Electrical discharge system and method for neutralizing explosive devices and electronics

Disclosed are a system and method for discharging electrical potential into the earth to disable or destroy electronics and/or explosive devices. The disclosed system includes an electrical power supply providing a pulsed electrical potential exceeding 30,000 volts with at least 30 Joules of energy in each pulse. The system includes a cathode emitter and an anode emitter configured to be moved along the earth in close proximity to the earth. The electrical potential is discharged into the earth through the cathode emitter and/or the anode emitter.

BACKGROUND

Disclosed herein is a system and method for providing a mobile means to produce a high voltage electric discharge capable of disabling or destroying electric devices, detecting conductors and/or initiating detonation of an explosive device. For example, such an electric discharge can be used to detonate hidden explosive devices such as improvised explosive devices, electronically dispersed devices such as chemical, biological, radiological or nuclear (CBRNE) devices, or commercially produced land mines that may be hidden or otherwise obscured from an observer. High voltage can penetrate into the earth and/or travel along the surface of the earth to reach a conductor.

High explosives generally used in such explosive devices can be subdivided into classes by their relative sensitivity to heat and pressure as follows. The most sensitive type of explosives are commonly referred to as primary explosives. Primary explosives are extremely sensitive to mechanical shock, friction and heat to which they respond by rapid burning and/or detonation. The term “detonation” is used to describe an explosive phenomenon whereby chemical decomposition of an explosive is propagated by an explosive shock wave traversing the explosive material at great speeds typically thousands of meters per second. Secondary explosives, also referred to as base explosives, are comparatively insensitive to shock, pressure, friction and heat. Secondary explosives may burn when exposed to heat or flame in small unconfined quantities but when confined, detonation can occur. To ignite detonation, secondary explosives generally require substantially greater heat and/or pressure. In many applications, comparatively small amounts of primary explosives are used to initiate detonation of secondary explosives. Examples of secondary explosives include dynamite, plastic explosives, TNT, RDX, PENT, HMX and others. A third category of high explosives, referred to herein as tertiary explosives, are so insensitive to pressure and heat that they cannot be reliably detonated by practical quantities of primary explosives and instead require an intermediate explosive booster of a secondary explosive to cause detonation. Examples of tertiary explosives include ammonia nitrate fuel mixtures and slurry or wet bag explosives. Tertiary explosives are commercially used in large-scale mining and construction operations and are also used in improvised explosive devices (IED) due to their relative ease of manufacture from commercially available components (e.g., fertilizer and fuel oil).

Explosive devices, including IEDs, generally contain an explosive charge which could be comprised of either a secondary or tertiary explosive (in devices where a tertiary explosive is used, an additional booster charge of a secondary explosive is often found as well), a detonator (which generally includes a primary explosive and possibly a secondary explosive), and an initiation system to trigger the detonation of the detonator. Initiation systems commonly utilize an electric charge to generate heat through resistance to heat the primary explosive sufficiently to initiate detonation.

A common example of a detonator is a blasting cap. There are several different types of blasting caps. One basic form utilizes a fuse that is inserted in a metal cylinder that contains a pyrotechnic ignition mix of a primary explosive and an output explosive. The heat from a lit fuse ignites the pyrotechnic ignition mix which subsequently detonates the primary explosive which then detonates the output explosive that contains sufficient energy to trigger the detonation of a secondary explosive as described above.

Another type of blasting cap uses electrical energy delivered through a fuse wire to initiate detonation. Heat is generated by passing electrical current through the fuse wire to a bridge wire, foil, or electric match located in the blasting cap. The bridge wire, foil or electric match may be located either adjacent to a primary explosive or, in other examples, the bridge wire, foil or electric match may be coated in an ignition material with a pyrotechnic ignition mix located in close proximity to detonate a primary explosive, which, as described above, detonates an output explosive to trigger detonation of the explosive device. Electric current can be supplied with an apparatus as simple as connecting the fuse wire to a battery or an electric current can be triggered by an initiation system that includes a triggering control such as a remote signal or a timer.

Mines, CBRNE devices, and IEDs are extremely diverse in design and may contain many types of initiators, detonators, dispersing technologies, penetrators and explosive loads. Anti-personnel IEDs and mines typically contain shrapnel-generating objects such as nails or ball bearings. IEDs and mines are designed for use against armored targets such as personnel carriers or tanks that generally include armor penetrators such as a copper rod or cone that is propelled by a shaped explosive load. Mines and IEDs are triggered by various methods including but not limited to remote control, infrared or magnetic triggers, pressure sensitive bars or trip wires and command wires.

Military and law enforcement personnel from around the world have developed a number of procedures to deal with mines and IEDs. For example, a remote jamming system has been used to temporarily disable a remote detonation system. In some cases it is believed that the claimed effectiveness of such remote jamming systems, proven or otherwise, has caused IED technology to regress to direct command wire because physical connection between the detonator and explosive device cannot be jammed. However, in other situations it has been found that jamming equipment may only be partially effective because they may not be set to operate within the correct frequency range in order to stop a particular IED. Much of the radio frequency spectrum is unmanaged and in other cases jamming of some portions of the radio frequency spectrum can dangerously interfere with other necessary radio communications.

Other known methods of dealing with mines and IEDs include the use of mine rollers to detonate pressure sensitive devices. High-powered lasers have been used to detonate or burn the explosives in the mine or IED once the mine or IED is identified. Visual detection of the mine or IED and/or alterations to the terrain that were made in placing the mine or IED are some of the current methods used to combat such explosive devices. In any event, mines and IEDs continue to pose a threat and improved systems and methods for safely dealing with them are still needed.

DETAILED DESCRIPTION OF THE DRAWINGS

For the purpose of promoting an understanding of the disclosure, reference will now be made to certain embodiments thereof and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended, such alterations, further modifications and further applications of the principles described herein being contemplated as would normally occur to one skilled in the art to which the disclosure relates. In several FIGs., where there are the same or similar elements, those elements are designated with similar reference numerals.

Referring toFIG. 1, a prior art detonator typical of an electric type blasting cap80is illustrated. Blasting cap80includes lead wires81and82, bridge wire83, electric match84, pyrotechnic ignition mix85, primary explosive86and output explosive87all contained in casing88and header89. Blasting cap80is used to initiate an explosive sequence by passing an electric current through lead wires81and82sufficient to heat and cause instantaneous combustion of electric match84. The electric match ignites ignition mix85and subsequently primary explosive86resulting in the detonation of output explosive87. Blasting cap80is generally constructed to have electric static discharge protection in order to protect against accidental detonation from an electric spark. One of the uses of the system(s) disclosed below is to generate an electric discharge sufficient to defeat the electrostatic discharge protection of standard blasting caps. An electric discharge with sufficient potential (voltage) and energy (Joules) has the ability to penetrate the insulation of the command wires or to find a path to conductive portions of the mine or IED. Once electric current flows through the bridge wires or generates a spark in proximity to electric match84, detonation of blasting cap80may occur. Applicants have also observed situations where appropriate electric energy is passed through blasting cap80that bridge wire83is vaporized without igniting electric match84, resulting in dudding blasting cap80so that it is inoperable to initiate detonation via intended triggering methods.

