Patent Description:
A conventional barrel weapon means here a weapon of the type of an artillery piece, a naval piece, or a tank piece or other piece containing a barrel in which a projectile is fired and propelled through the barrel by a propellant charge which is ignited by means of a pyrotechnical igniter, such as a spark plug, an ignition cartridge, etc. The propellant charge, also called the propellant, refers here to a powder of solid form, which gives off gases during its burning, driving the projectile forward to the mouth of the barrel under high pressure in the barrel. The propellant can also be a type other than a solid powder.

High gas pressure for a long time means a high muzzle velocity of the projectile when the projectile leaves the barrel. The high muzzle velocity of the projectile is utilized, for example, to increase the range of the weapon, to improve the projectile's penetrating power or reduce the time course of the projectile's trajectory.

A pressure curve for an optimal combustion process, and thus high launch speed, should show an almost immediate pressure increase to Pmax, then a long-lasting plateau phase with a maintained constant barrel pressure at Pmax for the entire time that the propellant charge is burning inside the barrel, and then dropping immediately to zero when the projectile leaves the barrel. All of the propellant charge should have normally been burned at this time.

Regardless of the choice of propellant charge, the ignition process is of great importance to the pressure course and therefore the igniter and ignition system are critical to achieving high launch speed.

While at the same time the highest possible launch speed is desired, there is a need to reduce the vulnerability of the propellant. A propellant of this type is known as LOVA (LOw VulnerAbility). The low-vulnerability propellant is hard to ignite, which lessens the risk of accidental initiation of propellant in risky situations, for example, when a combat vehicle is being fired upon by enemy fire. The decreased vulnerability also means increased requirements for the igniters. The igniters must then generate an increased amount of energy and/or increased pressure in order to create the ignition process. The igniters normally consist of an easily initiated explosive, and if the quantity of the explosive is increased, this stands in direct opposition to adopting a propellant of LOVA type. Basically, ignition occurs through an ignition chain, where a very small quantity of sensitive explosive, known as the primary set, such as lead azide or silver azide, is ignited by mechanical shock or electrical pulse. The primary set then ignites the secondary set of the igniter, usually black powder, which in turn initiates the propellant. By replacing the pyrotechnical igniter or the entire ignition chain with a plasma igniter, the vulnerability of the system to unintentional initiation is decreased. At the same time, an increased dynamism is made possible for generating the more powerful ignition pulses needed to ignite the low-vulnerability (LOVA) propellant.

Conventional igniters also have a logistical and technical problem. For barrel weapons using propellant charges separated from the projectiles, such as artillery and heavy ship cannons, a separate ignition cartridge is often used for initiation of the propellant charge. An ignition cartridge is used for each firing. Thus, a mechanical system mounted on the cannon is needed for storing, loading, and removing of the ignition cartridge. By using a plasma igniter, the logistical problems of ignition cartridges are avoided. A commonly occurring problem is that the ignition cartridge gets stuck in the cartridge position. Ignition cartridges expand when the weapons system is fired, so that the ignition cartridge gets wedged in the cartridge position and firearm malfunction occurs. By adopting a plasma igniter, firearm malfunction is avoided and the functional safety is increased.

Plasma igniters for initiation of propellant charges have been described, for example, in patent documents <CIT>) and <CIT>). The plasma igniters are built on the principle of exploding wires, that is, an electrically conductive wire which is heated, gasified, and partly ionized by an electric current. The drawback is that the wire is consumed and needs to be replaced with a new one before each firing. Thus, the plasma igniter is a onetime type.

Repeatable plasma igniters are known, for example in patent documents <CIT>) and <CIT>). The plasma igniters are built on the principle of spraying an electrically conductive liquid between two electrodes with an electrical potential difference, whereupon the electrical circuit is short-circuited and generates a discharge and a plasma generation. The use of liquids means complicated devices for dispensing and supplying, and also problems with possibly toxic, high-energy or easily ignitable substances. The use of liquids also requires a complicated logistics for handling of liquids.

Swedish patent application <CIT> shows a plasma igniter with ionization electrodes for ionization of a combustion chamber body, where the ionization makes possible an electrical flashover between two electrodes. The proposed plasma igniter is only partially adjustable for different lengths of the plasma igniter and different ignition energies.

