Abstract:
A technique and apparatus for generating high voltage (100s-1000s kV) and supplying high current (fractional to many tens of kilo-amperes), projecting a parallel, two wire electrical transmission line over a large distance (10s-100s m), or a single conductor in which the return path is the earth, which is capable of sustaining high voltages and conducting high currents, and landing the terminating terminals of the transmission line across a pre-defined target zone resulting in a low impedance closure of the electrical circuit causing high electrical current to flow. The applications for the present invention, which falls into a class of directed energy and/or non-lethal device, include: suppression of Improvised Explosive Devices (IED) and landmines; halting motorized platforms, including two and four wheeled motor vehicles and boats; damage and destruction of electronic systems; and destruction or incapacitation of electronic systems at substantial distances from a high voltage device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on U.S. Provisional Application Ser. No. 60/817,044, entitled “Electric Water Cannon,” filed on Jun. 28, 2006, the teachings of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention (Technical Field) 
         [0003]    The present invention relates to explosive deterrence and more particularly to an apparatus and method to destroy or incapacitate the operation of improvised explosive devices (IEDs), mines or electronic systems that lie on or below the surface of the earth, or in structures away from the earth, by driving high electrical currents through their electronic components, their detonators, or their fuses. 
         [0004]    2. Background Art 
         [0005]    An Improvised Explosive Device (IED) is an explosive, anti-personnel, anti-vehicle device fabricated in a makeshift manner. Though they can vary widely in shape and form, IEDs share a common set of components that typically consist of: an initiation system or fuse; high explosive (HE) fill; a detonator; a power supply for the detonator; and a container. An IED often incorporates HE scavenged from conventional military stores such as land mines, mortars, artillery shells and bombs for the explosive fill, along with a military or civilian fuse, and a detonator or arming device. Frequently, the original bomb or mortar casing is utilized as the container. An arming device can be made from easily purchased electronic components and consumer devices such as mobile phones, pagers, garage door openers, infrared (IR) sources or wired triggers. The fuse is typically a commercially available component as is often used in the mining industry. In many cases the IED is triggered or detonated by an electrical signal coupled to the IED though wires, an electrical antenna or a passive IR sensor. 
         [0006]    Various forms of electrical energy have long been used to incapacitate humans, animals, and electrical equipment. In 1852, A. Sounenburg and P. Rechten, in U.S. Pat. No. 8,843, described a harpoon connected to an electric generator, such that once harpooned, a whale could be electrocuted. In 1957, T. Ryan, in U.S. Pat. No. 2,805,067, taught how conventional weapons such as spears, arrows, and lances could be provided with self-contained electrical power supplies. In addition to the physical trauma these weapons could inflict, they could also impose high voltage impulses to a target producing lethal or merely irritating effects. Whereas these earlier devices used electrical shock effects as a secondary mechanism to the primary physical trauma induced by the delivery system, J. Cover, in U.S. Pat. No. 3,803,463, taught in 1974 a device that utilized electrical shock as the primary effect and the trauma of the delivery system as the secondary or otherwise harmless effect. Specifically, he described a device that launched a harmless projectile that is connected to an electrical supply by a relatively fine, conductive wire. When the projectile comes in contact with a living target, an electrical charge is delivered with the intention to immobilize or potentially kill it. At least two embodiments were taught by Cover. The first utilized a single wire and operated in a conducting mode wherein the ground or earth was used to complete the electrical circuit. The second utilized a pair of wires to constitute the current delivery and return path. 
