EP0232594A2 - Dispositif et procédé de propulsion par plasma - Google Patents

Dispositif et procédé de propulsion par plasma Download PDF

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Publication number
EP0232594A2
EP0232594A2 EP86308921A EP86308921A EP0232594A2 EP 0232594 A2 EP0232594 A2 EP 0232594A2 EP 86308921 A EP86308921 A EP 86308921A EP 86308921 A EP86308921 A EP 86308921A EP 0232594 A2 EP0232594 A2 EP 0232594A2
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EP
European Patent Office
Prior art keywords
plasma
projectile
bore
fluid
barrel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP86308921A
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German (de)
English (en)
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EP0232594A3 (fr
Inventor
Yeshayahu Shyke A. Goldstein
Derek A. Tidman
Rodney L. Burton
Dennis W. Massey
Niels K. Winsor
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GT-DEVICES
GT Devices Inc
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GT-DEVICES
GT Devices Inc
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Publication of EP0232594A2 publication Critical patent/EP0232594A2/fr
Publication of EP0232594A3 publication Critical patent/EP0232594A3/fr
Withdrawn legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41B—WEAPONS FOR PROJECTING MISSILES WITHOUT USE OF EXPLOSIVE OR COMBUSTIBLE PROPELLANT CHARGE; WEAPONS NOT OTHERWISE PROVIDED FOR
    • F41B6/00—Electromagnetic launchers ; Plasma-actuated launchers

Definitions

  • the present invention relates generally to an apparatus for and method of accelerating a projectile and more particularly to a projectile accelerating method and apparatus wherein an electric pulse source for energizing the plasma has a waveshape and duration for initially igniting the plasma and for thereafter applying energy to the ignited plasma to control the pressure of a propelling agent derived in response to the plasma.
  • a confined mass of projectile propelling fluid mixes with the plasma to cool the plasma initially and is subsequently heated by the plasma so low atomic weight constituents thereof become sufficiently energetic to accelerate the projectile in a bore of a barrel in which the projectile is located.
  • the plasma is derived from an ablatable, low atomic weight dielectric granular filler or a liquid containing low atomic weight elements located in many large surface area dielectric containers, e.g., spheres or long thin tubes, which together form a capillary discharge.
  • the dielectric containers have differing wall thicknesses to control the time when the contents thereof are ignited.
  • the constant pressure is desirable because it provides constant acceleration for a relatively prolonged time interval to the projectile, to increase the total energy applied to the projectile at the time the projectile leaves the barrel muzzle.
  • the constant pressure in the bore also enables the bore strength to be reduced relative to the situation of a pulsed propulsive force. This is because the pulse must have a higher initial force to achieve a muzzle velocity which is attained with a constant pressure source.
  • a projectile is accelerated from a gun having a barrel with a bore adapted to receive the projectile and a breech block having a bore aligned with the barrel bore.
  • a cartridge in the breech block bore responds to an electric source to supply a high temperature, high pressure plasma jet to the rear of the projectile in the bore.
  • the plasma jet source includes a tube having an interior wall forming a capillary passage, i.e., a passage having a length to diameter ratio of at least 10:1.
  • a discharge voltage is supplied by a suitable source between spaced regions along the length of the interior wall while a dielectric ionizable substance is between the regions.
  • the dielectric ionizable substance includes at least one element that is ionized to form a plasma in response to the discharge voltage being applied between the spaced regions.
  • the passage has a diametric length that is short relative to the distance between the spaced regions to form the capillary passage. First and second ends of the passage are respectively opened and blocked to enable and prevent the flow of plasma through them.
  • the plasma forms an electric discharge channel between the spaced regions. Ohmic dissipation occurs in the electric discharge channel to produce a high pressure in the passage to cause the plasma in the passage to flow longitudinally in the passage through the first, i.e., open, end to form the plasma jet which accelerates the projectile through the bore.
  • the electric source preferably has a waveform and duration such that the pressure supplied by the plasma jet to the barrel bore enables the pressure within the barrel bore and acting on the projectile to be accurately controlled.
  • the pressure acting on the rear of the projectile and, to a large extent within the barrel bore is controlled so that it is substantially constant while the projectile is being accelerated during the electrical pulse, which has a duration of about one-half of the travel time of the projectile through the barrel bore.
  • the plasma pressure acting on the rear of the projectile remains substantially constant during the time the electrical pulse is being generated.
  • the pressure is prevented from falling while the projectile is in the bore by increasing the power applied to the plasma as the projectile is accelerated in the bore.
  • the electric power applied to the plasma increases approximately linearly with time as the projectile is accelerated in the bore.
  • the square of the current fed by the electric supply to the plasma increases in an approximately linearly manner as a function of time.
  • the electric source applies a potential across the dielectric in the capillary passage to heat the dielectric so that the amount of plasma from the dielectric injected from the passage into the bore increases as the projectile is accelerated in the bore.
  • an object of the present invention to provide a new and improved apparatus for and method of enabling a gun to accelerate projectiles efficiently to a very high speed.
  • a further object of the invention is to provide a new and improved apparatus for and method of accelerating a projectile in a bore by using a plasma source that is controlled in such a manner as to provide a predetermined time varying pressure against the projectile while it is in a barrel bore.
  • a further object of the invention is to provide a new and improved apparatus for and method of accelerating a projectile through a bore so that pressure acting on the rear of the projectile remains substantially constant while the projectile is in the bore.