Swedish patent application <CIT> (<CIT>) shows a plasma igniter where filling gas in a combustion chamber is ionized by ionization electrodes energized with high voltage. The ionization in the combustion chamber makes possible an electrical flashover between two electrodes. The proposed plasma igniter has only ionization electrodes arranged on the outer enclosure of the plasma igniter. High pressure is generated in a plasma igniter, so that openings in the outer shell of the plasma igniter mean a risk of gas leakage or malfunction of the plasma igniter.

One purpose of the present invention is to solve the above-identified problem.

Another purpose of the present invention is an improved plasma generator for repeatable initiation of propellant charges in a weapons system, avoiding complicated arrangements for dispensing and supplying of liquids between electrodes.

Another purpose of the present invention is an improved plasma generator for repeatable initiation of propellant charges in a weapons system, where the length and ignition energy of the plasma generator can be adapted.

Another purpose of the present invention is an improved plasma generator for repeatable initiation of propellant charges in a weapons system, where the plasma generator lacks openings in the outer shell of the plasma igniter.

Another purpose of the present invention is an ammunition unit comprising said improved plasma generator.

Another purpose of the present invention is a launching device comprising said improved plasma generator.

Said purposes, and other purposes not listed here, are achieved in satisfactory manner by what is set forth in the present patent claims.

The neutral filling gas may be composed of atmosphere gas or residual gas from a previous firing. The electrical discharge may consist of a surface flashover, a volume flashover, or a transition from a surface flashover from bound charges in the surface of the combustion chamber body to a volume flashover in the combustion chamber channel. The volume flashover in the combustion chamber channel and the following power development increases the gas pressure in the combustion chamber and energy is surrendered via recombination between free electrons and ions, as well as neutral particles, to photons which dissociate and ionize the filling gas as well as the surface of the combustion chamber body. This surface thereby releases gas to the combustion chamber channel, which further increases the pressure and supplies further neutral particles to the volume, having a braking effect on the impedance collapse which occurs in the combustion chamber channel and increases the share of the electrical power in the combustion chamber, where the impedance does not drop to zero as in gas discharges with an open geometry. The pressure and the temperature rise in the combustion chamber expel the ignition gas with plasma-like and electrically conductive characteristics from the passageway of the one terminal to reach the propellant being initiated.

Thus, according to the present invention an improved plasma generator has been created for initiation of propellant charges in a weapons system, for example when launching projectiles from a barrel weapon, by electrical discharge between a rear electrode and a front electrode in a combustion chamber channel enclosed in a combustion chamber body and filled with filling gas, designed to ignite at least one propellant charge, where the plasma generator comprises at least one ionization electrode situated inside the enclosing combustion chamber body, where ionization electrodes are connected to an initiation circuit comprising at least one first high-voltage generator, for ionization of the filling gas in the combustion chamber channel (<NUM>), and a second high-voltage generator designed for electrical discharge in the electrically conductive gas from the rear electrode via at least one ionization electrode onward to the front electrode so that hot ignition gas under high pressure is formed.

Having at least one ionization electrode situated inside the enclosing combustion chamber body means that ionization electrodes do not penetrate the combustion chamber body.

Ionization electrodes are entirely enclosed by the combustion chamber body. Ionization electrodes are not in physical contact with the combustion chamber body.

According to further aspects of the improved plasma generator of the invention:.

The ionization electrodes are designed with at least one flashover conductor at least at one point.

The ionization electrodes are arranged in circular symmetry around a center line and an electrical insulator is formed between the ionization electrodes by the conical holder, which is situated at the center of the rear electrode, the conical holder and the rear electrode being arranged such that electrical contact is possible between the initiation circuit and the ionization electrodes.

The rear electrode situated at the rear end of the combustion chamber channel is electrically connected to the second high-voltage generator and the front electrode situated at the front end of the combustion chamber channel is connected to ground, said rear and front electrode being made of an electrically conductive material, and a gas outlet is arranged in the front electrode, emerging at the propellant charge.

The gas outlet is one of a convergent nozzle or a divergent nozzle or a convergent-divergent nozzle.