Referring toFIG. 2, system100is illustrated. System100includes vehicle102and module104. The illustrated configuration vehicle102is a remotely controlled robotic vehicle as supplied by iRobot, 8 Crosby Drive Bedford, Mass. 01730. Phone (781) 430-3000 or at www.irobot.com. Vehicle102includes antennae103to receive remote control inputs. Vehicle102may be modified to send control signals to unit104via inputs received through antennae103. While a specific robot is illustrated, it should be understood than any appropriate robotic vehicle could be used.

Unit104is generally defined by frame106that carries high voltage module108, power converter110and power source112. Power converter110and power source112define power supply114. Power converter110includes cover111and power source112includes cover113. Unit104also includes one or more emitters116and118extended away from frame106by supports120and122. Emitters116and118in the illustrated configuration are flexible metal chains constructed and arranged to flex in one direction while maintaining relative rigidity in the other direction. This may permit emitters116and118to conform to the shape of the earth or whatever surface they are dragged across while maintaining a spaced apart relationship with each other. In other embodiments, emitters116and118may be rigid or semi-rigid structures that are supported above the ground or other surface being interrogated. Non-limiting examples of other emitter configurations includes cables, rods and straps. Emitters116and118are configured with emitter surfaces that are in close contact with the earth. In one embodiment, the emitter surfaces of emitter116and118are approximately 0.5 meters in length. In another embodiment, the emitter surface of emitter116and118are at least 0.3 meters in length. In yet another embodiment, the emitter surface of emitter116and118are at least 0.2 meters in length. In other embodiment, the emitter surfaces may be between approximately 0.5 to 1.5 meters in length. In yet other embodiments, the emitter surfaces may be between approximately 0.5 to 2.25 meters in length.

Supports120and122are comparatively rigid structures constructed of a non-conductive material that supports a conductor that electrically connects emitters116and118to high voltage module108. Examples of non-conductive structural materials include EXTREN®, a pultruded fiberglass reinforced with polyester or vinyl ester resin manufactured by Strongwell and available at www.strongwell.com. Another non-conductive structure material is G10 GAROLITE glass epoxy materials available from JJ Orly at (866) 695-9320 and www.jjorly.com. Yet another non-conductive structural material is Acetron® copolymer acetal available at www.quadrantplastics.com.

Referring toFIG. 4, an alternative perspective view of casing130is illustrated showing housing140connected between supports136and138. Housing140contains a load resister coupled between emitters116and118as described below.

Referring now toFIGS. 5-7, Marx generator142is illustrated. Marx generator142is housed within casing130. Marx generator142includes frame144, capacitors146, resistors148, electrodes150and152defining spark gaps154and plates156electrically coupling electrode152, capacitors146and resistor148together. Frame144may be constructed of a comparatively non-conductive material. Note that the circuit defined by the illustrated assembly is described below inFIG. 10. Also note that Marx generator142may optionally included inductors as described below with regard toFIGS. 15-18and Marx generator242.

Referring now toFIGS. 8-9, power supply114is illustrated with covers111and113removed. Power source112includes a pair of batteries158. Power converter110includes insulator160, resistors162, control board164and power converters166. Power converters166include power output terminals168and resistors162connected in parallel defining resistor170. While not shown inFIGS. 8-9, batteries158are connected in parallel as well as power converters162being connected in parallel to increase the power output. Circuit board164controls the output of power converters166. In the illustrated embodiment, power converters166correspond to model number 30C24-P125 or 30Z24N125 supplied by Ultravolt® at www.ultravolt.com at 1800 Ocean Avenue, Ronkonkoma, N.Y. 11779, telephone number (631) 471-4444.

Referring toFIG. 10, an electrical schematic of unit104is provided. As seen inFIG. 5, capacitors146are connected in parallel defining capacitor147. Capacitors147, resistors148, electrodes150and152are arranged as a Marx generator with a plurality of stages. The illustrated embodiment includes eight stages. It should be understood that this is a non-limiting example and more or fewer stages may be used. The output of this Marx generator is electrically coupled to emitter116with emitter118electrically coupled to the input for the Marx generator with load resistor172coupled between emitters116and118. Load resistor172is contained in housing140.

In one specific embodiment unit104includes the following characteristics. Individual capacitors146are rated 0.005 μF with four capacitors146combined in parallel to make capacitor147rated 0.020 μF. Resistors148are ceramic resistors rated at 10 kΩ. Load resistor172is rated at 25 kΩ. The breakdown voltage of spark gaps154are approximately 25 kV. The illustrated system is configured with power supply114providing 25 kV of output power which is used to charge each of the eight capacitors in high voltage module108to generate an approximate 200 kV output from high voltage module108with approximately 50 J of energy in each discharge. It should be understood that the breakdown voltage of spark gaps154can be adjusted upward or downwards within the voltage capacity of the power supply. Similarly, the voltage and energy outputted can be adjusted upward or downward by varying the breakdown voltage and/or the number or capacity of the capacitors.

High voltage module108operates automatically as power is continuously supplied from power supply114to continuously charge capacitors147. When sufficient electric potential is contained within each of the capacitors147, the breakdown voltage of spark gaps154is reached and the electric potential generates a plasma field and spark between electrodes150and152. The spark effectively closes the circuit across each of the spark gaps. Once a first spark gap sparks over, the increase voltage generated results in the remaining spark gaps154almost simultaneously also sparking over, effectively linking all capacitors147in series, resulting in a multiplication of the input voltage by the number of capacitors in the Marx generator. In one embodiment, this generates a 200 kV output applied to emitter116.

Spark gaps154may all be constructed and arranged to have substantially similar break down voltages. Alternatively, one spark gap154may be constructed and arranged with a slightly lower break down voltage than the rest of the spark gaps. The spark gap with the lowest breakdown voltage will become the triggering spark gap with the resulting increased voltage being sufficient to immediately break down all other spark gaps154connected to the triggering spark gap.

Another alternative is to include a mechanical trigger associated with a triggering spark gap that initiates the break down and spark over of the trigger spark gap on a controlled command. For example, a conductor can be introduced into the trigger spark gap to lower the effective break down voltage or an energy source such as a laser could be used to heat the air or gas in the triggering spark gap to also lower the effective break down voltage of the triggering spark gap.

Referring toFIG. 11, an electric schematic of module105is provided. Module105is an alternate embodiment of module104. Capacitors147, resistors148and electrodes150and152are arranged again as an nine-stage Marx generator. (Note that any number of stages can be used as desired. Applicants are currently using an seven-stage Marx generator instead of the illustrated nine-stage unit.) Once again, the output of the Marx generator is electrically coupled to emitter116with emitter118electrically coupled to the low voltage side of power supply114. In module105load resistor172is electrically coupled between emitter116and to the input to the Marx generator. Module105also differs from unit104in that resistor148positioned between the low side of power supply114and the input to the Marx generator is omitted. In module105, emitter118may be directly coupled to a relative ground such as a vehicular ground.

In system100, high voltage module108, power converter110and power source112operate together, as described above, to define a source of pulsed electrical potential.

Referring toFIG. 12, system200is illustrated. System200includes vehicle202and assembly203. In the illustrated configuration vehicle202is a U.S. military flatbed truck and assembly203is mounted on a modified U.S. military mine roller assembly.

