NASA / TMn2002-211880 AIAA-2002-3675

NASA's Hall Thruster Program 2002

Robert S. Jankovsky, David T. Jacobson, Luis R. Pi_ero,

and Charles J. Sarmiento

Glenn Research Center, Cleveland, Ohio

David H. Manzella

University of Toledo, Toledo, Ohio

Richard R. Hofer, and Peter Y. Peterson

QSS Group, Inc., Cleveland, Ohio

September 2002
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NASA / TM--2002-211880

NASA's Hall Thruster Program 2002

AIAA-2002-3675

Robert S. Jankovsky, David T. Jacobson, Luis R. Pi_ero,

and Charles J. Sarmiento

Glenn Research Center, Cleveland, Ohio

David H. Manzella

University of Toledo, Toledo, Ohio

Richard R. Hofer, and Peter YoPeterson

QSS Group, Inc., Cleveland, Ohio

Prepared for the

38th Joint Propulsion Conference and Exhibit

cosponsored by the AIAA, ASME, SAE, and ASEE

Indianapolis, Indiana, July 7-10, 2002

National Aeronautics and

Space Administration

Glenn Research Center

September 2002
This report contains preliminary

findings, subject to revision as

analysis proceeds.

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

Available from

National Technical Information Ser_,ice

5285 Port Royal Road

Springfield, VA 22100

Available electronically at http://gltrs.grc.nasa.gov
NASA'S HALL THRUSTER PROGRAM 2002

Robert S. Jankovsky, David T. Jacobson, Luis R. Pifiero, and Charles J. Sarmiento

National Aeronautics and Space Administration

Glenn Research Center

Cleveland, Ohio 44135

David H. Manzella"

The University of Toledo

Toledo, Ohio 43606

Richard R. Hofer and Peter Y. Peterson

QSS Group, Inc.

Cleveland, Ohio 44135

Abstract

The NASA Hall thruster program currently supports a number of tasks related to high power thruster development

for a number of customers including the Energetics Program (formerly called the Space-based Program), the Space

Solar Power Program, and the In-space Propulsion Program. In program year 2002, two tasks were central to the

NASA Hall thruster program: 1.) the development of a laboratory Hall thruster capable of providing high thrust at

high power; 2.) investigations into operation of Hall thrusters at high specific impulse. In addition to these two

primary thruster development activities, there are a number of other on-going activities supported by the NASA Hall

thruster program. These additional activities are related to issues such as high-power power processor architecture,

thruster lifetime and spacecraft integration.

Introduction

The NASA Hall thruster program at the Glenn Research

Center (GRC) currently supports a number of tasks

related to high power thruster development for a

number of customers including the Energetics Program

(formerly called the Space-based Program), the Space

Solar Power Program, and the In-space Propulsion

Program. High power thruster development is being

emphasized because recent mission analyses have

shown a need for higher power electric propulsion

systems for both Earth orbital and deep space

applications. However, these different applications

require propulsion systems with different optimal

characteristics. Earth orbital applications such as space

tugs, spacecraft orbit insertion, etc. benefit from high

thrust electric propulsion systems for timely space

transfers. In contrast, deep space missions typically

have large delta V requirements necessitating high

specific impulse._-t° For recently considered power rich

spacecraft architectures, both high power and high

specific impulse propulsion systems are required, t_ The

application of Hall thrusters to either mission type

requires substantial technology advancements from

state-of-the-art (SOA) thrusters.

In program year (PY) 2002, two tasks were central to

the NASA Hall thruster program: 1.) the development

of a laboratory Hall thruster capable of providing high

thrust at high power; 2.) investigations into operation

of Hall thrusters at high specific impulse.

Specifically the first task resulted in investigations of

the issues associated with scaling a single thruster to

power levels substantially in excess of the SOA. A 50-

kW class Hall thruster was designed, built and operated

over the range of 9 to 72 kW. The second task has

focused on investigating factors critical to high specific

impulse operation. This year the investigation has

considered the role of magnetic field topography on

high voltage operation.

In addition to these two primary thruster development

activities, there are a number of other on-going

activities supported by the NASA Hall thruster

program. These additional activities are related to

issues such as thruster lifetime, high-power power

processor architecture and spacecraft integration.

Thruster lifetime issues were investigated by

considering the impact of Hall thruster operation at high

voltage on thruster lifetime. Breadboard power system

tests were conducted with a single power converter that

may be suited for high-power power processing unit

(PPU) architecture studies. Impedance measurements of

a Hall thruster were made in an effort to develop an

electrical model of a Hall thruster to enable optimum

"NASA Resident Research Associate at Glenn Research Center.