Furthermore, according to the present invention an improved ammunition unit has been created, comprising a mortar tube, a projectile, a propellant charge and an ignition device, said ignition device being comprised of a plasma generator.

Furthermore, according to the present invention an improved launching device comprising a barrel, a propellant charge and an ignition device, said ignition device being comprised of a plasma generator, is provided.

The invention shall be described more closely below, making reference to the enclosed figures, where:.

The plasma generator <NUM> shown in <FIG> comprises a front electrode <NUM>, a combustion chamber body <NUM> having a combustion chamber channel <NUM>, and a rear electrode <NUM>. Moreover, the plasma generator <NUM> has a number of ionization electrodes <NUM> and <NUM>, two in the figure and the embodiment. The ionization electrodes are connected to the initiation circuit <NUM>, not shown in <FIG>.

The combustion chamber body <NUM>, preferably tubular, is part of the plasma generator <NUM> and forms the combustion chamber channel <NUM> of the plasma generator. The combustion chamber body <NUM> is designed to withstand high pressure and has no passageways, holes, or other physical conformation which can weaken its strength. The combustion chamber channel <NUM> extends axially through the plasma generator between a front electrode <NUM> and a rear electrode <NUM>. The front part of the combustion chamber channel <NUM>, i.e., the gas outlet <NUM> of the plasma generator <NUM>, is preferably configured as a nozzle mounted or directly worked into the front electrode <NUM>. The front electrode <NUM> is connected to electrical ground <NUM>. The rear electrode <NUM> is electrically connected to a high-voltage generator <NUM>, also known as the second high-voltage generator, and mounted toward the combustion chamber body <NUM>.

The plasma generator <NUM> shown in <FIG> comprises a front electrode <NUM>, a combustion chamber body <NUM> having a combustion chamber channel <NUM>, and a rear electrode <NUM>. Moreover, the plasma generator <NUM> has a number of ionization electrodes <NUM>, <NUM>, <NUM> and <NUM>, four in the figure and the embodiment. The ionization electrodes are connected to the initiation circuit <NUM>, not shown in <FIG>.

One or more ionization electrodes <NUM>, <NUM>, <NUM> and <NUM> are arranged inside and not making contact with the combustion chamber body <NUM> inside the combustion chamber channel <NUM> and are connected to an outside initiation circuit <NUM> having an outside high-voltage generator <NUM>, also called the first high-voltage generator. The ionization electrodes <NUM>, <NUM>, <NUM> and <NUM> are preferably arranged on a conically shaped holder <NUM>, where the conical holder <NUM> is situated at the rear electrode <NUM>. The conical holder <NUM> is preferably arranged in circular symmetry inside the combustion chamber body <NUM> and made of insulating material, and it may be composed of multiple parts making possible the positioning of the ionization electrodes.

The ionization electrodes <NUM>, <NUM>, <NUM> and <NUM> are preferably in circular symmetry and situated centrally inside the combustion chamber body <NUM> around the center line <NUM>; moreover, the parts of the conical holder <NUM> which are situated between the ionization electrodes <NUM>, <NUM>, <NUM> and <NUM> are preferably in circular symmetry and arranged about the center line <NUM>. Inside the conical holder <NUM>, not shown in the figure, is an arrangement for electrical connecting of the ionization electrodes <NUM>, <NUM>, <NUM> and <NUM>, situated for example by coaxially arranged coupling paths. The conical holder <NUM> may contain a sacrifice material, which is part of the ionization and/or the electrical flashover under electrical influence. Besides a conical shape, other shapes may be used where the radius of the circular symmetrical segment decreases from the rear electrode <NUM> forward in the lengthwise extension of the plasma generator.

