine laser (COIL) with beam control, which 

lases at a 1.315-μ wavelength. The ATL was developed to engage tactical targets from a moving platform at ranges of approximately 10 km. It can spot 

a 10-cm-wide beam on a distant target for up to 

100 shots. This beam has enough power to slice 

through metal at a distance of 9 miles. The aircraft 

equipped with the ATL weapon system is shown in 

Figure 7.

A specially modified 46th Test Wing NC-130H 

aircraft equipped with the ATL weapon system 

fired its laser while flying over White Sands Missile Range, New Mexico, successfully hitting a target board located on the ground. Equipped with a 

chemical laser, a beam control system, sensors, and 

weapon-system consoles, the ATL is designed to 

damage, disable, or destroy targets with little or no 

collateral damage.

Airborne Laser (ABL) (CO2

) Chemical Oxygen

The ABL C-130H aircraft contains three laser 

beam systems: the powerful killing primary laser 

beam (ATL), a set of illuminating laser beams for 

infrared surveillance and high-speed target acquisition, and a beacon laser for a high-precision laser 

target tracking beam control system. The primary 

It uses electrons to create photons instead of some 

type of matter. The electrons are produced, collected, and directed to flow at very high speeds. To 

excite the electrons, they are passed through a “wiggler,” i.e., a series of magnets positioned in such a 

way that electromagnetic radiation (light) is produced when the electrons release photons. The significant feature of the FEL is that the wavelength 

can be controlled, depending on the magnet positions and the speed of electrons. This versatility makes the FEL particularly appealing. However, 

the footprint of the FEL system is too large to transform into any ideal defense weapon. The Jefferson 

Laboratory in Newport News, Virginia, has an FEL 

and continues to maintain and test its capabilities 

and effects. This laser was new to the military in the 

late 1990s and received funding to optimize its capabilities and integrate as a defense weapon. Although great progress has been made, the required 

footprint could be much larger than desired. Consequently, some interest in the FEL has shifted to 

other HEL sources.

Many scientists foresee the probability of using the laser as a global weapon. This possibility is 

proven through basic laws of physics. Actually implementing such a system, however, can be more 

difficult. The global weapon concept uses a base 

laser with optics and is strategically positioned in 

space to be able to direct its beam multiple places on Earth at the speed of light with maximum 

power levels. This idea faces significant problems, 

including appropriate power levels, optics to handle such levels, propagation issues, and the ethical 

measures behind any global weapon. Still, the idea 

presents interesting possibilities.

Laser Weapon Development

The following paragraphs highlight some of 

the laser weapons that have been successfully developed over the last 40 years.

Baseline Demonstrator Laser (BDL) Hydrogen 

Fluoride (HF)

In 1973, TRW Inc. produced the world’s first 

high-energy chemical laser, the Baseline Demonstration Laser, for DoD. After that, TRW Inc. produced and demonstrated six more HELs, including 

the MIRACL (1985) and Alpha (2000), the nation’s 

only megawatt-class chemical lasers.

Navy-ARPA Chemical Laser (NACL) HF

The NACL was mated with the Navy Pointer 

Tracker at TRW Inc.’s San Juan Capistrano, California, facilities in the 1975–1978 time frame. This 

was the Navy’s initial, integrated HEL system test 
33

History of Laser Weapon Research

Figure 6. Tactical High-Energy Laser (THEL)

laser beam is generated by a megawatt COIL located at the rear of the fuselage. The high-power laser beam travels towards the front of the aircraft 

through a pipe. The pipe passes through a Station 

1000 bulkhead/airlock, which separates the rear 

fuselage from the forward cabins. The high-power beam passes through the fine beam control system mounted on a vibration-isolated optical bench. 

Beam pointing is achieved with very fast, lightweight steering mirrors, which are tilted to follow 

the target missile. The ABL finally destroyed a target while in flight at White Sands Missile Range in 

August 2009. The 12,000-lb ABL locked onto an unspecified ground target and fired the laser, making 

the target disappear. Although it was successful at 

this demonstration, using the ABL in the fleet has 

fallen out of favor due to affordability and technology problems. The ABL is shown on an aircraft in 

Figure 8. 

Joint High-Power Solid-State Laser (JHPSSL)

In hopes of accelerating SSL technology for 

military uses, work is being performed by the 

U.S. Army Space and Missile Defense Command 

(SMDC) and the Army Test and Engineering Center at White Sands Missile Range. The technology 

uses an electric laser diode to shoot light into 32 

garnet crystal modules that combine to create “laser 

amplifier chains” producing 15 kW. By using seven chains and by combining multiple beams, they 

have reached 105  kW in the laboratory operating 

in a clean room. The program’s ultimate goal is for 

a laser system to reach high powers outside a laboratory environment. Fielding such a delicate optical structure can present significant barriers for this 

laser system. Nonetheless, it will be a great accomplishment for a variety of force protection missions, 

such as shipboard defense against cruise missiles. 

The JHPSSL system is shown in Figure 9.

Navy Laser Weapon System (LaWS)

The Navy LaWS is the most recent, successful laser weapon. It uses an electric-fiber laser design, avoiding the problems that chemical lasers 

present. In the summer of 2009, the Naval Sea 

Systems Command (NAVSEA)—with support 

from NSWCDD—successfully tracked, engaged, 

and destroyed unmanned aerial vehicles (UAV) 

Figure 7. 46th Test Wing NC-130H Aircraft Equipped with the 

ATL Weapon System 
34

Directed Energy

Past, Present, and Future

Figure 8. Airborne Laser (ABL)

Figure 9. Joint High-Power Solid-State Laser (JHPSSL) System
35

History of Laser Weapon Research

in flight at the Naval Air Warfare Center, China 

Lake, California. A total of five targets were engaged and destroyed during the testing, which 

represented a first for the U.S. Navy. The laser was 

fired through a beam director on a Kineto Tracking Mount similar to the Sea Lite beam director. 

The system used fiber lasers in the configuration 

and has proven to be a rugged and dependable 

choice for the warfighter’s needs. A photograph of 

LaWS is shown in Figure 10.

Laser weapon systems development in recent 

years has taken giant steps forward. Dedicated 

R&D has advanced the state of the art considerably. What was unimaginable only a few short 

years ago, today has become reality. Accordingly, given continued R&D, warfighters in the near 

term will have additional weapon options to 

choose from for dealing with a spectrum of threats 

and contingencies.

References

1. Beason, Doug Ph.D., The E-Bomb: How America’s New Directed 

Energy Weapons Will Change The Way Future Wars Will Be Fought, 

Da Capo Press, 2005.

2. Pike John, Mid-Infrared Advanced Chemical Laser (MIRACL), FAS 

Space Policy Project, Military Space Programs, March 1998, http://

www.fas.org/spp/military/program/asat/miracl.htm

3. Albertine, John R., “History of Navy HEL Technology Development and Systems Testing,” (Proceedings Paper), Proc. SPIE,

Vol.  4632, Laser and Beam Control Technologies, Santanu Basu 

and James F. Riker, Eds., pp. 32–37. 

4. Anderberg, Major General Bengt and Dr. Myron L. Wolbarsht, Laser Weapons: The Dawn of a New Military Age, Plenum Press, New 

York, 1992.

Figure 10. Navy Laser Weapon System (LaWS)
36

Directed Energy

Past, Present, and Future

Laser Weapon System (LaWS) Adjunct to the 

Close-In Weapon System (CIWS)

By Robin Staton and Robert Pawlak
37

Laser Weapon System (LaWS) Adjunct to the 

Close-In Weapon System (CIWS)

The Naval Sea Systems Command (NAVSEA) 

established the Navy Directed Energy Weapons 

Program Office in January 2002 and subsequently 

chartered the Directed Energy and Electric Weapon Systems Program Office (PMS 405) in July 

2004.1, 2 Its mission is to change the way the Navy 

fights in the 21st century by transitioning directedenergy and electric weapon technology, providing 

the warfighter with additional tools to fight today’s 

and tomorrow’s wars. In support of this mission, 

the Laser Weapon System (LaWS) was developed, 

which potentially adds a suite of tools for offensive 

and defensive operations.

The LaWS program is managed by PMS 405 in 

cooperation with the Program Executive Office Integrated Warfare Systems (PEO  IWS), the Navy’s 

Close-In Weapon System (CIWS) manager. A multilaboratory/multicontractor organization led by 

the Naval Surface Warfare Center, Dahlgren Division (NSWCDD), has been executing the program 

since March 2007. The potential advantages of a lethal, precise, speed-of-light weapon are numerous 

and have been recognized for many years. However, even in light of these advantages, there are realities that need to be considered for any program to 

succeed to the point that an actual system is placed 

in the hands of the warfighters.

The LaWS system offers viable solutions for an 

important subset of threats while fitting into acceptable size and weight constraints. In addition, 

since LaWS is a fully electric laser, the operation 

of the system does not require the handling and 

storage of hazardous chemicals, such as hydrogen 

fluoride. As will be discussed later, due to the incorporation of high levels of commercial off-theshelf (COTS) technology, the LaWS system also 

has advantages for topside design, logistic supportability, and cost. Thus, LaWS could enable the 

Navy to address adverse cost-exchange situations, 

which can occur when engaging proliferated inexpensive threats such as unmanned aerial vehicles (UAVs).

Background

Based on mission analysis work conducted prior to the LaWS program and additional work done 

as part of the program, it became clear that a number of factors require careful consideration. First, a 

high-power laser is not likely to replace anything 

on a ship in the next 5 years. For a new system to 

be added to a ship, a high-power laser must supplement current capabilities or provide new capabilities that clearly justify its addition. Second, because 

a laser provides such a diverse set of capabilities, 

conventional air-to-air warfare (AAW) models—

such as the Fleet AAW Model for Comparison of 

Tactical Systems (FACTS), Antiair Warfare Simulation (AAWSIM), and Extended Air Defense Simulation (EADSIM), as well as other existing AAW 

analysis approaches—are not well suited for showcasing current or near-term laser-weapon capabilities. While they can (and have) been used for 

laser-weapon analysis, their application to a megawatt-class laser that could “instantly” destroy boats 

or cruise missiles (akin to missile engagements) is 

a more straightforward application of the existing 

models and techniques.

In November 1995, the Chief of Naval Operations requested that the National Research Council initiate, through its Naval Studies Board, a 

thorough examination of the impact of advancing 

technology on the form and capability of the naval 

forces to the year 2035. A major observation of the 

report is quoted below:

Numerous laboratory and field-test versions of laser weapons have been developed 

and demonstrated. They have worked as 

expected and demonstrated suitable lethality 

against their intended targets. The primary 

factors that have inhibited the transition of 

the technology into deployed systems are size 

and weight. Generally, the conceptual designs 

of laser weapons that are scaled for combat 

effectiveness are too large to be appealing to 

users; conversely, weapons that are sized for 

platform convenience generally lack convincing lethality.3

Subsequently, an August 2006 U.S. Air Force 

(USAF) Scientific Advisory Board Study examined 

the increasing threat posed by UAVs in some detail. Key conclusions included:

No single system can completely address 

the UAV threat. A single sensor solution 

is inadequate because of the size and speed 

challenges presented by small UAVs. A single-weapon-layer solution fails to provide for 

adaptability to multiple scenarios or adequate 

probability of kill.

Key recommendations of the USAF Advisory 

Scientific Board Study included:

Develop and field longer-term upgrades 

to counter increased UAV threats. They 

include:...a small, multimission air/air and 

air/ground weapon; and directed-energy air 

defense weaponry.4
38

Directed Energy

Past, Present, and Future

In addition to the USAF Scientific Advisory Board study, a 2007 OPNAV Deep Blue Study 

noted the potential advantage of nonkinetic defeat 

options and recommended that the Navy accelerate development of nonkinetic systems to include 

high-energy lasers (HELs).5

The laser power levels likely to be available in 

the near term, within reasonable size and cost, are 

in the neighborhood of 100 kW of radiated power. While this power level is not adequate to engage certain threats, such as cruise missiles or 

tactical ballistic missiles at tactically useful ranges, 

there is still a wide spectrum of threats that could 

be engaged at ranges that are comparable to many 

current ship-defense weapons, including minorcaliber guns and small missiles. The spectrum of 

threats includes:

•	 UAVs

•	 Missile Seekers

•	 Intelligence, Surveillance, and 

Reconnaissance Systems

•	 Rockets

•	 Man-Portable Air-Defense Systems 

(MANPADS)

•	 Mortar Rounds

•	 Floating Mines

•	 Artillery Rounds

LaWS on CIWS

The Mk 15 Phalanx CIWS can often detect, track, and (sometimes) identify potential threats at ranges well outside the effective 

range of the 20mm gun. These functions are 

accomplished using the search/track radar system and the Phalanx Thermal Imager (PTI). 

When added to the Phalanx mount and pointed in the same direction as the gun (see Figure 1), a laser weapon could potentially add 

a number of useful functions and capabilities 

to the mount, but technical challenges must 

be overcome. Preliminary analyses of the mechanical characteristics of the mount suggest 

that the additional weight that could be added to the mount must be kept under approximately 1200–1500 lb. Additionally, it is highly 

desirable that the addition of the laser weapon not substantially affect the train/elevation 

operation of the mount in angle, peak velocity, or acceleration. Consequently, use of rapidly evolving fiber laser technology appears to be 

the only currently foreseeable path to adding 

significant laser energy directly to the mount 

within these constraints. 

One major driver in the genesis of the 

LaWS system was the availability of relatively 

low-cost COTS fiber-optic lasers. Because these fibers are flexible, they obviate the need for an expensive coudé path system (an optical mirror/lens 

assembly that turns radiation 90° and may also support rotation of the beam director), thus allowing 

the use of low-cost mount technology, as well as the 

retrofitting of the system on existing mounts. The 

last factor is extremely important because of the 

scarcity of topside real estate on today’s ships. These 

fiber-optic lasers do have limitations in terms of 

power, although power levels are growing with advancing technology. The reality today is that, in order to get adequate lethality from a system based on 

this technology, the use of a beam-combining apparatus utilizing several individual fibers is necessary. (Figure 2 depicts combining multiple fibers in 

the same beam director.) Furthermore, a smaller 

beam size is desirable since this drives power density up—increasing the performance required for the 

tracking and pointing elements of the system. Thus, 

a high-resolution fine track sensor is needed, as well 

as an appropriately robust line-of-sight control.

A Potential Suite of LawsRelated Capabilities

Potential added capabilities that an adjunct 

LaWS could contribute to the total ship combat 

system are briefly outlined in the following subsections.

Figure 1. LaWS Mounted on CIWS
39

Laser Weapon System (LaWS) Adjunct to the 

Close-In Weapon System (CIWS)

Target Identification, Tracking, and Intent 

Determination at Range

The optics that would be added for the laser 

to detect and track targets in support of a laser engagement would immediately contribute additional capabilities to the entire ship combat system even 

without operating the laser. A laser-gated illuminator, part of the tracking system, significantly increases the signal to the background level of tracked 

targets and provides good range resolution as well. 

The additional sensitivity and angle resolution provided by the LaWS optics would allow the identification, precision tracking, and “monitoring” (at 

high resolution) of potential threats or vehicles of 

interest at substantially greater ranges than could 

be achieved by the PTI alone. The Phalanx radar, 

or another source, would have to provide an initial, 

accurate cue to facilitate initial acquisition. Once acquired, the target could be examined and monitored 

with high resolution at range. This capability could 

make a substantial contribution to identification efforts—efforts to determine intent and potentially 

even to documenting target behavior to resolve issues with rules-of-engagement doctrine. It is widely recognized that rules-of-engagement issues, such 

as threat identification and intent determination, 

are among the most difficult problems faced by ship 

commanding officers.

Unambiguous Warning at Range

If a fraction of the laser energy is routed through 

a frequency-doubling crystal, an intense, visible 

beam can be projected to significant ranges to provide a clear, unambiguous warning that a potential 

target is about to be engaged unless an immediate 

change in behavior is observed. This feature also 

would have utility for dazzling aircraft, surface vehicle, or submarine sensors, and would provide exceptional long-range, unambiguous warning to 

boats or aircraft at night.