  • Still a further object of the invention is to provide a new and improved apparatus for and method of accelerating a projectile wherein a barrel through which the projectile is accelerated can be designed to withstand lower forces than with chemically driven forces, even though the projectile is driven to hypervelocity that cannot be achieved by chemical explosives.
  • this long pulse can be used without heating the barrel excessively by providing a confined mass of projectile propelling fluid having a low atomic weight constituent between a nozzle for injecting the jet into the barrel and a location in the barrel where the projectile is located.
  • the plasma is energized by the electric source so that the plasma initially projected through the nozzle into the projectile propelling fluid mixes with the fluid to cool the plasma and heat the fluid.
  • the fluid is dragged into the plasma when they are mixed to cool the plasma sufficiently to prevent substantial damage to walls of the bore.
  • the plasma injected into the fluid heats the fluid sufficiently so the low atomic weight constituent of the fluid enters a highly energetic gaseous state having a high sound speed to accelerate the projectile through the barrel.
  • the waveshape of the electric source can easily control the amount of heating of the fluid by the plasma jet during the initial and subsequent stages of operation.
  • the geometries of the barrel, a chamber for the fluid, and a nozzle for injecting the plasma from the capillary into the chamber and barrel are such that a boundary layer is established between the fluid and the plasma. The boundary layer prevents the plasma from contacting the barrel wall, whereby the barrel is not heated excessively by the plasma.
  • the plasma is controlled so it is initially mixed with the fluid to cool the plasma with the mixture developing sufficient initial pressure close to the constant pressure which is applied to the projectile while the projectile is accelerated to high speed, as occurs when the main pulse is generated to accelerate the pressure.
  • the initial mixing occurs for a time period sufficiently long to accelerate the projectile from rest and increase the volume in the bore.
  • the power applied to the plasma increases during the main pulse, during continued mixing between the plasma and fluid, to form the high pressure mixture which propels the projectile to hypervelocities by acting on the rear thereof.
  • An additional object of the invention is to provide a new and improved apparatus for and method of accelerating a projectile in a bore to hypervelocities by using a plasma source that is controlled in such a manner as to prevent damage to a barrel through which the projectile is being accelerated by gases resulting from derivation of the plasma.
  • An additional object of the invention is to provide a new and improved projectile propulsion system and method wherein a controlled source causes a plasma jet to interact with a fluid which prevents excessive heating of a barrel by plasma and wherein the same source applies additional energy to the plasma to cause the projectile to be accelerated through the barrel.
  • the capillary passage in which the plasma is formed is advantageously formed is an elongated structure having a hollow center containing many large surface area containers for an ablatable, low atomic weight dielectric powder-like or granular filler or a liquid containing low atomic weight elements, e.g., hydrogen and oxygen.
  • the large surface area containers are preferably formed as elongated straw-like tubes or small spheres.
  • the filled straw-like containers cause the electric resistance between electrodes at opposite ends of the capillary to increase during the plasma discharge, which decreases the output current and power requirements of a power supply for deriving the plasma.
  • the large surface area and increased resistance decrease the length to diameter ratio requirements of the capillary passage between the electrodes from a ratio of about 30:1 to about 10:1.
  • the lower current requirement reduces the temperature of the plasma jet exiting the capillary to assist maintaining the temperatures in a mixing chamber containing the cooling liquid and the barrel bore wall at a lower level.
  • different ones of the containers have differing wall thicknesses and are appropriately positioned in the capillary passage. The contents of thick walled containers are ignited after the contents of thin walled containers.
  • the thick walled containers are upstream in the capillary of the thin walled containers (i.e., the thick walled containers are farther from the barrel than the thin wall containers) so that the contents thereof are ignited and contribute to the plasma formation after the thin walled container contents.
  • the thin walled containers preferably contain a liquid that forms a plasma boundary layer on the barrel wall to cool the wall as the high temperature plasma from solid grains in the thick wall containers propagates through the barrel.
  • gun 11 is illustrated as including elongated barrel 12, containing rifled or smooth bore 13 that ends at muzzle 10.
  • Gun 11 includes a breech 14 where cartridge 15 is loaded.
  • Cartridge 15 contains projectile 16 that can be shaped as a bullet or have some other suitable shape, e.g., a sphere.
  • High voltage power supply 17 selectively supplies high voltage, high current electric pulses having a predetermined waveshape and duration, by way of leads 19 and 20, to a plasma source in cartridge 15; typically the current and voltage are approximately a few hundred kiloamperes and a few tens of kilovolts, respectively.
  • the cartridge In response to the electric energy supplied to cartridge 15 by power supply 17, the cartridge supplies a high temperature, high pressure plasma jet to the rear of projectile 16 which is loaded in breech 14 of barrel bore 13.
  • the plasma jet is derived from a dielectric tube in cartridge 15.
  • the tube contains an ionizable substance in spheres or thin elongated drinking straw- like tubes; the contents can be water or powder fillers containing polyethylene or combinations thereof.
  • the tube has an interior wall that forms a capillary passage.
  • the diameter of the tube interior across the passage is relatively short compared to the distance between the electrodes to form the capillary passage.
  • the end of the capillary passage adjacent projectile 16 is flared to form a nozzle through which the jet is injected into barrel 13 at the rear of projectile 16.
  • the jet expands and becomes cooler as it flows through the outwardly flared nozzle as it enters bore 13.
  • the blocked end of the capillary tube passage closes the bore in breech 14 where cartridge 15 is located.
  • the plasma in the capillary passage between the electrodes forms an electric discharge channel in which ohmic dissipation occurs to produce a high pressure.