Assembly203is generally defined by mine roller205which is a standard US military mine roller. It should be understood that other vehicular platforms may be used in conjunction with the disclosed electrical discharge systems. Mine roller205carries a plurality of units204that include high voltage modules208and209. Vehicle202carries one or more power converters210and power source212. Power converters210and power source212define power supply214. Power converters210and power source212are carried in the bed of vehicle202. Note that power converters210and power source212may be located in any desired position on the vehicle, including on mine roller205or elsewhere on vehicle202. In the illustrated embodiment, power source212is a NATO standard 10 kW palletized generator/engine assembly. However, any other power source can be used including solar cells, batteries, an onboard vehicle alternator or generator, etc.

High voltage modules208and209also include emitters216and218extended away from mine roller205by rigid supports220and222and flexible supports221and223. Emitters216and218as illustrated are flexible metal chains constructed and arranged to flex in one direction while maintaining relative rigidity in the other directions. As discussed above, emitters216and218may be constructed from alternative materials, as desired. Supports220and222are comparatively rigid structures constructed of a comparatively non-conductive material that carries emitters216and218and flexible supports221and223. Flexible supports221and223are located between emitters216and218and rigid supports220and222. Flexible supports221and223include some degree of flexibility and bias.

Emitters216and218are configured with emitter surfaces that are in close contact with the earth. In one embodiment, the emitter surfaces of emitter216and218are approximately 0.5 meters in length. In another embodiment, the emitter surfaces of emitter216and218are at least 0.3 meters in length. In yet another embodiment, the emitter surfaces of emitter216and218are at least 0.2 meters in length. In another embodiment, the emitter surfaces may be between approximately 0.5 to 1.5 meters in length. In one embodiment, emitters216and218may be spaced apart between approximately 0.5 meters to approximately 2.25 meters. In another embodiment, emitters216and218may be spaced apart between approximately 0.6 meters to approximately 1.2 meters. In any event, it should be noted that emitters216and218may be any desired length.

Assembly203is shown in isolated detail inFIG. 13. High voltage module208is mounted on frame206and high voltage module209is mounted on frame207. Frame206is coupled to mine roller205via swivel connection224. Frame207is coupled to mine roller205via tilt connection225. Swivel connection224and tilt connection225are configured and arranged to permit emitters216and218to be stowed for transport.

Frames206and207and swivel connection224and tilt connection225are all constructed of comparatively non-conductive material to isolate high voltage modules208and209from mine roller205. In general, a minimum of a 15 cm clearance between high voltage modules208and209and mine roller205was sought. Dielectric materials may be optionally located between high voltage components and mine roller205.

Also mounted on mine roller205are junction boxes226. Junction boxes include wire terminations between power converters210and high voltage modules208and209(wires not illustrated). Junction boxes226also include emergency disconnects to disconnect power converters210from high voltage modules208and209. Junction boxes226may optionally be omitted in other embodiments.

Blowers228are optionally mounted on mine roller205and are coupled to high voltage modules208and209by flexible air lines229to assist with heat removal from high voltage modules208and209. High voltage modules208and209include casings230with caps232and234. Cap234includes air inlet236and air outlet238. Flexible air lines229are coupled between blowers228and air inlets236on each high voltage modules208and209.

Referring now toFIG. 14, high voltage modules208and209are illustrated in isolated detail. High voltage modules208and209also include wire fitting239on cap234and output terminal240in casing230. Wire fitting239is a strain relief fitting through which a high voltage cable passes to connect to unit204. Output terminal240is coupled to unit204contained within casing230.

Referring now toFIGS. 15-18, Marx generator242is illustrated. Marx generator242is housed within casing230in each of high voltage modules208and209. Marx generator242includes frame components244, capacitors246, resistors248, inductors250, electrodes251and252defining spark gaps254. Capacitors246are connected in parallel defining capacitor groups247and resistors248are also connected in parallel in groups defining resistor groups249. Note that the circuit defined by the illustrated assembly is described below inFIGS. 23-24.

As best seen inFIGS. 17-18, Marx generator242is assembled from stacked frame components244each including individual stages of the Marx generator. Larger or smaller Marx generators may be assembled by including additional or fewer frame components244assemblies. Also as best seen inFIGS. 17-18, frame components244include recess255that goes through the length of Marx generator242. Recess255defines a continuous air path for cooling air as well as the space where a load resistor is located (as shown inFIG. 19and described inFIGS. 23-24).

While not specifically illustrated, Marx generator242may optionally include a luminance meter configured to monitor the relative luminance of one or more spark gaps254. For example, in one embodiment, an exposed end of a fiber optic cable is directed at a spark gap254to transmit emitted light to a separately located luminance meter. The relative luminance of sparks emitted from the spark gap change based on the relative resistivity experienced during a particular discharge. Discharges into relatively high impedance environments result in lower relative luminance while discharges into relatively low impedance environments result in a significantly higher relative luminance. The measured luminance for a particular discharge can be compared against a baseline standard for a particular environment. If the standard is exceeded that may indicate the presence of a conductive material that warrants further investigation. If the luminance for a particular discharge exceeds the standard, then the operator of system200(or100) can be notified of such by illuminating an indicator light or activating a marking system to mark the location on the ground or record GPS coordinates where the discharge took place. The detected conductive material can then be re-scanned by systems100and/or200, can be investigated immediately, or recorded coordinates can be transmitted via communications systems for further investigation.

Referring now toFIG. 19, load resistor256is illustrated. Load resistor256is assembled from five groups of three resistors248connected in parallel. Load resistor256is configured and arranged to fit within recess255defined in Marx generator242. Load resister256can be constructed from any desired combination of resistors in series and/or parallel to achieve desired characteristics such as resistance, heat dissipation, etc.

Referring now toFIGS. 20-21, power converters210are illustrated. Power converters210include casing258which includes air conditioning/heating unit259attached to one side of casing258. While not specifically referenced, casing258includes connectors for high voltage cables and control cables. Each casing258may also optionally include one or more emergency stop button(s) to disconnect the output of power converters210from the rest of system200.

Referring now toFIG. 22, an interior layout of components contained within casing258is provided. Power converter210includes insulator260holding a pair of resistors262, control boards264covered by shields265and two power converters266and relays268. Resistors262are connected in parallel defining resistors270. Control boards264control the output of power converters266and engagement of relays268to control both the output of power converter266and the availability of output power from power converters266. Power converters266are known in the industry as capacitor charging power supplies. Power converters266correspond to model number 202A-40 KV-POS-PFC or 202A-40 KV-NEG-PFC supplied by TDK-Lambda at 3055 Del Sol Boulevard, San Diego, Calif. 92154, telephone number (619) 575-4400, www.tdk-lambda.com. However, any other type of capacitor charging power supply known in the art that meets the requirements of a particular system my be used.

Referring toFIG. 23, an electric schematic of module204is provided as seen inFIGS. 17-18, capacitors246are connected in parallel defining capacitor groups247and resistors248are connected in parallel defining resistor group249. Capacitor groups247, resistor groups249, inductors250and electrodes251and252are arranged as a multi-stage Marx generator (as shown inFIGS. 15-16). The output of this Marx generator is electrically coupled directly to emitter216with emitter218electrically coupled to chassis ground272. Load resistor256is electrically coupled between emitter216and the low power side of Marx generator242. The illustrated system can be configured with power supply214providing a nominal 54 to 81 J of output power used to charge seven capacitors in high voltage module208or209to generate approximately 224 kV output applied to emitter216.