         [0007]    Each of the inventions described above taught the use of electrical energy to disable, immobilize, capture or kill a living target. Others have described the use of electrical energy to disrupt the operation of electro-mechanical systems such as automobiles. For example, U.S. Pat. No. 6,371,000 B1 to Hutmacher, et al., taught the use of electrical energy to stop an uncooperative, fleeing or moving vehicle. Specifically, Hutmacher, et al., described a system that used an electrical power supply to deliver an electrical current to the target vehicle by establishing a momentary forward and reverse current paths. These paths could be established between the electrical power supply and the target vehicle via conductive linkages laid down on the roadway over which the vehicle passes, one or two electrically conducting wires deployed from a pursuing vehicle, or a single electrically conducting fluid stream. Also, in 1994, Sutton, et al., in U.S. Pat. No. 5,293,527, described a system to disable or disrupt the electronics controlling operation of a target vehicle that uses radiated electromagnetic fields. The system comprises a power conditioning unit, an oscillator that generates a time varying electrical waveform, a transmission line to carry the electric signal(s) to a radiating structure, and a radiating structure that radiates an electromagnetic wave into free space with characteristics similar to that of an Electromagnetic Pulse (EMP) that is associated with a high altitude atmospheric nuclear explosion. This radiated signal propagates to the location of the target vehicle at the speed of light, penetrates the vehicle enclosure, and disrupts or destroys the vehicle&#39;s electronics responsible for controlling its locomotion. 
         [0008]    With regard to land mines and IEDs there have been prior descriptions of devices designed to uncover, disable and destroy buried land mines. Hansen, et al., in U.S. Pat. No. 6,619,177 B1, taught an apparatus for clearing land mines. Their method utilized a carrier machine and a flail unit. The flail unit is comprised of a motor, rotating head, metal chains attached at one end to the rotating head, and weights attached to opposite ends of the chains. When operating, the apparatus described by Hansen, et al., rotates the head and drives the weights into the ground. As the weights pass through the earth, buried land mines are detonated. 
       SUMMARY OF THE INVENTION 
     Disclosure of the Invention 
       [0009]    The present invention discloses embodiments for an apparatus and method to generate a high voltage potential, project and deliver a high voltage potential difference from a few meters to greater than 100 meters, apply the electrical potential difference across two contact points at a target location, and conduct high electrical amplitude current through the resulting low impedance electrical circuit. It is assumed that a volume between, or in the general vicinity of, these two contact points contains a target IED or mine. When high amplitude electrical currents are caused to flow in the volume surrounding the target area, various desired effects can occur. For example, due to sufficient ohmic losses in the volume containing the IED or mine, or adequate ohmic losses in electrical wires internal to the IED or mine, a rapid temperature increase will occur and detonate the target IED or mine. In addition, the high-voltage dispersed around the target and high currents flowing through the target volume will directly couple to the electronic circuits of a mine or IED and destroy or disable the operation of these electronic circuits that are required for IED and mine operation. Further, the high voltage dispersed around the target and high currents flowing through the target will disrupt electronic systems associated with the IED or land mine such that energy stored in the circuits or batteries within the IED or land mine are discharged into explosive elements, such as detonators, or into the IED&#39;s or land mine&#39;s explosive material. This energy can lead to the detonation of the IED or mine. In addition, various non-linear effects and processes in the conductivity of the medium surrounding the IED, or the land mine, or their electronic systems, or their control wires, are possible and these non-linear effects can be exploited to increase the level of current in the soil containing an IED or land mine or other electronic device. These include processes such as, but not limited to, high voltage induced air breakdown, high voltage induced surface flashover, volume dielectric breakdown, or related high voltage induced phenomena that can occur to cause a rapid increase in the conductivity of the soil during application of the high voltage potential. Due to this reduction in material resistivity, the high electrical current that flows through the volume containing the target IED or mine can be enhanced above what the apparatus would otherwise deliver to a linear media. Here we use the term “linear media” to mean a uniform, isotropic media characterized at high voltages by the same conductivity that it displays at low voltage. Dry, damp or wet soil and sand are examples of materials that do not display constant conductivity with voltage. 