Figure 2. Cutaway View of the LaWS Beam Director
40

Directed Energy

Past, Present, and Future

Sensor Destruction at Range

Many electro-optical (EO) sensors are quite 

susceptible to damage by laser energy in the fiberlaser band as is the case with infrared (IR) missile 

seekers with germanium optics. The frequencydoubling feature described in the previous paragraph also would be useful to ensure that a band-pass 

filter at a single frequency could not be applied as 

an effective countermeasure. The intent here would 

be to destroy the seeker or imager at ranges well beyond those achievable by the Phalanx 20mm gun. 

Other examples include intelligence, surveillance, 

reconnaissance, and targeting sensors on UAVs or 

unmanned surface vehicles (USVs).

IR Missile Assist at Range

Many targets of interest—including UAVs, 

USVs, and small boats—are somewhat “marginal” 

from a target-signature standpoint, particularly at 

the maximum range of existing IR guided missiles 

such as the FIM-92 Stinger, the FGM-148 Javelin, 

the RIM-116 RAM, and the AIM-9X Sidewinder. 

The CIWS laser adjunct could potentially “correct” 

this situation by laser heating target vehicles to enhance their signature to existing IR guided missiles. 

Note that this is NOT “conventional” semiactive-laser (SAL) guidance—the LaWS is not a coded illuminator, nor do the seekers in question rely on 

this coding. The IR missiles would be unmodified 

weapons taken from inventory. The LaWS adjunct 

would simply contribute laser energy that heats 

the target and enhances its signature for the missile. While, at the ranges envisioned, this laser heating alone would not be sufficient to “kill” the target, 

it could definitely heat the target. It should also be 

noted that the laser “illumination” could potentially be used to preferentially select a specific target 

from among a group of targets for engagement by a 

missile. It is expected that these engagements could 

occur at ranges of two to four times the effective 

Phalanx gun engagement ranges. Use of LaWS in 

this manner would be exactly analogous to the use 

of a SAL designator for a SAL guided missile, such 

as the AGM-114 Hellfire. It is expected that similar 

rules of engagement would apply.

Direct Target Destruction by Laser Heating

Some threats are known to be vulnerable to direct destruction by the application of laser energy for an appropriate period of time. The currently 

envisioned system would be able to destroy a subset of naval threats at ranges comparable to, and 

in some cases greater than, the ranges achieved 

with modern, stabilized guns using EO fire control systems and modern ammunition. In the case 

of a LaWS adjunct, the addition of the laser would 

open new options for a firing/engagement doctrine 

and would be expected to conserve CIWS rounds 

for use on threats that are not appropriate for this 

laser power level. While the laser is often quoted as 

having an “unlimited magazine,” the true number 

of threats that can be engaged by the laser in any 

period of time is limited by the required illumination time and by the time required to evaluate a 

kill and transition to the next target. Thus, for particular target velocities and numbers, the “effective 

laser magazine” might be added to the CIWS magazine to increase the total number of targets engaged by the combined system.

LaWS Accomplishments

A government/industry team, led by government technical personnel, have achieved significant accomplishments since the start of the LaWS 

program in 2007; specifically, the team:

•	 Conducted mission analyses

•	 Developed threat lethality estimates

•	 Performed industry surveys for critical components and subsystems

•	 Performed extensive trade-off analyses

•	 Designed a prototype system

•	 Constructed the system—the prototype director and mount (see Figure 3)

•	 Performed numerous laboratory-based tests 

of subsystems and the complete prototype

•	 Validated system operation with a full-up 

field test at high power using BQM-147A 

UAV target drones

Additionally, the team was able to minimize the 

cost of the prototype by leveraging hardware that 

had already been developed or procured for other applications, including an L3-Brashear tracking 

mount, a 50-cm telescope, and high-performance 

IR sensors. Some components were commercially 

procured, such as the 5.4-kW fiber lasers. Figure 4 

shows three laser cabinets, containing two lasers 

apiece, resulting in a total power output of 32.4 kW. 

Other components, such as the beam combiner 

and much of the system software required for operation and target tracking, had to be specifically 

designed, fabricated, and tested.

The LaWS program achieved a highly successful field test/demonstration in June 2009 when the 

prototype successfully engaged and destroyed five 

drone targets at tactically significant ranges at the 

China Lake, California, test range (see Figure 5).

Additional Work to be Done

Since the LaWS prototype sits on a dedicated 

gimbal, much additional work needs to be done 
41

Laser Weapon System (LaWS) Adjunct to the 

Close-In Weapon System (CIWS)

Figure 3. Photo of LaWS During Testing at the Naval Weapons Center, China Lake

Figure 4. IPG Laser Cabinets
42

Directed Energy

Past, Present, and Future

Figure 5. BQM-147A During LaWS Engagement

to place the weapon on the CIWS mount. The 

latter would require new control systems and 

optomechanical hardware for line-of-sight stabilization. Other aspects of the shipboard environment are also more stressful, and future mission 

areas may require an increasingly robust capability to deal with optical turbulence and the 

high-clutter environment of the ocean surface. 

Additional laser power might also be required. 

These modifications, depending on the level 

of capability desired, will require engineering 

modifications to the system. Engineering analysis and design to address these issues is currently underway at NSWCDD.

While the aforementioned engineering issues 

are important to address, there are additional technical issues that have yet to be analyzed. These issues are concerned with the potential utility of 

the system. Indeed, most of the detailed technical analyses and experiments performed thus far 

have focused on target destruction, with some effort expended on the issue of seeker damage/destruction. Developing credible lethality estimates 

for various potential threat targets is clearly very 

important, but one consequence of the lethality focus is that necessary, detailed, defendable technical 

analysis, analytic model development, and experiments have not been performed to explore the other functions/features that a CIWS Adjunct LaWS 

might provide to the overall ship combat system. 

Some of these contributions might become “routine” if the LaWS were available.

For example, a hard-kill engagement of a target by a Navy shipboard weapon is a relatively rare 

event, even during wartime conditions. On the other hand, ships in combat zones—and elsewhere—

constantly have the problem of detecting potential 

threats, tracking them, identifying them, determining their intent, and providing warning. Thus, 

use of the LaWS system, at less than its full lethal 

potential, could become a daily, standard practice. 

It is still not clear how these potential benefits and 

capabilities could be measured or quantified to the 

satisfaction of key decision makers.

Likewise, other potential advantages of laser 

weapons—such as the potential for precision engagement, covert engagement, fire starting, graduated lethality, low cost per shot, and “unlimited” 
43

Laser Weapon System (LaWS) Adjunct to the 

Close-In Weapon System (CIWS)

magazine—have not been subjected to rigorous 

technical analysis for feasibility, utility, and practicality. These investigations need to be performed 

and are gradually being addressed within the 

LaWS program.

Although the Phalanx CIWS system is currently installed on a number of Navy surface 

warships—either a single mount or a double 

mount—there are still significant numbers of 

ships that do not have a Phalanx system. It is highly desirable to make LaWS potentially available to 

virtually any ship that could benefit from the enhanced capabilities.

While the technical issues associated with the 

addition of LaWS to the Phalanx CIWS will be 

somewhat different from those associated with 

adding a LaWS system to other weapon systems—

or the provision of a “stand-alone” LaWS—they do 

not appear to be insurmountable. For example, a 

LaWS beam director might be added to the stabilized Mk 38 Mod 2 25mm gun or the Mk 46 Mod 2 

30mm gun. A LaWS beam director might be added to (or even substituted for) the Mk 46 EO Sight 

on DDGs or added to the trainable RAM launcher. 

Other options may exist as well.

The issue of defending combat logistics force 

ships, joint sealift ships, and certain support vessels 

from attacks from small boats or UAVs is also relevant. These ships often have little or no installed defensive capabilities for potential terrorist or pirate 

threats, and expeditionary security detachments do 

not have decisive warning or engagement capability. In addition, there are severe limitations placed 

on concept of operations (CONOPS) and rules of 

engagement due to the limited objectives/limited 

means of the various missions.

A system such as LaWS could provide graduated lethality from warning to destruction. It also 

could provide additional applications to minimize 

risk to sea base platforms and enhance sea shield 

capabilities against nonstate threats. If acceptable 

rules of engagement can be established, the advantages of graduated lethality might be extended to 

ships in port or entering/exiting harbors.

While considerable additional work needs to 

be done to produce a tactical system, the LaWS 

program’s recent demonstration of capability provides strong evidence that a useful, tactical system 

could be produced within reasonable cost, volume, 

weight, and power constraints to provide the warfighter with a suite of additional tools to fight today’s and tomorrow’s wars.

References

1. NAVSEA Notice 5400, Ser 09B/240, “Establishment of the Navy Directed Energy Weapons Program Office (PMS 405),” 4 January 2002.

2. NAVSEA Instruction 5400.101, Ser SEA 06/058, “Directed Energy and Electric Weapon Systems Program Office (PMS 405) Charter,” 21 July 2004.

3. Technology for the United States Navy and Marine Corps 2000–

2035: Becoming a 21st-Century Force, Naval Studies Board, National Research Council, National Academy Press, 1997, Volume 

5: Weapons, Chapter 6, “Navy and Marine Corps Applications for 

Laser Weapons.”

4. Report on the Air Defense Against Unmanned Vehicles, USAF Scientific Advisory Board, SAB-TR-06-01, August 2006.

5. “Counter Unmanned Aerial Systems (UAS),” OPNAV Deep Blue 

Report 08-01, August 2007.
44

Directed Energy

RDT&E, Acquisition, and 

Warfare Management

The Acquisition Challenge Associated 

With Directed-Energy RDT&E

By Mike Kotzian

An already tense situation quickly escalated. Everyone within the combat information center of the Navy’s newest all-electric ship suddenly realized that two surfaceskimming, antiship missiles were bearing down on their destroyer. With less than 30 seconds to impact, the tactical warfare officer gave the order to fire. Seconds later, the first 

surface-skimming missile vanished from all tracking consoles. Another order to fire 

closely followed, and the second missile threat was also destroyed. Consequently, within a matter of 10 seconds from threat recognition to threat elimination, the Navy’s newest all-electric ship was able to destroy two incoming threats by using one of the Navy’s 

newest weapon systems—the free-electron laser.

Does this scenario of a Navy all-electric ship, employing a high-energy laser to 

shoot down enemy surface-skimming antiship missiles, sound like inevitable reality or 

unattainable science fiction? For scientists and engineers working on directed-energy 

systems for the Navy, the answer does not lie solely in the advanced technical challenges associated with developing directed-energy weapons. Rather, the answer also lies in 

how well scientists and engineers understand and adhere to the Department of Defense’s 

(DoD’s) Defense Acquisition Management System (DAMS) framework governing the 

development of new weapon systems.

Evolution of Defense Acquisition

The way in which DoD identifies needs and subsequently develops, tests, procures, 

and sustains weapon systems has evolved over time. Today’s acquisition foundation can 

be traced back to the Packard Commission report in 1986, where many of this report’s 

recommendations became part of the Goldwater-Nichols DoD Reorganization Act of 

1986. This evolution continued along three tracks:

1. Requirements moving from threat-based to capability-based

2. The resource allocation system adding execution reviews with concurrent program and budget reviews

44

Directed Energy

RDT&E, Acquisition, and 

Warfare Management
45

The Acquisition Challenge Associated 

With Directed-Energy RDT&E

3. The acquisition process attempting to incorporate a more flexible and tailored process

These three tracks form the Defense Support 

System organizational structure: the Joint Capabilities Integration and Development System (JCIDS) 

process; the Planning, Programming, Budgeting, 

and Execution (PPBE) process; and the DAMS 

process, respectively. These three processes operate as “systems of systems” and are referred to as 

the “Big A” acquisition process shown in Figure 1.1

While all three of these phases hold their own 

level of importance, the major focus for scientists 

and engineers at research and development (R&D) 

facilities is the “Little a” acquisition process. It is 

this “Little a” acquisition process, where the rules 

and processes are found, that governs how DoD 

goes about developing a new materiel solution to 

a validated warfighter requirement. These rules 

and processes are codified within DoD Instruction 

5000.02, Operation of the Defense Acquisition System, which was issued in December 2008.

The acquisition framework associated with 

DoD Instruction 5000.02 is the DAMS structure. 

This framework, shown in Figure 2, consists of numerous strategically placed milestones and major 

program reviews to ensure proper programmatic oversight.2

 Each of the milestones has specific Figure 1. Defense Support System Organizational Structure

45

The Acquisition Challenge Associated 

with Directed-Energy RDT&E
46

Directed Energy

RDT&E, Acquisition, and 

Warfare Management

criteria that must be satisfied before a program is 

allowed to further proceed along the DAMS. The 

program’s Milestone Decision Authority (MDA) 

rests with the individual responsible for deciding if the milestone criteria have been met and, 

if so, for allowing the program to proceed to the 

next phase of the acquisition process. Designation 

of a program’s MDA depends on a program’s level of research, development, test, and evaluation 

(RDT&E) and procurement funding. For example, 

an Acquisition Category (ACAT) I program is defined as an eventual total expenditure for RDT&E 

of more than $365 million in fiscal year (FY) 2000 

constant dollars or, for procurement, of more than 

$2.19 billion in FY 2000 constant dollars. In this 

case, for an ACAT ID (“D” refers to the Defense 

Acquisition Board (DAB)) the Under Secretary of 

Defense for Acquisition, Technology and Logistics 

(USD(AT&L)) is the MDA; for an ACAT IC (“C” 

refers to Component or Service), the MDA is the 

Head of the DoD Component or, if delegated, the 

Component Acquisition Executive.3

In addition, civilian and military workforce 

members within the DoD whose job responsibilities are deemed acquisition-related find themselves 

with a training requirement necessary to carry out 

their acquisition-related job responsibilities. Specifically, these workforce members are required to 

gain acquisition training and education with the 

passage of the Defense Acquisition Workforce Improvement Act (DAWIA) signed into law in 1990. 

The current certification process comprises three 

levels covering 16 different career fields. Each of 

these 16 career fields has a set of specific training, education, and experience requirements that 

must be met in order for an individual to achieve 

Level 1, Level 2, or Level 3 certification. The Defense Acquisition University (DAU) provides the 

necessary training classes required for the certification. DAU identifies “core-plus” training classes and continuous learning modules for each level 

of certification. The core-plus classes and modules 

are not required for certification but are identified 

as additional sources of information to assist individuals in becoming more knowledgeable about 

their career field beyond the minimum standards 

required for certification. The most up-to-date certification frameworks for all 16 career fields can be 

found at the following DAU website: http://icatalog.dau.mil/onlinecatalog/CareerLvl.aspx

Defense Acquisition Reform

The DoD acquisition environment is undergoing continuous change. The issuance of DoD Instruction 5000.02 marked the opening salvo of what 

has become seemingly constant updates, modifications, and guidance impacting how DoD procures 

weapon systems to meet warfighter requirements. 

In addition to DoD’s issuance of DoD Instruction 

5000.02, the Government Accountability Office 

published a stream of reports and findings that indicate significant cost growth and schedule delays 

in major defense acquisition programs. In 2009, 

Secretary of Defense Robert M. Gates proclaimed 

Figure 2. DoD Acquisition Framework
47

The Acquisition Challenge Associated 

With Directed-Energy RDT&E

a new way of doing business within DoD when it 

comes to weapon systems acquisition. Pressures are 

building for every program to maintain cost and 

schedule estimates while delivering the technical 

requirements originally developed to support the 

warfighter.

Moreover, there have been two major policy 

issuances. As previously mentioned, the first was 

DoD Instruction 5000.02 in December 2008. This 

update of the rules and processes governing DoD 

weapon systems acquisition primarily impacted 

the early part of the DAMS framework. The problem was that weapon system programs were failing 

their initial operational test and evaluation phases 

at alarming rates—many times traced to program 

offices attempting to design weapon systems with 

immature technology. Such failures were preventing those programs from proceeding to a full-rate 

production decision review and, more importantly, 

causing a repeat of some of the DAMS framework, 

which translated to increased costs and delayed 

initial operational capability timelines.

DoD Instruction 5000.02 attempted to solve 

this problem with three main emphases. First, a 

mandatory requirement was inserted for competitive prototyping prior to program initiation at 

Milestone B. The intent was to ensure a competition 

among contractors competing for a contract award. 