  • the high pressure in the capillary causes the plasma in the passage to flow longitudinally in the passage and through the open, nozzle end of the passage to accelerate projectile 16.
  • the energy of supply 17 necessary to form the plasma can be obtained from several different sources, such as an inductor, a capacitor bank, a homopolar generator, a magneto hydrodynamic power source driven by explosives, or a compulsator, i.e., rotating flux compressor.
  • the current of supply 17 is shaped and has a duration to produce an approximately constant pressure in barrel bore 13, acting on the aft end of projectile 16, while the projectile is being accelerated through almost the entire bore length, i.e., from breech 14 to muzzle 10.
  • the electric energy from supply 17 heats the dielectric in the plasma source of cartridge 15 to a temperature in the range of 3, 000°K to 500,000°K; this is to be contrasted with the temperatures of no greater than 3,000° Kelvin achieved with chemical explosives.
  • Typical chemical explosives in cartridges contain nitrogen, oxygen, carbon and hydrogen.
  • the plasma source of cartridge 15 uses ions of carbon, hydrogen and electrons thereof.
  • the pressure of the plasma generated in the cartridge of Figure 1 contains a large fraction of the plasma energy, whereby the energy is very efficiently transferred to kinetic energy that is applied to projectile 16, either directly or through the intermediary of a contained fluid having low atomic weight constituents (e.g., hydrogen).
  • a contained fluid having low atomic weight constituents e.g., hydrogen
  • the plasma or the plasma and the fluid constituents are able to keep up with the projectile being accelerated through bore 13 because the sound speed of the low atomic weight elements of the plasma and fluid is much higher than the speed of projectile 16.
  • the energy supplied by the plasma typically exerts a pressure in the range of 100 bars to approximately a few hundred kilobars on projectile 16.
  • the plasma flows longitudinally in bore 13 without contacting the wall of barrel 12 because the plasma passes through a cooling fluid 102 (which may be liquid or gaseous) in rigid wall container 101 (Fig. 2) immediately downstream of the nozzle in the plasma source; projectile 16 rests against a wall of container 101 in a chamber for the liquid.
  • the plasma drags fluid 102 from container 101; if the fluid is a liquid, the plasma vaporizes the liquid. Vapor thus derived from fluid 102 forms a boundary layer in bore 13 between the plasma jet and the wall of barrel 12 to prevent the very hot plasma from contacting and ablating the wall.
  • the plasma flow in bore 13 is maintained longitudinal and the boundary layer is established by proper selection of the cross-sectional area of the nozzle, container 101, and bore 13.
  • the exit cross-sectional area of the nozzle for the plasma jet is considerably smaller than that of container 101, which in turn has a cross-sectional area appreciably larger than that of bore 13.
  • the exit cross-sectional area of the nozzle is at least one-third to one-fourth that of bore 13, and at least one-fifth to one-tenth that of container 101.
  • Container 101 has sufficient length to enable the fluid in the container to exert a drag force on the plasma jet to create the boundary layer; typically the container 101 has a length of about three times the diameter of bore 13. The length of container 101 and, therefore, the distance that the jet travels thru the fluid in the container are also a function of the energy in the plasma jet.
  • the plasma jet establishes a pressure differential between opposite end faces of container 101, i.e., between first and second faces against which the nozzle and projectile 16 respectively bear initially.
  • the pressure differential along the length of container 101 provides a continuous flow of the cold fluid in the container into bore 13 so the boundary layer is continuously replenished while plasma is flowing out of the nozzle to enable the boundary layer to stay cold and protect the wall of barrel 12 from very high temperature plasma.
  • the gas behind projectile 16 is at a relatively constant temperature, typically about 3000 o K, from the time the projectile begins to move until it leaves barrel 12. The constant temperature of the gases in barrel 12 helps to maintain the pressure in bore 13 behind projectile 16 constant.
  • the pressure in bore 13 remains constant throughout the interval while projectile 16 is accelerated through barrel 12.
  • the plasma jet is generated for about one-half of the time while projectile 16 is moving through bore 13.
  • the length of barrel 12 and the duration of pulses from supply 17 are such that the pressure behind projectile 16 when it passes through muzzle 10 is low enough to prevent the projectile from being kicked off the axis of bore 13 and yet provides proper sabot discard action. If the pressure is too high a side kick is likely, while too low a pressure causes improper sabot action.
  • Dielectric tube 21 is formed from a dielectric ionizable substance including at least one element that is ionized in response to a discharge voltage from power supply 17.
  • the ionizable substance or fuel is formed as an ablatable filler contained in many small, individual spheres 69 packed between metal end faces 65, as well as between thin cylindrical rigid walls 70 and 72 of tube 21.
  • Spheres 69 are formed of a dielectric ionizable compound and contain a solid dielectric ionizable powder or granular filler compound.
  • the compound consists of low molecular weight elements, e.g., hydrogen and carbon, as formed, e.g., from polyethylene.
  • Walls 70 and 72 are formed of an easily ruptured dielectric, e.g., a copolymer of vinyl chloride and vinyl acetate.
  • the spheres 69 have a combined surface of 100 to 1000 times the surface area of wall 70. Typically the spheres 69 have an inertial mass density much greater, e.g., 100 times, that of the plasma.
  • the geometry and materials in and of spheres 69 are such that the spheres increase the electric resistance of the plasma to match the impedance of a pulse forming network included in power supply 17, to ease the requirements of the power supply.
  • the plasma quickly flows through the filler in the spheres and is cooled by them to help prevent ablation of the walls of bore 13 of barrel 12 by the plasma.