In one specific embodiment high voltage module208includes the following characteristics. Individual capacitors246are rated 0.0075 μF with three capacitors246combined in parallel to make capacitor group247rated 0.0225 μF. Resistors248are ceramic resistors rated at 10 kΩ with two resistors249connected in parallel to make resistor group249rated 5 kΩ. Inductors250are rated 3 mH. Load resistor256is assembled from five groups of three resistors248connected in series, with the groups of three resistors248connected in parallel for an overall rating of 16.7 kΩ for load resistor256. The breakdown voltage of spark gaps254are approximately 32 kV, although the breakdown voltage could optionally be set between 25 kV and 38 kV. The illustrated system is configured with power supply214providing up to 40 kV of output power which is used to charge seven capacitor groups in high voltage module208to generate a nominal 224 kV output from high voltage module108with approximately 81 J of energy in each discharge. This described embodiment of high voltage module208is constructed and arranged to continuously discharge approximately 10 times each second, although the pulse frequency can be adjusted via the control software.

In one specific embodiment high voltage module209includes the following characteristics. Individual capacitors246are rated 0.0075 μF with two capacitors246combined in parallel to make capacitor group247rated 0.0015 μF. Resistors248are ceramic resistors rated at 10 kΩ with two resistors249connected in parallel to make resistor group248rated 5 kΩ. Inductors250are rated 3 mH. Load resistor256is assembled from five groups of three resistors248connected in series, with the groups of three resistors248connected in parallel for an overall rating of 16.7 kΩ for load resistor256. The breakdown voltage of spark gaps254are approximately 32 kV, although, once again, the breakdown voltage could be varied between 25 kV and 38 kV, as desired. The illustrated system is configured with power supply214providing up to 40 kV of output power which is used to charge seven capacitors in high voltage module209to generate a 224 kV output from high voltage module108with approximately 54 J of energy in each discharge. This described embodiment of high voltage module209is constructed and arranged to continuously discharge approximately 15 times each second. Note that alternative configurations of high voltage module209may utilize components, including capacitors246, resistors248, inductors250, load resistor256and spark gaps254with different ratings, as desired. High voltage module209may also be constructed and arranged to discharge at different frequencies by modifying hardware and/or control system inputs.

Referring now toFIG. 25, pulse rate clock waveform300, power supply command voltage input waveform310and power supply output voltage waveform320are shown. Pulse rate clock waveform300represents a control timing signal provided by or to control board264in power converter210. Pulse rate clock waveform300includes control voltage signal302, zero volt signal304and delay305between successive signals306. Signal306is the transition from zero volt signal304to the control voltage signal302. Signal306indicates to control board264to command power converter266to begin providing the programmed output voltage. In one embodiment, delay305between successive signals306is equal to approximately 100 ms. In another embodiment, delay305between successive signals306is equal to approximately 66 ms.

Power supply command voltage input waveform310represents the electrical control signal provided by control board264to power converter210. Power supply command voltage input waveform310includes inhibit output312, charging output314, delay315and break over output316. Charging output314and break over output316are a scaled voltage signal provided to power converter210indicating the relative voltage that power converter210is commanded to produce. Delay315is a programmed delay between the initiation of charging output314and break over output316. Delay315may be generated internally by control board264via a timing mechanism similar to pulse rate clock waveform300. Charging output314may be set below the break over voltage of all spark gaps254in Marx generator242while break over output316may be configured to be above the break over voltage of all spark gaps254. In one embodiment, power converter210outputs between 0 V and 40 kV with charging output314being approximately 30 kV, break over output316being approximately 40 kV with spark gaps254having a break over voltage of approximately 32 kV.

Power supply output voltage waveform320shows the voltage output of power converter210when controlled by power supply command voltage input waveform310. Power supply output voltage waveform320includes inhibited output322, charging output324, charged output326and overcharge output328. Power converter210is a current limited voltage controlled power converter, so when power converter210receives the signal to provide charging output314, the ability of power converter210to actually provide the requested voltage is limited by the power output of power converter210compared to the applied load. In system200, the load is capacitor groups247, inductors250and resistor groups249. Thus, charging output324represents the voltage output of power converter210while capacitor groups247are being charged up to charging output314. Charged output326represents a period when capacitor groups247are fully charged to charging output314. Overcharge output328represents the voltage output of power converter210while capacitor groups247are charging to break over output316. At some point between charging output314and break over output316, the voltage across capacitor groups247will exceed the break over voltage of spark gaps254, initiating a comparatively rapid discharge of capacitor groups247as described above. (In this regard, capacitor groups247do not discharge instantaneously. However, the time it takes for capacitor groups247to discharge can be measured in microseconds, which is much quicker than the illustrated waveforms with millisecond timing can distinguish.)

Power converter210includes a feedback signal to control board264that indicates when the voltage output of power converter210drops. Upon discharge, control board264signals inhibit output312until detecting the next signal306. The time when power converter210is inhibited allows Marx generator242to substantially completely discharge through emitter216. The inhibit time may also be used to increase the amount of time available to resister groups249and load resistor256to cool down between discharges.

In system200, high voltage modules208or209, power converter210and power source212operate together, as described above, to define a source of pulsed electrical potential. Power converter210and high voltage modules208and209operate together, as described above, to define a pulsed voltage converter.

Emitters116and216may be configured as cathode emitters directly coupled to the output of Marx generators142or242. Emitters118and218may be configured as anode emitters coupled to either the input of Marx generators142or242or to a relative vehicular ground such as the chassis of vehicle102or202. Emitters116,118,216and218may include an emitter surface on the surface facing the earth. In the illustrated embodiments, emitters116,118,216and218are dragged along the earth in direct contact with the earth. However, in other embodiments, emitters116,118,216and/or218can be suspended above the earth in close proximity to the earth. For example, emitters116,118,216and/or218could be constructed of a rigid material and small wheels or other device could be located on emitters116,118,216and/or218to define a gap between the earth and emitters116,118,216and/or218. In another embodiment, a rigid or flexible material could be placed between emitters116,118,216and/or218and the earth. For example, emitters116,118,216and/or218could be woven in a flexible material. In another example, a thin sled could be placed between emitters116,118,216and/or218and the earth. The thin sled could optionally include spaces or voids to create air passages through the sled between the earth and emitters116,118,216and/or218. Such a sled could optionally be constructed of a dielectric material. Additionally, while emitters116,118,216and/or218are shown oriented parallel to the direction of travel of systems100and200, the emitters can alternatively be oriented in other directions including perpendicular to the direction of travel or a combination of different directions, including both parallel and perpendicular can be utilized.

Power converters110and210may be switched-mode power supplies or non-switched power supplies.

Systems100and200are constructed and arranged to move emitters116,118,216and218across the ground. One possible use of this apparatus is to scan an area for explosive devices, for example, Improvised Explosive Devices (IEDs), CBRNE devices or land mines. In particular, devices such as those currently being encountered in Afghanistan and Iraq. Systems100and200produce an electrical potential sufficiently high to transfer that electrical potential through substances normally considered non-conductive such as air, soil and coatings on wires. High voltage electrical potentials will seek a path to a lower potential ground, or at least a lower potential ground relative to the electrical potential.

The high voltage electric field presented on emitters116and216can cause air molecules to ionize, which results in much more conductive air due to the mobility of free electrons and therefore the promotion of electric current away from or toward emitters116and216(depending on the polarity of the applied voltage). Conductive objects located in or near the electric field and/or the created plasma can act as a conduit to a lower potential (a relative ground) for the electrical potential to dissipate through.