NASA/TM--2002-211880 1
andcosteffectivePPUdesign.Finally,aneweffortto

considerthedynamicelectrical behaviorof Hallthruster

dischargeswasinitiated.This was deemed necessary

due to the importance of electro-magnetic interference

(EMI) concerns as a spacecraft integration issue. A

detailed overview of each of these activities and their

current status are included in this report.

High Power-High Thrust Performance

Mission planners for future NASA applications have

considered Hall thruster propulsion systems up to

megawatt class power levels. These studies have shown

that Hall thrusters offer a unique combination of thrust,

specific impulse, and efficiency that make them well

suited for Earth-orbital applications and other

applications involving significant gravity wells. 4"vTwo

technical approaches to developing high power Hall

propulsion systems have been considered: building a

large monolithic, high-power thruster of the desired

power level or building an array of smaller thrusters that

collectively operate at the desired power level. _-''_3 Due

to ground testing constraints, _4"_5 likely spacecraft

architectures and reliability/redundancy issues a

multiple thruster approach would likely be preferred,

especially at megawatt power levels. However, the

maximum size for any single thruster has not been

adequately investigated, so it is yet unclear what

number of thrusters would be required for high power

missions. Clearly, a megawatt cluster of I kW Hall

thrusters (the current SOA) is not the answer, as this

would result in a system consisting of 1000 engines. A

more manageable and reasonable approach suggests

clusters of no more than ten engines, or 100 kW per

thruster for a megawatt class mission. The current

effort seeks to experimentally investigate the issues

associated with scaling a single thruster to power levels

substantially in excess of the 1 kW SOA. Synergistic

work funded by the United States Air Force is

concurrently investigating issues of developing

clusters. _3 The understanding gained in both programs

will significantly advance the mission applicability of

high power Hall thruster propulsion systems.

The NASA Glenn Research Center (NASA GRC)

experimental program utilized the laboratory model

NASA-457M thruster (Figure I). The thruster was

designed and fabricated to nominally operate at 50 kW

and 100 A. The initial test program focused on

establishing the operational characteristics and

performance of the thruster at conservative power

densities to identify any potential design deficiencies

and to evaluate the viability of the scaling relationships

used to design the thruster. Subsequent tests

investigated thruster performance over an extended

range of operating conditions. The results, as can be

seen in Figure 2, demonstrated operation up to 72 kW

and 3 N of thrust. At the design point of 500 V, 100 A

discharge specific impulse and efficiency were 2747

seconds and 63°//,, respectively. Total specific impulse

and efficiency with a non-optimized cathode were 2528

seconds and 56%, also at 500 V, 100 A. Thruster

operation was stable over all conditions; the maximum

power demonstrated thus far being limited only by

available power supplies. Manzella, et al. has a

complete description of the thruster and test results.16

An extensive follow-on test effort is planned. This will

include an attempt to evaluate the influence of the test

facility on the measured results as well as additional

efforts to maximize the performance envelope of the

NASA-457M with regard to thrust density and power

density. Very high thrust density operation will be

investigated by considering operation at discharge

currents much greater than 100 A at discharge voltages

of 150 to 200 V. High power density operation will also

be revisited at voltages in excess of the nominal 500 V

design point.

These efforts will focus on the effect of an auxiliary

magnetic trim coil incorporated in the NASA-457M.

Other NASA GRC funded efforts have recently shown

how similar trim coils can enable efficient operation

over a wide range of operating conditions. TM

Figure I - NASA-457M (large thruster in the center),

NASA-120M (small thruster in the center), SPT-100

(left), T-160E (right).

NASA/TM--2002-211880
3.5

3

2.5

2

1.5

1

0.5

0

+i_ I+"

0 10 20 30 40 50

Power, kW

,,,+ •

_..'-

60 70 80

Figure 2 - NASA-457M Hall thruster demonstrated

operating range.

Previous tests on smaller thrusters at NASA GRC have

shown maximum discharge efficiencies at discharge

voltages of 500 to 800 V depending on the flow

rate. l°'2° Operation up to 1000 V and 100 kW will be

investigated in order to establish maximums with regard

to efficiency and specific impulse for the NASA-457M.

These results will be incorporated into the findings from

the high specific impulse work to be described

subsequently.

50 kW Hall Thruster Development

This development effort is sponsored by the In-Space

Program and is developing a 50 kW-class Hall

propulsion system through contract with industry. In

February 2001, NASA released a request for offer

(RFO) for the design and development of a 50 kW Hall

thruster that could minimally provide 2.5 N of thrust at

50 kW using xenon as a propellant with a target thruster

efficiency of at least 60%.

Proposals were received, evaluated and Phase 1 design

awards were made to General Dynamics and Busek Co.