The theory was that such a competition would reduce technical risk, validate designs, improve cost 

estimates, evaluate manufacturing processes, and 

refine requirements. Reducing technical risks was 

especially important because weapon system programs were expected to demonstrate a technology readiness level (TRL) of six—where the system/

subsystem model or prototype is demonstrated in a relevant environment—by the time a program reached Milestone B. TRLs are categorized 

on a scale of 1 to 9. A TRL of 1 is the lowest level of 

technology readiness, where scientific research begins to be translated into applied R&D. A TRL of 9 

is the highest level of technology readiness, where 

the actual system is proven through successful mission operations. A TRL of 6 represents a major step 

up in a technology’s demonstrated readiness. Using 

TRLs enables consistent comparisons of technical 

maturity across different types of technologies, giving program decision makers a common benchmark to consider when assessing program risk. 

Note that TRLs are meant to capture a level of technical maturity, not the probability of occurrence 

(i.e., the likelihood of attaining a required maturity 

level) or the impact of not achieving a level of technical maturity.4

The second emphasis was on a stricter adherence to systems engineering processes and technical reviews. Too often weapon system programs 

were not closely following systems engineering 

processes or avoiding due diligence when it came 

to the definition of successful exit criteria for a 

technical review. Consequently, all technical efforts must be outlined in a program’s systems engineering plan. The program manager will use the 

eight technical management processes—decision 

The Acquisition Challenge Associated 

with Directed-Energy RDT&E
48

Directed Energy

RDT&E, Acquisition, and 

Warfare Management

analysis, technical planning, technical assessment, 

requirements management, risk management, configuration management, technical data management, and interface management—to manage the 

technical development of the system increments, 

including the supporting or enabling systems.5

The program manager will use the eight technical processes—stakeholders requirements definition, requirements analysis, architectural design, 

implementation, integration, verification, validation, and transition—to design the system, subsystems, and components, including the supporting 

or enabling systems required to produce, support, 

operate, or dispose of a system.6

 Figure 3 provides 

an overlay of the new DoD Instruction 5000.02 

and Secretary of the Navy (SECNAV Instruction) 

5000.2D (Implementation and Operation of the 

Defense Acquisition System and the JCIDS), and 

shows the timing of specific systems engineering 

technical reviews as a program matures through 

the DAMS.

The third emphasis was a more prominent role 

of the MDA, starting with a mandatory requirement 

that all weapon system programs seeking a full or 

partial materiel solution must hold a Materiel Development Decision chaired by the MDA. Thus, the 

old Design Readiness Review was replaced with the 

Post-Critical Design Review Assessment chaired by 

the MDA. In short, the MDA was to become a more 

prominent figure in the oversight of a weapon system program’s progress.

The second relatively recent major policy issuance was the Weapon Systems Acquisition Reform Act (WSARA) of 2009, implemented by 

Directive-Type Memorandum (DTM) 09-027 in 

December 2009. This DTM amended DoD Instruction 5000.02, the Defense Federal Acquisition 

Regulation Supplement (DFARS), and associated 

business practices within the Defense Acquisition 

Guidebook (DAG). The WSARA implementation 

brought about changes to policies and procedures 

across 13 categories. Some of the WSARA changes most relevant to the Navy directed-energy community include:

•	 Analysis of alternatives study guidance

•	 Acquisition strategies to ensure competition

•	 Competitive prototyping

•	 Developmental test and evaluation

•	 Systems engineering

•	 Preliminary design reviews

•	 Critical cost growth

The Acquisition Impact

So why should the directed-energy community care about these acquisition policy changes? Because these policy changes impact the community’s 

Figure 3. Systems Engineering Technical Review Timing
49

The Acquisition Challenge Associated 

With Directed-Energy RDT&E

ability to develop, produce, and/or sustain directed-energy weapon systems. The ultimate goal of 

the directed-energy community is to deploy directed-energy weapons to the fleet. Accordingly, regardless of which phase or phases an organization 

in the community supports, its actions are impacted by the language in DoD Instruction 5000.02 and 

the WSARA of 2009. The more scientists and engineers in the organization are aware of governing 

policy documents like DoD Instruction 5000.02, 

the better their chances are of meeting DoD leadership’s expectations in terms of cost, schedule, and 

technical effectiveness.

Actions have shown that DoD senior leadership has come to expect all weapon system programs to adhere to the current acquisition-related 

policy and guidance changes. As mentioned earlier, 

major weapon system programs have recently been 

canceled or restructured for not meeting DoD senior leadership expectations—something that 

rarely occurred previously. In today’s environment, 

technology alone will not carry the argument for a 

program’s survivability. Directed-energy weapons 

definitely carry the allure of a “Star Wars-like” capability, but these same weapon systems will need 

to show sustainable cost and schedule compliance 

if they are to come to fruition. Resources are too 

limited, and the warfighter has too many needs to 

allow unsustainable weapon system programs to 

continue. Therefore, everyone involved with the 

development, procurement, and/or sustainment of 

a directed-energy weapon system needs to have an 

adequate understanding of the acquisition underpinnings now governing DoD.

Summary

The proverbial “winds of change” are blowing across the DoD acquisition landscape. The 

management of major weapon systems dependent 

upon cutting-edge technologies—such as those of 

directed energy—cannot afford to conduct business in a manner reminiscent of bygone days. 

Everyone involved with the development, production, or sustainment of a directed-energy weapon 

system needs to understand the “rules of engagement” laid down by the most recent DoD acquisition policy guidance. Highly skilled scientists and 

engineers typically already understand the need 

for a structured systems engineering approach to 

problem solving. Today, though, more than ever, 

cost and schedule must be factored in as potential 

tradespace to deliver the ultimate goal: a cost-effective, directed-energy weapon system delivered in a 

timely manner while meeting the warfighter’s requirements. Scientists and engineers who adhere 

to these recent acquisition changes will help their 

organizations achieve this goal, thereby ensuring 

that warfighters will be armed with the most technologically superior weapons possible.

References

1. Congressional Research Service Report 7-5700, 10 July 2009, p. 3.

2. Ibid., p. 8.

3. DoD Instruction 5000.02, 8 December 2008, p. 33.

4. Defense Acquisition Guidebook, 5 May 2010, paragraph 10.5.2.2.

5. Ibid., paragraph 4.2.3.1.

6. Ibid., paragraph 4.2.3.2.
50

Directed Energy

Technology, Modeling, and Assessment

The Basics of Electric Weapons and 

Pulsed-Power Technologies

By Stuart Moran

What Are Electric Weapons?

Most conventional weapons rely on chemical energy (explosives) as their destruction mechanism, either to explode on target, like bombs, or to create kinetic energy, like 

a bullet. Electric weapons are different. Electric weapons use stored electrical energy, 

rather than explosives, to attack or destroy the target. Electric weapons generally fall into 

two categories: directed-energy weapons (DEWs) and electromagnetic (EM) launchers. 

DEWs send energy, instead of matter, toward a target, and can be separated into three 

types: laser weapons, particle-beam weapons, and high-power microwave (HPM) or radio-frequency (RF) weapons. EM launchers use electrical energy to throw a mass at a 

target, thus making them distinct from directed energy. There are also three types of EM 

launchers: rail guns, coil guns, and induction drivers. All involve the use of strong magnetic fields to push against projectiles. While electric guns are an electric weapon, they 

are not a DEW.

High electrical powers and large energies are needed for all these weapons. Technologies for storing and controlling electric power are needed and are commonly called 

pulsed-power technologies. Electric guns are often associated with DEWs due to their 

common reliance on pulsed-power technology. The types of electric weapons are shown 

in Figure 1.

Figure 1. Types of Electric Weapons
51

The Basics of Electric Weapons and 

Pulsed-Power Technologies

There are a number of powerful advantages of 

electric weapons over conventional explosives:

•	 DEWs have a near-zero time of flight compared to conventional ordnance, allowing 

longer decision times and quicker reaction 

times.

•	 Electric weapons have a large “magazine” capacity, often limited only by the ability of the 

power source to recharge the system. The firing rate depends on how fast the system can 

be recharged, which in turn, depends on the 

available power source.

•	 The cost of engagement is greatly reduced. 

With increasingly sophisticated conventional weapons, the cost of practice rounds, such 

as a missile, can be millions. For an electric 

weapon, the cost per engagement is greatly 

reduced, making the attack of small targets 

(the asymmetric threat) less costly and training much more affordable.

•	 There is the potential for variable lethality, 

where the weapon effects can be controlled 

or attenuated to provide a warning or nonlethal effect. Otherwise, a full-power setting 

can be used to destroy the target.

•	 Electric weapons have the benefit of increased safety since less ordnance needs to 

be stored. Logistics costs less, and underway 

replenishment is easier since explosives are 

reduced or eliminated.

•	 Electric weapons can be used in conjunction with conventional weapons to heighten overall combat system effectiveness, such 

as knocking out electronics before engaging 

with a kinetic weapon.

Historically, the key Navy scenario for using directed-energy technologies has been closein protection of naval vessels from antiship cruise 

missiles, particularly in a littoral environment. The 

ability of a DEW’s speed-of-light engagement is 

particularly attractive under conditions of short 

warning times from supersonic stealthy missiles. 

However, increasingly difficult and problematic 

threats from nonmilitary aircraft and surface ships, 

countersurveillance platforms, fast patrol boats, 

unmanned aerial vehicles (UAVs), and terrorist inflatable boats or jet skis present different challenges. The threat has shifted from small numbers of 

expensive targets in open water to large numbers 

of small and cheap targets among neutral forces. The unique characteristics offered by DEWs, 

when compared to traditional weapon systems, allow them to be applied across a spectrum of threat 

roles, particularly in friendly or neutral-rich regions where precision pointing or less-than-lethal 

capability is paramount. The potential for HPM to 

counter electronics at levels below human effects 

makes them ideal nonlethal weapons. Electromagnetically launched projectiles allow longer range, 

shorter flight times, reduced reliance on air strikes 

and missiles, and safer storage and replenishment. 

With military budgets being squeezed, the low cost 

of directed-energy engagements, which often require just a few gallons of fuel, cannot be overemphasized. Instead of million-dollar missile shots, 

electric weapons allow new tactics, warning shots, 

and continual fire against large and small targets. 

They also allow inexpensive practice and training 

for improved readiness.

Pulsed Power for Electric 

Weapons

A useful rule of thumb is that a stick of TNT 

contains about a megajoule (MJ) of chemical energy, and this amount is often needed to destroy 

a military target. To destroy a target with an electric weapon, the electrical energy must also be deposited quickly. Surprisingly, a candy bar also has a 

megajoule of chemical energy, but it is released very 

slowly when we eat it. Many electric weapons require peak powers of more than a gigawatt (GW) or 

energies more than a megajoule. The time scales for 

delivery range from milliseconds to nanoseconds. 

As an example, delivering 1 MJ of energy in 10 μs 

requires 100 GW of power, which is more than a 

commercial power plant can produce. It is not practical to build continuous power supplies to directly 

drive most electric weapons. Consequently, pulsedpower technologies are needed to store energy at 

low power rates and release it quickly for weapon 

use. A pulsed-power system takes electrical power from a prime source (like a motor), stores it, and 

transforms the power to meet specific user requirements. The importance of a pulsed-power system is 

often underappreciated. For most electric weapon 

systems, the system size, weight, volume, and reliability are dominated by the pulsed-power chain. 

Pulsed-power components must be improved 

along with the weapon technology to make electric weapons systems practical. A block diagram of 

a pulsed-power system is shown in Figure 2.

Electrical energy can be stored in many ways, 

such as a battery (actually a chemical storage). A 

car battery has about a megajoule of energy, but 

it takes many seconds to drain it. A much faster 

method of storing electrical energy is in a capacitor, 

which can be discharged in milliseconds or faster. 

Inductive methods store the energy in the magnetic fields of a coil. This has the potential of achieving higher energy density than capacitors, but 
52

Directed Energy

Technology, Modeling, and Assessment

when the supporting systems are considered, the 

technology becomes less attractive. Energy storage 

for electric weapons can also be done with chemical explosive energy, where an explosive force is 

converted into electrical energy using techniques 

such as flux compression. Energy can be stored in 

the inertia of rotating machines and flywheels, but 

the energy can be released only as fast as the flywheel or motor can be stopped, usually in seconds. 

In many cases, several stages of energy store are 

used where each stage is faster than the last. Once 

the energy is stored, it must be released quickly using a high-power switch. There are many types of 

switches. Perhaps the most common type for electric-weapon applications has been the spark gap. 

Many types of controlled spark gaps exist, including pin-triggered, laser-triggered, field distortion, 

and simple overvolted. To achieve high repetition 

rates, flowing oil or gas can be used to flush the hot 

spark products, or sealed gaps using special fast-recovery gases, such as hydrogen, can be employed. 

Other switches, such as vacuum tubes and solidstate switches, can be used if they can handle the 

voltages and currents needed. Solid-state technologies, such as thyristers, have become very capable in recent years. Once the energy is switched 

out, there is usually some additional power conditioning, where transformers or pulse-forming networks are used to provide the desired pulse shape, 

voltage, and current required for the weapon. For 

rapid firing rates or continuous use, high average 

input powers are needed.

All-Electric Ship

One of the major impediments to the development of electric weapons systems for Navy ships 

has been a lack of electrical prime power. Current 

surface combatant designs employ up to 90 percent 

of engine power mechanically dedicated solely to 

propulsion. These designs are unable to provide 

the tens to hundreds of megawatts (MW) of electrical power capacity required for many electric 

weapons. The solution is an electric-drive ship that 

uses all the engine power to generate electricity, enabling it to allocate power to weapons or propulsion as needed. In recent years, the Navy has been 

investigating cost-effective power-system options 

to meet future platform requirements.

High-Power Microwave (HPM) 

and RF Weapons

Microwave weapons are generally considered 

to use frequencies above a gigahertz, whereas lower frequencies are generally called RF weapons. 

These weapons are more powerful than electronic warfare systems and are designed to create extended disruption or permanent damage. An HPM 

weapon is considered to have a peak power of more 

than 100 MW, or energies above 1 J. The energy can 

enter a target through intended RF paths, such as 

target antennas (front door), or unintended paths, 

such as housing joints, cavities, and circuit wires 

(back door). Pulses ranging from a few nanoseconds to microseconds in duration can be sufficient 

to reset computers, cause loss of stored data, or 

Figure 2. Block Diagram of a Pulsed-Power System
53

The Basics of Electric Weapons and 

Pulsed-Power Technologies

cause microprocessors to switch operating modes. 

Nonlinear circuits and components can rectify signals and absorb energy outside of their normal operating parameters. Figure 3 illustrates some of the 

vulnerability areas on a missile body.

RF or HPM devices can be divided into narrowband or wideband systems, dependent upon 

the employed pulse length. Narrowband systems 

are similar to high-power radar pulses and produce 

RF radiation with a very narrow bandwidth (frequency coverage). The damage concept is to create 

enough energy in a target to overheat or overload 

electronic components. Wideband systems generally produce very short pulses (nanoseconds) and 

typically operate in lower frequency ranges. Wideband systems produce much lower average powers 

and rely on high-peak electric fields to produce reset or arcing of digital components. Creating short 

pulses—often only a few RF cycles long—generates 

a very broad frequency output to take advantage 

of a target’s weak point. But, it also means that the 

energy is spread over many frequencies, so there 

may be very little energy at a specific vulnerable 

frequency. Vulnerability data is critical to estimate 

the effectiveness of HPM weapons. Ultimately, air 

breakdown will limit the amount of energy out of 

an antenna to around 1 MW/cm2

.

HPM devices can produce effects that range 

from denying the use of electronic-based equipment to disrupting, damaging, or destroying such 

equipment. HPM weapon advantages include allweather capability, low precision pointing requirements, and effects persistence after the radiated 

EM energy “beam” has been turned off. One major 

advantage of HPM is that electronics are generally more vulnerable to high fields and high energies 

than humans. This provides the ability to attack 

electronics without harming people, which makes 

HPM an ideal choice for nonlethal applications.

Two major challenges of implementing HPM 

technologies into an operational weapon systems 

platform are:

1. Fratricide, or self-destruction, can be a problem because of the large areas affected by the 

sidelobes and near field of any meaningful HPM weapon system. Therefore, when 

attacking a target of interest with an HPM 

weapon, there is a greater risk of disruption 

to systems that were not intended to be targeted but fell within the sphere of influence. 

Host platforms, therefore, may need to undergo interference hardening.

2. With regard to battle damage assessment, 

kinetic weapons have the advantage of typically leaving visual evidence. HPM weapon 

systems do not leave large holes in a target 

but create more subtle influences as a result 

of attacking critical electronic components. 

Consequently, it can be more difficult to ascertain whether a target’s capabilities have 

been sufficiently degraded or destroyed—

and for how long—in determining whether a mission was successful.

