Dense plasma focus apparatus

In an aspect, a plasma focus apparatus produces pulsed high temperature plasma that emits multi-radiation including ion beams, electron beams, fast plasma streams, x-rays and nuclear fusion neutrons. This plasma focus apparatus includes an electrode assembly including an inner and at least one outer electrode, as well as a plurality of capacitors connected to the electrode assembly in parallel to form the high energy density, high current density plasma, where the arrangement and shape of the capacitors and other elements of the circuitry and electrode assembly provide a system with low stray inductance.

FIELD OF THE DISCLOSURE

The present invention relates generally to plasma generating systems. In particular, the invention relates to a dense plasma focus apparatus.

BACKGROUND

Plasma focus systems are pinch-based, plasma generation systems in which the voltage of a charged capacitor is applied between two coaxial electrodes placed inside a vacuum chamber that is filled with a working gas. The application of the voltage from the charged capacitor leads to the ionization and breakdown of the working gas, and the formation of a current sheath spanning across the electrodes.

Under the effect of the Lorentz force created by the radial current flowing in the plasma and the current-induced azimuthal magnetic field, the current sheath that arcs between the electrodes is driven axially along the electrodes toward an open, focused end of the system, where the current sheath is radially compressed inwards to form a hot and dense pinched plasma column. During the pinching of the plasma, plasma instabilities lead to the emission of electron and ion beams, electromagnetic radiation pulses, and, if the working gas contains deuterium, fusion neutrons.

Regarding the function of the capacitors provided in plasma focus systems, the idealized energy stored inside the capacitor is proportional to the capacitance C at a constant applied voltage V. In the real capacitor elements, losses associated with the true performance of the capacitor include the losses from the stray inductance of the capacitor. Stray inductance is an essential phenomenon in any capacitor, and it cannot be avoided or controlled. Stray inductance reduces the capacity C of the capacitor and potential energy (U) storage in the capacitor. stray inductance increases with increasing the frequency of the applied potential.

In present generations of small-scale, plasma focus systems, the electrodes are typically charged by a single foil-wound capacitor, which is bulky, and which tend to have minimum stray inductances of at least 40 nH, thereby reducing the output of the capacitor and the resulting output of the plasma focus system. It is therefore desirable to provide a means by which the stray inductance of the plasma focus system is reduced, thereby increasing the actual, peak voltage applied by the pulse generating circuitry, and consequently increasing the output power of the plasma focus apparatus.

It is therefore an object of the invention to provide a novel plasma focus apparatus for generating pulsed plasmas at high temperature and high density, where the circuitry of the plasma focus apparatus has a reduced total stray inductance compared to other plasma focus apparatuses known in the art. The plasma focused apparatus as disclosed herein operates with an axial plasma phase followed by a plasma radial compression leading to a plasma pinch phase, where multi-radiations including x-rays and ion and electron beams are emitted from the plasma pinch.

SUMMARY OF THE DISCLOSURE

According to an aspect, there is provided a plasma focus apparatus comprising: a vacuum chamber, an electrode assembly including an inner electrode having a discharge end and a focus end, at least one outer electrode being disposed about the inner electrode, the at least one outer electrode and the inner electrode defining therebetween an annular ionization region for containing at least one working gas; and an insulator being disposed between the at least one outer electrode and the inner electrode. The plasma focus apparatus also includes a gas supply conduit for supplying the at least one working gas to the annular ionization region; and a pulsed power circuit including a spark gap switch being electrically connected to the inner electrode; and a plurality of capacitor elements being electrically connected in parallel between the at least one outer electrode and the spark gap switch, the spark gap switch and the plurality of capacitor elements being arranged to provide a pulsed discharge voltage between the inner electrode and the at least one outer electrode so as to ionize at least one working gas contained within the annular ionization region, the at least one outer electrode, the inner electrode and the insulator being relatively positioned such that when a pulse of discharge voltage is applied, an ionized working gas will form a plasma current sheath extending between the inner and at least one outer electrodes.

DETAILED DESCRIPTION OF THE EMBODIMENTS

For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

The indefinite article “a” is not intended to be limited to mean “one” of an element. It is intended to mean “one or more” of an element, where applicable, (i.e. unless in the context it would be obvious that only one of the element would be suitable).