The dynamics involved with an electric potential dissipating into the ground are complex and subject to a large number of variables. The results can be analogous to lightning propagation through the atmosphere where the path of the lightning is rather chaotic and unpredictable paths are taken in what is presumably the course of least resistance (or most conductance) to ground.

In general, homogenous metal objects common to many explosive devices are more conductive than water and minerals with metallic content. Examples of such materials include wire, blasting cap casings and munitions casings. Such materials may represent a much more attractive charge collectors for a discharged potential than surrounding materials in the ground. Table 1 shows the resistivity and permittivity of several reference materials and terrain types.

Another significant variable effecting arc penetration of the ground is moisture content. Table 2 shows the resistivity of silica based sand and clay mixed with sand with varying moisture content.

Another significant variable is soil density. Soil density in combination with moisture saturation determines possible arc channels through and around aggregate. Higher density results in fewer channels of air or water which generally results in higher arc impedance.

The relative resistance of the anticipated operating environment for systems100and200can affect the resistance of load resistors172and256. Load resistors172and256may be optionally included to reduce the dissipation load on Marx generators142and242when emitters116or216have a relatively high impedance to the earth. As discussed above, conductors in the earth may create a comparatively low impedance discharge path. In addition, conductors in the earth may create a partial bridge between emitters116and118or emitters216and218. However, if no relatively low impedance paths are available, discharge pulses may end up feeding back into Marx generators142and242and dissipating through resistors148and248. In such an event, load resistors172and256may define an alternative or additional source for discharged pulses to dissipate through. In one embodiment, the relative resistance of load resistors172and256are balanced with the relative resistance provided by Marx generators142or242. Load resistors172and256may optionally be configured to have a load resistance greater than an earth resistance between emitters116or216and the earth when there is a conductive material in the earth located proximate to emitters116or216and within about 8 cm of the surface of the earth.

Applicants have determined that discharging at least 30 kV of electrical potential into the ground with at least 30 Joules of energy provides the desired scanning capacity. Lower potential and energy levels are certainly capable of disabling electronics and/or pre-detonating or dudding explosives, with successful detonation with energy as low as 3 Joules or voltage as low as 15 kV. Applicants have simply determined that at least 30 kV of potential and at least 30 Joules of energy provide more reliable results in various situations. However, improved results may be obtained with higher potential and/or energy levels. For example, 100 kV provides more reliable results than 30 kV and 200 kV provides more reliable results than 100 kV. In some situations up to 400 kV or more may be desirable. Similarly, more power in each discharge may provide more reliable results. 50 Joules per discharge may provide more reliable results than 30 Joules. 75 Joules per discharge may provide more reliable results than 50 Joules. The required potential and energy levels may be highly dependent upon the characteristics of the terrain being scanned and the characteristics of the electronic and/or explosive target. For example, a system configured for the deserts of Iraq may have significantly different requirements than a system configured for jungles in the Philippines.

In addition to direct conduction, the high voltage electrical field generated around emitters116and216may induce current to flow in conductors located in that electrical field. The high voltage electrical field generated around emitters116and216varies with time, from a high potential when voltage is generated in high voltage modules108and208and released to emitters116or216as a pulse to a low potential after an individual pulsed discharge has dissipated. This generates a changing transverse magnetic flux around emitters116and216that can induce current to flow through a conductor located within range of the magnetic flux. (Transverse meaning that the direction of the magnetic field is perpendicular to the emitter). The current induced by the changing magnetic flux is proportional to the degree of perpendicularity of the conductor compared to the magnetic field with the highest induced current being generated in conductors perpendicular to the magnetic field and almost no current being generated in conductors parallel to the magnetic field. Because the magnetic field is perpendicular to the emitter, then a conductor parallel to the emitter will experience the highest magnetic flux induced current while a conductor perpendicular to the emitter will experience almost no magnetic flux induced current.

Emitters116and216can also be viewed as transmitting antenna with potential target conductor, such as command wires, pressure plates, and remote control devices acting as relay antenna that both receive and transmit the radiating energy.

Thus there are at least two different mechanisms through which systems100and200can pre-detonate or otherwise neutralize an explosive device. First, a high voltage can be emitted near enough to the explosive device or to a conductive path to the explosive device to overcome the impedance between the high voltage and the initiation circuit of the explosive device to transfer sufficient energy to the explosive device to either detonate the explosive device or to render it inoperative (for example by dudding a blasting cap or disabling the initiation circuitry). Second, electromagnetic coupling can occur between emitters116or216and conductors connected to or part of the explosive device to generate an induced current sufficient to either detonate the explosive device or to render it inoperative.

Enhanced scanning may be achieved by having emitters positioned relatively perpendicular to each other. For example, a first emitter can be positioned parallel to the direction of travel while a second emitter can be positioned perpendicular to both the direction of travel and the first emitter. This provides at minimum a 45 degree angle between an emitter and a conductor, potentially enhancing the potential to electromagnetically induce a current in the conductor.

Emitters116,118,216and218are dragged along the earth in close proximity to the earth. In general, closer proximity to the earth results in greater energy being available to pass into the earth, as less energy is expended ionizing the air between the emitters and the earth. Thus, direct contact with the earth usually utilizes the greatest percentage of available energy for interrogating the earth and any items in the earth in proximity to the emitters. However, direct contact with the earth can result in wear on emitter surfaces, so, in some cases, emitter surfaces can be located spaced apart from the earth. In one embodiment, within 3 cm. In another embodiment, within 8 cm.

In a multi-emitter system, such as system200, it is also possible to configure high voltage modules208and209so that the high voltage modules each discharge independently and out of phase with each other (i.e., only one high voltage module discharges at a particular time), or high voltage modules208and209may be configured to all discharge simultaneously.

Vehicles102and202are both configured with a direction of straight travel. The illustrated emitters116,118,216and218are all oriented parallel to the direction of straight travel for the respective vehicles. However, both vehicles102and202are configured to be turn-able for steering.

Systems100and200described above have pulsed power generators producing pulsed electrical discharges. For purposes of this application, pulsed refers to discharging accumulated energy very quickly. For example, but not limited to, within 100 microseconds. Systems100and200include components that accumulate relatively low power and potential energy over a relatively long period of time and then release comparatively high power and potential energy in a comparatively very quick time increasing the instantaneous power discharged. Using pulsed power generation, systems100and200are able to be relatively small and lightweight compared to the amount of power emitted, i.e., a non-pulsed power generation system would have to be much larger and heavier to output comparable levels of power continuously. In addition, pulsed discharges may have advantages over continuous discharges. As discussed above, pulsed discharges produce changing electromagnetic fields that can induce current in nearby conductors. In addition, pulsed discharges can be more efficient at creating plasma in air.

Systems100and200described above include specific characteristics for various components and performance levels. It should be understood that these are merely examples and are not restrictive in scope. Different system performance can be obtained by varying components. Larger or smaller power sources112and212may be utilized. Larger or smaller power converters210and212may be utilized to achieve different voltage output and power throughput. Larger or smaller Marx generators142and242may be utilized. Various components disclosed in Marx generators142and242may be varied as desired, including the number of stages, the type and number of components, etc. Actual system parameters are determined based on criteria such as soil type and conditions, target device type or configuration, environmental conditions, desired movement speed and other factors.