For HPM system development, a fundamental 

challenge is the understanding of what it takes to 

affect the target. Coupling mechanisms, where EM 

energy enters and affects the target system, are extremely complex. The vulnerability of components 

is often vastly different if it is outside or inside a circuit board or enclosure. Effects depend upon the interactions with other components, connectors, and 

nearby conductors. The effects on a component can 

vary many orders of magnitude depending on frequency, orientation, cracks and seams, protective 

circuits, pulse energy, and duration. Research regarding effects on missiles has shown large variations not only between designs, but also between 

different serial numbers due to assembly methods, cable routing, and component variations. With 

the increasing use of commercial equipment by 

the military, such as computers and radios, effects 

are difficult to predict due to constant design and 

component changes. In general, electronics are getting smaller and operating at lower voltages, making them more sensitive to high fields. But smaller 

components often have lower pickup areas, and the 

proliferation of interfering signals has increased the 

amount of shielding on modern electronics. When 

Figure 3. HPM Coupling Paths on Missile Body
54

Directed Energy

Technology, Modeling, and Assessment

target systems are located inside structures or buildings, it becomes even more difficult to predict. Efforts to predict reflections and interference inside 

complex structures become extremely complicated. 

Accordingly, generic electronics kill using universal 

waveforms is not likely. There continues to be a lot 

of hype about what RF weapons can do, but the idea 

that a backpack device can wipe out all electronics 

in a city is no more realistic than a hand-held laser 

cutting through a bank vault door.

High-Energy Lasers (HELs)

A laser generally produces a beam of coherent light at a specific wavelength dependent on 

the atomic structure of the lasing substance. Only 

certain substances have the atomic properties appropriate for producing laser light, and these are 

often limited in power. Lasers are characterized 

by the substance being lased (gas, liquid, or solid) 

and the “pumping” process (light energy, electricity, or chemical reaction). A resonant optical cavity provides the means for aligning the energy in 

the beam and extracting that energy. A military laser system also includes beam processing or beampath conditioning, beam pointing and control 

and—for long-range applications—adaptive optics 

to compensate for the atmosphere.

Until recently, HELs have been driven by chemical energy, so very little electrical power or pulsed 

power was needed. Chemical lasers use the reactions of gases or liquids to create the excited energy 

states necessary for laser emission. Large chemical 

lasers and beam directors have been developed by 

the Navy in recent decades and have successfully 

ruptured fuel tanks and downed supersonic missiles. However, these lasers required high-velocity, 

chemical-reaction chambers and emitted hazardous gaseous by-products. They often operated at 

wavelengths where the atmosphere absorbed much 

of the energy. Absorption creates thermal blooming, whereby absorbed energy in the air creates 

a negative lens that defocuses the beam. Increasing the power of the laser increases the energy absorbed and worsens the problem. The Army and 

Air Force are developing chemical lasers for airborne applications, where atmospheric absorption 

is less of a problem. Recent Navy interest in HELs 

has concentrated on lasers that are electrically powered, rather than chemically powered, and that operate at shorter wavelengths to allow smaller optics 

and more efficient propagation near the water.

Small semiconductor (or diode) lasers use current flow through an electrical junction to excite 

electrons and create laser light. These lasers are 

very limited in power, so research has focused on 

using large numbers of lasers assembled into a coherent array. Semiconductor lasers also create efficient light to excite or “pump” other types of lasers. 

Solid-state lasers (SSLs) use crystalline materials 

mixed (doped) with elements needed for proper 

lasing. SSLs show strong promise for compact, medium-power HEL weapon systems. Scaling these 

systems up to megawatt levels creates extreme heat 

in the crystal material, making it very difficult to 

prevent internal damage. Forced cooling and the 

heat capacity of large masses are under study.

Fiber lasers—which use semiconductor diode 

lasers to pump a flexible, doped crystalline fiber 

(similar to a fiber-optic line)—have demonstrated 

high efficiency and relatively high power. The technology is being used in the welding and cutting industries. Methods of pumping large numbers of 

fiber-optic lasers and combining them are being investigated. An example is shown in Figure 4.

The free-electron laser (FEL) operates differently from a conventional laser. An FEL uses a 

high-voltage electron accelerator to push electrons 

through a magnetic “wiggler” to create light radiation across a tunable band of frequencies. The FEL 

is extremely complex and large, but scaling to very 

high powers may be possible. Perhaps the biggest 

promise of the FEL is the ability to design the laser 

at an ideal atmospheric propagation wavelength. 

Significant technical hurdles remain in reaching 

the status of a deployable FEL, in scaling the beam 

to megawatt powers and in providing the necessary 

engineering to turn a laboratory device into a weapon system of reasonable size. For Navy application, 

FELs will require improvements in areas of radiation shielding, high vacuum, high-current photoinjectors, and probably cryogenic cooling—all of 

which must be integrated into a ship’s basic design.

Fiber lasers and SSLs are the leading-candidate Navy lasers for medium power, as FELs are 

for high power. All are electrically driven and can 

meet the requirement for shorter wavelength, capable of transmitting at the “maritime window” of 

approximately 1 μ.

HEL weapons’ advantages include a highly directional and narrowly focused beam, providing:

•	 Minimal collateral damage

•	 Speed-of-light delivery

•	 Rapid retargeting

•	 Low cost of engagement

Disadvantages center on:

•	 Limited range due to atmospheric attenuation

•	 Weather limitations

•	 Low efficiency (often less than 10 percent)

•	 Need for eye protection

•	 Relatively large size and weight requirements
55

The Basics of Electric Weapons and 

Pulsed-Power Technologies

Figure 4. Drawing of Laser Weapon System (LaWS)

Long dwell times (seconds) will be needed for 

most targets. As with RF systems, there is a potential 

nonlethal or variable lethality capability since the 

energy can be easily defocused. A critical challenge 

is the understanding of a laser beam’s propagation 

through a maritime boundary layer environment, 

where the sea and air interface creates turbulence 

and moisture gradients. Measuring the atmosphere 

and compensating for variations in real time may require adaptive optics or “rubber mirrors” that can be 

constantly adjusted to compensate for changes. Focusing a small spot at long range will require high 

beam quality and large optics, probably meter-size 

mirrors that are very highly reflective and very clean.

HELs in the future are expected to be able to focus energy to a spot size of much less than a meter 

at ranges of kilometers. This will necessitate very 

accurate target tracking systems, and precise stabilization and beam-pointing systems, both of which 

are difficult but should be feasible in the near term. 

Real-time atmospheric measuring systems will be 

needed for compensation techniques. Methods to 

protect the sensitive optical system from salt spray 

and corrosion will also be needed.

From a lethality perspective, three considerations need to be better understood before a HEL 

can be deemed a true weapon system:

1. Achievable spot size of beam on target at 

range

2. Amount of coupling into the target material

3. Subsequent effects of the damage inflicted

For the more severe threats, 

such as high-speed, antiship cruise 

missiles, HELs face the difficult 

task of engaging maneuverable, 

stealthy, inbound missiles. As 

such, a better quantitative understanding of the interactions 

among a laser beam’s energy deposition, target material, and 

flight dynamics is needed.

Particle Beams

A particle-beam weapon is 

a directed flow of atomic or subatomic particles. These particles can be neutral or electrically 

charged. Neutral beams need to 

be used outside the atmosphere 

(in space), where charged particles would repel and fly apart. 

Charged-particle beams (CPBs) 

are easier to make and are used 

within the atmosphere, where 

air molecules can constrain the 

beam. A CPB weapon transmits matter—not just 

EM waves—like lasers and microwave weapons. 

The particles are near the speed of light and deposit 

their kinetic energy deeply into any target material. They have the potential to be highly destructive 

weapons and are very difficult to shield against.

Charged particles are produced by applying a 

strong electric field near a material that emits electrons. These electrons then pass through accelerating stages with high voltage gradients (often 

megavolts), which increase the electron’s velocity. As the electrons pass each stage, the velocity increases until they approach the speed of light 

(become relativistic), at which point they have substantial energy to penetrate a target. The accelerating systems can be linear, but a recirculating design 

is more compact and can reuse stages. These systems are basically high-current versions of scientific particle accelerators.

Once the electron beam is produced, it must 

propagate to the target. High-velocity electrons 

will not go far before they collide with air molecules and lose energy. The fact that air molecules 

struck by the beam are heated and moved out of 

the way for a short period of time creates a rarified 

“hole” in the atmosphere through which a second 

pulse can travel farther. In this manner, a fast series 

of pulses can “hole-bore” to the target, each pulse 

going farther than the last. The final pulse must 

have enough energy to damage the target. The deceleration of electrons in the atmosphere causes 
56

Directed Energy

Technology, Modeling, and Assessment

Bremsstrahlung radiation in the forward direction 

toward the target, creating gamma rays that, in 

turn, create X-rays and RF radiation.a

 These effects 

can cause electronic upset and “soft-kill” mechanisms even if the beam slightly misses the target.

The beam of electrons is typically a few centimeters in diameter. When a beam strikes a target, 

the energy is deposited deep in the material (the 

collision cross section is small because of the relativistic speeds) in microseconds (much faster than a 

laser), creating thermal shock that is very difficult to 

shield against. For an explosive target, there is also 

the possibility of causing a deflagration or low-order 

burn, disrupting the normal warhead mechanism.

Scientists studying CPB weapons made significant technical advancements in the 1980s, but 

the weapons are still far from being practical. A 

CPB weapon is technically very challenging and 

expensive to build. Studies project that the volume requirements necessary for a CPB system 

could be on the order of a 5-inch gun system. Advantages of a CPB weapon include rapid penetration, a deep magazine, all-weather capability, and 

soft-kill mechanisms for a near miss. Problems include complexity, size, limited range, and the need 

to demonstrate compact accelerators and propagation mechanisms.

Electromagnetic (EM) Launchers

A number of technology concepts to launch 

projectiles exist using electrical energy. These systems rely on large currents in conductors, creating 

strong magnetic fields that drive a projectile. The 

velocity of a normal powder gun projectile is limited by the expansion speed of the explosive powder, 

and present military guns are reaching that limit. 

With an electric gun, the fields can push projectiles 

much faster, providing longer ranges and increased 

kinetic energies. The simplest version is an EM rail 

gun, shown in Figure 5.

In any conducting loop, the generated magnetic field tries to expand the loop. If everything is held 

in position, the only movable item is the conducting 

projectile, which moves down the rails in an attempt 

to expand the loop. Since megajouoles of projectile 

energy are needed for EM rail guns, energy storage 

Figure 5. Electromagnetic (EM) Rail Gun Concept
57

The Basics of Electric Weapons and 

Pulsed-Power Technologies

mechanisms that can store about 100 MJ are needed, along with the ability to discharge the energy in 

milliseconds. To generate useful forces, millions of 

amps of current are needed—a major challenge and 

significant loss mechanism. Large capacitor banks 

with very high-current switches are required. Spark 

gap switches have historically been the only option, 

but new high-current solid-state switches are now 

becoming available. Capacitor energy densities, too, 

have improved an order of magnitude in the last few 

decades. Rotating machines have also been considered because they are smaller than equivalent capacitor banks, but extracting the energy quickly, 

without tearing the machine apart, has been problematic. The launch energy of various projectiles is 

shown in Figure 6.

A rail gun is probably the most compact form 

of electric launcher. However, it requires direct 

electrical contact between the projectile and barrel 

rails, creating the potential for arcing, melting, and 

erosion. Coil guns use a series of sequentially fired 

coils around a “barrel” to push the projectile in 

stages. This does not require direct electrical contact, so it avoids rail erosion but requires a series of 

fast timed switches and more space. Linear induction motors are basically unrolled electric motors 

and have been used on electric trains and roller 

coasters, typically with magnetic levitating systems 

to avoid contact erosion. This concept is being developed by the Navy for launching aircraft. The 

energy to launch an aircraft is similar to a largecaliber projectile—more weight but less speed. The 

slower speeds are more suitable for rotating machines since the launch times are seconds rather 

than microseconds.1

 Electrothermal guns and electrothermal-chemical (ETC) guns use a combination of electricity and chemicals. Electrical energy 

is used to initiate chemical reactions that can produce lightweight driving gases, like steam, or allow 

more energetic propellants that are difficult to ignite in a conventional fashion.

Some advantages of electrically driven projectiles include:

•	 Higher projectile velocity (over conventional explosives)

•	 Very long range (>100 miles) with lower cost 

than missiles

•	 Time-critical delivery (because of shorter 

time of flight)

•	 Safer projectile stowage (minimal explosives)

•	 Potentially adjustable velocity levels, for better accuracy and controllable damage

The potential of having nonexplosive rounds 

and magazines is very attractive for the Navy. For 

long-range, large-caliber EM projectiles, the kinetic energy from the projectile velocity is greater than 

the chemical explosive energy in a conventional 

round traveling much slower. Therefore, damage 

can be equivalent even without explosives. System 

size and lifetime are still behind conventional systems, but getting close.

Outlook

Challenges remain for many electric weapon 

concepts. These weapon systems appear promising to meet the increasingly important asymmetric threats with low-cost precision rounds. They 

also can be employed across the energy spectrum 

for nonlethal targeting. Electric weapon systems 

will, in many cases, continue to supplement existing kinetic weapon systems in the near term. Despite technology challenges, directed-energy and 

electric weapons hold great promise in offering the 

future warfighter unique combat capabilities not 

currently available.

Endnote

a. Bremsstrahlung—a type of radiation emitted when high-energy 

electrons are decelerated. (German for braking radiation)

Reference

1. Shope, S. et al., Long-Range Naval Fire Support with a Coilgun, 

Sandia Report 2001-3832, February 2002.
58

Directed Energy

Technology, Modeling, and Assessment

Solid Modeling of Directed-Energy Systems

By Joseph F. Sharrow

Not long ago, around the mid-1980s, development of most new mechanical systems—such as automobiles, consumer products, and military devices—was performed 

manually on a drafting table or drawing board, much like the present-day version shown 

in Figure 1. These tables and boards performed a necessary function, but they offered 

little assistance other than for drawing lines. Engineers used them to prepare layouts, or 

two-dimensional sketches of what they were designing. They then would take these layouts to a draftsman, who would create drawings of each part in the device. The drawings 

would subsequently be sent to a manufacturing facility.

This layout and drawing preparation process typically would need to be repeated 

multiple times because mistakes would be made, or design issues would be discovered 

late in the process. Similarly, the manufacturing process would sometimes require multiple iterations as well because of the inherent limitations in designing three-dimensional (3-D) devices on two-dimensional boards. This less-than-ideal process made it 

difficult to design and manufacture even mundane products and frequently resulted in 

things that just didn’t work. With the emergence of early computerization, numerical 

analyses of more complex systems began to be performed. These analyses were conducted to ensure that the systems worked in the real world. For example, engineers might 

conduct a structural analysis of the forces in a loaded dump-truck bed to make sure that 

the frame wouldn’t bend and fail. Because of the difficulty in performing these analyses, they would often require a specially trained group of structural engineers, expensive 

software, and large mainframe computers, limiting their use to only the largest, most 

well-funded companies or organizations.

Emergence of Computer-Aided Design (CAD) 

and Solid Modeling

With the availability of smaller scale computers and more economical software in 

the mid-to-late 1980s, CAD was born, initiating a period of rapid improvement in the 

design process. This was driven, in part, by the introduction of software packages such 

as AutoCAD. Initially, these software packages only attempted to automate drawing 

lines by making wireframe (stick-figure) versions on the computer of what previously had been made by hand on the drafting board. This reduced the difficulty in making 

changes in the development process, but it still limited the engineer’s pallet to a two-dimensional space. What was really needed was a 3-D method of design. Solid modeling 
59

Solid Modeling of Directed-Energy Systems

addressed this need beginning in the late 1980s to 

early 1990s. 

Solid modeling is analogous to taking blocks of 

clay and cutting and forming them into the shape 

of a solid part on a computer. These 3-D parts are 

then put together in an assembly, more accurately 

representing real-world devices. Though originally used only in a limited way for specialized applications in the aircraft and automobile industries, 

it wasn’t until the 1990s that solid modeling experienced widespread availability and mainstream 

acceptance due to software packages such as Pro/

ENGINEER. Figure 2 summarizes how Pro/ENGINEER and other similar packages fit into the development of new products. The general flow of the 

process moves from left to right. 