Due to funding limitations, only the General Dynamics

Phase II fabrication option was exercised. General

Dynamics offered two concepts including an SPT-type

device and a SPT/TAL hybrid device. These proposed

devices have been designed with an aggressive power

density to enhance performance and reduce thruster

mass. Typical Hall thruster power densities are

nominally 0.55 W/mrn 2 whereas the thrusters being

considered will have a nominal power density of

1. I W/mm 2.

In PY2002, funding constraints limited the scope of this

effort to the fabrication of these devices. In PY2003,

the functionality and performance of both thrusters will

be evaluated. The thermal design will be verified and

feasibility of the elevated power density assessed.

High Specific Impulse Performance

The Hall thruster program at NASA GRC has in recent

years awarded several contracts to explore extending

the operational envelope of Hall thrusters from the

current SOA. These efforts have included

investigations of operating thrusters at specific impulses

(Isp) as low as 1000 seconds 17 and as high as 4100

seconds, t+-2

Extending the operational envelope of Hall thrusters

will benefit the two most prevalent trends in the

community today, multi-mode and high power thrusters.

For multi-mode thrusters, developing an understanding

of the processes involved has the potential to lead to

Hall thrusters that operate at lsps and efficiencies

comparable to ion thrusters while offering the benefits

of operating the same thruster in high thrust mode at

reduced lsp (~1000 seconds). For high power thrusters,

developing the design knowledge to extend the efficient

operating range could be vitally important in controlling

waste heat. A 50 kW Hall thruster utilizing standard

design philosophies will most likely be about 60%

efficient, which translates to as much as to 20 kW of

waste heat that must be radiated or conducted away

from the thruster. Clearly, the ability to increase the

efficiency of a high power Hall thruster beyond the

SOA would be beneficial to spacecraft integration

issues.

In the high lsp regime, contracts were awarded in

previous years to investigate Hall thruster performance

characteristics at Isp's greater than 3000 seconds. The

first supplier was the Boeing Corporation, which

through subcontract to TsNIIMASH delivered the D-80

anode layer thruster. '° The Atlantic Research

Corporation supplied the second thruster, through

subcontract to Fakel. This device was a magnetic layer

thruster designated the SPT-I.]9 The third supplier was

the Busek Co., which built the BHT-HD-1000, also a

magnetic layer thruster. -,l The thrusters have been

operated at maximum voltages of 1700 V, 1250 V, and

1000 V for the D-80, SPT-I and BHT-HD-1000,

respectively. The D-80 demonstrated an lsp range of

1600--4100 seconds, the SPT-I a range of 1600-3700

seconds and the BHT-HD-1000 a range of 1600-3300

seconds. Each thruster exhibited a range of voltages

where the anode efficiency was maximized. This

voltage was between 500-800 V depending on the mass

flow rate. Precise evidence for this peak efficiency was

not identified, but it was likely attributable to either

increased electron current due to insufficient magnetic

NASA/TM----2002-211880 3
trappingor increasedproductionof multiply-charged

speciesduetothehighvoltages.

Buildingon theseefforts,the objectivesof NASA

PY2002andbeyondareto: 1) identifythephysical

mechanisms thatresultinthismaximumefficiencywith

voltage,and2) developthedesigntoolsnecessaryto

extendefficientoperationiexcessofthe800Vceiling

recentlyobserved.To achievethesegoals,internal

GRCeffortsareunderwayaswellasinvestigations

throughagrantwiththeUniversityofMichiganj8"2-" and

throughanNRAwithMITandBusek. -'3

InconjunctionwiththeUniversityof Michigan, a 5 kW

high voltage thruster designated the NASA-173M V.l

has been constructed and is shown in Figure 3. Initial

testing has concentrated on characterizing the

performance and identifying design variables most

likely to increase efficiency through improvements. A

follow on thruster designed entirely at GRC, the NASA173MV.2, is currently in fabrication and scheduled for

testing in Fall 2002.

Figure 3 - Studio portrait of the NASA-173M V. 1.

Recent results from the NASA-173M V.I operating at

300-1000 V and 5 mg/s are shown in Figure 4.18 The

figure shows two sets of data, with and without a trim

coil energized. When there is no trim coil, only the

inner and outer coils are used (the traditional design),

the previously observed peak efficiency is found. With

the trim coil energized, the efficiency is maintained at

>50% above 600 V, demonstrating that efficient Hall

thruster operation is possible at high voltage when the

magnetic field is tailored for the operating point.

Similar investigations at higher flow rates, and

correspondingly higher efficiencies, are planned for the

NASA-173M V.2 in coming months.

Work beyond PY2002 will focus on characterizing the

plasma parameters of the NASA-173M thrusters using

several diagnostics to assess what effects changes in the

thruster are having on performance. These diagnostics

will likely include the use of ion current density probes,

and energy diagnostics such as ExB probes or ion

energy analyzers. Internal plasma diagnostics using a

high-speed probe system at the University of Michigan

are also planned.