Similarly, system200includes disclosure of operation at 10 Hz and 15 Hz. Other embodiments can operate at different frequencies as desired. Pulse rates can be varied to deliver higher or lower pulse frequency to compensate for factors such as speed of travel and emitter length. If desired, pulse frequency can be controlled manually or automatically at least in part based on vehicle speed or with other criteria such as soil moisture content.

Referring now toFIG. 26, Marx generator142is illustrated incorporating a luminescence detection system. Specifically,FIG. 26illustrates fiber optic cables350directed between electrodes150and152toward spark gaps154. The other ends of fiber optic cables350enter signal processing units352, that contain light detection and processing equipment, for example, a luminescence meter with signal processing hardware to determine the luminescence of each individual spark in multiple spark gaps154.

Referring toFIG. 27, a similar system is illustrated and incorporated with Marx generator242. Specifically,FIG. 27illustrates fiber optic cable350is directed between electrodes251and252at spark gap254. Light generated by sparks in spark gap254are transferred by fiber optic cable350to signal processing unit352, that contains light detection and processing equipment, for example, a luminescence meter with signal processing hardware to determine the luminescence of an individual spark in spark gap254.

Referring now toFIG. 28, an embodiment of assembly203is illustrated with a pair of high voltage modules208and a pair of high voltage modules209coupled to emitters216and218through supports220and222as discussed above. The embodiment illustrated inFIG. 28also includes antennas360extending between supports220and222and high voltage modules209. In the illustrated embodiment, antennas360are omnidirectional whip antennas.

Antennas360may optionally be located on or near the ground on either side of emitters216and218or between emitters216and218. Antennas360may optionally be coated with a high impedance material or may optionally be constructed of a high impedance material.

Referring toFIGS. 29-34, several embodiments of system400are illustrated. System400generally includes vehicle402and assembly403. In the illustrated embodiment, vehicle402is a armored U.S. military flatbed truck and assembly403includes a modified U.S. military mine roller assembly405. Mine roller405carries a plurality of modules404that each include a high voltage module configured as sources for pulsed electrical potential.

Vehicle402carries power supply414with is electrically coupled to modules404. Modules404are each electrically coupled to emitters416and418. Emitters416and418are extended away from mine roller405by rigid supports and flexible supports. Emitters416and418may be constructed of flexible materials. Emitter416and418may be configured to be dragged along the earth or they may be configured to be held in close proximity to the earth similar to emitters216and218as discussed above.

FIGS. 29-34disclose various embodiments of system400incorporating unidirectional and omnidirectional antenna in various locations on system400. It should be understood that the types and locations of antenna disclosed herein are only examples of potential types of antenna and locations to position different antenna. Antenna types and locations may be optimized based on performance characteristics of individual systems and the type and accuracy of radio frequency information desired.

Referring specifically toFIG. 29,FIG. 29illustrates uni-directional antenna362mounted on mine roller405. Referring toFIG. 30, the illustrated embodiment of system400includes omnidirectional antenna364mounted on mine roller405. Referring toFIG. 31, the illustrated embodiment of system400includes omnidirectional antenna364mounted on vehicle402. Referring toFIG. 32, the illustrated embodiment of system400includes uni-directional antenna362mounted on vehicle402. Referring toFIG. 33, the illustrated embodiment of system400includes a pair of uni-directional antennas362mounted on the rear end of mine roller405. Referring toFIG. 34, the illustrated embodiment of system400includes a omnidirectional antenna364mounted on mine roller405and a pair of uni-directional antennas362mounted on front end of vehicle402.

Antenna arrangement illustrated inFIGS. 28-34are examples of antenna arrangements that may be used to detect emissions from emitters416as well as electric magnetic fields generated by current flows in conductors induced by electrical discharges from emitters416. As discussed above, the high voltage electrical field generated around emitters416varies with time from a high potential when voltage is initially discharged from modules404to a low potential after an individual false discharge is dissipated. This generates a changing transverse magnetic flux around emitter416that can induce the current to flow through a conductor located within range of the magnetic flux. Antenna360,362and364may be used to detect that induced current as a method of locating conductors within range of system400.

Referring toFIG. 35, sensor370is illustrated. Sensor370is a current transformer or current sensor. Sensor370is positioned with cable372passing through sensor370. Cable372is an electrical cable coupling between module404and emitter416. The illustrated embodiment of sensor370is a current transformer such as that produced by Pearson Electronics (www.pearsonelectronics.com); however, any other form of current sensor known in the art may be used including, but not limited to, a Rogowski coil.

Referring toFIG. 36, schematic of various detection methods is illustrated. TheFIG. 36schematic includes a representative high voltage module408coupled to emitters416and418. Also shown inFIG. 36is a representative target conductor90capable of receiving an electrical discharge from emitter416. Target conductor90may receive the electrical discharge from emitter416directly, indirectly through direction conduction through an intermediary such as air or the earth, or indirectly through current flow induced by the magnetic field generated by emitter416. The current received by target conductor90generates electromagnetic energy92which is received by antenna362and is processed by radio frequency receiver366producing a signal sent to signal processor390.

In addition to the representative high voltage module408with emitters416and418.FIG. 36also illustrates several sensors and signal processing components including signal processing unit352, antenna362, RF receiver366, current sensor370, signal processing unit374, and voltage meters380. It should be understood that every sensor illustrated is not necessary for detection operation. Various components and/or sub combinations of the illustrated sensors may be used to obtain any desired level of detection capacity. For example, multiple sensors may be integrated together or single sensors may be used alone.

As discussed above, signal processing unit352is coupled to fiber optic cable350which is directed toward a spark gap in high voltage module408. Signal processing unit352generated luminescence signal354sent to signal processor390. Antenna362receives electromagnetic energy92emitted from target conductor90. RF receiver366generates RF signal368sent to signal processor390. Sensor370is coupled to signal processing unit374which generates current signal376sent to signal processor390. Voltage meters380are positioned on cables372and373between high voltage module408and emitters416and418. Voltage meters380generate voltage signals382that are sent to signal processor390. In alternative embodiments, voltage meters380may be positioned on the surface of the case of high voltage module408.

Signal processor390may be configured to process one or more the aforementioned signals including relative luminescence, voltage, current, and detected radio frequency emissions to determine the location and nature of conductors in proximity with emitters416and418. Voltage signals382from various emitters may be separately monitored in signal processor390. For example, an emission from a particular emitter416may result in a corresponding voltage change across multiple emitters418. Signal processor390may be configured to monitor multiple emitters418in conjunction with an emission through an emitter416to determine relative directions of current flow.

In this regard, in a system utilizing multiple emitters416and418coupled to multiple high voltage modules408, various high voltage modules408may optionally be controlled to operate discretely to facilitate analysis of various signals generated by a single discharge event. Including multiple high voltage modules408on system400and operating them discretely, providing additional information related to the relative location of a high voltage at a point in time, may facilitate more precise signal processing to help determine the location, size, depth and conductivity of target conductor90. In addition, the return signals of particular conductors, such as particular landmines or a command wire, may be tabulated or otherwise categorized to add in future identification of similar structures.

Signals such as luminescence signal354, voltage signal382and/or current signal376may be utilized as time signals in signal processor390to establish when a particular emission occurs. This may be used in conjunction with the signals received from radio frequency receiver366to facilitate calculating distance and position of target conductor90.