Initially, nearly all 3-D solid modeling packages required significant computing and graphics 

display power, necessitating the use of large graphics workstations running the UNIX operating system. Rapid advances in computing and graphics 

power have since enabled nearly all packages to 

run efficiently on personal computers (PCs) and 

laptops, bringing solid modeling and analysis capability into the mainstream. 

Figure 1. Drawing Board

Figure 2. Solid Modeling in the Development Process
60

Directed Energy

Technology, Modeling, and Assessment

Solid Modeling of 

Directed-Energy Systems

Engineers working in the Directed Energy Division at the Naval Surface Warfare Center, 

Dahlgren Division (NSWCDD), use solid modeling to develop hardware for nearly all of its programs. Both Pro/ENGINEER and SolidWorks are 

used extensively to develop new products in virtual 

3-D space. Additionally, the structural simulation 

package within Pro/ENGINEER is used to determine stresses and natural frequencies of parts and 

assemblies. Consequently, these packages have enabled a single mechanical engineer in the Directed 

Energy Division and a draftsman in the Engagement Systems Department at Dahlgren to perform 

the design and analysis work that would have required an entire group of engineers and draftsmen 

just a few years ago. Today, collaboration among 

many organizations using similar packages has become commonplace. Insofar as solid modeling has 

become an indispensable tool for development and 

collaboration, its successful implementation requires proper training and experience before engineers can use it effectively, just as medical surgeons 

require training in the use of advanced robotic surgical devices before they can be used effectively. 

Thus, while these high-tech modeling systems not 

only have reduced the number of personnel needed for design and development, they have enabled 

the Navy to get significantly more bang for its buck 

while supporting warfighting needs. An example of 

how solid modeling is currently being used is discussed below.

Navy Laser Weapon System 

(LaWS) Beam Director

The Directed Energy Warfare Office (DEWO) 

and Directed Energy Division at Dahlgren are currently developing the Navy LaWS for the Naval Sea 

Systems Command’s Directed Energy and Electric 

Weapon Systems (DE&EWS) Program Office (PMS 

405). The program’s goal is to take advantage of currently available industrial laser technology and incorporate it into a future naval weapon system. As 

part of the development process, major subsystems 

have been integrated with a Kineto Tracking Mount 

(KTM) into a LaWS beam director. The KTM/beam 

director was modeled and analyzed using Pro/ENGINEER. Ultimately, the resulting LaWS will be 

installed on Navy ships on the Close-In Weapon 

System (CIWS) gun mount. During field testing in 

June 2009 at the Naval Air Warfare Center, China 

Lake, California, the prototype KTM/beam director successfully destroyed five unmanned aerial vehicles (UAVs). The actual beam director used in the 

China Lake testing is shown in Figure 3; the Pro/

ENGINEER assembly model used for development 

is shown in Figure 4. 

The LaWS effort took advantage of many aspects of solid modeling including collaboration, 

structural and modal analysis, and manufacturing drawing creation. The project required development of new, unique hardware, as well as the 

integration of electronic models from commercial 

vendors. The KTM model was provided by L-3 

Brashear and was originally designed using Pro/

ENGINEER. The beam-directing telescope model was provided by RC Optical Systems, Incorporated, and was originally made in SolidWorks. 

These models were combined with many new optical and structural components developed by the 

Directed Energy Division into a single, comprehensive assembly model. This model was instrumental in understanding the interaction of the 

many components, and its use increased accuracy and precision that would have been impossible 

with old-fashioned two-dimensional development processes. Figure 5 shows a cross section 

through the main portion of the beam director, 

revealing the complexity of the many parts and 

subassemblies required for such a device. In addition to modeling the mechanical components, the 

actual laser beams were also included to better understand their path through the various mirrors 

and optical devices in the beam director, and to 

better highlight any interference they might have 

with structural components within the KTM or 

telescope. 

Numerous analyses were performed to make 

sure that everything worked the way it was intended. One major analysis addressed the telescope 

mount. To ensure that the beams were stable at 

range, the mount had to be extremely stiff. The best 

way to ensure this was to perform a structural analysis using the structural simulation package within 

Pro/ENGINEER. Figure 6 shows the results of that 

analysis: a displacement plot in which different colors represent how much the telescope will move 

when the KTM rotates at its maximum speed. The 

large cylindrical object simulates the mass of the 

telescope. The minimum amount of displacement 

is indicated by blue, and the maximum is shown 

in red. This analysis verified that the movement of 

the telescope, relative to the optical components 

within the optics breadboard, was acceptable and 

should perform well at the range specified by the 

program office. 

After modeling and analysis were completed, 

manufacturing drawings of custom parts were created by the Engagement Systems Department to be 
61

Solid Modeling of Directed-Energy Systems

Figure 3. LaWS Beam Director

Figure 4. LaWS Beam Director Assembly Model
62

Directed Energy

Technology, Modeling, and Assessment

Figure 5. LaWS Beam Director Cutaway

Figure 6. Displacement Plot
63

Solid Modeling of Directed-Energy Systems

sent to manufacturing facilities, such as machine 

shops. One example is shown in Figure 7, which 

shows the first sheet of the multisheet drawing 

needed to manufacture the large plates that support the telescope from the center platform of the 

KTM. One of these plates is also shown in the displacement plot in Figure 6. 

Even though it would be possible for one person 

to do all of the modeling, analyses, and drawings for 

a particular program, a more efficient process takes 

advantage of using the best skills available by collaborating with other experts. Collaboration enables assembly, part, and drawing files to be sent 

electronically, eliminating the need for collocating 

personnel. Drawings for the LaWS program, for instance, were made using noncollocated personnel 

across base at NSWCDD. They could just as easily have been made using personnel from across the 

country. 

The LaWS program exemplifies how the Directed Energy Division uses solid modeling to 

enhance the quality and effectiveness of Navy directed-energy capabilities. As a result, warfighters 

will be better armed with more effective weapons 

and capabilities for future naval conflicts.

Acknowledgment

The author would like to acknowledge the 

valuable contributions of the Engagement Systems Department’s drafting group in support of 

numerous DEWO and Directed Energy Division 

programs.

Figure 7. Manufacturing Drawing
64

Directed Energy

Technology, Modeling, and Assessment

A Fundamental Key to Next-Generation 

Directed-Energy Systems

By Directed Energy Division, Electromagnetic and Sensor Systems Department

Imagine an explosive ordnance disposal (EOD) unit on a routine scouting patrol 

deep in the notorious “Triangle of Death” south of Baghdad, where Marines, Sailors, 

and Soldiers frequently find themselves exposed to improvised explosive devices (IEDs). 

Fortunately, this newly outfitted unit is equipped with the latest unmanned, mobile, remote-controlled, radio frequency (RF) transmitter used as a directed-energy weapon 

(DEW). The integrated system provides comprehensive IED prediction, detection, prevention, and neutralization capabilities. Lightweight, pocket-sized transmitters carried 

by each warfighter constantly communicate sensor intelligence, key vital signs, critical 

conditions, and location telemetry to a geostationary satellite (GEOSAT). It intercepts, 

collects, and retransmits intelligence and situational awareness data simultaneously to 

any command post in the world and to each member of the unit on patrol. Highly efficient, miniature, switch-mode, RF amplifiers with high-power density (small size and 

weight with high-power output) enable these visions of future capabilities as their systems’ transmitter backbone. 

To civilians, the miniaturization of modern wireless (electromagnetic) devices is 

considered a mere convenience or luxury, i.e., Blackberries, mobile phones, and highspeed wireless network connections. To the next-generation warfighter, miniaturized, 

wireless, directed-energy (DE) systems open the door to the realization of a whole new 

set of effective and efficient wireless modalities. And while the capabilities mentioned 

in the above scenario are not yet available to warfighters, researchers believe they have 

uncovered the key to next-generation DE systems leading to the miniaturization of 

DE devices.

Next-Generation DE System Requirements

At the Naval Surface Warfare Center, Dahlgren Division (NSWCDD), key system 

requirements for effective next-generation DE systems are being researched and developed for applications to counter IEDs, to detect explosively formed penetrators (EFPs), 

to neutralize explosives, and to predict threat locations. Next-generation DE systems 

must yield a high probability of mission success and be inherently safe to operate. By 

design, they must minimize or eliminate the risk of hostile attack or collateral damage 

especially during screening missions. Considering the DEW example above, practical 
65

A Fundamental Key to Next-Generation 

Directed-Energy Systems

next-generation DE systems must be physically 

characterized by:

•	 Low mass (weight)

•	 Small size (volume)

•	 High-power output with respect to size or 

high-power density

•	 High efficiency for extended mission use

•	 Minimized prime power and cooling support

•	 Portability

•	 Mobility

•	 Configurability

They must also ensure a high probability of mission effectiveness. The DEW must be easily transportable and agile, adapting to the immediate, local 

military mission requirements in various warfighting environments. Additionally, DE systems must 

be mechanically robust and able to withstand the 

shock and vibration of combat missions in rough 

and rugged environments. The key requirement—

efficiency—fundamentally facilitates all required 

characteristics, including mass and size.

Moving Beyond Requirements

Scientists at NSWCDD, sponsored by the Office of Naval Research (ONR), are researching and 

developing key system requirements for effective 

next-generation DE systems to counter IEDs, to 

detect EFPs, to neutralize explosives, and to predict threat locations. 

Researchers at NSWCDD are leading the way 

toward realizing small, lightweight, RF transmitters using high-power, solid-state, switch-mode 

amplifiers, theoretically 100 percent efficient. These 

practical switch-mode amplifier realizations are 

at least 1/100 the volume and weight of any commercially available linear solid-state amplifier of 

comparable power output. The challenges included assessing what type of active amplifier device 

and operation would provide the greatest power 

density (power output per unit volume and mass) 

with its necessary auxiliary systems, such as prime 

power generation and cooling of waste heat. Such 

a device also needed to provide sufficient output 

power based on required standoff range and IED 

system-coupling efficiency while also maintaining 

a manageably-sized, easily transportable system. 

Researchers initially considered tube-based systems, but large, heavy, direct-current (DC) power 

supplies are required, and typically 40 percent of 

the input power is dissipated in heat, which negates 

any possibility of miniaturization.

Upon a practical review of amplifier-class operations and suitable active amplifier devices, however, research pointed to contemporary switch-mode 

080102-N-1132M-006 SHEIK SA’ID, Iraq (2 January 2008) U.S. Army Soldiers attached to 3rd Squadron, 2nd 

Cavalry Regiment patrol and search for weapons or Improvised Explosive Devices (IEDs) during a clearing 

mission. (U.S. Navy photo by Mass Communication Specialist 1st Class Sean Mulligan/Released) 

A Fundamental Key to Next-Generation 

Directed-Energy Systems
66

Directed Energy

Technology, Modeling, and Assessment

amplifier schemes (e.g., Class-E and Class-F) using solid-state technology—such as the high-electron mobility transistor (HEMT)—as satisfying 

the high-power density and abusive mechanical 

requirements for expected worst-case transportation and operation in a rugged environment. To 

significantly impact reduction of size and weight, 

practical, high-efficiency thresholds were defined 

for next-generation DE systems at 90 percent and 

greater. The key technology enabler to realize amplifier high efficiency in high-power amplifiers 

up to 60  kW was found in exploiting contemporary switch-mode amplifier architecture with efficient power combining. Particularly, switch-mode 

schemes in Class-E and Class-F operation as solid-state, active-hybrid planar topology designs 

were found to be necessary and sufficient for DE 

applications. These analyses led to a novel, Class-E 

RF switch-mode amplifier design. A Class-E RF 

switch-mode amplifier can theoretically operate at 100-percent efficiency. For every input watt 

supplied, an RF output watt is produced. The conductors and dielectric substrate of the hybrid planar load network and the commercial off-the-shelf 

(COTS) transistor all exhibit some small degree of 

power loss, suggesting an estimated practically realized efficiency of 90 percent.

Moreover, the amplifier under research consisted of a novel microwave load network operating with high-power output at ultrahigh frequency 

(UHF). This research led to the state of the art in 

Class-E designs leading by hundreds of watts, several hundred megahertz in frequency, and roughly 10 

percentage points in efficiency. A common, solidstate, high-power amplifier design technique sums 

the phase and amplitude of smaller amplifier units 

to the large values required for DE systems. A practical hardware limitation exists that limits the theoretically infinite number of fixed RF output power 

units to a finite number. Approximately 60-kW 

RF output power sets the boundary as the largest 

hardware realization. By applying spatial power 

combining in the propagating medium, phasedarray antennas can be employed with constructive 

wave interference in air that would allow sufficient 

RF power densities on target, based on the number 

of elements in the array. This technique eliminates 

the traditional hardware necessary to power combine the smaller power-amplifier elements, realizing a much simplified DE system with enhanced 

power density in the transmitter, and reduced mass 

and volume.

The key to ultrahigh efficiency in a switchmode amplifier, such as Class-E or Class-F, is found 

in zero-voltage switching (ZVS). Here, the load 

network is not only designed to be resonant at and 

around a particular desired switching frequency, it 

must simultaneously act to force the voltage across 

the switch to be zero when current flows and when 

it switches off; hence, theory suggests that no power is dissipated because the product of current 

through, and voltage across, the switch is zero. 

It is this aspect of the design that makes the job 

of switch-mode amplifier realization difficult. Of 

course, in practice, a small voltage exists for a very 

short time during the switching action, resulting 

in a small amount of input power being dissipated 

in heat. This theoretical description also assumes 

that all components are ideal (i.e., no impedance 

to current flow exists in the switch when turned 

on). All realistic switches exhibit finite impedance 

when turned on, which does dissipate some wasted energy, but again, this is very small in modern 

HEMT devices using the ZVS technique.

Class-E switch-mode amplifier theory development began in the United States during the 

1960s, with details published in 1975, although 

some earlier reports were published in Russia. 

Lumped element electrical components (RF choke 

inductors and metal film capacitors) were initially used in lower frequency (3 to 30 MHz) prototypes. As engineers attempted higher frequency 

designs in the very high frequency (VHF) range, 

solid-state transistor switch parasitic intrinsic and 

packaging elements found inside the transistor began to be used as some of the key components necessary for ZVS. These parasitic elements included 

stray capacitance caused by differences of potential between parts inside the transistor and inductance caused by bond wire length that is used to 

connect the transistor to accessible terminals in its 

packaging. At microwave frequencies, these parasitic elements become sensitive, invoking unintended significant changes to load networks 

designed to operate with the transistors. Intrinsic 

elements include drain-to-source breakdown voltage capability and peak current capability. As the 

need for higher frequency operation and higher 

power increased, constraints of key transistor parameters became difficult to produce in traditional silicon technology:

•	 High instantaneous transient (peak) current 

capability through the transistor

•	 Moderate breakdown potential across the 

transistor

•	 Low output capacitance

Only within the past few years have transistor manufacturers produced COTS transistors that 

meet the required capabilities necessary to operate in switch mode for microwave frequencies and 
67

A Fundamental Key to Next-Generation 

Directed-Energy Systems

081107-N-1120L-072 RAMADI, Iraq (7 November 2008) Joint EOD Rapid Response Vehicles (JERRVs) assigned to Naval Mobile Construction Battalion (NMCB) 7’s convoy security element are secured following an escort mission from a forward operating 

base. The Cougar-type JERRVs are employed by coalition forces for escort and logistics missions, and to protect personnel from 

IEDs. NMCB 7 is deployed to U.S. Forces Central Command to provide contingency construction support to coalition forces in support of Operations Enduring Freedom and Iraqi Freedom. (U.S. Navy photo by Mass Communication Specialist 2nd Class Michael B. 

Lavender/Released)

high-power output. Selection is still somewhat limited for designers.

New transistor technology known as gallium nitride (GaN) HEMTs—using state-of-theart manufacturing processes with GaN on silicon 

carbide materials—now facilitates Class-E highpower amplifier (100-W) designs at ultrahigh frequencies. The design process for switch-mode 

amplifiers is radically different than linear amplifiers, so engineers have tended to continue using linear amplifier design techniques due to familiarity, 

rather than advance to the switch-mode designs. 

Today, the Class-E and Class-F unit power output 

(greater than 100 W) capability and upper frequency limitation is based on a lack of available HEMTs 

with the necessary parameter capabilities.