0.53

0.51 I']

[]

0.49

047

0.45

0,43 ]

0

/k

A

6Trim coil current = 0 I

m

o Trim coil current ¢:0

200 400 600 800 1000 1200

Discharge Voltage. V

Figure 4 - Efficiency versus voltage for the NASA

173M V.I operating at 5 mg/s.

High Voltage Thruster Life

In 1999, NASA GRC began investigating Hall thrusters

with specific impulses greater than the 1500 to 1700

seconds of SOA thrusters. 19--'2"24This increase in

specific impulse over conventional xenon Hall thrusters

was achieved by increasing discharge voltages from

300V up to 1700 V. Operation at these elevated

discharge voltages substantially increased the kinetic

energy of the ions produced during thruster operation.

At any discharge voltage, some small fraction of the

ions accelerated by the thruster impinge upon the

thruster itself, eroding critical components, eventually

causing the thruster to wear out. While experiments

have shown this in the laboratory at voltages of 300-

500 V, the effect of discharge voltages in excess of

500 V on thruster lifetime has not been investigated.

The objective of the current investigation was to

evaluate the effect of high voltage operation on thruster

erosion. Specifically, a D-80 anode layer thruster was

operated at 700 V and 4 A. A 700 V discharge voltage

NASA/TM-----2002-21 i 880
was selectedbecausea previousperformance

investigation demonstrated maximum efficiency at

voltages between 500-800 V. -_° A 4 A discharge

current was selected for extended operation because this

was the maximum value that could be achieved while

maintaining the desired steady state thermal conditions.

The anode efficiency and specific impulse at this

operating point were 57% and 2625 seconds,

respectively. While efficiency over 70% and specific

impulse over 4000 seconds were demonstrated at higher

discharge voltages and currents, high thruster

temperature prohibited operation for extended periods

of time. The thruster was operated for a total duration

of 1200 hours in this investigation. Erosion of critical

thruster components was evaluated every 300 hours.

The thruster exhibited asymmetric erosion that exposed

the magnetic poles between the 600 and 900 hour

increment (Figure 5). Even as the magnetic poles were

exposed the robustness of the thruster was demonstrated

by no change in operating parameters. Jacobson has a

complete description of the thruster and test results. _,5

/

l

T= 1200 hours

Magnet Pole

T=0 hours

Guard Ring

2nd Stage Anode

I n Stage Anode

power and discharge voltage in excess of 600 V. SOA

power processing units (PPUs) include a single

converter as well as modular power architectures.

Single converter designs are simple but their efficiency

is largely reduced as the output and input voltage ranges

increase. Also, for packaging considerations, these are

only applicable to a few kilowatts. Modular designs can

process more power with higher efficiency at the

expense of added complexity. They also allow the use

of redundant modules for higher PPU reliability.

A breadboard discharge power module capable of

operating at ! kW was designed, built and integrated

with the NASA-120M Hall thruster. A printed circuit

board (PCB), shown in Figure 6, was fabricated based

on the design to facilitate fabrication of additional

modules. These 300 V modules will then be used to

build a high power discharge supply capable of

operating the modules in either parallel for high current

operation or series for high voltage operation. This

design will also be used as foundation for a multi-kW

PPU for high power applications.

Figure 5 - D-80 Hall thruster high voltage erosion

cross-sections.

Power Electronics

Discharge Power Module Development

Previous efforts to develop power electronics for Hall

thruster systems were targeted for the 1 to 5 kW power

range and output voltages of approximately 300 V.

New Hall thrusters are being developed for higher

power, higher specific impulse, and multi-mode

operation. These thrusters require up to 50 kW of

Figure 6 - NASA GRC's l-kW discharge power

module.

The discharge power module operates from an input

voltage range of 80 to 120 V. Efficiencies in excess of

96 percent were measured, as shown in Figure 7. The

mass of the PCB version of the power module is

0.765 kg. Pifiero has a complete description of the

development and testing. 26

NASA/TM--2002-211880 5
9"7 ...................................................................

/

240Vout

94

93

92

91

0 500 1000 1500

Module Powe

Figure 7 - Performance of the NASA l-kW discharge

power module.

Hall Thruster Impedance Measurements

Hall thrusters exhibit discharge current oscillations in

the 104 Hz range. A two-stage L-C output filter is

traditionally used on the output of the discharge supply

to protect it from these oscillations, which could induce

instabilities and/or cause failure. If this filter is underdesigned, it will not provide enough protection and

over-designing could unnecessarily increase PPU mass.