  • a confined mass of the solid dielectric ionizable powder compound or a liquid such as water is located in a dielectric, ionizable plastic bag having an annular cross section and rigid walls that are the same as walls 70 and 72.
  • the solid or liquid filler is contained in many thin drinking straw-like, dielectric, ionizable plastic tubes 80, having longitudinal axes parallel to the common axis of bores 13 and 22.
  • Different ones of containers 80 have different wall thicknesses to control the length of time from the breakdown between electrode assemblies 23 and 24 to ignition of the ablatable ionizable material in the containers.
  • the material in the thin walled containers is ablated and ionized into a plasma prior to the material in the thick walled containers.
  • the thin walled containers are in proximity to electrode assembly 23 and barrel 12, and contain a liquid, while the thick walled containers are proximate breech 14 and electrode assembly 24. Thereby the plasma formed from the liquid in thin walled containers has a lower temperature than that of the thick walled containers.
  • the lower temperature plasma from the liquid in the thin walled containers has a tendency to form a boundary layer on the wall of the barrel 12 to help cool the barrel when the higher temperature plasma from the solid ablatable grains in the thick wall containers flows through the barrel a few microseconds after the boundary layer has been formed.
  • Control of the ignition time of the contents of the various containers 80 is also important to achieve shaped, time dependent pressure curves, as illustrated in Figure 3.
  • Electrode segment 25 is formed as a carbon ring that abuts against planar end 55 of end plate 65 for tube 21, to assist in holding the tube in situ.
  • Ring 25 includes a central cylindrical aperture that is tapered outwardly to assist in forming the nozzle for the plasma jet.
  • Ring 25 is also dimensioned and positioned so that face 56 thereof abuts against the portion of the planar rear face of cylindrical water container 102 farthest from the axis of tube 21.
  • Projectile 16 abuts against the front face of container 102. Container 102 and projectile 16 are thereby maintained by ring 25 and collar 37 in situ in cartridge 15, at breech end 14 of barrel bore 13.
  • Tube 21 is flared at end 27 to match the flare of ring 25 so the tube and ring 25 form the nozzle for the plasma jet formed in capillary passage 22.
  • the plasma jet flowing through the outwardly flared nozzle is ultimately injected against the back face of projectile 16 and into barrel bore 13; the jet expands and is cooled as it enters the barrel bore because it flows through flared nozzle end 27.
  • the jet -flow is basically longitudinal in bore 13 by designing the flared area of ring 25 that abuts against container 101 to have an area that is about one-third to one-fourth that of the cross-section of bore 13 and about one-fifth to one-tenth that of the cross-section of container 101.
  • the length of container 101 in the axial direction of bore 13 is about three times the diameter of the bore.
  • Electrode 24, at the closed end of passage 22, includes a cylindrical metal segment 28 from which stub segment 26 extends.
  • Cylindrical segment 28 is coaxial with stub segment 26, and has a longitudinal axis coincident with the longitudinal axis of tube 21 and a radius equal to the radius of wall 72.
  • Cylindrical segment 28 includes a threaded portion 29 which extends axially in the direction opposite from that of stub segment 26. Segment 29 is threaded into a threaded bore on metal plate 31; plate 31 has a circular cross section with a radius considerably greater than the common radii of wall 72 and cylindrical segment 28.
  • electrode 24 is formed of stub segment 26, cylindrical segment 28 and metal plate 31 which block passage 22 at the end of dielectric tube 21 proximate breech 14 and remote from the region where projectile 16 enters barrel bore 13.
  • Lead 20 is connected to plate 31 by a suitable connector which can fit about the circular periphery and exposed face of plate 31, to provide a low impedance path between power supply 17 and electrode 24.
  • a low impedance connection from lead 19 to carbon ring 25 of electrode assembly 23 is established by metal plate 32 that extends radially of cartridge 15 and the axis of tube 21.
  • Metal plate 32 abuts against and is fixedly connected to the periphery of copper sleeve 33 at the end of the sleeve remote from collar 37.
  • Sleeve 33 is concentric with tube 21 and the elements of electrode 24.
  • Sleeve 33 is electrically insulated tube 21 by dielectric tube 34 that is coaxial with tube 21 and extends between plate 31 and carbon ring 25.
  • the exterior wall 70 of tube 21 and the cylindrical wall of electrode segment 28 abut against the interior wall of tube 34, which assists in holding tube 21 and electrode assembly 24 in situ.
  • the exterior wall of tube 34 abuts against the interior wall of sleeve 33; the exterior wall of sleeve 33 abuts against the wall of the bore in breech 14 when cartridge 15 is inserted into the breech.
  • This construction enables sleeve 33 and tube 34 to withstand the very high pressure which is generated in bore 22 when the dielectric of tube 21 is ionized in response to the application of a voltage pulse from power supply 17.
  • Carbon ring 25 has a radius less than that of the chamber filled by container 101, so that the carbon ring provides a seat for one face of rigid cylindrical container 101 that contains projectile propelling fluid 102, having low atomic weight constituents and the proper geometry for the boundary layer.
  • Typical of the fluids 102 are water, propane [CH 2 (CH 3 ) 2 ], CH 4 , high pressure hydrogen gas (H 2 ), liquid hydrogen, lithium hydride (LiH), pentane (C 5 H 12 ), methanol (CH 3 0H), a boron hydride (e.g., B 2 H 6 ) and chemical mixture which are in separate containers that are reprimed by the jet to react and produce high pressure fluids (e.g., 4H 2 0 + 3Fe ⁇ Fe 3 O 4 + 4H 2 ), as well as metal hydrides (e.g., of N or Fe).