Most recently, transistor manufacturers have 

limited their investment in the Class-E amplifier solid-state switch market due to no commercial market mandate. An assortment of presently available 

HEMTs provides a low-power capability in terms of 

1- to 10-W output power for Class-E amplifiers in 

the cell phone market. The need remains to continue 

advancing in commercially manufactured HEMTs 

with key capabilities necessary to realize larger unit 

power output, hundreds of watts to a thousand 

watts, for practical implementation in DE systems.

Possible Multiple Applications

Directed-Energy Weapon Systems

Expanding on the vision of the next-generation DEW system mentioned at the beginning of 

this article, further imagine that EOD scouts detect a laser fluorescence signature of C4 high explosive and chlorine outgasses in the vicinity of an 

abandoned vehicle 2-km north of their current position. An electronic support measure (ESM) team 

on board an approaching clearing vehicle initiates 

RF jamming and electromagnetic surveillance procedures. Electronic specialists also scan the area 

with ground-surface differential thermography—

particularly to detect possible buried IEDs and 

EFPs or their tiny command wires, crush wires, or 

pressure plates—while clearing a pathway to the 

abandoned roadside vehicle.

A Fundamental Key to Next-Generation 

Directed Energy Systems
68

Directed Energy

Technology, Modeling, and Assessment

Upon arrival at a 500-m safe distance, the EOD 

specialists command the RF transmitter’s robotic 

platform, also equipped with sensitive gamma-ray 

planar and computed tomography (CT) imaging 

to navigate toward and around the vehicle, interrogating every possible hiding place. It discloses an IED in the fuel tank. The specialist lifts the 

transmitter arming safety and commands the remote transmitter to radiate a prescribed dose of 

RF energy directed at a carefully chosen component of the vehicle-borne IED (VBIED) system. Without entering the vehicle, the advanced 

screening system detects and defuses the deadly 

IED buried within the rusty, metal vehicle chassis. Within minutes, the suspected VBIED threat 

is entirely neutralized, with absolutely no wounded warfighters or casualties.

Mobile Ad-Hoc Wireless Network (MANET)

Beyond IED detection and neutralization, 

imagine an expeditionary unit on patrol, with each 

member equipped with an RF transceiver about 

the size and weight of a cigarette pack with an ultrahigh-efficient switch-mode amplifier. The miniature transceiver constantly communicates sensor 

intelligence, key vital signs, critical conditions, 

and location telemetry to a GEOSAT. This small 

switch-mode amplifier has the needed output 

power to reach an altitude of 35786 km, where the 

GEOSAT intercepts, collects, and retransmits this 

intelligence and situational awareness data to any 

command post in the world and to each member 

of the unit on patrol simultaneously. The expeditionary unit, spread out over a wide area with large 

interspacing, shares the situational awareness and 

intelligence data of each other at the speed of light. 

Thus, near real-time, worldwide communications 

with ubiquitous secure access from the battlefield 

is possible in a multiple-input, multiple-output 

(MIMO) architecture. The same system could provide a soldier-to-soldier MANET.

Next-generation switch-mode RF amplifier 

designs could also optimize payload weight and 

volume on board new communication satellites 

while supplying higher power density and making efficient use of the solar power supply budget. 

Improved switch-mode amplifier power output, 

when combined with enhanced antenna design, 

would minimize Earth-station antenna size requirements. The recently launched satellite shown 

at left demonstrates an example of the latest antenna technology. 

Looking Forward

Miniaturizing next-generation DE systems 

opens up a whole new world of applications to support warfighters in ways unimaginable just a few 

years ago. Reduction of transmitter mass and volume, accompanied with high efficiency, creates a 

welcome trickle-down effect. Low profile, small, 

lightweight DE systems means:

•	 Less vulnerability to attack

•	 Greater mobility and maneuverability

•	 Simplified logistics with less fuel-supply demands

•	 Less impact on the environment

Clandestine operations, too, could be executed with greater ease and simplified logistics support. In the case of MIMO MANETs, miniaturized 

high-power density transmitters could further expand capabilities for the warfighter, enabling them 

to carry high-power transmitters to communicate 

with satellites or other supporting platforms. The 

Pictured here is the National Aeronautics and Space Administration/National Oceanic and Atmospheric Administration (NASA/

NOAA) Geostationary Operational Environmental Satellite-P 

(GOES-P) launching from Cape Canaveral Air Force Station, 

Florida, aboard a Delta IV rocket procured by Boeing Launch 

Services on 4 March 2010. Built by Boeing Space and Intelligence Systems, GOES-P will provide NOAA and NASA scientists with data to support weather, solar, and space operations, 

and will enable future science improvements in weather prediction and remote sensing. Additionally, GOES-P will provide data 

on global climate changes and capability for search and rescue.
69

A Fundamental Key to Next-Generation 

Directed-Energy Systems

satellite industry itself could benefit from miniaturized switch-mode amplifiers with much higher power density microwave transmitters, resulting 

in reduced payload mass and volume; this also reduces Earth-station antenna gain and size requirements.

Conclusion

NSWCDD is meeting the demanding requirements of next-generation DE systems with Class-E 

RF transmitter switch-mode amplifiers designed to 

operate at ultrahigh efficiency, greater than 90 percent. Having discovered the key to next-generation 

DE systems, researchers at NSWCDD are focusing 

on the urgent need to counter IED systems with 

small, lightweight, highly efficient transmitters that 

use switch-mode amplifiers. Considering the multiplicity of additional applications, all advancements made in amplifier counter-IED applications 

can be transferred to other applications in the future. Accordingly, while the capabilities suggested 

in this article might seem somewhat far-fetched, in 

reality, they are realizable in the near term. It is projected that NSWCDD will soon have its first 250-W 

UHF amplifier unit prototype ready. These units 

will fit in the palm of an average-sized adult’s hand 

and can be power combined to the level necessary 

for platform and mission requirements. A fully realized, fieldable DEW system prototype is possible 

in just a few years.

69

A Fundamental Key to Next-Generation 

Directed-Energy Systems
70

Directed Energy

Technology, Modeling, and Assessment

Active Denial Array

By Randy Woods and Matthew Ketner

Active Denial Technology (ADT)—which encompasses the use of millimeter waves 

as a directed-energy, nonlethal, counterpersonnel weapon—has the potential to provide 

an important new escalation-of-force capability to U.S. operating forces. ADT projects 

a focused beam of 95-GHz millimeter waves to induce an intolerable heating sensation 

on an adversary’s skin, repelling the individual with minimal risk of injury. More than a 

decade of research has established the biological and behavioral effects of ADT for large 

spot size systems, such as Active Denial System 1 (Figure 1). While the effects of this 

large spot size system have been successfully established, the technology that produces 

those effects has the potential to progress in a number of ways, particularly with the development of smaller, lighter, and lower-cost systems.

One research effort focuses on the development of smaller, lighter, and lower cost 

ADT demonstrators that produce commensurate “ADS-effects,” with effective spot size 

and power densities on target. In support of this effort, the Joint Non-Lethal Weapons Program (JNLWP) sponsored the Naval Surface Warfare Center, Dahlgren Division 

(NSWCDD) to develop a “smart target system,” which measures the millimeter-wave 

beam using fast-response, 95-GHz diode detectors. NSWCDD subsequently developed 

and tested the W-Band Beam Diagnostic Array to characterize the system’s beam with a 

temporal resolution of 30 Hz and a high spatial resolution of 1 inch.

The current method of measuring the 95-GHz beam is to use carbon-loaded Teflon 

(CLT) to produce an average power beam image. This method works as the CLT is exposed to the system’s beam. The material heats, over a period of seconds, proportional to 

the magnitude of the radio frequency (RF) field, resulting in an image as shown in Figure 2. After the exposure, the specific heat capacity of the CLT can be used with the temperature increase in the CLT to provide an indication of the total energy deposited in the 

material. This method produces a good representation of the average RF field; however, 

any peak variations in the beam are averaged out.

To allow for high temporal-resolution measurements of the 95-GHz beam, a highdensity, 95-GHz diode-detector array was commissioned by the Joint Non-Lethal Weapons Directorate (JNLWD), and was designed and built by NSWCDD, with support from 

Millitech, Inc. The array consists of a center 11 × 11 matrix (shown in Figure 3) with four 

removable arms that can be attached (shown in Figure 4), resulting in a measurement 

area of approximately 1 × 1 m.
71

Active Denial Array

Figure 2. CLT Representation of Small, 95-GHz Spot

Each element’s profile consists of the individual horn antenna from the array, an attenuator, 

a detector, and a SubMiniature version A (SMA) 

connection to the digitizer circuitry. This configuration allows for the 

power received from the antenna 

to be attenuated and converted to a 

direct current (DC) output capable 

of being measured by an analog-todigital converter. The machined antenna elements provide a uniform 

effective area for each element, allowing field strength (W/cm2

) to be 

converted into power received (W 

or dBm). The aperture antennas 

also provide an impedance match 

between free space and the waveguide system. A cross-sectional 

view of the array element is shown 

in Figure  5, followed by a signal 

flow diagram shown in Figure 6.

The basic principle of operation 

behind the array is that the derivative of the diode detector’s power vs. output voltage curve is very 

repeatable between detector elements. Therefore, 

when the detector elements arrived at NSWCDD, 

each detector element was paired with a variable 

Figure 1. Active Denial System 1
72

Directed Energy

Technology, Modeling, and Assessment

attenuator and calibrated as a single unit. The calibration was accomplished by inserting a known 

input power of +5 dBm into the input of the attenuator and setting the DC output voltage at a predetermined millivolt (mV) output. This allowed the 

detector’s individual offset voltages to be removed 

and caused the detectors to behave in a repeatable 

manner. The attenuator is able to be adjusted by 

varying the depth that the aluminum nickel card is 

inserted into the section of waveguide.

The final section of the electrical system converts the DC voltage output from the detectors to 

a digital signal to send back to the operator station. For this, it was determined that a 16-bit digitizer would be required to enable measuring the 

microvolts output by the detectors on the low end 

of their range, while still allowing the digitizer to 

measure the full output voltage of 1.8 V for highinput powers. Also, due to the proximity of the 

operator to the array and overall system flexibility, it was determined that Ethernet communications would provide a sufficient means of reading 

the system data. 

To display the data to the operator, a two-dimensional array is populated and displayed for the 

user (shown in Figure 7). This allows values to be 

Figure 3. Main Array Face

Figure 4. Full W-Band Array

Figure 5. Cross-Sectional View of Array Element
73

Active Denial Array

read directly from the display corresponding to the 

watts per centimeter squared (W/cm2

) present at 

the array face. Data also is recorded so that it can be 

viewed later in a player application, such as a video file, or it can be viewed in a spreadsheet application, frame by frame. The data shown in Figure 7 

is representative of small-source testing performed 

recently and very clearly shows the beam profile.

Conclusion

NSWCDD engineers successfully met the 

W-band array’s design goals of providing a high 

temporal-resolution image of 95-GHz beams. The 

system has been tested against two active denial systems, providing good agreement with the 

currently accepted methods, as well as valuable 

information regarding the system’s beam characteristics. These accomplishments will allow future 

system development to take advantage of this better understanding to possibly reduce system size 

and increase the effective range. A better understanding of the 95-GHz beam helps to facilitate 

future ADT development for this much-needed, 

nonlethal escalation-of-force capability for U.S. 

warfighters, homeland defenders, and law enforcement personnel.

Figure 7. Array’s Operator Interface Showing a Small Spot Source

Figure 6. Signal Flow Diagram
74

Directed Energy

Technology, Modeling, and Assessment

Directed Energy in the Military Environment

By LT Leedjia Svec, Jeremy Beer, and Dave Freeman
75

Directed Energy in the Military Environment

The military operates in the land, air, and maritime environments. In each of these environments, 

lasers and laser devices are increasingly being seen 

and used in a variety of ways. Accordingly, the 

military must protect itself and civilians from the 

potentially dangerous effects of lasers and other directed-energy devices.

Lasers are being used on the ground to determine the intentions of people who approach 

checkpoints and to dissuade aircraft from entering 

restricted airspace. Laser weapons are also being 

developed for use in the maritime environment. 

With the use of lasers comes the requirement for 

eye protection. The eye is particularly sensitive to 

lasers and its anatomy includes optical components 

that amplify the power of incoming light. Consequently, the potential for injury or blinding is great.

Naval Medical Research Unit–San Antonio (NAMRU-SA) is poised to lead the way in researching and testing laser glare devices and laser 

eye protection. The mission of the NAMRU-SA 

is to conduct medical, dental, and directed-energy biomedical research, which focuses on ways to 

enhance the health, safety, performance, and operational readiness of Navy and Marine Corps personnel, and addresses their emergent medical and 

dental problems in routine and combat operations. NAMRU-SA was officially commissioned on 

6 May 2009 and is a subordinate command under 

the Naval Medical Research Center (NMRC) in Silver Spring, Maryland, reporting to Navy Medicine 

Support Command (NMSC) in Jacksonville, Florida. NAMRU-SA consolidates the Naval Health 

Research Center Detachment Directed Energy 

Bioeffects Laboratory, the Naval Institute for Dental and Biomedical Research in Great Lakes, and 

the NMRC Combat Casualty Care research function. As part of the Base Realignment and Closure (BRAC) 2005, NAMRU-SA has moved to Fort 

Sam Houston. Two new buildings that have been 

constructed are the Battlefield Health and Trauma Research Institute and the Tri Service Research 

Laboratory. A conceptual drawing of the NAMRUSA Tri-Service Research Laboratory (to house directed-energy research) is shown in Figure 1.

Many factors must be considered when lasers 

operate in military environments. On the ground, 

lasers offer a greater likelihood of close contact exposure. In aviation and maritime environments, 

the mobility of lasers is limited to permanent fixtures on aircraft or ships, so target acquisition can 

be much more complicated. Often ignored, but just 

as important and common to all environments, are 

the psychological factors that need to be explored. 

These factors include clarifying intentions, communications, and effectiveness. In certain situations, 

Figure 1. Naval Medical Research Unit – San Antonio Tri-Service Research Laboratory at 

Fort Sam Houston, San Antonio, Texas (artist’s concept)
76

Directed Energy

Technology, Modeling, and Assessment

sometimes lasers are coupled with other modalities, such as auditory instructions.

On the ground, laser exposure has been shown 

to interfere with driving vehicles, making color 

judgments, and target shooting. In aviation, lasers 

can interfere with pilot vision, causing afterimages, 

glare, or temporary ocular injury, with attendant 

effects on navigation and control. In the maritime 

environment, lights frequently are used to signal a 

variety of messages, from direction (left, right, etc.) 

to more complicated messages such as “man overboard.” More prolific use of lasers underscores the 

need for laser eye protection, a dynamic area of 

research, which must respond to changing threat 

wavelengths and changing environments. Figure 2 

shows NAMRU-SA personnel executing an operational field test at Kennedy Space Center, July 2009.

Recent studies undertaken by NAMRU-SA 

have investigated the use of laser dazzlers on sailors in small boats.a

 In these studies, participants 

were exposed to the laser glare at different angles 

and distances, in both day and night conditions. 

Study protocols were approved in accordance with 

the Institutional Review Board in compliance with 

all applicable federal regulations governing the protection of human subjects. Participants were given a 

survey assessing their subjective response to the laser, as well as a more objective visual eye chart. The 

Figure 2. NAMRU-SA personnel execute operational field test at Kennedy Space Center, July 2009, in 

which a nonlethal laser prototype is evaluated for power delivery (stability and beam propagation) at range 

and human visual effectiveness aboard a maritime target.

Directed Energy

Technology, Modeling, and Assessment
77

Directed Energy in the Military Environment

results suggested that participants were 

most affected by the laser at night when 

they were looking straight at it (as opposed 

to many degrees away) and at the closest 

exposure distances. The most surprising 

finding, however, was that some participants reported being drawn to the laser 

rather than away from it, especially at farther distances. Participants remarked that 

they couldn’t tell what the signal was, so 

they would want to go closer to find out. 

This illustrates that the assumption (by 

some)—that distant laser lights will deter 

and repel innocent mariners—might not 

always be true. Further research is needed 

to verify this finding, however, before employing laser glare devices in the maritime 

environment. Figure  3 shows NAMRUSA personnel executing operational field 

tests, which were conducted at Cheatham 

Annex, Virginia, and Panama City, Florida, in 2008–2009.

These studies also brought the factor 

of communication to light. Participants 

remarked that “green is not a threatening color,” and some thought “it could be 

a signal for help.” Many felt curious about 

the “blinking light” used in the study and 

would go closer or try to contact the vessel to determine the intent of the message. Green lasers are used because they 

are more visually salient; however, they 

may not be as psychologically salient. 