The electrical circuit diagram for the outside initiation circuit <NUM>, in the case when four ionization electrodes are used, is described in <FIG> shows how the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM> are connected to the initiation circuit <NUM>. Two high-voltage capacitors, <NUM> and <NUM>, are charged to high voltage by a high-voltage generator <NUM>. The charging current is limited by a charging resistor <NUM>. The charging resistor <NUM> also minimizes the discharge current to the high-voltage generator <NUM> from the capacitors <NUM> and <NUM>. The connection node of the capacitors <NUM>, <NUM> which is connected to the high-voltage generator <NUM>, is charged to a high-voltage potential. The opposite side of the capacitors <NUM>, <NUM>, the side not connected to the high-voltage generator, is connected to ground <NUM> across current-limiting resistors <NUM>, <NUM>. The resistors <NUM>, <NUM> are designed to produce a current limiting during the charging of the capacitors <NUM>, <NUM> and to act as a current limiting of the current pulse passing through the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM> upon discharging of the capacitors <NUM>, <NUM> and thus initiation of the plasma generator. Current-limiting electrode resistors <NUM>, <NUM>, <NUM>, <NUM> are connected between the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM>. In the case of using four ionization electrodes <NUM>, <NUM>, <NUM>, <NUM>, as shown in the figure, only two of the electrode resistors <NUM>, <NUM> are needed. In the case of using two ionization electrodes, none of the electrode resistors <NUM>, <NUM>, <NUM>, <NUM> are needed. The electrode resistors <NUM> and <NUM> shown in the figure are meant to exemplify how the connection can be increased for further coupling of a larger number of ionization electrodes than four. The number of ionization electrodes can be chosen freely based on the desired size of the plasma generator <NUM>, the desired operating voltages, and the available and desirable energy levels. A circuit breaker <NUM>, also known as a switch, can switch the high-voltage side of the capacitor to ground at a certain point in time. The circuit breaker <NUM> may be of the trigatron, spark gap, semiconductor or other type. The resistors <NUM> and <NUM> prevent the discharge current from the second high-voltage generator <NUM> being discharged through the ionization electrodes. The electrical discharge is designed to proceed from the rear electrode <NUM> to the front electrode <NUM> while the resistors <NUM> and <NUM> and the electrode resistors <NUM>, <NUM>, <NUM>, <NUM> prevent the current from flowing to ground <NUM> through the initiation circuit <NUM>.

<FIG> shows an alternative circuit diagram for the outside initiation circuit <NUM>' through a connecting of the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM>. A certain inductance, also called stray inductances, occurs in all electrical circuits, where the inductances in the circuit affect how the electrical signals are propagated in the circuit. By inserting inductances <NUM> in the circuit from the ionization electrodes located at further distance from the rear electrode <NUM>, the electrical flashover in the combustion chamber channel <NUM> can be controlled. The introduced inductances <NUM> are preferably larger than the stray inductances occurring in the circuit.

The conical holder <NUM> of <FIG> is configured in one embodiment to be consumed layer by layer through successive burning of the two material layers <NUM> and <NUM> shown in <FIG>. Additional material layers may be present, of course. A layer is consumed in each initiation, each new energy pulse at the surface of the conical holder <NUM> exposed in the combustion chamber channel <NUM> gasifying the surface entirely or partially and generating a plasma created by the electrical discharge between the rear electrode <NUM> and the front electrode <NUM>. The first pulse gasifies the material layer <NUM>, thereby exposing the material layer <NUM> to the combustion chamber channel <NUM>. After this comes the next pulse, gasifying the next layer <NUM>, and so forth.

The gasification may occur layer by layer in either the axial or the radial direction, but may also occur through an increased consumption of material around the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM> and decreasing toward the front electrode <NUM> and the rear electrode <NUM>. Other consumption patterns are also possible. The fully or partially consumed conical holder <NUM> can be easily replaced with a new one as needed.

The conical holder <NUM> may be formed, e.g., by a lamination technique, where a particular number of layers are assembled, corresponding to the number of ignition pulses which the plasma generator <NUM> is dimensioned to generate. The conical holder <NUM> may also be made from a homogeneous material or a homogeneous material in combination with lamination, or by sintering, pressing, or another joining technique which is suitable for joining of metallic and polymer material where the portion of metallic material is on the order of <NUM>-<NUM> wt. % and the portion of polymer material is on the order of <NUM>-<NUM> wt. A variation of the amount of energy supplied to the plasma generator may also be utilized to gasify one or more layers in a laminated conical holder <NUM> or a varying mass in the conical holder <NUM> made from a homogeneous material.