Any reference to upper, lower, top, bottom or the like are intended to refer to an orientation of a particular element during use of the claimed subject matter and not necessarily to its orientation during shipping or manufacture. The upper surface of an element, for example, can still be considered its upper surface even when the element is lying on its side.

Referring toFIG. 1andFIG. 2, the plasma focus apparatus100comprises a vacuum chamber100and an electrode assembly200, the electrode assembly200including an inner electrode150having a discharge end150aand a focus end150b,at least one outer electrode140being disposed about the inner electrode150and extending along at least a portion of the inner electrode150, where the at least one outer electrode140and the inner electrode150define therebetween an annular ionization region210for containing at least one working gas, and where the electrode assembly200also includes an insulator152disposed between the at least one outer electrode140and the inner electrode150.

The plasma focus apparatus also includes a gas supply conduit112for supplying the at least one working gas to the annular ionization region210within the vacuum chamber110, and a pulsed power circuit230which includes a spark gap switch120being electrically connected to the inner electrode150, and a plurality of capacitor elements130being electrically connected in parallel between the at least one outer electrode140and the spark gap switch120, the spark gap switch120and the plurality of capacitor elements130being arranged to provide a pulsed discharge voltage between the inner electrode150and the at least one outer electrode140so as to ionize at least one working gas contained within the annular ionization region210. Referring toFIG. 2, the at least one outer electrode140, the inner electrode150and the insulator152are relatively positioned such that when a pulse of the pulsed discharge voltage is applied, the ionized working gas within the annular ionization region210will form a plasma current sheath220extending between the inner and at least one outer electrodes150,140.

In an embodiment, the plasma focus apparatus100is operated according to the following procedure:

An external power supply is provided to the pulsed power circuitry230, including the spark gap switch120and the plurality of capacitor elements130, where the external power supply is used to charge the plurality of capacitor elements130. After a predetermined period of charging time, the plurality of capacitor elements130becomes at least partially charged by the external power supply.

Once the plurality of capacitor elements130are at least partially charged, the spark gap switch120is closed, allowing a discharge of the current stored in the plurality of capacitor elements130. The discharge of current supplies a voltage across the at least one outer electrode140and the inner electrode150, where the discharge voltage generates an arc between the at least one outer electrode140and the inner electrode150corresponding to each pulse of the pulsed voltage. In this embodiment, the arc generated within the annular ionization region210(between the inner electrode150and the at least one outer electrode140) dilutes and ionizes the at least one working gas contained in the annular ionization region210.

As shown inFIG. 2, as the at least one working gas becomes ionized and is continually provided in the annular ionization region210through the gas supply conduit112and the vacuum chamber110, the inner electrode150is charged by each pulsed discharge of the plurality of capacitor elements130and will generate the arc of plasma at the path of least resistance of the annular ionization region210, which is towards the discharge end150aof the inner electrode150. The arc from the inner electrode150forms the plasma current sheath220across to the at least one outer electrode140. The plasma current sheath220will be driven along the annular ionization region210, from the discharge end150ato the focus end150bof the inner electrode150, where a pinch process of the plasma current sheath220will occur. The pinch process of the plasma current sheath220will cause the plasma current sheath220to radially collapses toward a long axis250of the inner electrode150, where the collapsing plasma current sheath220form a dense plasma column at a output end of the electrode assembly200.

The plasma focus apparatus100generally includes a gas supply conduit112for supplying the at least one working gas to the annular ionization region210of the electrode assembly200. In an embodiment, the at least working gas supplied to the vacuum chamber110via the gas supply conduit112is a low-pressure gas or gas mixture at a pressure in a range from 0.1 Torr to 15 Torr.

In an embodiment, the at least one working gas is a variety of gases including, but not limited to, argon, nitrogen, deuterium and mixtures or combinations thereof.

In an embodiment, the at least one working gas is selected such that the plasma pinch process of the plasma current sheath220will generate and emit radiation. For example, the at least one working gas can be a gas or a gas mixture including one or more noble gases such as argon, krypton and xenon such that the pinch process will emit radiation. In an alternate embodiment, the at least one working gas is selected such that the plasma pinch process of the plasma current sheath220will generate and emit neutrons. For example, the at least one working gas can be a gas or a gas mixture including deuterium or a deuterium-tritium gas such that the pinch process will emit neutrons.