         [0010]    None of the prior art has disclosed a method and apparatus utilizing direct injected electrical energy into the earth to destroy or disable IEDs or land mines. The present invention uses bi-polar, or uni-polar, high voltage potential and high current, in combination with a liquid solution and/or conducting wires, to efficiently deliver electrical energy for the purpose of defeating or disabling IED systems and land mines. One embodiment uses intelligence supplied by a separate system, such as described in U.S. Pat. No. 7,173,560 to locate the position of a potential target. The present invention relies on direct injection of one or more short pulses (typically less than 1 millisecond in duration), of high current (typically exceeding 1 kA) into the target area, and into any system that wholly or partially occupies the volume through which the current passes for the desired effect (detonation or neutralization of the IED). One operational concept of the invention is as follows: 
         [0011]    a. Obtain, or otherwise assign, the location of a suspect IED or land mine. This location is referred to as the “target area;” 
         [0012]    b. If required or desired, pre-soak the target area with a highly conductive liquid, such as water with dissolved salt; 
         [0013]    c. Generate a high voltage, bi-polar, electrical potential difference; 
         [0014]    d. Project a highly electrically conducting transmission line from the high voltage generator to the target area; 
         [0015]    e. At some time after the end points of the parallel, two wire transmission line land at the target area, a high voltage potential is applied between them; 
         [0016]    f. The path between the landing zones completes the electrical circuit and allows high current (kAs) to flow through the target volume; and 
         [0017]    g. The high potential and high current initiates the fuse of the IED or land mine, or destroys the electrical circuits associated with the detonator, or directly initiates the high explosive material or the IED or land mine. 
         [0018]    The end result is the destruction of the IED or land mine, or the disablement of the electronics of the detonator or its controlling electronic systems. In either case, the IED or mine or other electronic system is rendered impotent. 
         [0019]    These embodiments identified as an “electric cannon” achieves its desired effect from one or more interaction mechanisms. The first mechanism is direct injection of high current into the target area and any system that wholly or partially occupies the volume that is the conducting path between the landing zones of the two end points of the transmission line. It is well known that a wide variety of electronic systems can be disabled and destroyed with the direct application of high currents to them. Second, the desired effects can be achieved by initiation of explosives (in the fuse or the HE store of the IED or land mine) caused by passing high current through their bulk. The resulting sparking, mechanical shock and/or temperature rise can initiate the associated explosives. Third, the desired effects can also be achieved via electromagnetic coupling and radiation from the high current traveling in the transmission line. It is well known that radiated fields, of the type known as Electromagnetic Pulse (EMP) and associated with high altitude nuclear explosions can damage and destroy electronic systems. For the electric current levels associated with the present invention, magnetic field levels that meet and in some cases exceed EMP levels can be achieved out to substantial ranges beyond the target area. These magnetic fields can induce electrical currents in the electrical circuits of the target IED or land mine, via the process know as magnetic induction, that disable, damage or destroy them and, consequently, the capability of the host IED or land mine. In addition, the electromagnetic fields may indirectly cause detonation due to a secondary effect from damaged electronics causing discharge of their stored energy into the detonator or bulk explosive. 
         [0020]    The present invention is a method and apparatus of incapacitating and/or destroying IEDs and land mines, and an apparatus that contains several of the following sub-systems: a delivery platform; electrical circuits that generate high voltage (tens to thousands of kilo-volts) with capacity to deliver high current (fractional kilo-amperes to meg-ampere levels); a transmission line and transmission line delivery system; an optional liquid and liquid delivery system (to preferentially pre-condition the conductivity of the target area and/or potentially to form the transmission line); electrical switching systems; and a command and control system to target transmission line delivery system, initiate high voltage production and switch the high voltage onto the transmission line. 
         [0021]    A primary object of the present invention is to intentionally disable or destroy IEDs or land mines. 
         [0022]    A primary advantage of the present invention is that it can be used with a broad range of IEDs or land mines. 
         [0023]    Another advantage of the present invention is that it can be used to disable or destroy electronic or electrical systems in general, including those not associated with IEDs or land mines. 
         [0024]    Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings: 
           [0026]      FIG. 1  is a schematic illustration of a fully operational Electric Cannon. 
           [0027]      FIG. 2  is a schematic illustration of a partially buried Improvised Explosive Device (IED). 
           [0028]      FIG. 3  is a schematic illustration of an electrical circuit diagram. 
           [0029]      FIG. 4  is a transverse cross section of a two wire transmission line. 