Participants remarked that if the signal 

were paired with another signal, such as 

an auditory one, then the message of “warning” or 

“do not come closer” might be clearer. 

Lastly, these studies brought to light the matter of effectiveness. Laser glare devices are used to 

stop or alter the behavior of the recipient, but one 

study yielded mixed results. At close distances, participants noticed the signal, felt affected by it, and 

reported that their behavior changed in the manner desired by the person pointing the laser. But 

at greater distances, behavior might not change. 

Thus, these findings need to be replicated in different maritime scenarios in order to be truly useful in 

developing laser glare devices. This particular study 

Figure 3. A compact hand-held laser is evaluated for effectiveness in 

maritime defense against small-boat attacks.

was encouraging regarding the effectiveness and visual usefulness of glare devices, but it brought up 

new questions about their psychological impact on 

behavior. Resolving these questions must be an integral goal of technical research and development 

studies to determine the operational effectiveness of 

directed-energy devices, not just for the maritime 

environment, but for all military environments.

Endnote

a. Results and technical reports are available upon request from 

the corresponding author or from the NAMRU-SA Public Affairs Officer.
78

Directed Energy

High-Power Microwave

Directed Energy Using High-Power 

Microwave Technology

By Jacob Walker and Matthew McQuage

The Directed Energy Warfare Office (DEWO) and Directed Energy Division at the 

Naval Surface Warfare Center, Dahlgren Division (NSWCDD) merge past research 

and data with continuous innovation in the field of high-power microwave(s) (HPM) 

to address the critical need for nonlethal, nonkinetic weapons. HPM weapons can be 

described as nonkinetic devices that radiate electromagnetic energy in the radio frequency (RF) or microwave spectrum. They are designed to disrupt, deny, degrade, 

damage, or destroy targets. In essence, this is achieved when high-power electromagnetic waves propagate through air and interdict targets by traveling through the exterior layers of structures and coupling energy to critical electronic components. Since 

effectiveness against a wide range of targets is the goal, HPM has become a collective 

term for various technologies: wave shapes, source frequencies, and the distribution of 

varying signal bandwidths. It is the objective of HPM research and assessment, therefore, to address targets for which no engagement option currently exists. NSWCDD is 

working to identify optimal HPM mission platforms and move relevant technologies 

into the field. 

HPM Initiatives

NSWCDD has actively pursued HPM research since the advent of the field in the 

1970s. Since then, scientists and engineers have conducted HPM research and development in many areas, including hydrogen spark-gap switching, spiral generators, and 

related technologies. More currently, the Directed Energy Division developed a variety of high-power wideband RF systems based on pulsed power and Marx generators 

(Figure 1). In addition to the extensive work accomplished in HPM and RF source development, NSWCDD contributed substantially to the area of counter-HPM vulnerability assessments. Researchers developed site assessment guides and threat brochures, 

as well as a number of wideband RF sources, to determine the susceptibility of electronic equipment to high-power RF interference. This latter effort involved assessing 

and exploiting the weaknesses of specified electronic targets to various HPM and RF 

threats. Data gleaned from these efforts was then used to support optimized prototypes 

and system designs employing effects-based design methodology. NSWCDD utilized 

these wideband RF sources to determine the susceptibility of a multitude of military 
79

Directed Energy Using High-Power 

Microwave Technology

Figure 1. Examples of NSWCDD Marx Generators
80

Directed Energy

High-Power Microwave

and electronic infrastructure equipment to highpower RF interference. 

HPM Counterattack 

Operational Overview

Research in support of HPM-driven electronic attack increased significantly as the demand 

for nontraditional warfare emerged. Traditional kinetic weapons often are of limited value in 

peace-keeping missions, for example, as today’s 

enemies frequently are embedded within civilian populations and structures. This creates the 

need for novel HPM technologies that minimize 

the risk of collateral damage while effectively 

neutralizing threats. Dahlgren researchers conduct HPM system research and development—as 

well as lethality and weapon effectiveness assessments—to address this need while developing 

technologies against a wide variety of electronic targets. These projects leverage NSWCDD’s assets, including the Maginot’ Open Air Test Site 

(MOATS), state-of-the-art RF diagnostics, and 

modeling and simulation tools to identify applications and platforms in which HPM technologies can be employed. Figure 2 shows a computer 

model of the MOATS facility and a modeling and 

Figure 2. Modeling and Simulation Depicting (a) NSWCDD Test Facility and (b) Simulation of Radiated RF

(a)

(b)
81

Directed Energy Using High-Power 

Microwave Technology

simulation graphic depicting the RF emitted by 

an HPM dipole antenna.

Potential platforms for HPM integration include: man-portable, aerial, vehicle, and vesselmounted systems. These platforms all provide 

unique methods for delivery of HPM sources. For 

example, aerial delivery—which, in many ways, is 

the most challenging due to size and weight constraints—can increase the effective range of these 

systems and can engage multiple targets at close 

range without endangering personnel. Likewise, 

vehicles and vessel-mounted HPM systems provide a way for law enforcement and the military to 

stop vehicles in chase scenarios almost as soon as 

they begin. The goal of all of these projects is to 

provide military forces with the ability to employ 

nonkinetic, electronic strike technologies against 

an adversary’s electronics.

The DEWO and Directed Energy Division are 

uniquely positioned to provide numerous capabilities for in-house development while engaging 

with the private sector to test and provide feedback on HPM systems developed externally. In 

the past decade, NSWCDD has evaluated several 

HPM systems at Dahlgren to determine their effectiveness against various electronic targets while 

maintaining the Office of the Secretary of Defense’s 

Tri-Service RF Directed Energy Weapon (DEW) 

Database. This database contains all effects data 

collected from directed-energy tests performed 

within the U.S. Air Force, Army, and Navy.

Conclusion

NSWCDD continues to pioneer HPM source 

development and lethality and integration studies, leading to the demonstration and delivery of 

prototype capabilities. It also is committed to researching and developing critical subsystems for 

HPM delivery. By leveraging numerous target assets and sophisticated diagnostic equipment—in 

conjunction with MOATS—NSWCDD has positioned itself at the forefront of HPM electronic 

attack, leading the way in the development and delivery of these capabilities to the warfighter.

Acknowledgment

Nancy Muncie, Bowhead, contributed to this 

article.

81

Directed Energy Using High-Power 

Microwave Technology
82

Directed Energy

High-Energy Laser

Laser Counter Rocket, Artillery,

and Mortar (C-RAM) Efforts

By Michael Libeau

Mortars and rockets are common weapons confronting U.S. troops abroad. Insurgents fire the inexpensive projectiles into populated areas, intending to kill or injure 

service members and to inflict physical damage. While kinetic solutions like guns and 

missile interceptors are used to counter rockets and mortars, laser counter rocket, artillery, and mortar (C-RAM) systems present a promising solution to counter these challenging threats in the near future. 

Scientists and engineers at the Naval Surface Warfare Center, Dahlgren Division 

(NSWCDD) have been researching, developing, testing, and evaluating laser C-RAM 

systems through collaboration, modeling and simulation, and experimentation. The 

Joint Technology Office (JTO) and the Directed Energy and Electric Weapons Program 

Office (PMS 405) sponsored the first year of these initiatives in 2007. Consecutive and 

current work has been sponsored by the Office of Naval Research (ONR) Expeditionary 

Maneuver Warfare and Combating Terrorism S&T Department.

Background

In preparation for the development of a laser C-RAM system, an understanding 

of the vulnerability of rockets and mortars to laser energy was crucial. Engineers from 

NSWCDD and the U.S. Army Space and Missile Defense Command (SMDC) collaborated on laser C-RAM efforts. Engineers analyzed the RAM threat and examined a 

variety of targets, accessing RAM vulnerabilities to laser energy by utilizing theoretical, numerical, and experimental work. They then developed theoretical models that 

captured the physics of the laser-induced failures of targets containing high explosives 

(HE). Additionally, NSWCDD engineers enhanced lethality simulations using a tool 

called the Effectiveness Toolbox to model engagements of RAM targets with laser energy. Figure 1 shows a screen capture from the Effectiveness Toolbox. 

The resulting simulations included results from a laser atmospheric propagation 

model and a thermal model to determine the effect of the laser energy on the target. The 

simulations also incorporated target trajectories necessary for modeling the changing 

laser conditions on the target resulting from the engagement of a ballistic target. Subsequent to modeling these effects, live testing was performed. Figure 2 shows the lasing 

and destruction of a RAM target during live testing.
83

Laser Counter Rocket, Artillery, 

and Mortar (C-RAM) Efforts

Figure 2. Explosive Target is Destroyed with NSWCDD’s Fiber Lasers

Figure 1. Screen Capture from the Effectiveness Toolbox Showing the Laser Engagement of a Mortar Target
84

Directed Energy

High-Energy Laser

Figure 3. Laser Power Spatial Variation from a C-RAM Test

NSWCDD engineers conducted two large experimental tests to determine the vulnerability of 

HE targets to laser energy using NSWCDD’s HighEnergy Fiber lasers. The first test was conducted 

jointly with SMDC. During these two tests, over 

40 RAM targets were destroyed under different laser conditions, producing significant information 

on laser lethality. Researchers measured the failure 

times of multiple targets for different laser powers, 

spot sizes, incidence angles, and aimpoints. The experimental data yielded by the tests increased engineers’ understanding of the vulnerability of targets 

containing energetic materials. This data was then 

used to benchmark predictive models.

Future tests are planned with additional HE 

targets to further the knowledge of RAM vulnerability. These tests are controlled and conducted 

carefully to ensure that good data is obtained. Accurate measurements of laser power on the target 

and the resulting target failure times must be made 

during the tests. To that end, NSWCDD engineers 

leverage Division-wide expertise in lasers and optics with its long history of explosives testing to 

achieve meaningful test results. NSWCDD personnel have been instrumental in improving techniques to measure the spatial profile of laser power 

on a target. The spatial distribution of laser power 

on a target is critical to understanding the target’s 

failure. Figure 3 shows a laser beam’s spatial power 

distribution measured during a test. 

Ongoing Laser C-RAM Initiatives

Recent advances in fiber lasers have increased 

the power outputs of these rugged, solid-state devices. Both government and contractor efforts are 

examining the application of commercial off-theshelf (COTS) lasers and other electric lasers for 

application into advanced weapon systems. The 

Navy’s Laser Weapon System (LaWS) Program, for 

example, is examining a laser system built around 

efficient fiber lasers. This is significant because a 

high-energy fiber laser system offers two critical 

advantages over gun and missile interceptor CRAM systems. First, the laser has a great depth of 

magazine since it requires only electricity for operation. Consequently, unlike a gun system, which 

has a limited supply of ammunition, a laser system is limited only by its supply of electrical energy. Second, a laser system offers a cost per kill 

that is significantly lower than alternative systems 

because only electricity is being expended instead 

of gun ammunition or a costly missile interceptor. 

This low cost per kill also better matches the low 

cost of the RAM target being engaged. 

High-Energy Fiber Laser C-RAM systems will 

provide significant advantages in defeating the 

RAM threat while augmenting existing C-RAM 

solutions. More importantly, laser C-RAM systems will help protect members of the armed forces from the inexpensive, yet often deadly threats 

posed by rockets and mortars.

84

Directed Energy

High-Energy Laser
85

Laser Counter Rocket, Artillery, 

and Mortar (C-RAM) Efforts
86

Directed Energy

Nonlethal Capabilities

Multifrequency Radio-Frequency (RF) 

Vehicle Stopper

 By Stephen A. Merryman

The widespread use of vehicle-borne improvised explosive devices (VBIEDs) in Iraq 

and Afghanistan has resulted in large numbers of military and civilian personnel being 

killed or injured. Consequently, the Joint Non-Lethal Weapons Directorate’s (JNLWD) 

top priority is to identify, investigate, and develop technologies and capabilities to nonlethally stop both vehicles and vessels outside of minimum “keep-out ranges” (i.e., ranges where the rules of engagement would dictate the use of lethal force) and to mitigate 

the blast effects from a VBIED.

One of these technologies is the multifrequency Radio-Frequency (RF) Vehicle 

Stopper (RFVS), a high-power microwave (HPM) weapon under development at the 

Naval Surface Warfare Center, Dahlgren Division (NSWCDD). A prototype RFVS system, designed to meet the mission criteria for fixed-checkpoint protection and compound protection, is slated for completion in FY13. Science and technology (S&T) work 

continues in parallel to the prototype system’s construction to broaden its applicability 

to include convoy protection and the establishment of a quick safe zone. This article describes the 4-year research effort that resulted in the specification of the RFVS system 

design. Figure 1 shows an illustration of a candidate RFVS platform with the system set 

up for fixed-checkpoint protection.

The RFVS system uses high-power magnetron tubes to generate intense RF pulses 

that interfere with a vehicle’s electronics, rendering it temporarily inoperable. The engine cannot be restarted while the RF is on but is readily restarted once the RF is turned 

off. Thus, the RFVS system allows for the maintenance of a safe keep-out zone in situations that might otherwise require the use of lethal force. The defined measure of success 

for this system is a demonstrated, effective capability against more than 80% of the candidate target-vehicle-class list, which includes passenger cars and large vehicles.

As a nonlethal capability, the effects to the target vehicle are short term and almost 

always reversible, so that the vehicle is not stranded, which would burden the warfighter with the task of its removal. Moreover, as with all directed-energy weapons, the RFVS 

system delivers energy at the speed of light. In contrast with other nonlethal vehicle 

stopping concepts and systems, however, RFVS does not need to be pre-emplaced and 

has a limitless magazine.
87

Multifrequency Radio-Frequency (RF) 

Vehicle Stopper

Background

Using HPM or RF energy to stop an automobile engine is not a new concept; it has been under 

investigation for some time in private, academic, 

and military sectors. To that end, the RFVS program leveraged as much historic work as possible while collaborating with academic and military 

laboratories and while aggressively pursuing contacts in the automobile industry to gain knowledge 

of vehicle electronic design and function.

In 2005, the JNLWD funded the then-Directed 

Energy Technology Office (DETO) at NSWCDD 

to perform an extensive reverberation chamber 

test series to characterize the vulnerability of a representative cross section of automobiles to a wide 

range of HPM source frequencies.a

 The purposes of the tests were twofold. First, the applicability of the Army’s Ground Vehicle Stopper (GVS) 

data set needed to be established for newer vehicles, and second, a thorough, source-technology 

independent assessment of vehicle vulnerabilities 

needed to be performed. The rationale behind the 

latter was to establish vehicle vulnerabilities without inadvertently biasing the process. Only after 

the full assessment was performed would factors 

such as concept of operations (CONOPS) and system requirements come into play. Figure 2 is a photograph of reverberation chamber testing.

Over the past decade, a significant number of 

private, academic, and military laboratories have 

investigated the susceptibility of automobiles to 

HPM energy. The range in approaches spans the 

gamut from isolated component testing, through 

direct injection and radiated testing of electronic 

control units (ECUs), and continuing through full 

vehicle radiated testing. Each of the different test 

methods has its strengths and weaknesses. Testing 

of isolated ECUs in controlled laboratory conditions is arguably the best way to determine exactly 

how a specific unit is responding to the RF. However, whether or not the identified susceptibilities 

continue to hold true when the unit is in place in a 

Figure 1. Illustration of Candidate RFVS System Setup for Checkpoint Protection
88

Directed Energy

Nonlethal Capabilities

vehicle, or whether the results apply to other vehicles’ ECUs, remains a significant question that limits the applicability of the results.

Full vehicle testing and failure analysis of the 

ECU can be a daunting task. That said, full vehicle testing affords the advantage of ensuring that 

the response is commensurate with expectations 

of genuine engagements. The test approach one 

chooses to take depends upon resources, test facility availability, and most importantly, the objectives 

of the program. For the RFVS program, the objectives were to identify an HPM waveform that is 

effective against a broad class of the candidate target vehicles and to ensure that the identified waveform could be generated with a source that can be 

packaged in a footprint and cost amenable to military users. To meet the program’s objectives, the 

RFVS program chose to invest the majority of its 

resources in full vehicle testing. While the focus of 

the effects testing portion of the RFVS program has 

remained on full vehicle testing, both time and resources have been devoted to fostering and maintaining connections with academia and the auto 

industry. There is concerted effort to keep abreast 

of the latest trends in automotive technology, to 

ensure that the current RFVS system design will 

continue to be effective against future vehicle designs, and to leverage all research that might aid in 

future RFVS designs.