Vacuum Chamber and Conduit

In the specific embodiments provided inFIGS. 3A, 3B, 4 and 5, the plasma focus apparatus100includes a vacuum chamber110that is a tubular vacuum chamber. In the embodiment shown inFIG. 3A, the tubular vacuum chamber has a top chamber portion316and a bottom chamber portion314. The top chamber portion316is defined within a tubular housing310, where the tubular housing310is mounted to a retaining structure320with a through-aperture312that defines the bottom chamber portion314. As shown inFIGS. 3A and 3B, the retaining structure320can include a pair of annular flanges322,326on which the tubular housing310is mounted, as well as an O-ring324for providing a vacuum seal between the annular flanges322,326to prevent leakage of the at least one working gas from the vacuum chamber110. In the embodiment shown, the through-aperture312that defines the bottom chamber portion314is provided in the bottom flange of the pair of annular flanges322,326.

In the specific embodiment provided inFIG. 3B, a top end of the tubular housing310is in fluid connection with the gas supply conduit112for injection therethrough of the at least one working gas. The gas supply conduit112can also be used as an evacuation conduit for evacuating air from the vacuum chamber110to produce a vacuum pressure. In an alternate embodiment, the tubular housing can include an evacuation conduit in fluid connection with the vacuum chamber, where the evacuation conduit is separate from the gas supply conduit112.

In an embodiment, the plasma focus apparatus100includes a vacuum pump that is in fluid connection with the evacuation conduit (either as part of the gas supply conduit112or as a separate evacuation conduit), where the vacuum pump is sized to evacuate gas from the vacuum chamber110so as to produce a vacuum pressure therewithin. The vacuum pump may be a variety of suitable vacuum pumps for evacuating gases including a rotary vane vacuum pump, a diaphragm vacuum pump, a liquid ring vacuum pumps and a scroll vacuum pump.

In the embodiment shown inFIG. 4, the tubular housing310is an at-least-partially transparent housing410. In an additional embodiment, the material of the at-least-partially housing410is a glass or glass mixture including a quartz glass component. The transparent property of the at-least-partially transparent housing410provides a means for non-invasively accessing the interior of the vacuum chamber110during the plasma formation process so that optical measurements may be performed to characterize at least a first property of the plasma arc generated from the electrode assembly200. The optical measurements may be an imaging analysis or a spectroscopic analysis of the plasma arc. The optical measurement may also be an ion or electron beam time-of-flight measurement.

While the present disclosure describes a vacuum chamber110, it will be readily understood that the pressures within the reaction chamber need not be a perfect vacuum.

Electrode Assembly

As disclosed herein, the electrode assembly200includes an inner electrode150that has a discharge end150aand a focus end150b,at least one outer electrode140that is disposed about the inner electrode150, and an insulator152disposed between the at least one outer electrode140and the inner electrode150.

In an embodiment, the at least one outer electrode140defines the cathode of the electrode assembly200, and the inner electrode150defines the anode of the electrode assembly200.

Referring toFIGS. 6, an embodiment of the plasma focus apparatus100is shown, where the at least one outer electrode140extends along at least a portion of the inner electrode150, where the at least one outer electrode140and the inner electrode150define therebetween the annular ionization region210for containing at least one working gas. Within the electrode assembly200, the at least one outer electrode140, the inner electrode150and the insulator152are relatively positioned such that when a pulse of discharge voltage is applied to the inner electrode150and at least one outer electrode140, the ionized working gas will form a plasma current sheath extending between the inner and at least one outer electrodes150,140.

As discussed, the at least one outer electrode140is disposed about the inner electrode150, with a gap therebetween that defines the annular ionization region210. The at least one outer electrode140can be various numbers of suitably shaped electrodes. In an embodiment, the at least one outer electrode140is a plurality of identical outer electrodes that are symmetrically disposed about the inner electrode. The plurality of outer electrodes may be symmetrically disposed about the inner electrode150in a circular pattern. The number of the at least one outer electrode140and the distance between outer electrodes (in embodiments where the at least one outer electrode140is a plurality of electrodes) can be selected based on a total capacitance of the plurality of capacitor elements130or a total stray inductance of the plurality of capacitor elements130and spark gap switch120such that a stray inductance of the electrode assembly200is minimized. In the specific embodiment provided inFIG. 6, the at least one outer electrode140is six outer electrode rods640, where each outer electrode rod640is symmetrically disposed about the inner electrode150in a circular arrangement to define a radial dimension of the annular ionization region210. In an additional embodiment, each of the outer electrode rods640are spaced radially outwards from the inner electrode150at a distance of at least 3 mm.