           [0030]      FIG. 5  is a transverse cross section of a schematic illustration of a fully operational embodiment of the Electric Cannon. 
           [0031]      FIG. 6  is a top down schematic illustration of the cargo area of the platform of an embodiment of the Electric Cannon. 
           [0032]      FIG. 7  is a schematic illustration of an electrical circuit diagram of a Cockcroft-Walton voltage multiplier. 
           [0033]      FIG. 8  is a schematic illustration of a fully operational embodiment of the Electric Cannon. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Best Modes for Carrying Out the Invention 
       [0034]      FIG. 1  shows a carrier machine  1 , whose purpose is to support and transport all sub-systems required by the Electric Cannon for operation. In this case carrier machine  1  is a platform, or vehicle, which carries electrical prime power (not shown), a high voltage generator (not shown), a high voltage switch (not shown) a water reservoir (not shown), command and control sub-system (not shown) and a water projection system  2 . Also indicated in the illustration of  FIG. 1 , is a target area  4  that is down range of the Electric Cannon. Target area  4  is shown to contain a buried IED or mine  5 . Also indicated in  FIG. 1  is how transmission line  3  (in this case a parallel, two wire transmission line constituted of a conductive liquid solution) lands astride target area  4 . Carrier machine  1  is also intended to house and protect one or more human operators.  FIG. 1  also shows two water launching apparatuses such as electric cannons  2  whose purpose and function is to project two columns of water to target area  4 . Other embodiments of the Electric Cannon can employ electrically conducting wires to constitute the transmission line  3 . In this case the wires are dispensed from the carrier by trailing behind a spike or arrow that is directed and launched to the landing or target area  4 . 
       Platform 
       [0035]    The platform for the Electric Cannon is typically a mobile delivery system; however it can also be a stationary system. For example, as indicated in  FIGS. 1 and 5 , the platform may be a standard military transport vehicle of the type known as a five (5) ton cargo vehicle such as a model M1085 A1.  FIG. 5  is a transverse cross section of a schematic illustration of a fully operational embodiment of the preferred embodiment of a carrier machine  1 . In the embodiment depicted in  FIGS. 1 and 5  an aqueous solution is used to form conducting channels that constitute a transmission line  3  that conducts high electric current to target area  4 . Major sub-systems are depicted in the illustration, including: main water storage vessel  19 ; high pressure pump  20 ; sulfur hexafluoride (SF 6 ) storage tank  21 ; high voltage generator  22 ; high pressure charge vessel  23 ; water nozzles  24 ; water storage vessels for next shot  25 ; and SF 6  recovery pump  26 . It should be noted that other insulating materials, such as transformer oil, could be used, or in other cases, no insulation other than ambient air is required. Other embodiments of the Electric Cannon could utilize airborne or waterborne craft, rail mounted, or possibly realized from a physically fixed (not mobile) platform or station. 
       High Voltage Generator 
       [0036]      FIG. 3  is a schematic illustration of an electrical circuit diagram  11 . The depicted circuit indicates a voltage source  12  of strength V that is representative of the electric cannon&#39;s high voltage source  22 , a switch  13  that is representative of the high voltage switch that isolates the high voltage energy store from the intended load, a resistor  14  that is representative the resistance of the forward path, a second resistor  15  that is representative of the electrical resistance of the path in the earth, and a third resistor  16  that is representative of the resistance of the return path. From first principles, current  17  of strength I that flows through the earth once high voltage switch  13  has been closed, will be I=V/(R1+R2+R3). With amply strong voltage and adequately low resistance the resulting current that flows through the earth would be sufficient to disable or destroy an IED or mine that is wholly or partially surrounded by the earth through which the current flows. For example, with an ideal voltage source of intensity V, realized typically by a charged capacitor bank, assuming a wire resistance of 10Ω (each way), an earth channel resistance of 35Ω, and a 1 MV potential difference (two 500 kV bipolar voltage sources, one providing +500 kV and one providing −500 kV yielding a total potential difference of 1 MV), Ohm&#39;s law gives an injected current of ˜18.2 kA. The bi-polar nature of the applied voltage concentrates the current along a path between the landing zones (as well as minimizes the voltage to ground required at the source end, i.e., a earth-to-electrode potential difference with a magnitude of 500 kV as opposed to an earth-to-electrode potential difference of +1000 kV in unipolar operational mode), compared to a uni-polar injection with an earth-return to a distant point. 