The filling gas in the combustion chamber channel <NUM> is ionized with the ionization electrodes <NUM>, <NUM>, <NUM> and <NUM>, which increases the conductivity and enables the very powerful electrical pulse initiated with a given time duration, amplitude and shape between the front electrode <NUM> and rear electrode <NUM>, which causes the surface layer to be heated, gasified, and ionized entirely or partially, layer by layer, into plasma, hot gas and hot particles, whereupon a predetermined plasma is made to flow out through the end muzzle opening <NUM> with a very high pressure and a very high temperature and with a large quantity of gas and hot particles.

The conical holder <NUM> preferably comprises at least one sacrifice material or outer layer which falls apart in the resulting plasma into molecules, atoms or ions. Such a sacrifice material or outer layer advisedly contains hydrogen and carbon, for example. For the generating of hot particles, metallic material in combination with hydrogen and carbon, for example, can also be part of the conical holder <NUM>. The conical holder <NUM> in the described embodiment is enclosed by at least one dielectric polymer material, preferably a plastic with high melting temperature (preferably over <NUM>), high gasification temperature (over <NUM>, preferably over <NUM>) and low thermal conductivity (preferably below <NUM> W/mK). Especially suitable plastics include thermoplastics or thermosetting plastics, such as polyethylene, fluoroplastic (such as polytetrafluorethylene, etc.), polypropylene etc., or polyester, epoxy or polyimides, etc., to ensure that only one outer layer <NUM>, <NUM> of the conical holder is gasified for each energy pulse.

The sacrifice material in the conical holder <NUM> should also preferably be sublimating, i.e., pass directly from the solid to the gas form. It is also conceivable to arrange different layers of material, thickness, etc., to form a laminated conical holder <NUM> to bring about said layered <NUM>, <NUM> gasification of the laminate in the conical holder <NUM>, or to combine metallic and/or polymer material by sintering, pressing, or other joining technique into a conical holder <NUM> to bring about said layered <NUM>, <NUM> gasification of the laminate in the conical holder <NUM>.

The outer surface of the conical holder <NUM> is designed, dimensioned, and manufactured such that only the outermost surface of the conical holder <NUM>, i.e., the portion exposed from the combustion chamber channel <NUM>, the free outer layer <NUM>, <NUM> between the front electrode <NUM> and the rear electrode <NUM>, is gasified during each electrical pulse. Optimally, the conical holder <NUM> will be consumed during the last conceivable plasma generation for the plasma generator <NUM>.

Since the consumption of the conical holder <NUM> may be thought of as being dynamically variable between each use, depending on the configuration of the propellant, the projectile, the ambient temperature or the nature of the target, for example, the conical holder is manufactured with a certain margin so that it can function within the conceivable embodiments of the application.

The conical holder <NUM> may also be made for example of a ceramic, a semiconductor ceramic, or another material such as a plastic or other substance not consumed upon initiation of the plasma generator <NUM>. Upon initiation of a plasma generator <NUM> with a nonconsumable conical holder <NUM>, the filling gas contained in the combustion chamber channel <NUM> is ionized by the electrical discharge. After an electrical discharge, the conical holder <NUM> may be coated with an outer layer of soot, for example, which thereafter becomes part of the process. An entirely new conical holder, not yet exposed to an electrical discharge, may be coated with an outer layer, for example one of grease, soot, or the like, which is ionized by the ionization electrodes to initiate a first electrical discharge between the rear and front electrode. With a conical holder <NUM> made of a nonconsumable material, the conical holder <NUM> does not need to be replaced during repeated use.

<FIG> shows a tube-equipped ammunition unit <NUM> with integrated plasma generator. The plasma generator <NUM> is mounted in a cartridge tube <NUM>, together with a propellant charge <NUM> and a projectile <NUM>. The propellant charge <NUM> can be, for example, a solid powder containing at least one charging unit in the form of one or more cylindrical rods, disks, blocks, etc. The charging units are multiperforated with a large number of burn channels so that a so-called multi-hole powder is produced. Alternative configurations of the propellant charge <NUM> are possible, of course.

<FIG> shows an ionization electrode <NUM> designed with a flashover conductor <NUM>. The flashover conductor <NUM> is designed to control the electrical flashover so that the electrical flashover moves between the flashover conductors situated on the respective ionization electrode. The flashover conductor is arranged as a piece projecting from the ionization electrodes, preferably sticking out from the conical holder <NUM>.

