United States of America as Represented by the Secretary of the Air Force

USA as Represented by Secretary of the Navy

Other

R & D Associates

Peter J Turchi

Ihor M Vitkovitsky

James H Degnan

Daniel J Jenkins

A novel arrangement that combines in a single compact embodiment a plasma flow switch source of ultrahigh speed plasma and an electromagnetically-imploded cylindrical shell. The shell, known as a liner, forms the wall of a cavity that receives and stagnates the plasma flow. The plasma and the liner are connected electrically in series so that a single multi-megampere current serves both elements and operates from the same power source and switch. The operation is timed so that the plasma is injected into the cavity once the liner has attained sufficient implosion speed. The liner then continues to implode, reducing the cavity volume and compressing the plasma further to very high temperatures and densities, thereby creating a compact, intense pulsed neutron source generated by thermonuclear reactions in the compressed plasma. Such a neutron source has application for neutralizing bio/chemical warfare agents, radiography, and material processing.

Combined plasma source and liner implosion system

For several years, there has been interest in obtaining fast-rising, high-voltage pulses to drive particle-beam diodes and antennas in mobile situations. The Magnetic Voltage-Pulser (MVP) is a new device to satisfy this interest. The regime of operation of the basic unit comprises--output voltage=0.2 to 1.0 MV, pulse duration=1 microsec, and load impedance=1 to 10 ohms. For higher voltage and higher impedance needs, a plurality of pulsers can be used in a series-parallel arrangement. Typical dimensions for the basic pulser are: length=20 cm, and diameter=15 cm. The weight of the system will vary with the details of the technical approach selected for each application. Also, the basic arrangement can be used for single-shot or repetitive operation by selecting options in the technical details. The repetition rate can exceed 10 kHz. Typical applications include high-power microwave and other electronic warfare devices.

Magnetic voltage-pulser

A compact source of intense radiation includes: a multi-element, disc-style, explosive magnetic flux compression generator, switching, peaking-stage generator, plasma flow switch, and a dense-plasma-focus type, pulsed neutron source. The main explosive generator receives initial amounts of magnetic flux and energy from a smaller explosive generator. Explosive action drives the conductors of the main generator together, reducing the inductance and thereby increasing both the current and magnetic energy. A switch closes to connect the peaking-stage generator and plasma flow switch in series with the main generator (and in parallel with the ballast inductor). As the current rises in the plasma flow switch, its plasma armature is electromagnetically-accelerated axially along coaxial electrodes, attaining speeds above 60-70 km/s. Meanwhile, explosive action on the peaking-stage generator provides additional magnetic flux compression. The arrangement makes use of the moderating influence of hydrogen-bearing products (from the explosive generators), that remain between the neutron source and the target during the neutron burst. The entire combination of explosive, electrical, plasmadynamic and neutronic action is designed to provide a compact source of intense electromagnetic radiation for accelerated protection against chemical and environmental weapons.

Compact intense radiation system

The Plasma-Gun Voltage-Generator (PVG) uses a pulsed plasma-flow to displace magnetic flux, thereby inducing high voltages across multi-turn coils. Typical operating parameters are voltages of 0.5 to 1 MV, pulsetimes in the microsecond regime and output impedances in the few Ohm range. The use of capacitor-bank sources to drive the plasma-gun discharge permits repetitive operation of the PVG at rates of several kHz. The PVG includes 1) a coaxial plasma-gun that serves as a source high speed, electrically-conducting plasma; 2) a source of axial magnetic field; and 3) a multi-turn coil or set of multi-turn coils that will experience an induced voltage when plasma flow displaces magnetic flux from the region interior to the coil(s). The magnetic flux source and the multi-turn coil(s) are placed near the end of the coaxial gun to receive the high speed plasma flow. The coaxial plasma-gun provides an axisymmetric discharge between coaxial electrodes. Interaction of the discharge current with its azimuthal magnetic field accelerates plasma axially downstream (after an initiation phase that may involve an inverse-pinch discharge). Axial plasma flow at speeds of 50-100 km/s is sufficient to displace magnetic flux at the end of the gun. Such displacement past the multi-turn coil induces high voltages between the ends of the coil(s). These voltages can then be used to drive a high impedance load, such as an electron-beam diode.

Plasma-gun voltage generator

A first magnetic flux field is produced in the vicinity of a generally cylindrical pulse generating coil arrangement and a plasma is abruptly and radially displaced outwardly toward the coil arrangement, which in turn displaces the first magnetic flux field to a sufficient degree to enable it to cut across the output coil to generate an output pulse. Displacement of the plasma is effected by producing a second magnetic field transverse to the direction of the first magnetic field and to the direction of current within the plasma by means of a longitudinal, centrally positioned conductor coupled to a source of electrical power.