  • the gases produced by the fluid 102 in container 101 have a relatively high pressure of about two to four thousand atmospheres to assist in providing the boundary layer between the plasma jet in bore 13 and the wall of barrel 12.
  • Projectile 16 bears against the face of container 101 closest to bore 13.
  • container 101 is positioned at the open end of the capillary passage formed by passage 22 and projectile 16 is immediately downstream of the container to be responsive to high pressure low atomic weight gases of the plasma and contained fluid 102 in container 101.
  • Container 101 has a diameter appreciably greater than that of the exit flared end 27 of passage 22 and of bore 13 so that the cylindrical surface of the container bears against and extends along the majority of the cylindrical inner wall of collar 37 so that a large quantity of contained fluid 102 is provided.
  • the forward end of container 101 is tapered toward barrel 12 to facilitate the flow of fluid 102 against the back end of projectile 16.
  • plates 31 and 32 are spaced from each other by dielectric face plate 42, formed of a material able to withstand high pressure shocks, such as polyethylene.
  • Metal plate 32 is bonded to the face of plate 42 facing bore 13.
  • Plate 31 and polyethylene film 43 are fixedly mounted on the other face of plate 42 by screws 44 which extend through threaded bores in plates 31 and 42.
  • Dielectric 0-rings 45 and 46 assist in holding the entire assembly in place.
  • O-ring 45 has inner and outer diameters approximately equal to the outer diameter of stub cylinder 26 and the diameter of the inner wall of tube 34, respectively.
  • O-ring 45 fits between end plate 65 of tube 21 remote from barrel 12 and shoulder 66 on cylindrical segment 28 and bears against the inner diameter of sleeve 34.
  • O-ring 46 fits in peripheral, circular groove 67 about the periphery of tube 34, and has an outer portion that bears against the inner circumference of annular plate 42.
  • O-rings 46 and 45 also aid in preventing electrical breakdown since they stop gas or plasma from blowing past electrode 24 and around tube 34, to prevent an electrical short-circuit from electrode 24 to plate 32 or sleeve 33.
  • electrode 24 includes an elongated rod 71 preferably made of carbon, or a metal wire, made, e.g., of aluminum; rod 71 extends longitudinally from the tip of stub cylinder 26 along the axis or inner wall of passage 22 into proximity with ring 25.
  • rod 71 In response to sufficient voltage being fed by supply 17 to cartridge 15, current flows between rod 71 and ring 25 via a discharge space between the rod and ring. The rod is consumed by the current but the discharge between ring 25 and cylinder 26 continues.
  • Othertypes of atmospheric discharge initiators can be used; for example, a thin carbon coating can line passage 22.
  • a reusable spark plug type structure is located between ring 25 and stub cylinder 26.
  • the spark plug type structure is supplied with a very high voltage breakdown pulse immediately before the pulse from supply 17 is generated. The breakdown caused by the spark plug type structure occurs between ring 25 and cylinder 26 at the time when energy from supply 17 is initially applied between ring 25 and cylinder 26.
  • the energy from supply 17 is applied between electrodes 24 and 25.
  • the energy from supply 17 maintains the discharge between electrodes 24 and 25 to cause plasma to flow longitudinally in passage 22 to form an electric discharge channel between stub cylinder 26 and carbon ring 25.
  • the resistance of the electric discharge channel is on the order of one-tenth of an ohm, which is considerably higher than the sum of all other resistances in the circuit between the terminals of power supply 17. Thereby, virtually all of the energy from power supply 17 is dissipated in the discharge channel formed in passage 22.
  • the plasma formed in passage 22 is highly ionized and very hot, with temperatures ranging from 3,000° Kelvin to as high as 500,000 0 Kelvin. Because of the capillary nature of passage 22, i.e., the fact that the length to diameter ratio of the passage is at least ten to one, a high pressure is produced in the passage to cause the plasma in the capillary to flow longitudinally into nozzle 27.
  • the breakdown between stub cylinder segment 26 and carbon ring 25 is initiated along inner dielectric wall 70 of dielectric tube 21 and spreads to dielectric spheres 69 in sleeve 21. Once breakdown along inner wall 70 and of spheres 69 occurs, plasma from the inner wall and spheres rapidly expands radially into passage 22 to fill the capillary passage defined by the passage. In response to the plasma filling passage 22, there is formed an electric discharge channel which is effectively a resistor between electrodes 24 and 25.
  • ohmic dissipation in the plasma transfers energy efficiently from high voltage supply 17 into the plasma.
  • radiation emission and thermal conduction transport energy from the plasma in passage 22 to spheres 69, to ablate additional plasma from the spheres and replace plasma ejected through nozzle 27.
  • spheres 69 remain approximately in situ even though they are not physically confined because the plasma sweeps through the passage at very high speed and with a very high pressure. Thereby, material in tube 21 is consumed as fuel and ejected as plasma in response to the electric energy provided by high voltage supply 17.
  • passage 22 causes the plasma in the passage to flow longitudinally along the passage and rapidly out of nozzle 27. Because the other end of passage 22 is blocked by electrode 24, plasma can blow only out of nozzle 27.
  • the length, l , radius, ⁇ , and atomic species, typically hydrogen and carbon, in the plasma on the interior diameter of tube 21 are chosen such that the discharge resistance R is relatively large, such as 0.10 ohm, so that it considerably exceeds the sum of the resistance of power supply 17, leads 19 and 20, and electrodes 24 and 25.