         [0037]      FIG. 3  refers to a voltage generator  12 ;  FIG. 5  and  FIG. 6  refer to a high voltage generator  22 .  FIG. 6  is a top view schematic illustration of the cargo area of the platform of an Electric Cannon  27 . In the embodiment depicted in  FIG. 6 , an aqueous solution is used to form the transmission line  3  that conducts high electric current to target area  4 . Major sub-systems are depicted in the illustration, including: a main water storage vessel  19 ; a high pressure pump  20 ; a sulfur hexafluoride (SF 6 ) storage tank  21 ; high voltage generators  22 ; high pressure charge vessels  23 ; water nozzles  24 ; water storage vessels for next shot  25 ; and a SF 6  recovery pump  26 . High voltage generators  22  provide the intense electric potential difference, or voltage, that energizes the transmission line  3  that is projected to target area  4 , and supplies the high current that flows through the target volume and destroys target IED or land mine  5 . High voltage generators  22  are realized by one of several well know methods. A preferred method to generate the high voltage potential utilizes the Cockcroft-Walton circuit; a typical configuration of a Cockcroft-Walton voltage multiplier circuit is indicated schematically as the electrical circuit diagram  28  shown in  FIG. 7 . 
         [0038]    Electrical circuit  28  indicated in  FIG. 7  is commonly called a Cockcroft-Walton voltage multiplier. Circuit  28  indicates an output voltage strength  29  of 2nV max  where n is the number of stages in the circuit and V max  is the peak voltage (Vmax=½ of the peak-to-peak voltage) of oscillating voltage source  30  that charges the circuit. Two diodes, D and D′, and two capacitors, C and C′, configured as indicated, are the collection of elements that constitute a stage  31  in circuit  28 . High voltage generators based on the Cockcroft-Walton voltage multiplier circuit, with DC output voltages to multi-MV, are commonly used worldwide and manufactured for commercial sale. This Cockcroft-Walton generator can be used to charge low inductance capacitors, which can act as a low impedance voltage source, relative to the load impedance, to energize the transmission line  3  of  FIG. 1 . Other commonly used systems for generating high voltage are Marx-type circuits and voltage step-up transformers, including both air core and high magnetic permeability core types. For the present application, two Cockcroft-Walton high voltage generators are utilized; one generates the positive polarity voltage potential  22 , while the second generates the negative polarity voltage potential  22 ′. Other types of high voltage generators can also be utilized, including those based on the Marx generator, transformers and other well known methods. The high voltage generator is typically immersed in an insulating media, such as sulfur-hexafluoride gas or transformer oil for the high voltage contemplated here, although some lower voltage systems, typically with output voltages less than 150 kV, do not require insulating media other than ambient air. Typically, the high voltage generator charges a collection of low inductance capacitors, which could be discharged into a load in a fraction of a microsecond using a triggered or self-break switch, and produce kA to 100s of kA, or higher, current levels. 
       Transmission Line Delivery System 
       [0039]    Transmission lines  3  of  FIG. 1 ,  7  of  FIGS. 2 ,  14  and  16  of  FIGS. 3 and 18  of  FIG. 4  physically extend from the platform and high voltage generator  22  to target area  4 .  FIG. 2  is a schematic illustration of a partially buried Improvised Explosive Device (IED)  5 . Standing astride IED  5 , and partially buried in surrounding earth  9 , are indicated two stakes  6  that are connected to the Electric Cannon  1  via two metallic, high conductivity wires  7 . These wires  7  are attached to high voltage generator  22  of Electric Cannon  1 , and when the high voltage switch is enabled the full output voltage of high voltage generator  22 , less the potential dropped across wire transmission lines  7 , is applied across ground stakes  6 . Once the high voltage is applied to ground stakes  6 , high current  10  is caused to flow in earth  9  surrounding IED  5  and in detonator wire  8 . Note that current  10  depicted in  FIG. 2  is notional, and does not represent an actual distribution of current. This current causes destruction or disablement of IED or mine  5  within the current path. 