In an embodiment of the electrode assembly200such as the embodiment provided inFIG. 2, the at least one outer electrode140is a single, tubular electrode that is disposed concentrically about the inner electrode.

The insulator152is provided in the electrode assembly200to prevent undesired arcing or discharge of current between the inner electrode150and the at least one outer electrode140in certain regions along the electrode assembly200. In an embodiment such as the embodiment provided inFIG. 6, the insulator152disposed between the at least one outer electrode140and the inner electrode150is a tubular insulator652that is coaxially disposed between the at least one outer electrode140and the inner electrode150and extends from the discharge end of the electrode assembly, along a portion of the length of the inner electrode150. The insulator152can be disposed between the at least one outer electrode140and the inner electrode150such that it is in contact with one, both or none of the at least one outer electrode140and the inner electrode150.

In an embodiment, the insulator152is composed of one or more electrically insulating materials. For example, the insulator may be composed of an insulating ceramic material like quartz glass.

In the specific embodiment ofFIG. 6, the inner electrode150is a tubular inner electrode150, the insulator152is a tubular insulator652that surrounds a lower portion of the tubular inner electrode150, and the outer electrode140is the six outer electrode rods640. In this embodiment, the tubular inner electrode150and the tubular insulator652are directly mounted to the spark gap switch120such that at least a portion of the tubular inner electrode150and a portion of the tubular insulator652each extend along at least a portion of the vacuum chamber110.

In an embodiment, the at least one outer electrode140and the inner electrode150are composed of a conductive material including aluminum, copper, beryllium, chromium, copper, gold, nickel, molybdenum, palladium, platinum, silver, tantalum, titanium, tungsten, and zinc) and alloys thereof (e.g., copper-alloy, beryllium-alloy, copper-beryllium-alloy, aluminum-alloy and other metal alloys). The at least one outer electrode140and the inner electrode150may be composed of the same conductive material or different conductive materials.

Pulsed Power Circuit

The plasma focus apparatus100includes the pulsed power circuitry230for controlling the pulse discharge voltage applied to the electrode assembly. As shown inFIGS. 1 and 2, the pulsed power circuitry230includes the plurality of capacitor elements130and the spark gap switch120.

In an embodiment, the plurality of capacitor elements130are electrically connected in parallel between the at least one outer electrode140and the spark gap switch120. The spark gap switch120is connected between the plurality of capacitor elements130and the inner electrode150. The spark gap switch120and the plurality of capacitor elements130are arranged to provide the pulsed discharge voltage between the inner electrode150and the at least one outer electrode140so as to ionize at least one working gas contained within the annular ionization region210.

In an embodiment, the plurality of capacitor elements130are connected to the spark gap switch120and the at least one outer electrode140and are symmetrically disposed around the electrode assembly200. In an additional embodiment of the plasma focus apparatus100including the symmetrically disposed, plurality of capacitor elements130, the plurality of capacitor elements130are disposed about the electrode assembly in a circular arrangement.

In a specific embodiment where the inner electrode150is an inner electrode rod, the plurality of capacitor elements130are disposed in a circular arrangement such that the circular arrangement is concentric with the inner electrode rod.

In an embodiment, each of the plurality of capacitor elements130is a high-voltage, thin-film capacitor in a range from 3 kVdc to 30 kVdc.

In the specific embodiment provided inFIG. 4, the plurality of capacitor elements130are at least twenty cylindrical, thin-film capacitors330that are symmetrically disposed about the inner electrode150. In this embodiment, the at least twenty capacitors330are arranged symmetrically, in a circular pattern relative to the inner electrode150.

In the embodiments where the plurality of capacitors elements130is at least twenty capacitors, each of the at least twenty capacitors of the plurality of capacitor elements130may be a 10 kV miniature-film capacitor with a capacitance of 0.1 uF and individual stray inductances of 100 nH. When the plurality of capacitors elements130are exactly twenty 0.1 uF capacitors arranged in parallel and connected in parallel between the at least one outer electrode140and the spark gap switch120, the twenty cylindrical capacitors have a total capacitance of 2 uF and a total stray inductance of 5 nH. Although this embodiment specifically describes a plasma focus apparatus100with twenty capacitors, it will be readily understood that the number and sizing of the plurality of capacitor elements130in the plasma focus apparatus100may be various amounts. For example, the number of capacitor elements130may be fifty 10 kV, miniature-film capacitors with a total stray inductance (in parallel) of 2 nH, or the number of capacitor elements130may be one-hundred 10 kV capacitors with a total stray inductance (in parallel) of 1 nH.