The function and application of the plasma generator <NUM> according to the invention is as follows in the case when four ionization electrodes are used.

During the firing and initiation of the plasma generator <NUM>, the capacitors <NUM>, <NUM> charged by the high-voltage generator <NUM> are made to discharge by the circuit breaker <NUM>. The capacitors <NUM>, <NUM> are connected to the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM>, and the charge redistribution upon discharging of the capacitors brings about an ionization of the filling gas in the combustion chamber channel <NUM>. When the degree of ionization is such that plasma generation can be initiated, the second high-voltage generator <NUM> is made to produce a powerful electrical energy pulse, having a high current strength and/or a high voltage, both with a particular determined amplitude and pulse length adapted to the properties of the particular weapon, the temperature, the propellant charge, the projectile, the target, the surroundings, etc. The impedance of the plasma generator <NUM> is low in the active state, i.e., during the plasma generation, so that preferably a high current is generated from the second high-voltage generator <NUM>, on the order of <NUM> to <NUM> kA, but in order to have a successful flashover a high voltage is needed, on the order of <NUM> to <NUM> kV. To produce an effective plasma, for flashover of the propellant bed, each energy pulse should exceed <NUM> kJ, but it may be as much as <NUM> kJ, and is supplied to the plasma with a pulse length between <NUM> and <NUM>.

The design with multiple successive ionization electrodes <NUM>, <NUM>, <NUM> and <NUM> in the combustion chamber channel <NUM> causes the electrical flashover between the rear electrode <NUM> and the front electrode <NUM> to move step by step between the ionization electrodes. During the first flashover or discharge from the rear electrode <NUM> to the first ionization electrode <NUM>, UV light from the discharge ionizes the filling gas. The electrical field then moves from the rear electrode <NUM> to the first ionization electrode <NUM>, facilitating the next discharge from the ionization electrode <NUM> to the ionization electrode <NUM>. UV light is also produced during the discharge between the ionization electrodes <NUM> and <NUM> for further ionization and a further movement of the electrical field. In the same way, the electrical flashover occurs onward to the front electrode <NUM>. A very limited current will flow to ground in the ionization electrodes, since the resistance to ground is high. Most of the electrical energy in the high-voltage generator <NUM> will be discharged from the rear electrode <NUM> to the front electrode <NUM> and to the filling gas in the combustion chamber channel <NUM>. The resistors have a resistance on the order of <NUM> to <NUM> kOhm in order to limit the portion of the current flowing from the high-voltage generator <NUM> to ground via the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM>. When the initiation of the plasma generator <NUM> occurs by the closing of the circuit breaker <NUM>, a charged voltage in the capacitors <NUM> and <NUM> is discharged partly across the circuit breaker <NUM> to ground, at the same time that a charge redistribution occurs from the ionization electrodes <NUM>, <NUM>, <NUM> and <NUM> and the capacitors <NUM> and <NUM>. The charge redistribution from the ionization electrode <NUM> occurs through the resistor <NUM> and the charge redistribution from the ionization electrode <NUM> occurs through the resistor <NUM>.

The powerful electrical energy pulse generates an electrical flashover, also called an arc discharge, between the rear electrode <NUM> and the front electrode <NUM>, via the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM>, and in the plasma channel created by the arc discharge the temperature becomes so high that the outermost layer of the conical holder <NUM> is melted, gasified, and finally ionized to form a very hot plasma. In one alternative embodiment, a substance supplied to the combustion chamber channel <NUM> can be part of the substance forming a plasma in connection with the arc discharge. It may also be the case that only the filling gas is ionized; in this case, none of the conical holder <NUM> is consumed. Moreover, it may be the case that an outer coating on the conical holder <NUM> is ionized and creates a plasma channel so that an arc discharge occurs between the rear electrode <NUM> and the front electrode <NUM>; in this case, none of the conical holder <NUM> is consumed. Due to the high pressure generated by the gasification in the combustion chamber channel <NUM>, the generated plasma-like gas is caused to spurt out through the gas outlet <NUM>, which gas outlet <NUM> is shaped like a nozzle. The pulse length, pulse shape, current strength and voltage can be varied according to the current conditions of the firing situation, such as the surrounding temperature, the humidity, etc., and the special properties of the particular weapons system and ammunition or projectile type, as well as the current target type, including the range to that target.