         [0040]      FIG. 4  is a transverse cross section of a two-wire transmission line  17 . Each of the two wires  18  that constitute the transmission line have a radius a, and their centers are separated by a distance b. The material that makes up each wire  18  can be metallic (like copper, silver or aluminum), a highly conducting aqueous solution (saturated solution of salt and water), other highly conducting liquid, a plasma channel, or any other material that preferentially conducts electrical current along the path defined by the presence of the wires of the transmission line. Also, the wire radii and separation define a characteristic transmission line impedance, Z 0  given by the well known, approximate, formula Z 0 =120 In (b/a) ohms. If Z 0  is equal to the electrical resistance of the target volume, then the rise time of the current and voltage waveforms impressed through and across the target area will be maximized, a potentially desirable condition, arising from matching load resistance to source resistance. 
         [0041]    The purposes of the transmission lines are to provide a safe stand-off distance  36  between the platform of Electric Cannon  1  and target area  4 , supply a low electrical resistance path from high voltage generator  22  to target area  4 , and conduct electric current supplied by high voltage generator  22  to the volume of target area  4 . A safe stand-off distance  36  between the platform of the Electric Cannon and the target area is assumed to be on the order of 10 meters or more; however the engagement distance, which is the distance from the electric cannon launch point to the target area, is likely to be substantially more, perhaps as far as a few hundred meters. To realize the transmission line, whose length is likely to lie in the few meters to a few hundreds of meters range, one has several options. 
         [0042]    One option to realize the transmission line, as depicted in the illustration of  FIG. 1 , is to use a liquid such as an aqueous (water-based) solution suitably loaded with salt or other material to achieve high conductivity, as the material constituting the two wires  3  of the two-wire transmission line  18 . The conductivity of a solution of water (normally an insulator), can be enhanced to values of 150 S/m by adding various solutes such as common salts (NaCl, for example) and acids (HCl, for example). The water is projected from the platform using two high-pressure water nozzles  2  of the type commonly utilized by the water entertainment industry. The key feature of the water nozzles, for a liquid-based transmission line, is that they must project the water with as small a Reynolds number as possible, and with a geometry that demonstrates minimal divergence. In other words, the projected water columns must leave the Electric Cannon platform and nozzles and travel to the target area in a manner that minimizes the turbulent nature of the water flow. The purpose of this requirement is to maximize the insulation between the water columns and to maximize the conductivity of the water channels that together constitute the transmission line. While a water-based transmission line is described here, other liquid-based transmission lines could be considered for this use. The velocity of the liquid channels, the distance to the target area, the height of the launch point and the rate-of-fall of the uncoiled wire must all be chosen consistently so that the transmission line does not approach the ground too closely prior to being energized by the high voltage source. 
         [0043]    A second option to realize the transmission line is to use a thin metallic conductor, typically millimeters in diameter or less, as the material constituting the two wires  3  of the two-wire transmission line  18 . The conductivity of metals is many orders of magnitude greater than that possible in an aqueous solution, allowing a more efficient transfer of stored energy to the target volume. For example, copper has a conductivity of approximately 6×10 7  S/m, compared to the conductivity of 50 mS/m for heavily salted water. In this case the two-wire transmission line would be realized in a metal material. To deploy the transmission line, the two wires would be synchronously projected from the platform, perhaps by trailing behind projectiles ballistically fired to the target area by two high-pressure nozzles or explosively propelled from a barrel. The US Army&#39;s TOW (Tube-launched, Optically-tracked, Wire command-link guided) missile system is an example of this type of deployed transmission line. A similar technology would be employed to synchronously launch the two metallic wires, which comprise the transmission line from two individual launch points.  FIG. 8  is a schematic illustration of a fully operational Electric Cannon, for this second embodiment. In this case a platform  1 , or vehicle, carries electrical prime power (not shown), a high voltage generator (not shown), a high voltage switch (not shown), two projectile dispensers  32 , a metal wire distribution system (not shown), and a command and control sub-system (not shown). Also indicated in the illustration of  FIG. 8 , is a projectile  33  that has been launched by one of the dispensers. Also depicted in the  FIG. 8  is a metal wire  34  trailing behind the projectile. Two projectiles will eventually travel to the target area  4  that is down range of the Electric Cannon, and carry with them two metallic wires that will constitute the transmission line  3 . The velocity of the projectiles, the distance to the target area, the height of the launch point and the rate-of-fall of the uncoiled wire must all be chosen consistently so that the transmission line wire does not approach the ground too closely prior to being energized by the high voltage source. 