In an embodiment, the number of capacitors provided in the plurality of capacitor elements130is the minimum number of capacitor elements130which can provide a sufficiently large voltage to produce arc discharge between the at least one outer and the inner electrodes140,150. In this embodiment, the number of capacitor elements130may also be selected to achieve a stray inductance within the pulsed power circuitry230that is below a predetermined value of stray inductance, where the achieving a stray inductance below the predestined value of stray inductance will result in the pulsed power circuitry230providing a greater magnitude of discharge current through the discharge voltage.

In an additional embodiment, as more capacitors are included within the apparatus100as part of the plurality of capacitor elements130, the total capacitance of the pulsed power circuitry230will increase, as will the resulting discharge current. As the total capacitance is increased, the pressure of the at least one working gas and the length of the inner electrode150can also be adjusted to optimize the output power of the plasma discharge from the plasma focus apparatus100.

Referring to the specific embodiment provided inFIG. 3B, the spark gap switch120includes a switching electrode120ato which the plurality of capacitor elements130are connected, in parallel. The spark gap switch120also includes a switched electrode120bthat is disposed opposite the switching electrode120ato define a spark gap340therebetween. In the specific embodiment provided inFIG. 5, each of the switching and switched electrodes120a,120binclude a conductive, mounting body552,558, and a hemispherical electrode portion554,556. The hemispherical electrode portions554,556of the switching and switch electrodes120a,120bprovide the spark discharge therebetween. Each of the hemispherical electrode portions554,556are mounted on the conductive mounting bodies552,558. The conductive mounting body558of the switching electrode120ais conductively connected to the plurality of capacitor elements130, while the conductive mounting body552of the switched electrode120bis conductively connected to the inner electrode150. In an embodiment, the hemispherical electrode portions554,556of each of the switching and switched electrodes120a,120bare removably mountable to their respective conductive, mounting bodies552,558. In the specific embodiment ofFIG. 5, the hemispherical electrode portions554,556and conductive mounting bodies552,558have sets of corresponding threads for providing the removable mounting the hemispherical electrode portions554,556thereon.

In the specific embodiment ofFIG. 5, the switched electrode120bis directly connected to the inner electrode150of the electrode assembly, while the switching electrode120ais mounted on the second collector disc540. The switching and switched electrodes120a,120bare relatively and opposingly disposed along the long axis250of the inner electrode150such that the spark gap322is defined along the long axis of the plasma focus apparatus100, between the hemispherical electrode portions554,556.

Conduction Assemblies

In an embodiment, the spark gap switch120, plurality of capacitor elements130, and outer electrode140are electrically connected, in the configuration presented above, via first and second conductive assemblies. In this embodiment, the at least one outer electrode140is electrically connected to the plurality of capacitor elements130via the first conductive assembly, and the spark gap switch120is electrically connected to the plurality of capacitor elements130via the second conductive assembly.

In an embodiment, the first conductive assembly includes a first collector plate to which the at least one outer electrode140is mounted, and a first plurality of conductive conduits corresponding to the plurality of capacitor elements130. Each of the first plurality of conductive conduits are connected to the first collector plate and to a first end of one of the plurality of capacitor elements130. In this embodiment, the first collector plate includes an internally disposed through-opening for pass therethrough of a portion of the insulator152and the inner electrode150.

In an embodiment, the second conductive assembly includes a second collector plate that is electrically connected to the spark gap switch120, and a second plurality of conductive conduits corresponding to each of the plurality of capacitor elements130, each of the second plurality of conductive conduits being connected to the second collector plate and to a second end of one of the plurality of capacitor elements130.

In this embodiment, a central axis of the inner electrode150defines a central axis of the plasma focus apparatus100. In this embodiment, the first and second collector plates are spaced apart along the central axis of the plasma focus apparatus100, where the space between the first and second collector plates defines a spark region. The spark gap switch120is disposed in the spark gap region, between the first and second collector plates. In a specific embodiment shown inFIG. 5, the spark gap switch120is oriented within the spark gap region to extend along the long axis250of the inner electrode150.