  • Capillary passage 22 functions as a high impedance coupling device that efficiently transfers energy from supply 17 into fluid 102, which initially has a density of a typical liquid.
  • the power supplied by source 17 to the dielectric of cartridge 15 is increased, with a consequent increase in the quantity and pressure of plasma ejected through nozzle 27.
  • This initiates movement of projectile 16 from breech 14 into bore 13 toward muzzle 10.
  • the plasma heats fluid 102 to cause partial dissociation of the materials in the liquid into the low atomic weight constituents thereof, i.e., the hydrogen of the previously mentioned compositions is dissociated from the remaining elements.
  • the hydrogen constituents increase the sound speed of the propelling gas acting against projectile 16.
  • the gas sound speed continues to increase as projectile 16 is accelerated through the length of bore 13, from the proximity of the breech end 14 to the muzzle end 10.
  • the type of fluid in container 101 affects the peak temperatures of the gases in barrel 13 acting against projectile 16. By reducing the peak temperature due to the mixing action between the plasma and fluid 102 during the initial phase, there is a substantial reduction of barrel ablation.
  • FIG. 3a are illustrated one embodiment of exemplary waveforms 131-133 respectively indicative of: (a) the power supplied by supply 17 to the dielectric of cartridge 15, (b) the pressure in bore 13 acting on projectile 16, and (c) the velocity of the projectile; each of these variables is illustrated as a function of time.
  • Power curve 131 is obtained by properly shaping the pulse supplied by power supply 17 to cartridge 15.
  • the impedance across power supply 17 is predominantly resistive, comprising primarily the resistance of the capillary passage between electrodes 23 and 25.
  • the power coupled by supply 17 to cartridge 15 is the current (I) of the power supply squared times the resistance of the capillary, i.e., I 2 R; the capillary resistance is indicated supra, as .
  • the output power of supply 17 rises from an initial value, goes through a relatively small amplitude peak and then decreases toward zero, as indicated by portion 131a of power waveform 131. Thereafter, the power coupled by supply 17 to cartridge 15 increases approximately linearly, as indicated by the approximately linear variation 131b of curve 131.
  • the linear increase 131b in the output power of supply 17 continues for virtually the entire time while projectile 16 is travelling through bore 13. When projectile 16 has travelled through about one-half of bore 13, there is a sharp and sudden decrease of the power output of supply 17 to a zero value, as indicated by waveform portion 131c.
  • the plasma mixes with the low atomic weight constituents in fluid 102 so that the total quantity of low atomic weight, high sound speed molecules acting in bore 13 against the aft end of projectile 16 increases.
  • These low atomic weight, high sound speed molecules resulting from the plasma mixing with the fluid 102 and acting against the rear of projectile 16 have quite a high relatively constant temperature.
  • the combined effects of the increased number of low atomic weight molecules and the high constant temperature at the rear of projectile 16 enable the pressure in bore 13 behind projectile 16 to remain substantially constant, per wave segment 132, as the projectile is accelerated through the bore, from in proximity to the breech end thereof to about half way to the muzzle end.
  • the pre-heating and cooling effects provided by waveform segment 131a are attained at the beginning of motion of projectile 16, instead of while the projectile is at rest.
  • the power (square of the current) fed to supply 17 between electrode assemblies 23 and 24 initially increases in almost a step manner, as indicated by waveform segment 131d, then has a relatively constant value, as indicated by waveform segment 131e.
  • Segment 131e continues until it intercepts straight line variation 131f of power curve 131 that has approximately line variation 131f of power curve 131 that has approximatley the same slope as segment 131b; typically segment 131e intercepts segment 131f after projectile 16 has travelled about one-tenth of the way down barrel 12.
  • the power between wave segments 131d, 13le and 131f causes sufficient energy to be imparted by supply 17 to the plasma to cool the plasma by fluid 102 and mix the plasma and fluid to attain the same results as provided by waveform segment 131a. Thereafter, the power applied between assemblies 23 and 24 has the same characteristics as the remainder of waveform segment 131b and of segment 131c.
  • the power waveform illustrated in Figure 3b causes pressure and velocity waves 132 and 133 in the embodiments of Figures 3a and 3b to have the same shapes.
  • power supply 17 includes pulse forming networks 141 and 142, respectively connected to DC power supp] ies 143 and 144 by switches 145 and 146. Pulse forming networks 141 and 142 supply current to load resistor 147 by switches 148 and 149, respectively. Switches 148 and 149 are preferably triggered into a conducting condition and are cut off by a control source or in response to the current flowing through them dropping below a predetermined value; e.g., switches 148 and 149 are ignitrons or solid state equivalents thereof, such as triacs, or banks of power transistors.
  • Resistor 147 is, in actuality, the relatively constant capillary resistance of cartridge 15 between electrodes 24 and 25. As discussed supra, the 0.10 ohm resistance between electrodes 24 and 25 is typically the largest resistance between the output terminals of power supply 17. Switches 148 and 149 are opened and closed in a timed relationship by an external trigger source or by self-opening action in response to the current in them dropping below a predetermined level to supply current waveforms of pulse forming networks 141 and 142 to load 147. Pulse forming networks 141 and 142 are conventional devices, including shunt capacitors 151 and series inductors 152.
  • the number of shunt capacitors - series inductance stages in each of pulse forming networks 141 and 142, and the values of the shunt capacitors and series inductors, is determined by the amplitude and slope of , wave portion 131 necessary to achieve the desired velocity for projectile 16 as it leaves muzzle 10, as well as the ability of gun 11 to withstand the pressures and shocks associated with accelerating projectile 16 from breech 14 to muzzle 10.