         [0044]    The electric cannon application only requires that the wires extend several meters to a few hundred meters from the launch point, which is a much shorter distance than the already demonstrated multi-kilometer TOW application. Therefore, methods for launching a projectile with a trailing wire, which are low cost, robust and able to be implemented in a compact dispenser system, can be envisioned. Such delivery methods include, but not limited to (a) dart-like projectiles, launched via compressed air, or (b) slugs of metal (bullet like). 
         [0045]    A third option to realize the transmission line is to utilize an aerosol as the material constituting two conductors  3  of two-wire transmission line  18 . The aerosol could be the momentary mist left behind after a small volume of aqueous solution is projected at high speed through the atmosphere to the target area. Other materials, including hydrocarbon propelled mists and/or non-aqueous vapors, with or without particulates, could be used to create a mist trail. Under extremely high electric field conditions, which induce non-linear effects in the aerosol, the mist trail can undergo electrical breakdown along its length (unable to support a substantial electric potential across two points along its path and therefore able to support substantial current flow). Once the mist trail begins to break down, the remaining portion is subject to an even higher electric field causing additional breakdown and the entire channel can rapidly become highly conductive due to plasma formation driven by this avalanche effect. Thus, a highly conductive plasma is left along the path occupied by the mist. In this case, two-wire transmission line  18  would be realized by the plasma channels formed when the mist trail experiences electrical breakdown. Transmission line  18  comprised of the aqueous mist and plasma then presents a low electrical resistance path from high voltage generator  22  to target area  4 , and conducts electric current supplied by high voltage generator  22  to the volume of target area  4 . 
       Operation 
       [0046]    Generally speaking, Electric Cannon  1  operates as follows, for the specific case where an aqueous solution is used to constitute two-wires of the transmission line  18 . Referring to  FIGS. 1 ,  5 , and  6 , an Electric Cannon delivery vehicle  1  is located and oriented relative to target area  4 . Pump  20  draws water from main water storage  19  and supplies a full charge of water  25  to each electric cannon. High voltage generators  22  are then energized while a high-pressure compressor pump  20  fills each of two high-pressure cylinders  23 . Water nozzles  2  are then aimed and pointed toward the target areas  4 . Once high voltage generators  22  are fully charged to their design output voltage, water charges  25  are full and the high-pressure cylinders  23  are pressurized to the rated pressure, and the valves controlling the flow from water nozzles  2  are opened. Once opened, a water stream leaves nozzle  2  of each electric cannon with a velocity sufficient to propel it to target area  4 . The capacity of each water charge  25  and high-pressure cylinder  23  is sufficient to project a continuous stream of water to the target area and these two water columns constitute transmission line  3 . The time it takes for the leading edge of the water column to arrive at target area  4  is on the order of seconds. Next, when the far end of the transmission line arrives at the target area, a switch is closed to apply the high voltage potential to the near end of the transmission line. One of several methods of determining when to trigger the high voltage switch can be used. For example, a sensor  35 , in this case an inductively coupled current sensor depicted in a notional form and not as it would be physically implemented, located in the vicinity of the launch point of the water nozzles can detect the precise moment when the two water columns contact target area  4 , by detecting or measuring a rapid drop in the circuit resistance or change in the capacitance to ground. This rapid drop in the resistance or change in capacitance would indicate to the command and control system that it is time to synchronously close the high voltage switch  13 . Or, distance and velocity calculations can be used to determine the time of flight and contact time of the transmission line, and the command and control could asynchronously close the high voltage switch  13 . At this time a high voltage switch is closed  13  and the full bi-polar electric potential of the outputs of both high