To design an optimum filter, it is necessary to have a

clear understanding of the impedance of the plasma

discharge in the thruster. An optimum discharge filter

design provides impedance matching and stable

operation between the thruster and the discharge supply

under any operating condition. Understanding the

electrical impedance of the plasma discharge can also

help develop and validate electrical models of thrusters.

Electrical models will enable new PPU architectures

and trades to be made cost effectively.

Impedance as a function of frequency can be measured

using a frequency response analyzer. This instrument

injects a calibrated sinusoidal signal into the thruster by

means of a transformer. Then, it measures voltage and

current at the thruster. The magnitude and angle of the

impedance are calculated as the ratio of voltage and

current and the amount of phase shift between them.

A measurement technique using a frequency response

analyzer was tested and validated. Preliminary

impedance data using a NASA Hall thruster (NASA120M) is being studied. Additional testing on other

thrusters is scheduled in the near future and results are

planned for presentation at the International Electric

Propulsion Conference in 2003.

Radio Frequency (RF) Phenomenon

It is well known that Hall thrusters exhibit dynamic

electrical behavior in the form of discharge oscillation

following start-ups, operating point changes, and even

during otherwise "steady-state" operating regimes. Such

behavior can have an impact on e.g., thruster life, power

processor interface requirements, and communication

signals transmitted through the thruster plume. -'_-_

Investigations of the root causes of such oscillations

have revealed a variety of possible discharge

instabilities, illuminating much about the physics of

Hall discharges. What is less appreciated is that Hall

thrusters also radiate erratic impulses of radio frequency

(RF) emission during all phases of operation. These

pulses became evident during MIL-STD-461 EMI

measurement tests performed previously on both SPTtype and TAL-type thrusters. 3°'3L Collectively, the

pulses cover a wide frequency range, extending to at

least several GHz. Investigation of the RF pulse

characteristics may provide insights into thruster

discharge phenomena including anomalous electron

diffusion (near-wall conductivity), instabilities (e.g.,

electron stream type), plasma sheath transient behavior,

and erosion state or rate. The potential of RF pulse

emission measurement as a diagnostic method for such

thruster phenomena has been suggested by observed

correlation between larger RF pulses and discharge

current oscillation mode/phase in previous NASA EMI

tests (Figure 8). Also, Russian data on RF pulse

emission acquired over a life test showed an increase in

RF pulse emission intensity with erosion. 32

Aside from being a diagnostic, the GHz content of the

RF pulses makes them an important issue with regard to

compatibility with spacecraft (S/C) communication

bands. S/C receiver sensitivity to interference in such

frequency bands is evident in S/C interface control

document (ICD) requirements, which typically show

deep notches in a generic EMI limits (e.g., MIL-461) at

communication receive bands (Figure 9). Sub-5kW Hall

thruster EMI data have indicated collective emission

levels exceeding these notched limits. However, unlike

random or thermal (i.e., Gaussian) type noise, the

impulsive emission cannot be simply characterized by a

RMS value. Its impact on a communication channel

therefore cannot be evaluated without more detailed

scrutiny than has been achieved in standard EMI tests.

Development and application of higher power Hall

thrusters or cluster architectures may further complicate

S/C integration unless the impulsive EMI emission is

better understood.

The objective of this effort is to characterize the

magnitude, frequency content, duration, and timing of

individual RF pulses within a Hall thruster discharge.

NASA/TM--2002-211880
Tel< Run: 1.OOMS/s Sample

! ]

] il P ,

[]

20,Omv

MSO.OtJs Chl .1" '160mV

50.Oras

Figure 8 - Example of Hall thruster radiated RF pulse

event correlating with discharge current oscillation

minimum. RI (lower trace): RF signal at 1.4 GHz as

monitored by spectrum analyzer with 3 MHz

bandwidth, scale linear in arbitra D' units. R2 (upper

trace): Discharge current, scale 10 Amps/div

(5 Amps/lO mV).

m

itJ

OOI q) I

k.....

Figure 9 - Example of spacecraft broadband EMI limit

specification with "notch" at communication receiving

band.

Three methods are in the process of being applied to

capture individual RF pulse characteristics and allow

comparison to collective pulse data from EM1 tests.

First, a (tunable) single channel narrowband (-1 MHz

bandwidth) receiver, as used for standard EMI tests, is

being employed with a broadband antenna and low

noise amplifier (LNA) to monitor radiated pulse

intensity at a selected (GHz) frequency. A noise

amplitude distribution (NAD) of impulse amplitude vs.

rate will be measured for the selected frequency of

interest. Secondly, a very wideband or time-domain

capture of the sub-microsecond individual pulses is

being performed with a LNA, diode detector, and fast

digital storage oscilloscope (DSO). This should allow

characterization of true pulse durations and/or shapes.