  • the parameters of pulse forming network 141 are selected to achieve the desired shape and duration for waveform segment 131a or segments 131d and 131e which provide initial heating of fluid 102 and initial cooling of plasma injected into the fluid as well as the initial mixing of the fluid and plasma.
  • switches 145 and 146 which respectively connect DC power supplies 143 and 144 to networks 141 and 142, are closed for a sufficient period of time to charge each of shunt capacitors 151 of pulse forming networks 141 and 142 to the voltages of supplies 143 and 144.
  • the waveform of Figure 3a is synthesized by closing switch 148 to couple power from network 141 to load 147, while switch 149 remains open. While switch 148 is closed, a resonant circuit is provided by capacitors 151 and inductors 152 through switch 148 to load 147..
  • Pulse forming network 142 includes many more sections and has a much lower resonant frequency than that of pulse forming network 141.
  • the capacitors of network 142 are charged to a much higher voltage by source 144 than the capacitors of network 141 are charged by source 143.
  • positive current having a positive going slope and power waveform (as indicated by segment 131b) resembling a linear function is initially supplied by network 142 to load 147.
  • switch 148 is again activated to couple current from network 141 to load 147.
  • capacitors 151 are again charged to the voltage of supply 143 because switch 145 is closed immediately after switch 148 is open, whereby positive current again flows from network 141 to load 147.
  • current is supplied by pulse forming network 142 through switch 149 to load 147.
  • load 147 is responsive to the combined output currents of pulse forming networks 141 and 142.
  • the current from network 141 augments that from network 142 to maintain a linear relation for the squared current waveform and hence for the power waveform supplied by source 17 to cartridge 15. To this end the currents from networks 141 and 142 are decoupled from load 147 when the positive current of network 141 begins to decrease and the relative resonant frequencies of networks 141 and 142 are properly selected.
  • pulse forming network 141 has a characteristic impedance which provides a three to one mismatch between source 143 and load 147 when network 141 is solely connected to load 147.
  • the characteristic impedance of pulse forming network 142 provides a two to one mismatch between source 143 and the impedance of load 147, so that there is greater current flow to the load while switch 149 is closed and while switch 148 is closed to load 147.
  • the resonant frequencies of pulse forming networks 141 and 142 and the activation times of switches 148 and 149 are such that the squared current flow through load 147 is constantly increasing, as indicated by waveform portion 131b.
  • the resonant frequencies of pulse forming networks 141 and 142, the travel time of projectile 16 and the length of barrel 12 are such that projectile 16 is about half way between the breech and muzzle of barrel 12 when switches 148 and 149 open.
  • the waveform of Figure 3b can be synthesized by the pulse forming network of Figure 4, by appropriately adjusting the resonant frequencies of networks 141 and 142 and changing the activation times of switches 148 and 149, and by adjusting the voltages of the sources 143 and 144 so that they are equal.
  • the resonant frequency of network 141 is selected to be one-third that of network 142.
  • Switches 148 and 149 are activated so that network 141 supplies three half cycle current pulses to load 147, while network 142 is activated to supply current pulses having a duration of one-half cycle to load 147.
  • Wave segment 131d is derived during the first one-half cycle of current flow from network 141 to load 147.
  • network 142 is supplying a relatively linear current to load 147.
  • the square of some of the current supplied to load 147 by networks 141 and 142 increases in a substantially linear manner during the first positive half cycle of the current supplied by network 141 to load 147, as indicated by waveform segment 141d.
  • the negative current supplied by network 141 to load 147 is combined with the positive current supplied to the load by network 142, to maintain the square of the sum of the current supplied by both networks to the load substantially constant, as indicated by waveform segment 131e.
  • a positive current is again supplied by network 141 to load 147.
  • positive current is being supplied by network 142 to load 147.
  • the sum of the currents supplied by networks 141 and 142 to load 147 during the third half cycle of current flow in network 141 causes a linear upward ramping of the square of the sum of the currents in load 147, as indicated by the initial portion of wave segment 131f.
  • the square of the sum of the currents supplied to load 147 during the initial portion of wave segment 131f has a slope that is considerably less than that of the current supplied to the load during wave segment 131d because the slope of the sinusoidal contribution from network 142 is less during this interval than during the interval while wave segment 131d was being derived.
  • the sections of network 142 connected close to load 147 have a high internal impedance and short time constant relative to the low impedance and long time constant of the sections connected close to source 144.
  • the straight line variations of the square of the current supplied by networks 141 and 142 to load 147 are maintained relatively constant, as indicated by waveform segment 131f.
  • the straight line variation of the square of the current in load 147 is maintained despite the tendency for network 141 to cause less current to flow through the load during even half cycles of the current waveforms coupled by network 141 to the load.
  • the amplitude of the current from network 141 decreases due to the natural damping effect provided by the resistive components in the inductors of the network, whereby at the time that the linear portion of wave segment l3lb is completed, the current flowing to load 147 from network 141 is substantially zero, for a prolonged time interval, causing switch 148 to open. Simultaneously, the current supplied by network 142 to load 147 begins to decrease.
  • the characteristic impedance of network 142 is such that there is a reflected wave from capacitor 151 connected closest to switch 146, so that the current supplied by network 142 to load 147 decreases at a very fast rate, as indicated by waveform segment 131c.
  • the decreased current supplied by network 142 to load 147 causes switch 149 to open, whereby load 147 is decoupled from pulse forming networks 141 and 142 and energy is no longer supplied to the load, whereby the plasma derived from source 21 is extinguished.