System Operation

The majority of current HPM system concepts 

employ a narrowband, single-frequency HPM 

source. In contrast, RFVS utilizes multiple HPM 

Figure 2. Vehicle on a Dynamometer in the NSWCDD Reverberation Chamber
89

Multifrequency Radio-Frequency (RF) 

Vehicle Stopper

frequencies. The rationale for using multiple frequencies is associated with increased system effectiveness. Electromagnetic (EM) energy can be used 

to disrupt or damage an electronic target. In order 

for the energy to affect the electronics, however, it 

must be able to reach a critical component(s) inside the target. This involves a process referred to 

as coupling. Different EM waveforms are more or 

less effective against specific targets depending, in 

part, on their frequency, as different frequencies 

couple better or worse depending on varying target 

geometries. To be specific, each piece of electronics has specific resonance frequencies that most effectively facilitate coupling energy to the target. 

Unfortunately, these resonant frequencies can be 

unique to each piece of equipment. Consequently, 

a single-frequency waveform might be very effective against one target, but less effective against another target. Therefore, a system that utilizes either 

a sweep of frequencies or multiple frequencies will 

be more effective against a larger target set. This is 

not a novel idea, but rather one that has been readily acknowledged within the HPM community for 

some time and fervently embraced by the RFVS 

program. Current technology limitations prohibit high-power-swept frequency sources as viable 

options, leading to the idea of a multifrequency source. The more frequencies that are used, the 

more effective the system; however, a trade-off is 

made with system size and cost as the number of 

source frequencies is increased.

Brassboard System

After completion of the exhaustive vehicle effects characterization testing in 2006, the RFVS 

program identified the optimal number of frequencies needed to meet mission requirements. It 

then used this information in the design and construction of the Brassboard System. The purpose in 

constructing the Brassboard System was to demonstrate the benefit of the multifrequency approach 

and the ability to meet mission objectives with 

specified power on target requirements. Construction of the RFVS Brassboard System began in 2007 

and was completed in 2008. The Brassboard System was not constructed with specific system footprints in mind. Thus, the antenna and conex used 

are significantly larger than those in the prototype 

design. The RFVS team collaborated with a Marine Corps service representative identified by the 

JNLWD to flesh out the specifics of the mock 

checkpoint to be used in the RFVS Brassboard System Demonstration. Figure 3 provides a diagram 

of the checkpoint setup used in the RFVS Brassboard Demonstration. Figure 4 provides photographs of the RFVS Brassboard System.

Figure 3. Schematic of Checkpoint Setup
90

Directed Energy

Nonlethal Capabilities

Figure 4. Photograph of the RFVS Brassboard System and Demonstration Setup

Demonstration Test Setup
91

Multifrequency Radio-Frequency (RF) 

Vehicle Stopper

The Brassboard System Demonstration was 

conducted in Spring 2008. The Demonstration 

was a success, and funding for the RFVS prototype 

was consequently approved. To date, 42 passenger vehicles (cars, pickup trucks, vans, and sport 

utility vehicles (SUVs)) and 3 large trucks (dump 

truck and tractors) have been tested as part of the 

RFVS program.

Way Ahead

The JNLWD continues to work with the Directed Energy Warfare Office (DEWO) toward the 

development of a fieldable multifrequency RFVS 

system. Once the capability is fully developed, 

91

Multifrequency Radio-Frequency (RF) 

Vehicle Stopper

tested, and certified ready for operational use, 

warfighters and civilians alike will benefit greatly. 

Lives will no doubt be saved using the ability to 

stop vehicles nonlethally and mitigate the blast effects from VBIEDs.

Acknowledgment

Dr. Cynthia Ropiak (SAQ Consulting) contributed to this article.

Endnote

a. The Directed Energy Technology Office (DETO) was renamed the 

Directed Energy Warfare Office (DEWO) in August 2009. For reference, see the charter for the DEWO, NSWCDD, 17 August 2009.
92

Directed Energy

Nonlethal Capabilities

High-Power Electrical Vehicle-Stopping Systems

By Jordan Chaparro and Melanie Everton

The military needs devices that can safely and reliably stop or arrest vehicles. The 

primary concern is security at entry control points and vehicle check points similar to 

the one shown in Figure 1. In such scenarios, it is desirable to be able to stop unauthorized vehicles at predefined standoff ranges to protect personnel, equipment, and critical infrastructure.

Both the military and civilian law enforcement agencies face similar issues with 

chase scenarios, where concerns over bringing an offending vehicle to a stop without 

killing or injuring innocent civilians, or causing collateral damage, often prolongs highspeed pursuits. That said, currently employed nonlethal options for arresting vehicles 

have significant logistical limitations and carry a high cost per use.

The Naval Surface Warfare Center, Dahlgren Division’s Directed Energy Warfare 

Office (DEWO), under the sponsorship of the Joint Non-Lethal Weapons Directorate 

(JNLWD), investigated compact systems designed to couple high-power electrical impulses to a target vehicle to stop its engine. Such systems are highly portable, can operate remotely, can be deployed quickly by a two-man team, and can engage hundreds of 

targets before requiring any significant maintenance.

System Overview

Conceptually, electrical vehicle-stopping systems are fairly simple devices. The systems use several stages of energy compression to take a low-peak power source—like a 

battery pack—and create very intense, short-duration, oscillating electrical impulses. The 

block diagram, shown in Figure 2, illustrates the principal components of such a system.

A high-energy density, 300-V lithium battery pack, similar to what might be found 

in a hybrid vehicle, serves as the prime power source for the device. These batteries are 

capable of driving the system for hundreds of engagements before requiring recharge.

The direct current bus from the batteries is stepped up to several kilovolts in order 

to charge a capacitive voltage multiplier, such as a Marx Generator, Spiral Line Generator, or Tesla Transformer. Once triggered, these generators charge a resonant circuit to 

hundreds of kilovolts which, when switched, generate the desired oscillating waveform. 

Coupling this electrical pulse to a target may be accomplished by direct electrode contact, by radiating the waveform from a broadband antenna structure, or by a combination of both methods.
93

High-Power Electrical Vehicle-Stopping Systems

Figure 1. An Azerbaijani Soldier Guarding Entry Control Point 1 at the Haditha Dam in Support of Operation Iraqi Freedom

Figure 2. System Block Diagram for Generic Electrical Vehicle-Stopping Systems
94

Directed Energy

Nonlethal Capabilities

The system is monitored and controlled by 

an integrated system computer. A laptop computer, remotely connected to the system controller through either fiber optic or a wireless network, 

can be used to arm the system. At this point, motion detection sensors trigger the pulse train upon 

the targeted vehicle. The laptop can also be used to 

monitor the system’s status, change system parameters, and receive data collected during the last engagement event.

A conceptual rendering of how such a system might look when in use is shown in Figure 3. 

Traffic would be funneled with barriers to a single lane. When not engaged, the system electrodes 

would sit flush with the roadway unit, with an exposed height of less than 3 inches. When required, 

the electrodes could be released to make contact 

with a vehicle’s undercarriage and deliver the electrical impulses.

Comparison with Existing Systems

Tire spike systems are frequently employed but 

do not limit the momentum, drive, or control of a 

vehicle to an extent that could be useful in any type 

of control or checkpoint scenario. Consequently, 

while tire spike systems are primarily used in highspeed pursuit applications, they are limited, in that 

they cripple the target just enough to allow law enforcement to force the vehicle to a stop.

Restraining nets are most comparable to electrical vehicle stoppers with respect to their intended application and desired effect. Restraining net 

systems and electrical vehicle stoppers both completely arrest vehicles, although by different means. 

Restraining nets bind the front axle of the vehicle, 

causing it to forcibly lose momentum and skid to 

a stop. Thus, the vehicle operator loses the ability to steer the vehicle, further resulting in a lower 

potential for collateral damage. Electrical systems 

stop the engine of the vehicle, leaving the operator 

with control for the duration of the vehicle’s momentum. Physical barrier structures can then be 

employed to force an affected vehicle to stop in a 

fairly short distance. Modern vehicles lose power 

steering when the engine is cut off, such that the 

maneuverability of the vehicle is limited enough to 

Figure 3. Conceptual Rendering of an Employed Electric Vehicle Stopping System
95

High-Power Electrical Vehicle-Stopping Systems

allow normally nonrestrictive serpentines to be effective at limiting roll-off distances.

One key logistical advantage of electrical vehicle stoppers, compared to restraining nets, is the 

average cost per engagement. Restraining net systems are one-time use devices that cost several 

thousand dollars each. Electrical systems initially 

cost tens of thousands of dollars but can perform 

thousands of stops within the expected lifetime of 

the device. Also, there is no requirement to physically reset or reload an electrical system, as with 

restraining nets. The maintenance required for 

electrical systems involves the occasional replacement of electrode arms and the inspection of the 

system connections and pressure levels.

Operationally, both systems have limitations on 

the types of targets that can be effectively stopped. 

Restraining nets are limited by vehicle momentum, which can be a product of high speeds or large 

vehicles. Electrical systems are not limited by vehicle size or speed, but they require additional support from structures—such as serpentines or speed 

bumps—to force the target to brake and dissipate 

its momentum once the engine has been stopped.

Both devices typically cause damage to targeted, stopped vehicles. Restraining nets almost always cause tire damage. Less commonly, brake 

lines, front axles, wheels, and transmissions also 

might be damaged. Electrical systems typically 

damage engine controllers, security modules, and 

engine sensors. In addition, noncritical parts—

such as gauges, radios, and cabin fans—also might 

be damaged. Moreover, moving affected targets is 

much less of an issue with electrical stoppers than 

vehicles stopped by net systems, which must first 

have the net cut away and freed before the target is 

moved to the side of the roadway.

System Refinement and 

Look Forward

Previous attempts to field electrical vehiclestopping systems have been hampered by limited success rates on a large population of vehicles. 

Many models of vehicles are easily affected by any 

type of large injected current, while others are fairly resistant. Through carefully designed and controlled experiments, and logistical regression 

modeling techniques, the DEWO team has been 

able to determine key waveform attributes that 

scale with stopping effectiveness rates on a representative population of vehicles. Successful stop 

rates exceeding 90 percent have been achieved on 

a diverse vehicle test set by engineering system 

resonators to enhance system performance The 

DEWO team, through continued research, testing, 

and evaluation, is continuing its work to increase 

the reliability and effectiveness of these systems to 

make them more compact and to improve their 

functionality for future military and law enforcement applications.
96

Directed Energy

Nonlethal Capabilities

Nonlethal Small-Vessel Stopping With 

High-Power Microwave Technology

By Jacob Walker
97

Nonlethal Small-Vessel Stopping With 

High-Power Microwave Technology

Figure 1. Depiction of a Small-Vessel Swarm Ready to Attack 

The employment of small vessels to attack merchant ships and other seafaring units has emerged 

as a significant threat to international navigation 

and safe operations on the high seas. Along with 

swarm tactics, small vessels have been known to 

carry improvised explosive devices, help smuggle terrorists and weapons, and serve as attack 

platforms on the water for larger weapons. While 

kinetic solutions serve as the decisive option, alternative solutions that employ nonlethal means are 

being explored. A depiction of a swarm of small 

vessels ready to attack is shown in Figure 1.

The Naval Surface Warfare Center, Dahlgren 

Division’s (NSWCDD’s) Directed Energy Warfare 

Office (DEWO) is evaluating directed-energy (DE) 

concepts based on high-power microwave (HPM) 

technology for nonlethal vessel-stopping applications. Nonlethal weapons are defined by the Department of Defense (DoD) as weapons that are 

explicitly designed and primarily employed so as to 

incapacitate personnel or materiel while minimizing 

fatalities, permanent injury to personnel, and undesired damage to property and the environment.1

Several methodologies exist for using nonlethal means to stop small vessels. They include:

•	 Running-gear or prop entanglement systems

•	 Exhaust stack blockers

•	 A sea-anchor vessel-stopping system, which 

casts a net across the bow of a vessel to impart resistance

•	 Small-craft disablers, which insert a spear 

into the hull and deploy a fin that drags in 

the water, making steering impossible

Prop entanglement systems, exhaust stack 

blockers, and sea-anchor systems are useful and effective, but all are operationally difficult to deliver when deployment methods rely on positioning 

them in front of, or directly over, a vessel moving 
98

Directed Energy

Nonlethal Capabilities

at high speeds. Small-craft disablers also are a formidable vessel-stopping solution and may be easier to deploy, but they cause permanent damage to 

the vessel in question.

Under the direction of the Joint Non-Lethal 

Weapons Directorate (JNLWD), the DEWO is in 

the initial stages of a multiyear effort to evaluate 

DE concepts for nonlethal vessel-stopping applications. It is currently focusing on HPM technology. 

This technology uses HPM sources to radiate radio 

frequency (RF) pulses downrange to interfere with 

motor-control electronics and significantly impede 

or stop small-vessel motors with minimal collateral damage. These RF pulses can be generated using 

different technologies ranging from wideband LC 

oscillators and microwave tubes (e.g., magnetrons, 

klystrons, and backward wave oscillators) to emerging solid-state technologies (e.g., nonlinear transmission line and photo-conductive switching). An 

outboard motor on a test stand is shown in Figure 2.

In comparison to kinetic weapons or other nonlethal systems, HPM avoids gross physical destruction to the vessel while, more importantly, providing 

zero-to-low risk of human injury. HPM accomplishes this at safe distances using speed of light delivery, 

therefore making evasion difficult, if not impossible, 

with the added benefit of scalable effects ranging 

from disruption to damage. Despite its numerous 

advantages, the use of HPM technology as a nonlethal weapon presents challenges as well, including 

a trade-off between system size and standoff range. 

This is particularly important when considering the 

use of HPM systems in different environments.

Upfront HPM source development costs represent one of the biggest challenges. However, 

long-term savings associated with HPM technology can offset this challenge. For example, prop entanglement systems might be deployed only once 

before they are rendered useless. HPM sources integrated onto a ship or other military vehicle 

can be employed in potentially thousands of missions, therefore resulting in a lower cost per single 

use, bringing overall associated costs of the system down significantly. Priorities for HPM nonlethal weapons include developing a system effective 

against different types of small vessels.

NSWCDD’s Directed Energy Division began 

HPM susceptibility testing to determine the effectiveness of HPM weapons against relevant outboard engines. This involves testing small vessels in 

Directed Energy

Nonlethal Capabilities

Figure 2. Outboard Motor Test Stand 
99

Nonlethal Small-Vessel Stopping With 

High-Power Microwave Technology

a variety of environments, including reverberation 

and anechoic chambers, and open-air testing. All 

help identify different, effective waveform parameters such as frequency, pulse width, rise time, and 

required power or energy on target. They further 

facilitate the identification of design specifications 

necessary for an eventual HPM source. This source, 

once developed, will then be integrated into one 

of several potential platforms. Candidate concepts 

of deployment include U.S. Coast Guard and naval vessels in addition to unmanned surface or aerial vessels. Another potential application might be 

to supplement existing Coast Guard or Navy platforms used for fast-boat interdiction with an HPM 

vessel-stopping capability. A small-vessel test using 

an HPM source is shown in Figure 3.

Developing solutions for the growing threat 

that small vessels pose to navigation and safe operations in the world’s oceans is one of JNLWD’s 

top priorities. Using nonlethal HPM weapons to 

stop vessels will provide the warfighter with a viable option for swarm threat and fast-boat interdiction. DEWO is working diligently to accelerate this 

technology and provide a DE alternative to kinetic 

weapons and fulfill this long overdue capability gap.

Figure 3. Small-Vessel Testing Using a High-Power Microwave Source

Reference

1. Department of Defense Dictionary of Military and Associated 

Terms, Joint Publication 1-02, 12 April 2001 (as amended through 

19 August 2009).
Directed Energy

Volume 7, Issue No. 4

We look forward as we provide enterprise-wide 

technical and strategic leadership for the efficient 

and effective development, acquisition, and fielding 

of directed-energy systems for the warfighter.

Dale Sisson

Head, Electromagnetic and 

Sensor Systems Department 

NSWCDD, Dahlgren, Virginia
NSWCDD/MP-09/34

Statement A: Approved for public release; distribution is unlimited

Fallen Warriors

Here we honor those who died while serving their country

Volume 7, Issue No. 4