Inverse-pinch voltage pulse generator

A diode pulser is described which comprises a diode and an inductor connected in series, the impedance of the diode being controllable to suddenly increase the impedance to produce a high voltage pulse across the diode. The diode can include a pair of spaced electrodes (12, 14 in FIG. 2) forming a gap between them across which electrons move when a voltage is applied. To increase the impedance, a magnetic field (38) is suddenly applied parallel to the electrode surfaces, to bend the electron paths so as to require a much higher voltage to move the electrons across the gap, the inductor (26) creating such voltage to maintain the current flow for a brief time. The diode pulser is useful as a rapid-acting switch, and as a source of high energy electrons that are useful to generate X-rays, microwaves, and for other purposes.

Magnetically operated pulser

A diode pulser is described which comprises a diode and an inductor connected in series, the impedance of the diode being controllable to suddenly increase the impedance to produce a high voltage pulse across the diode. The diode includes concentric electrodes forming a gap between them across which electrons move. To increase the impedance, a magnetic field is suddenly applied parallel to the electrode surfaces, to bend the electron paths so as to require a much higher voltage to move the electrons across the gap, the inductor creating such voltage to maintain the current flow for a brief time. The diode pulser is useful as a rapid-acting switch, and as a source of high energy electrons that are useful to generate X-rays, microwaves, and for other purposes.

Magnetically energized pulser

A power circuit utilizing a switch comprised of Hall-effect-active resistive elements for interrupting a current flow in an inductive energy storage system. Interruption of the flow of current causes a high-voltage pulse which drives the current flow into a circuit leg which is parallel to the interrupting elements. The Hall effect switch is controlled by means of an exciter coil that is connected in parallel with the Hall-effect-active resistive elements to provide self excited operation.

Power circuit utilizing self-excited Hall effect switch means

An MPD intense beam pulser for generating high voltage, intense charged picle beams utilizing an electromechanical energy source and inductive energy storage in combination with a plasma opening switch including a source of directed plasma flow, a diode for accelerating particles in the plasma flowing from the source, and a plasma flow truncation circuit. In operation, a controlled plasma flow is used to conduct current from the energy source in order to supply a desired amount of energy to the magnetic field in the volume surrounding the plasma flow. Truncation of the plasma flow between the electrodes forming the diode then provides a high voltage in a short pulse which generates a high energy charged particle beam. Thus, the magnetic energy store surrounding the diode plasma flow is coupled directly to the intense particle beam.

MPD Intense beam pulser

Power circuit utilizing self excited Hall effect switch means

An inductive intense beam source utilizing a plurality of fuses (or a cylrical foil) surrounding a plasma column. The fuses (or foil) carry a current and thus establish an inductive energy storage volume therearound which is segregated from the plasma column. When the fuses or foil are vaporized, the energy stored therearound is converted to kinetic energy in the form of an accelorated particle beam.

Inductive intense beam source

A magnetoplasmadynamic switch adapted to be coupled in parallel with an ictive energy storage circuit carrying current through an initially closed circuit interrupter. The switch includes an electrode spaced by a gap from an arcjet source which is triggered by a capacitor. The capacitor is connected to the arcjet source by a closing switch so that a plasma jet is created between the source and the electrode. The voltage on the capacitor is chosen such that the arcjet source current will equal the current in the energy storage circuit at the time when the circuit interrupter has completely opened. The circuit interrupter is opened after the plasma jet is established between the source and the electrode, and the energy storage circuit current is conducted by the magnetoplasmadynamic switch until the dielectric strength of the circuit interrupter reaches a satisfactory level. Another switch is then closed providing a low impedance conduction path parallel to the arcjet source current. The arc current decays with a time constant equal to the arcjet source inductance divided by its resistance (typically several microseconds). The decay of arc current disrupts the magnetoplasmadynamic force balance, cutting off the plasma jet. Plasma already in the gap, however, continues to leave at high speed reducing the density of conducting material below that needed for high conductivity, thereby opening the switch on the timescale of gap distance divided by plasma jet speed. The current from the inductive energy storage circuit is then diverted into a parallel circuit including an inductive load.

Magnetoplasmadynamic switch

A payload (e.g., a plasma, gas, magnetic field) having an initial energy density is confined within an implosion chamber which also contains a rotating liquid liner having an approximately cylindrical inner surface due to the rotational forces. An annular piston, disposed in the implosion chamber, is free to move parallel to the axis of rotation and has a surface in contact with a portion of the rotating liner. Motion of the piston against the liner (due to a pulsed external driving means) causes the inner surface of the liner to implode radially in said implosion chamber, thereby compressing the initial energy density to a higher energy density. The inner surface of the liner remains stable throughout compression due to the rotation of the liner. The other surfaces of the liner are stabilized by contact with the implosion chamber or the piston. After peak compression, the inner surface of the liner is forced (by the high energy density confined within the liner) radially outward toward its initial position, thereby driving the annular piston toward its initial position and returning energy to the external driving means. An embodiment using a plurality of annular pistons to provide an implosion chamber of arbitrary length is also disclosed.

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Alexandria, VA, United States of America

Peter J Turchi