  • the shaped current pulse can be utilized exclusively without the intermediary of fluid 102, to provide a plasma drive for projectile 16, if barrel 12 is able to directly withstand the high temperatures associated with the plasma output of cartridge 16.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • Plasma Technology (AREA)
EP86308921A 1985-12-13 1986-11-14 Dispositif et procédé de propulsion par plasma Withdrawn EP0232594A3 (fr)

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US80907185A 1985-12-13 1985-12-13
US809071 1985-12-13

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0295136A1 (fr) * 1987-06-12 1988-12-14 Gt-Devices Méthode et dispositif de génération d'hydrogène, dispositif pour l'accélération des projectiles et méthode incorporant celui-ci
GB2218495A (en) * 1988-05-13 1989-11-15 Tzn Forschung & Entwicklung Cartridges
WO1990005278A1 (fr) * 1988-11-11 1990-05-17 Igenwert Gmbh Accelerateur
FR2681939A1 (fr) * 1991-10-01 1993-04-02 Tzn Forschung & Entwicklung Dispositif de tir electrothermique et cartouche a utiliser dans des dispositifs de ce type.
US5233903A (en) * 1989-02-09 1993-08-10 The State Of Israel, Atomic Energy Commission, Soreq Nuclear Research Center Gun with combined operation by chemical propellant and plasma
EP0338458B1 (fr) * 1988-04-18 1993-10-06 Fmc Corporation Arme de plasma à augmentation de combustion
WO1997012194A1 (fr) * 1995-09-28 1997-04-03 Brown, Keith, Edwin, Frank Dispositif de lancement de projectiles fluides
US5935461A (en) * 1996-07-25 1999-08-10 Utron Inc. Pulsed high energy synthesis of fine metal powders
US5970993A (en) * 1996-10-04 1999-10-26 Utron Inc. Pulsed plasma jet paint removal
US6001426A (en) * 1996-07-25 1999-12-14 Utron Inc. High velocity pulsed wire-arc spray
US6124563A (en) * 1997-03-24 2000-09-26 Utron Inc. Pulsed electrothermal powder spray

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3431816A (en) * 1967-07-21 1969-03-11 John R Dale Mobile gas-operated electrically-actuated projectile firing system
US3916761A (en) * 1974-01-29 1975-11-04 Nasa Two stage light gas-plasma projectile accelerator
US4590842A (en) * 1983-03-01 1986-05-27 Gt-Devices Method of and apparatus for accelerating a projectile

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3431816A (en) * 1967-07-21 1969-03-11 John R Dale Mobile gas-operated electrically-actuated projectile firing system
US3916761A (en) * 1974-01-29 1975-11-04 Nasa Two stage light gas-plasma projectile accelerator
US4590842A (en) * 1983-03-01 1986-05-27 Gt-Devices Method of and apparatus for accelerating a projectile

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0295136A1 (fr) * 1987-06-12 1988-12-14 Gt-Devices Méthode et dispositif de génération d'hydrogène, dispositif pour l'accélération des projectiles et méthode incorporant celui-ci
EP0338458B1 (fr) * 1988-04-18 1993-10-06 Fmc Corporation Arme de plasma à augmentation de combustion
GB2218495A (en) * 1988-05-13 1989-11-15 Tzn Forschung & Entwicklung Cartridges
GB2218495B (en) * 1988-05-13 1991-11-20 Tzn Forschung & Entwicklung Cartridge for an electrothermal firing device
US5115743A (en) * 1988-05-13 1992-05-26 Tzn Forschungs- Und Entwicklungszentrum Unterluss Gmbh Propellant casing assembly for an electrothermic projectile firing device
US5223662A (en) * 1988-11-11 1993-06-29 Igenwert Gmbh Accelerator
WO1990005278A1 (fr) * 1988-11-11 1990-05-17 Igenwert Gmbh Accelerateur
US5233903A (en) * 1989-02-09 1993-08-10 The State Of Israel, Atomic Energy Commission, Soreq Nuclear Research Center Gun with combined operation by chemical propellant and plasma
GB2260187A (en) * 1991-10-01 1993-04-07 Tzn Forschung & Entwicklung Electrothermal firing
FR2681939A1 (fr) * 1991-10-01 1993-04-02 Tzn Forschung & Entwicklung Dispositif de tir electrothermique et cartouche a utiliser dans des dispositifs de ce type.
US5331879A (en) * 1991-10-01 1994-07-26 Tzn Forschungs-Und Entwicklungszentrum Unterluss Gmbh Electrothermal firing device and cartouche for use in such devices
GB2260187B (en) * 1991-10-01 1996-01-17 Tzn Forschung & Entwicklung Electrothermal firing device and cartridge
WO1997012194A1 (fr) * 1995-09-28 1997-04-03 Brown, Keith, Edwin, Frank Dispositif de lancement de projectiles fluides
US5935461A (en) * 1996-07-25 1999-08-10 Utron Inc. Pulsed high energy synthesis of fine metal powders
US6001426A (en) * 1996-07-25 1999-12-14 Utron Inc. High velocity pulsed wire-arc spray
US5970993A (en) * 1996-10-04 1999-10-26 Utron Inc. Pulsed plasma jet paint removal
US6124563A (en) * 1997-03-24 2000-09-26 Utron Inc. Pulsed electrothermal powder spray

Also Published As

Publication number Publication date
IL80864A0 (en) 1987-03-31
EP0232594A3 (fr) 1990-01-24
IL80864A (en) 1992-12-01

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