Referring toFIG. 37, an example of an oscilloscope waveform recorded with a radio frequency antenna focused directly towards the output of emitter416. The waveform shown inFIG. 37represents the waveform with very low impedance due to emitters416and418being located close together. This waveform may be representative of the condition when a conductor is positioned at least partly between emitters416and418.

Referring toFIG. 38, illustrated is an oscilloscope waveform recorded with a radio frequency antenna focused directly towards the spark output where emitters416and418are spaced far apart without any conductor in-between. This waveform may be representative of a high impedance discharge condition.

There are several detection schemes that may provide useful information. One or more unidirectional antenna(s) aimed off-axis away from emitters416and418to detect electromagnetic energy92from target conductor90. Unidirectional antenna(s) aimed directly at emitters416and418to detect the electrical signature of individual discharges. These systems can be combined together and/or with other signals such as voltage, current and luminescence to determine the magnitude and phase relationship between the source discharge and the returned energy from target conductor90.

Referring toFIG. 39, system400is illustrated. System400is similar to system200described above and inFIG. 12. System400includes vehicle402and assembly403. In the illustrated configuration vehicle402is an armored U.S. military flatbed truck and assembly403is mounted on a modified U.S. military mine roller assembly.

Assembly403is generally defined by mine roller405which is a standard US military mine roller. It should be understood that other vehicular platforms may be used in conjunction with the disclosed electrical discharge systems. Mine roller405carries a plurality of modules404that each include a high voltage module408. Vehicle402carries one or more power converters410, system control unit411and power source412posited under sun shield413. Power converters410, system control unit411and power source412define power supply414. Power converters410, system control unit411and power source412are carried in the bed of vehicle402. Note that power converters410, system control unit411and power source412may be located in any desired position on the vehicle, including on mine roller405or elsewhere on vehicle402. In the illustrated embodiment, power source412is a NATO standard 10 kW palletized generator/engine assembly. However, any other power source can be used including solar cells, batteries, an onboard vehicle alternator or generator, etc.

Modules404include emitters416and418extended away from mine roller405by rigid supports420and422and flexible supports421and423. High voltage modules408are electrically connected to emitters416by cables372. Emitters416and418as illustrated are relatively rigid steel cables. However, emitters416and418may be constructed from any desired material. Supports420and422are comparatively rigid structures constructed of a comparatively non-conductive material that carries emitters416and418and flexible supports421and423. Flexible supports421and423are located between emitters416and418and rigid supports420and422. Flexible supports421and423include some degree of flexibility and bias.

Emitters416and418are configured with emitter surfaces that are in close contact with the earth. In one embodiment, the emitter surfaces of emitter416and418are approximately 0.5 meters in length. In other embodiments, the emitter surfaces of emitter416and418are at least 0.3 meters in length. In yet other embodiments, the emitter surfaces of emitter416and418are at least 0.2 meters in length. In another embodiment, the emitter surfaces may be between approximately 0.5 to 1.5 meters in length. In one embodiment, emitters416and418may be spaced apart between approximately 0.5 meters to approximately 2.25 meters. In another embodiment, emitters416and418may be spaced apart between approximately 0.6 meters to approximately 1.2 meters.

Assembly403is shown in isolated detail inFIG. 40. High voltage modules408are mounted mine roller405. Rigid supports420and422are mounted on frames406. Frames406is coupled to mine roller405via swivel connections424and425. Swivel connections424and425are configured and arranged to permit pairs of emitters416and418to be individual stowed for transport.

Frames406and407and swivel connection424and425are each constructed of comparatively non-conductive material to isolate high voltage modules408from mine roller205. In general, high voltage components such as high voltage modules408and cables372are spaced apart from mine roller405. Dielectric materials may be optionally located between high voltage components and mine roller405.

Blowers228are optionally mounted on mine roller405and are coupled to high voltage modules408by flexible air lines429to assist with removing heat and ionized air from high voltage modules408. High voltage modules408are located within casings431as described below.

Referring toFIG. 42, casing430is illustrated. Similar to casing230described above, casing430is configured and arranged to hold a Marx generator assembly (not illustrated). Marx generator242discussed above could be used as part of High Voltage module408. Casing430includes flanges433on either side with caps232and234covering the ends of casing430and permitting access to the Marx generator contained within. Cap434includes air inlet436and air outlet438. Flexible air lines429may be coupled between blowers428and air inlets436on each high voltage modules408.

Referring now toFIGS. 43-44, power converters410and system control unit411are illustrated with sun shield413removed (for clarity). Power converters410and system control unit411are each located inside casings458which includes air conditioning/heating unit459attached to one side of casing458. While not specifically referenced, each casing458includes connectors for high voltage cables and control cables. Each casing458may also optionally include one or more emergency stop button(s) to disconnect the output of power converters410from the rest of system400.

Referring now toFIG. 45, an interior layout of components contained within casing258in one power converter410is provided. Power converter410includes insulator460holding a pair of resistors462, two power converters466. Resistors462are connected in parallel defining resistors470. Power converters466are known in the industry as capacitor charging power supplies. Power converters466correspond to model number 202A-40 KV-POS-PFC or 202A-40 KV-NEG-PFC supplied by TDK-Lambda at 3055 Del Sol Boulevard, San Diego, Calif. 92154, telephone number (619) 575-4400, www.tdk-lambda.com. The output of each power converter466is coupled to an individual high voltage module408. However, multiple power converters466could be coupled to a single high voltage module408, or a single power converter466could be coupled to multiple high voltage modules408.

While not illustrated, system control unit411includes control circuitry, including a PLC, operable to control each individual power converters466and power source112. System control unit411may optionally be controlled from within the cab of vehicle102.

Referring toFIG. 46, an electric schematic of and individual module404is provided including a Marx generator similar to what is shown inFIGS. 17-18, capacitors246are connected in parallel defining capacitor groups247and resistors248are connected in parallel defining resistor group249. Capacitor groups447, resistor groups449, inductors450and electrodes451and452are arranged as a multi-stage Marx generator (with electrodes451and452defining spark gaps454). The output of this Marx generator is electrically coupled directly to emitter416with emitter418electrically coupled to chassis ground472. Load resistor456is electrically coupled between emitter416and the low power side of the Marx generator. The illustrated system can be configured with power supply414providing a nominal 54 J to 81 J of output power used to charge seven capacitors in high voltage module408to generate approximately 224 kV output applied to emitter416.

Referring now toFIG. 47, power supply command voltage input waveform510and power supply output voltage waveform520are shown. Power supply command voltage input waveform510represents the electrical control signal provided by system control unit411to an individual power converter466. Power supply command voltage input waveform310includes inhibit output512, charging output514, step charge increases515and break over output516. Charging output514and break over output516are a scaled voltage signal provided to power converter466indicating the relative voltage that power converter466is commanded to produce. Charging output514may be set below the break over voltage of all spark gaps454in a Marx generator while break over output516may be configured to be above the break over voltage of all spark gaps454. In one embodiment, power converter466outputs between 0 V and 40 kV with charging output514being approximately 30 kV, break over output516being approximately 40 kV with spark gaps454having a break over voltage of approximately 32 kV, although the break over voltage could be set between 25 kV and 38 kV, as desired.