voltage generators  22  are applied between the two water channels of the transmission line  3  causing current to flow. The current pulse reaches target area  4  in times less than a few microseconds, depending on the distance, which is essentially instantaneous on the time scale of the transmission line delivery. Once current begins to flow in the volume of target area  4 , the desired effect (destruction, disablement or disruption of the target IED or land mine  5 ) is achieved from one or more interaction mechanisms: direct injection of high current into target area  4  and any electronic system that wholly or partially occupies the volume that is the conducting path between the landing zones of the transmission line  3 ; initiation of explosives (in the fuze or the HE store of the IED or land mine  5 ) caused by passing high current through their bulk; and/or via intense electromagnetic fields that are produced by the high current traveling in transmission line  3  that couples into the electronics of the target IED or land mine  5 . In any case, IED or mine  5  is rendered impotent. 
         [0047]    A second possible operating scenario for Electric Cannon  1  is as follows. Instead of using an aqueous solution, metallic wires  18  are used to constitute the two wires of the transmission line  3 . An Electric Cannon delivery vehicle  1  is located and oriented relative to target area  4 . Pump  20  draws water from main water storage  19  and supplies a full charge of water  25  to a single electric cannon. As an optional augmentation that depends upon the conductivity of the earth at target area  4 , but not necessary in many circumstances, the water canon is then fired to soak the target area with a highly conductive aqueous solution. High voltage generators  22  are then energized while a high-pressure compressor pump  20  fills each of two high-pressure cylinders  23 . Instead of water nozzles, a pair of harpoon-like metallic spikes  6  are aimed and pointed toward target area  4 , as shown in  FIG. 2 . These can be as small as darts launched with compressed air, or even bullets launched by an explosive charge, provided they can rapidly carry a trailing wire to the target area. The trailing wire could be spooled from a dispenser. Once high voltage generators  22  are fully charged to their design output voltage, and high-pressure cylinders  23  are pressurized to the rated pressure, harpoons  6  are fired toward target area  4 . These harpoons  6  trail behind wires  7  that constitute the transmission line, and are fired with sufficient speed that the wires do not fall to the ground before being electrically energized. A sensor  35  detects the precise moment when harpoons  6  impact target area  4 . At this time a high voltage switch  13  is closed and the full bi-polar electric potential of the outputs of both high voltage generators  22  are applied between two wires  7  causing current to flow. Once current begins to flow in the volume of target area  4 , the desired effect is achieved via one or more of the interaction mechanisms described above. Again, IED or mine  5  is rendered impotent. The wires may be chosen in diameter and material to evaporate when the current flows through them, in a manner similar to a fuze. In such a case, the rapid opening of the wire can cause a very high voltage to be generated by the principle of magnetic induction. Such high voltage can then breakdown the air and a large current spike could potentially couple particularly high voltages into nearby circuits of the IED or land mine. This type of waveform is intrinsic to exploding fuses and could in principle result from the use of other non-continuous conductors, including liquids. This mechanism may provide enhanced lethality to electronic systems that inhabit the target area. 
         [0048]    The electric cannon apparatus also takes advantage of a reduction in the resistance of the earth, including soil and sand, at sufficiently high voltages, compared with lower voltages, to enable the flow of high levels of current through the earth in the vicinity of electrodes contacting the surface. This reduction in resistance occurs due to a multitude of high voltage effects in the soil, including surface tracking and dielectric breakdown in the soil particles, and gas breakdown in the voids between the soil particles, for example. Also, the apparatus may utilize a method to enhance surface conductivity via pre-soaking the target area with a highly conducting liquid. 
         [0049]    Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above, are hereby incorporated by reference.