In the specific embodiment shown inFIGS. 4 and 5, the first and second collector plates are first and second collector discs440,540. The first collector disc440includes a centrally disposed through-opening for pass therethrough of a portion of the electrode assembly200. The outer electrode140rods are mounted through the first collector disc440and are arranged symmetrically around the centrally disposed through-opening, in a circular pattern. The second collector disc540is formed such that the spark gas switch130can be mounted thereon. In the exemplary embodiment provided inFIG. 5, a portion of the spark gas switch130is mounted in a through-hole provided in the second collector disc540. The first-and second-collector discs440,540are connected, via the first and second plurality of conductive conduits420,520, to opposing ends of individual capacitor elements of the plurality of capacitor elements130. In an embodiment such as the embodiment provided inFIG. 5, the first and second plurality of conductive conduits420,520are connected around an outer region of each of the first and second collector discs440,540, and extend radially outward from each of the first and second collector discs440,540to connect to opposing ends of the plurality of capacitor elements130.

Each of the first and second plurality of conductive conduits420,520may be connected to the first and second collector discs440,540by various means. In an embodiment, the first and second collector discs440,540each include a plurality of conduit fastener elements disposed around the outer region of each of the first and second collector discs440,540. Each of the conduit fastener elements are shaped to releasably secure an end of each of the first and second plurality of conductive conduits420,520thereto. In an embodiment, the conduit fastener elements are metal nuts threaded through the first and second collector discs440,540.

In an embodiment, the first and second collector plates and the first and second plurality of conductive conduits are composed of a conductive material including, but not limited to copper, chromium, steel and nickel, or alloys and combinations thereof. In an alternate embodiment, the collector plates and conductive conduits are composed of at least two different, conductive materials including, but not limited to copper, chromium, steel and nickel, or alloys and combinations thereof. The first and second collector plates and the first and second plurality of conductive conduits may be composed of the same conductive material or, some or all of the first and second collector plates and the first and second plurality of conductive conduits may each be composed of different conductive materials.

In a specific embodiment of the plasma focus apparatus100presented inFIG. 5, the first and second collector discs440,540are each formed of pure copper, and have a total stray inductance of 10 nH. In this embodiment, the spark gap switch120has a 25 nH stray inductance, and the plurality of capacitor elements130are twenty, 0.1 uF capacitors, thin-film, cylindrical capacitors. In this embodiment, the first and second collector discs440,540, spark gap switch120and plurality of capacitor elements130have a combined, total inductance value of 40 nH.

Power Supply

In an embodiment, the plasma focus apparatus100further comprises an external power source connected to one of the at least one outer electrode140, the first collector plate, and one of the first plurality of conductive conduits, where the external power source will provide a discharge voltage to the plurality of capacitor elements130. The discharge voltage provided by an external power source has a sufficiently large voltage to produce an electrical discharge between the between the at least one outer electrode140and the inner electrode150of the electrode assembly200.

In an embodiment, the peak voltage of the discharge voltage applied by the external power source to the pulsed power circuitry230is in a range from 5v to 15 kV. In an specific embodiment, the power supplied by the external power source has a 10 kV peak output voltage and provides a 5 mA constant current.

Gas Supply System

In an embodiment, the plasma focus apparatus100includes a gas supply system700in fluid connection with the gas supply conduit112. The gas supply system700is connected to the gas supply conduit112to provide the at least one working gas to the vacuum chamber110, and to control at least one of: a rate of evacuation of the vacuum chamber110, a rate of injection for the at least one working gas, a pressure of the at least one working gas, or a composition of the at least one working gas injected into the vacuum chamber110.

In the specific example provided inFIG. 7, a section of an exemplary gas supply system700is shown. The section of the gas supply system700includes a distribution conduit710in fluid connection with the gas supply conduit112. The distribution conduit710includes at least one inlet714for connecting the distribution conduit710to a source of the at least one working gas. In the specific embodiment presented inFIG. 7, the distribution conduit710is a T-joint conduit724directly mounted on the gas supply conduit112via an adapter fitting720. The T-joint conduit724of the gas supply system700includes a working gas valve718connected along the first inlet714of the T-joint conduit724to control a rate of injection of the at least one working gas through the gas supply conduit112. The T-joint conduit724also includes a second inlet712and a vacuum control valve716connected along the second inlet712. The vacuum control valve716controls the evacuation of gas from the vacuum chamber110, through the distribution conduit710and the second inlet712when the vacuum pump is turned on, to thereby regulate an evacuation rate of the vacuum chamber110.