A plasma generator with variable ignition energy enables an instantaneous flashover of the entire propellant charge and thereby makes possible an immediate pressure rise. A plasma generator also has the advantage that the ignition energy can be varied over time, unlike a pyrotechnical igniter. Variable ignition energy means that the ignition energy can be adapted to different types and sizes of propellant charges, so as to vary the firing range of the projectile, and also to compensate for the temperature dependence of the propellant charge. The quantum of energy with which the high-voltage generator <NUM> is charged is adapted according to the size and performance of the plasma generator <NUM>. Since the impedance in the electrical flashover between the rear electrode <NUM>, via the ionization electrodes <NUM>, <NUM>, <NUM>, <NUM>, to the front electrode <NUM> approaches zero, electrical energy is no longer supplied to the plasma channel. Since no energy is supplied to the plasma channel, the pulse from the high-voltage generator <NUM> can be interrupted or terminated. Preferably, the quantum of energy in the high-voltage generator <NUM> is thus adapted so that the impedance in the electrical flashover approaches zero when the high-voltage generator <NUM> is discharged. In this way, the plasma generator <NUM> is optimized in terms of energy.

Weapons systems can be ignited more easily and safely with the proposed repeatable plasma generator. The avoidance of vulnerable ignition substances and ignition cartridges means that complete use of propellants with low vulnerability can be adopted. Problems with difficult mechanisms such as one for changing of ignition cartridges or dispensing equipment for liquids can be avoided. The technique provides increased control over the parameters of the ignition pulse, such as energy content, pulse length, and ignition time. The ignition pulse can be adapted to the size of the propellant charge depending on the quantity of propellant, the sensitivity of the propellant, and the ambient temperature.

The example of a plasma generator according to the invention, intended for use in an artillery system as replacement for a conventional ignition cartridge, utilized energy pulses of around <NUM> to <NUM> kJ with duration of several milliseconds and voltage in the range of <NUM> to <NUM> kV. Current strength in the range of <NUM> to <NUM> kA. Distance between front electrode <NUM> and rear electrode <NUM> was on the order of <NUM> to <NUM>.

The invention is not limited to the configurations shown especially, but instead can be varied in different ways within the patent claims.

It is evident, for example, that the number, size, material and shape of the elements and parts making up the ammunition unit and the plasma generator can be adapted according to the weapons system or systems and other design properties in the particular instance.

It is evident that the above-described ammunition embodiment may comprise many different dimensions and projectile types, depending on the area of application and the barrel width. However, the most commonly occurring projectiles today, between around <NUM> and <NUM>, are considered above.

In the embodiments described above, the plasma generator comprises only one front gas outlet, but it also comes under the notion of the invention to arrange several nozzle openings along the surface of the combustion chamber channel or several openings in the front opening <NUM>.

Claim 1:
A plasma generator (<NUM>) for initiation of propellant charges in a weapons system, for example when launching projectiles from a barrel weapon, by electrical discharge between a rear electrode (<NUM>) and a front electrode (<NUM>) in a combustion chamber channel (<NUM>) enclosed in a combustion chamber body (<NUM>) and filled with filling gas, designed to ignite at least one propellant charge (<NUM>), characterized in that the plasma generator (<NUM>) comprises at least one ionization electrode (<NUM>, <NUM>, <NUM>, <NUM>) situated inside the enclosing combustion chamber body (<NUM>), not in physical contact with the combustion chamber body (<NUM>), where ionization electrodes (<NUM>, <NUM>, <NUM>, <NUM>) are connected to an initiation circuit (<NUM>), comprising at least one first high-voltage generator (<NUM>), for ionization of the filling gas in the combustion chamber channel (<NUM>), and a second high-voltage generator (<NUM>) designed for electrical discharge in the electrically conductive gas from the rear electrode (<NUM>) via at least one ionization electrode (<NUM>, <NUM>, <NUM>, <NUM>) onward to the front electrode (<NUM>) so that hot ignition gas under high pressure is formed.