This is not possible with more narrow bandpass

detection as, e.g., with a 1 MHz resolution bandwidth

spectrum analyzer in EMI tests or the first method

mentioned above. With those methods, the pulses are

stretched and distorted by the detector's input filter.

Fourier analysis of un-rectified (i.e., diode detector

removed) RF pulses is also being attempted for those

with spectra falling within the Nyquist sampling limits

of available DSOs. Combining the measurements of

true pulse duration with NAD will provide a good

foundation for analysis of the effects of such emissions

on communication channels of various bandwidths or

modulation schemes.

Finally, to better understand the NAD for a fixed

frequency band and the possible mechanisms for RF

pulse generation by the Hall discharge, a multi-channel

detection scheme is being employed in an attempt to

determine the cartier frequency content and its

variability from pulse-to-pulse. That is, the fluctuating

spectra of individual pulses will be captured and

compared to the collective or envelope spectrum

acquired by sweeping a single channel detector across a

wide frequency range during many such pulses, as done

in conventional EMI measurements. It is expected that

an individual pulse spectrum will have much less

frequency extent than the several GHz wide spectrum

suggested by previous EMI test results.

This effort will provide an important baseline for

analysis and modeling of Hall thruster phenomenon.

Specifically, data on Hall thruster RF impulsive

emission on a communication channel and for thruster

design/operating point effects on such emission. This

type of data will help provide insight into the

fundamental processes taking place within Hall

thrusters and possibly how to design to a given EMI

specification.

The NAD for RF pulse emission at a particular GHz

frequency will be determined as best as signal to

instrument noise allows. Actual duration and frequency

spread of individual RF pulses will likely be lound to be

shorter and narrower, respectively, than previously

thought. Pulse-to-pulse frequency hopping in addition

to pulse energy variations will therefore affect the NAD

for a given GHz frequency. It is expected that the NAD

will shift and possibly also change shape as the thruster

changes operating mode or erodes significantly. It is

expected that the NAD should be reproducible from one

run to the next for the same operating point once the

thruster stabilizes. Different thruster types or designs

may be associated with different NADs for similar

NASA/TM---2002-211880 7
operatingconditions.Futuretestscouldexplorethis

aspectif themeasurement approachprovesfeasible.

Oncethemeasurement methodshavebeenestablished.

theeffectsofthrusterdesignandoperatingconditionon

RF pulseintensity(amplitudeand rate)can be

investigatedtoprobethepossiblemechanisms of pulse

generationandweighthe integrationrisksof new

thrusterdevelopments. Someexamplesof interest

include:

I. Effectof insulator wall material (e.g., secondary

electron emission) on RF pulses

2. Effect of thruster operating voltage on RF pulse

intensity

3. Effect of thruster magnetic field on RF pulse intensity

4. Effect of thruster scale (power or cluster #) on RF

pulse intensity

5. Effect of SPT vs. TAL acceleration geometry on RF

pulse intensity

6. Effect of single vs. two-stage operation on RF pulse

intensity

7. Variation of RF pulse intensity vs. thruster

life/erosion state

8. Correlation of RF pulses with signals from invasive

electrical probes in discharge

Summary

The NASA Hall thruster program currently supports

tasks for a number of customers including the

Energetics Program, the Space Solar Power Program,

and the in-space Propulsion Program. In program year

2002 the following was accomplished as part of these

tasks: I ) A laboratory Hall thruster was built and tested

to 72 kW and 3 N of thrust; 2) A 5.5% increase in

thruster efficiency at high voltage was demonstrated by

modifying the magnetic field profile; 3) High voltage

Hall thruster lifetime was quantified; 4) A 96.5%

efficient breadboard power module was demonstrated;

5) A technique for measuring the impedance of a Hall

thruster was demonstrated; and 6) A plan for

investigating the dynamic electrical behavior of Hall

thrusters was presented.

References

1. Oleson, S.R., "Advanced Hall Electric Propulsion

for Future In-Space Transportation". 3rd

International Conference on Spacecraft Propulsion,

Cannes, France, Oct., 2000.

2. Olesom S.R., "Mission Advantages of Constant

Power, Variable Isp Electrostatic Thrusters". 36th

Joint Propulsion Conference, Huntsville, AL July,

2000, AIAA-2000-3413.

3. Oleson, S.R., "'Advanced Electric Propulsion for

RLV Launched Geosynchronous Spacecraft", 26th

International Electric Propulsion Conference,

Kitakyushu, Japan, October, 1999, IEPC 99-185,

NASAJ'rM--1999-209646.

4. Oleson, S. R., "'Advanced Electric Propulsion For

Space Solar Power Satellites". 35th Joint

Propulsion Conference, June, 1999, AIAA-99-

2872, NASA/TM--1999-209307.