In an embodiment, the gas supply system700also includes a gauge722to monitor a gaseous pressure in the gas supply system700. In the specific example provided inFIG. 7, the gauge722is a dial gauge, but the gauge722could be any suitable gauge for reading a pressure of a gas flowing through a distribution conduit710.

EXAMPLES

In a non-limiting example of the sizing and operation of the plasma focus apparatus100disclosed herein, the plasma focus apparatus100includes a plurality of parallel capacitors with a total stray inductance of 5 nH, the plurality of parallel capacitors being connected to a spark gap switch120with a 25 nH stray inductance and to a pair of collector plates, each with a 5 nH stray inductance. This example of the plasma focus apparatus100has a total stray inductance of 40 nH. When a pulsed voltage with a peak operating voltage of 10 kV is applied between the at least one outer and the inner electrode150of the exemplary plasma focus apparatus100, the low total stray inductance enables the peak discharge, short-circuit current amplitude of the plurality of parallel capacitor to be at least 70 kA. (the short circuit current amplitude being calculated using the formula V/(L/C)0.5.

In a non-limiting example of the sizing and operation of the plasma focus apparatus100disclosed herein, the plasma focus apparatus100includes a plurality of parallel capacitors with a total stray inductance of 5 nH, the plurality of parallel capacitors being connected to a spark gap switch120with a 25 nH stray inductance and to a pair of collector plates, each with a 5 nH stray inductance. This example of the plasma focus apparatus100has a total stray inductance of 40 nH. When a pulsed voltage with a peak operating voltage of 6 kV is applied between the at least one outer and the inner electrode150of the exemplary plasma focus apparatus100, the low total stray inductance enables the peak discharge, short-circuit current amplitude of the plurality of parallel capacitor to be at least 42 kA. (the short circuit current amplitude being calculated using the formula V/(L/C)0.5.

In an embodiment, the plasma focus apparatus100as disclosed herein is used for radiation generation. In this embodiment, the at least one working gas includes a noble gas such as argon, krypton and xenon. The ionization, plasma formation and plasma pinching within this embodiment of the plasma focus apparatus100will emit radiation from the plasma discharge at the long axis250of the inner electrode150.

In an exemplary embodiment of the plasma focus apparatus100applied to generate radiation, the at least one outer electrode140is a single, tubular electrode having an inner diameter of 11 mm, the inner electrode150is a concentric electrode rod having an outer diameter of 3.5 mm and a length of 20 mm. In this example, the at least one working gas is Argon gas supplied at a pressure of 0.9 Torr. In this example, the power supply connected to the first collector plate provides a pulsed voltage with a 6 kV peak operating voltage to the pulsed power circuitry230. The resulting current has a current linear density of 205 kA/(cm of at inner electrode 150 radius) and the speed factor (S) is 216 (kA/cm)Torr0.5. The resulting Argon all-line radiation peak power is 1.7 MW and the integrated all-line radiation yield is 1.5 mJ.

In an embodiment, the plasma focus apparatus100as disclosed herein is used for neutron generation. In this embodiment, the at least one working gas is one of deuterium gas, or a gas mixture of deuterium and argon. The ionization, plasma formation and plasma pinching within this embodiment of the plasma focus apparatus100will generate a beam of neutrons from the plasma discharge at the long axis250of the inner electrode150.

In an exemplary embodiment of the plasma focus apparatus100applied to produces neutron beams, the at least one outer electrode140is a single tubular electrode having an inner diameter of 11 mm, the inner electrode150is a concentric electrode rod having an outer diameter of 3.5 mm and a length of 20 mm. In this example, the at least one working gas is deuterium supplied at a pressure of 12 Torr. In this example, the power supply connected to the first collector plate provides a pulsed voltage with a 10 kV peak operating voltage to the pulsed power circuitry230. The resulting current is 58 kA with a current linear density 331 kA/(cm of anode radius) and the speed factor S=is 96 (kA/cm)Torr0.5. The resulting nuclear fusion neutron yield is 1.5×104neutrons per shot.

The above-described embodiments are intended to be examples of the present invention and alterations and modifications may be effected thereto, by those of skill in the art, without departing from the scope of the invention that is defined solely by the claims appended hereto.