Power supply output voltage waveform520shows the voltage output of power converter466when controlled by power supply command voltage input waveform510. Power supply output voltage waveform520includes inhibited output522, charging output524, charged output526, stepped output527and overcharge output528. Power converter466is a current limited voltage controlled power converter, so when power converter466receives the signal to provide charging output514, the ability of power converter466to actually provide the requested voltage is limited by the power output of power converter466compared to the applied load. In system400, the load is capacitor groups447, inductors450and resistor groups449.

Thus, charging output524represents the voltage output of power converter466while capacitor groups447are being charged up to charging output514. Charged output526represents a period when capacitor groups447are fully charged to charging output514.

Stepped output527represents the voltage output of power converter466in response to each step charge increase515. Overcharge output528represents the voltage output of power converter466while capacitor groups447are charging to break over output516. At some point, the voltage across capacitors447will exceed the break over voltage of spark gaps454, initiating a comparatively rapid discharge of capacitor groups447as described above. (In this regard, capacitor groups447do not discharge instantaneously. However, the time it takes for capacitor groups447to discharge can be measured in microseconds, which is much quicker than the illustrated waveforms with millisecond timing can distinguish.)

Power converter466includes a feedback signal to system control unit411that indicates when the voltage output of power converter466drops. Upon discharge, system control unit411signals inhibit output512until delay505has elapsed. The time when power converter466is inhibited allows the Marx generator to substantially completely discharge through emitter416. The inhibit time may also be used to increase the amount of time available to resister groups449and load resistor456to cool down between discharges.

In system400, high voltage modules408, power converter210, system control unit411and power source212operate together, as described above, to define a source of pulsed electrical potential. Power converter410and high voltage modules208operate together, as described above, to define a pulsed voltage converter.

Similar to emitters116and216described above, emitters416may be configured as cathode emitters directly coupled to the output of a Marx generator. Emitters418may be configured as anode emitters coupled to either the input of a Marx generator or to a relative vehicular ground such as the chassis of vehicle402. Emitters416and418may include an emitter surface on the surface facing the earth. In the illustrated embodiments, emitters416, and418are dragged along the earth in direct contact with the earth. However, in other embodiments, emitters416and/or418can be suspended above the earth in close proximity to the earth as described above with regard to emitters116,118,216and/or218.

Similar to systems100and200, system400is constructed and arranged to move emitters416and418across the ground. One possible use of this apparatus is to scan an area for explosive devices, for example, Improvised Explosive Devices (IEDs), CBRNE devices or land mines. System400produces an electrical potential sufficiently high to transfer that electrical potential through substances normally considered non-conductive such as air, soil and coatings on wires.

Referring now toFIGS. 48-50, alternative emitter layouts602,604and606are shown. Emitter layout602, as shown inFIG. 48includes mesh support615, emitters616and618and lateral extensions emitters620and622extending from emitter616. Emitters616,618,620and622are interwoven in mesh support615. Mesh support may be attached to system100,200or400described above, replacing emitters116,118,216,218,416or418. Lateral extension emitters620and622generate an electromagnetic field that is oriented approximately 90 degrees from the electromagnetic field generated around emitter616when emitter616is charged with current from a high voltage emitter such as high voltage emitter108,208or408. As described above, the current induced by a changing magnetic flux is proportional to the degree of perpendicularity of the conductor compared to the magnetic field with the highest induced current being generated in conductors perpendicular to the magnetic field and almost no current being generated in conductors parallel to the magnetic field. Emitting through perpendicular emitters such as emitters616and620ensures that a conductor will experience some degrees of induced current because an individual conductor cannot be parallel to both emitter616and emitter620.

Emitters616,620and622can also be viewed as transmitting antenna with potential target conductor, such as command wires, pressure plates, and remote control devices acting as relay antenna that both receive and transmit the radiating energy.

Referring toFIG. 51, emitter630is illustrated. Emitter630include drop profile emitter632defining rounded top surface634and pointed bottom surface636. Emitter630may focus emitter electromagnetic energy downward through pointed bottom surface636. Emitter630may optional be substituted for any emitter disclosed herein, including, but not limited to emitters116,216,416,616,118,218,418and618. Emitter630may be rigid or flexible.

Referring toFIG. 52, emitter640is illustrated. Emitter640includes drop profile emitter632substantially covered with dielectric642on rounded top surface634. Dielectric642may provide some insulation against upwardly oriented discharges. Dielectric642may also provide some wear protection for drop profile emitter632when emitter640is used in direct contact with the ground.

Referring toFIG. 53an alternative embodiments of robotically mounted electrical discharge systems is illustrated as system700. System700includes vehicle702, housing704and supports706supporting emitters116and118. Vehicle702is a Mesa Technologies ACER Robot, although other robotic platforms could be used. Housing704contains high voltage module108and controls114as described above. Supports706are connected to emitters116and118and allow the standoff distance between emitters116and118and housing704to be increased.

Referring toFIG. 54, a second alternative embodiments of robotically mounted electrical discharge systems is illustrated as system710. System710includes vehicle712, mine roller714, supports716and718, high voltage modules108and emitters216,218,116and118. Vehicle712is a robot controlled Bobcat track loader. Mine roller714is a Minotaur Mine Roller. Support716holds a pair of high voltage modules108and two emitter pairs216and218, each connected to one high voltage module108. Emitters216and218are extended in front of mine roller714by support716. Support718holds high voltage module108and emitters116and118trailing behind vehicle712.

Referring toFIG. 55, a third alternative embodiments of robotically mounted electrical discharge systems is illustrated as system720. System720includes vehicle722, supports726and728, casing431containing high voltage module408, high voltage module108and emitters216,218,116and118. Vehicle722is a robot controlled Bobcat track loader. Support726holds casing431containing high voltage module408, two spaced emitters216on the forward end of support726and four spaced emitters218behind emitters216. Support728holds high voltage module108and emitters116and118trailing behind vehicle722. High voltage module408is connected to both emitters216. As describe above, emitters218may be connected to a vehicular ground or to the low voltage side of high voltage module408.

Referring toFIG. 56, a fourth alternative embodiments of robotically mounted electrical discharge systems is illustrated as system730. System730includes vehicle732, remote control system734, support736, three high voltage modules108and three sets of emitters116and118. Vehicle732is a robot controlled Bobcat track loader. Remote control system734is a QinetiQ remote control system with a camera mounted on top of vehicle732. Support716holds three high voltage modules108and three emitter pairs116and118, each connected to one high voltage module108.

It should be understood that the system disclosed herein can be configured to generate and emit a positive and/or negative polarity electrical potential. Emitters are labeled in the claims as cathode emitters and anode emitters, referring to by convention for discharging components, with the cathode emitters referring to the emitter in which electrons flow out of (positive polarity) and the anode emitters referring to the emitter in which the current flows into (negative polarity). If a positive potential is generated, then the cathode emitter is electrically coupled to the electrical power supply and the anode emitter may be coupled to a chassis ground and/or to the other side of the electrical power supply. If a negative potential is generated, then the anode emitter is electrically coupled to the electrical power supply and the cathode emitter may be coupled to a chassis ground and/or to the other side of the electrical power supply. Furthermore, it is possible to configure an electrical power supply to generate both a positive and a negative potential, for example, ±200 kV. In that case, the cathode emitter is electrically coupled to the positive output of the electrical power supply and the anode emitter is electrically coupled to the negative output of the electrical power supply.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.