5. Oleson S.R., et al. "'Advanced Propulsion for

Geostationary Orbit Insertion and North-South

Station Keeping", (rev.), Journal of Spacecraft and

Rockets, Voi. 34, Number I, pp. 22-28, 1997.

6. Oleson, S.R., Myers, R.M., "Launch Vehicle and

Power Level Impacts on Electric GEO Insertion",

32nd Joint Propulsion Conference, July, 1996,

AIAA-96-2978, NASA Contractor Report

198520.

7. Gefert, L.P., Hack, K.J., Options for the Human

Exploration of Mars using Solar Electric

Propulsion, AlP Conference Proceedings, No. 458,

STAIF-99, Nov. 1999, pp. 1275-1280.

8. Kerslake, T.W., Gefert, L.P., "Solar Power System

Analysis for Electric Propulsion Missions", 34th

Intersociety Energy Conversion Engineering

Conference, Vancouver, BC, Canada, Aug. 1999.

9. Leifer, Stephanie, Noca, Muriel, "Negative C3

Launch for Solar System Exploration", AIAA Joint

Propulsion Conference & Exhibit, 34th, Cleveland,

OH, July 13-15, 1998, AIAA-98-3925.

10. Johnson, L. and Leifer, S., "Propulsion Options for

Interstellar Exploration," AIAA Paper 2000-3334,

July 2000.

11. NASA's Office of Space Science, 2002 ROSS

NRA, "In-Space Propulsion Technologies"

Announcement,

http ://_wcw.spacetransportation.com/code_s/inspac

eannounce.html

12. Jankovsky, R., Tverdokhlebov, S., and Manzella,

D., "High Power Hall Thrusters," AIAA-99-

02949, June 1999.

13. Spanjers, G.G., Birkan, M., Lawrence, T.J., "The

USAF Electric Propulsion Research Program,"

AIAA-2000-3146, 36th Joint Propulsion

Conference, Huntsville, Alabama, July 16-19,

2000.

14. Hofer, R.R., Walker, M.L., and Gallimore, A.D.,

"A Comparison of Nude and Collimated Faraday

Probes for Use with Hall Thrusters," IEPC-01-20,

27th International Electric Propulsion Conference,

Pasadena, CA, October 14-19, 2001.

15. Hofer, R.R., Peterson, P.Y., Gallimore, A.D.,

"Characterizing Vacuum Facility Backpressure

Effects on the Performance of a Hall Thruster,"

IEPC_) 14)45, 27th International Electric

Propulsion Conference, Pasadena, CA, Oct 14-19,

2001.

NASA/TM--2002-211880
16. Manzella,D., Jankovsky,R. and Hofer,R.,

"LaboratoryModel50kWHallThruster,"AIAA2002-3676, 38th Joint Propulsion Conference,

Indianapolis, IN, July 7-10, 2002.

17. King, D.Q., de Grys, K.H., Jankovsky, R., "MultiMode Hall Thruster Development," AIAA-2001-

3778, 37th Joint Propulsion Conference, Salt Lake

City, UT, July 8-1 I, 2001.

18. Hofer, R.R., Gallimore, A.D., "The Role of

Magnetic Field Topography in Improving the

Performance of a High Voltage Hall Thruster,"

AIAA-2002-4111, 38th Joint Propulsion

Conference, Indianapolis, IN, July 7-10, 2002.

19. Manzella, D.H., Jacobson, D.T., Jankovsky, R.S.,

"High Voltage SPT Performance," AIAA-2001-

3774, 37th Joint Propulsion Conference, Salt Lake

City, UT, July 8-1 I, 2001.

20. Jacobson, D.T., Jankovsky, R.S., Rawlin, V.K.,

Manzella, D.H., "High Voltage TAL

Performance," AIAA-2001-3777, 37th Joint

Propulsion Conference, Salt Lake City, UT, July

8-11, 2001.

21. Pote, B., Tedrake, R., "Performance of a High

Specific Impulse Hall Thruster," 1EPC-01-O35,

27th International Electric Propulsion Conference,

Pasadena, CA, Oct. 14-19, 2001.

22. Hofer, R.R., Peterson, P.Y., Gallimore, A.D., "A

High Specific Impulse Two-Stage Hall Thruster

with Plasma Lens Focusing," IEPC-01-036, 27th

International Electric Propulsion Conference,

Pasadena, CA, Oct. 14-19, 2001.

23. Blateau, V., Martinez-Sanchez, M., Batishchev,

O., Szabo, J., "PIC Simulation of High Specific

Impulse Hall Effect Thruster," IEPC-OI_)37, 27th

International Electric Propulsion Conference,

Pasadena, CA, Oct. 14-19, 2001.

24. Jankovsky, R.S., et al. "NASA's Hall Thruster

Program", AIAA-2001-3888, 37th Joint

Propulsion Conference, Salt Lake City, UT, July

8-1 I, 2001.

25. Jacobson, D.J., "High Voltage TAL Erosion

Characterization," AIAA-2002--4257, 38th Joint

Propulsion Conference, Indianapolis, IN, July 7-

I0, 2002.

26. Pifiero, L.R., Peterson, P.Y., Bowers, G.E., "High

Performance Power Module for Hall Effect

Thrusters," AIAA-2002-3947, 38th Joint

Propulsion Conference, Indianapolis, IN, July 7-

I0, 2002.

27. Bugrova, A.I., Lipatov, A.S., Morozov, A.I., and

Kharchevnikov, V.K., "'Membrane Oscillations in

the Channel of a Steady-State Plasma Thruster,"

Tech. Phys. Lett. 25, 448 (1999).

28. Kim, V., Kozlov, V., Popov, G., and Skrylnikov,

A., "'Investigation of the Stationary Plasma

Thruster Scale Impact on the Electric Filter

Parameter Choice," I EPC-99-119.

29. Dickens, J.C., Kr.istiansen, M., and O'Hair, E.O.,

"Plume Model of Hall Effect Plasma Thrusters

with Temporal Consideration," IEPC-95-171.

30. Manzella, D., Sarmiento, C., Sankovic, J., and

Haag, T., "Performance Evaluation of the SPT140," IEPC-97_)59.

31. Sarmiento, C., Sankovic, J., Freitas, J., and Lynn,

P., "RHETT2/EPDM Hall Thruster Propulsion

System Electromagnetic Compatibility

Evaluation," IEPC-97-108.

32. Brukhty, V.I., Kirdyashev, K.P., and Svetlitskaya,

O.E., "'Electromagnetic Interference Measurements

within the T- 100 Endurance Test," IEPC-95-73.

NASA/TM---2002-211880 9
REPORT DOCUMENTATION PAGE FormApprove_

OMB No 0704-0188

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

gatbenng 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

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1. AGENCY USE ONLY (Leave b/ank) 2. REPORT DATE

September 2002

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

NASA's Hall Thruster Program 2002

3. REPORT TYPE AND DATES COVERED

Technical Memorandum

6. AUTHOR(S)

Robert S. Jankovsky, David T. Jacobson, Luis R. Pifiero, Charles J. Sarmiento,

David H. Manzeila, Richard R. Hofer, and Peter Y. Peterson

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

National Aeronautics and Space Administration

John H. Glenn Research Center at Lewis Field

Cleveland, Ohio 44135- 3191

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

WU-755-B4-05-O0

8. PERFORMING ORGANIZATION

REPORT NUMBER

E- 13562

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA TM--2002-211880

AIAA-2002-3675

11. SUPPLEMENTARY NOTES

Prepared for the 38th Joint Propulsion Conference and Exhibit cosponsored by the AIAA, ASME, SAE, and ASEE,

Indianapolis, Indiana, July 7-10, 2002. Robert S. Jankovsky, David T. Jacobson, Luis R. Pifiero, and Charles J. Sarmiento,

NASA Glenn Research Center: David H. Manzella, University of Toledo, Toledo, Ohio and NASA Resident Research

Associate at Glenn Research Center; Richard R. Hofer and Peter Y. Peterson, QSS Group, Inc., Cleveland, Ohio.

Responsible person, Robert S. Jankovsky, organization code 5430, 216-977-7515.

12a. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Category: 20 Distribution: Nonstandard

Available electronically at httD://_ltrs.grc.n;tsa._ov

This publication is available from the NASA Center for AeroSpace Information, 301-621_)390.

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

The NASA Hall thruster program currently supports a number of tasks related to high power thruster development for a

number of customers including the Energetics Program (formerly called the Space-based Program), the Space Solar

Power Program, and the In-space Propulsion Program. In program year 2002, two tasks were central to the NASA Hall

thruster program: ! ) the development of a laboratory Hall thruster capable of providing high thrust at high power; and 2)

investigations into operation of Hall thrusters at high specific impulse. In addition to these two primary thruster development activities, there are a number of other on-going activities supported by the NASA Hall thruster program. These

additional activities are related to issues such as high-power power processor architecture, thruster lifetime, and spacecraft integration.

14. SUBJECT TERMS

Hall thruster

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION

OF REPORT OF THIS PAGE

Unclassified Unclassified

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15

16. PRICE CODE

19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

OF ABSTRACT

Unclassified

Standard Form 298 (Rev 2-89)

Prescribed by ANSI Std. Z39-18

298-102