Abstract: A high voltage power supply having energy storage, charging and switching elements and using an interruptible switch as the switching element for efficient, compact and safe operation. In a specific embodiment, the interruptible switch is implemented with at least one cold cathode grid-controlled, crossed field plasma switch and associated control circuit. The charging element is a Marx bank which can be capacitive or inductive. Embodiments with a single master-slave control arrangement, a pulse-forming network providing high voltage regulation, an inductive implementation with a plurality of switching elements in a single envelope with the cathode of at least one switching element being the anode of the next switching element are disclosed. A current amplifier and voltage regulator implemented with a cold cathode grid-controlled, crossed field plasma switch having a cathode, an anode and a control grid therebetween are disclosed.

Abstract: A method is disclosed of employing free electron lasing action at a first frequency to achieve gain in output power at a second frequency. In a broadest sense, an electron beam is driven with an electromagnetic wave at said first frequency in a first stage, having a first spatial period, to cause bunching of the electron beam. The electrons in the beam are oscillated with a second stage, having a second spatial period, to generate electromagnetic wave power from said beam at the second frequency.In a specific embodiment, the second frequency is near a harmonic of said first frequency. And in a particular implementation, the first stage is provided by a free electron laser having a first wiggler with a first spatial period, the second stage is a second wiggler having a second spatial period and a drift region is disposed between the first and second stages.

Abstract: A high voltage stable pulse power supply 10 which includes a first power supply 11, ; a first capacitor 12 ; connected in parallel with the first power supply, a first switch 13 mounted in parallel with the first capacitor 12. The switch 13 selectively connects the first capacitor 12 to a load 14 so that the first capacitor 12 may discharge therethrough. An anti-droop network 15 is connected in series with the first capacitor 12. The anti-droop network 15 cancels droop in the output of the first capacitor 12 as it discharges into the load 14.In a specific embodiment, the anti-droop network 15 includes an inductive element 42 connected in series with the first capacitor 12 which is charged just prior to the activation of the first switch 13. The inductor 42 provides energy to compensate for the droop in the energy supplied by the first capacitor 12.

Abstract: An FEL array is comprised of adjacent FEL modules. Each module preferably uses a ribbon beam plasma-anode E-gun (PAG) or another plasma-assisted E-gun to produce a planar E-beam that interacts with a planar wiggler magnetic field. The modules may share a common electron gun. A control signal is input through a phase priming array to preselect the radiation mode. A planar, distributed Bragg resonator/reflector is used to set up a high-Q cavity, enabling the low gain module to produce high power radiation. The FEL modules are arranged in an array to reduce the output radiation flux density while achieving high output power density in the far-field, and to permit beam steering by phase control of individual modules. The relatively low current density of the individual E-guns lessens the size of the guiding magnetic field in each module to the extent that the wiggler magnetic field alone is sufficient to perform this guiding function.

Abstract: A free electron laser (FEL) is disclosed in which the phase of the output electromagnetic beam is inherently adjustable without the use of any extraneous optical phase shifting materials. This is accomplished by implementing the FEL as a pair of series-connected wiggler cavity sections, and varying the relative phases of the bunched electron flow in the first cavity section relative to the second. In a preferred embodiment a series of electrodes are provided in a transition region between the two cavity sections, and variable voltages are applied to the electrodes to electrostatically control the electron transit time through the transition region, and the electron velocity upon exiting from that region. This translates into a control over phase and frequency.

Abstract: A method of optimizing the design of waveguide reflector surfaces for high-Q cavities. The method assumes ideal conducting surfaces and proceeds from simple planar waveguide systems which are compatible with resonant standing waves to the development of the allowable surfaces which are necessary to contain the standing waves in a finite system. Apparatus constructed in accordance with the method achieves a Q in excess of 10,000.

Abstract: A plasma-anode electron gun includes a cathode means of a material such as molybdenum having a relatively high ratio of emission of secondary electrons to impinging helium ions. A hollow annular anode structure (16) contains an ionized plasma, and has a central opening (38) through which the electron beam (36) is directed, when ions from the anode are released to impinge upon the cathode (12). The anode and ion source structure may be grounded, and ions are released through openings facing the cathode when a positive trigger pulse is applied to one or more electrodes extending within the plasma. The cathode is preferably operated at a voltage in the order of thirty to two hundred thousand volts negative with respect to the cathode. Leakage of ions from the hollow anode may be inhibited by the provision of a supplemental grid biased to a low positive potential.

Abstract: A blazed corrugated reflector having internal corrugations or vanes, blazed at specified design angles, coherently reflects power at specified wavelengths. The corrugations meet the criteria of effecting retroreflection according to the Bragg conditions for gratings, eliminating higher order modes of reflection, and maximizing retroreflection and minimizing forward scattering according to the blaze condition. Two such reflectors can be configured into a laser resonator by placing them at opposing ends of a matching waveguide. The reflector does not obstruct the passage of an axial electron beam, thereby making it suitable to implement the resonator portion of a free electron laser.

Abstract: An electron beam controlled switch employing a radial geometry and a Wire-Ion Plasma-Electron gun (WIP E-gun) as an electron source is disclosed. The switch comprises an inner cylinder that serves as the WIP E-gun cathode, a cylindrical grid that serves as the WIP E-gun anode, an array of fine wire anodes disposed in the WIP E-gun ionization chamber, a foil support cylinder to support the foil windows which also serve as the switch anode, and an outer cylinder which also serves as the switch cathode. The WIP E-gun and ionization chamber is gas filled at low pressure, while the switch cavity is filled with a high pressure gas. A voltage pulse is applied to the wire anodes to ionize the gas in the ionization chamber. The ions are extracted through the chamber grid and accelerated through a high voltage to bombard the E-gun cathode.

Abstract: An improved Wire-Ion-Plasma Electron-gun (WIP E-gun) is disclosed, having a very rapid electron beam current interruption capability. An auxiliary grid is employed to provide a potential barrier to the reservoir of plasma ions in the ionization chamber, thereby containing these ions in the chamber after the wire anode is turned "OFF". The E-gun current fall time is reduced to the time required for the plasma potential to fall in the ionization chamber after the wire anode is turned "OFF". The WIP E-gun current fall time is reduced, from greater than fifteen microseconds for devices not employing the invention, to less than two microseconds.

Abstract: A cold-cathode, plasma discharge modulator switch is disclosed. A crossed-field discharge plasma supplied charge carriers for the switch. A dc magnetic field is employed to provide a highly localized cusp magnetic field near the cathode, so that gas ionization occurs primarily in the cathode-source grid gap. The region between the cathode and anode is filled with a relatively low pressure gas. A highly transparent control grid with small apertures is closely spaced from the anode. The switch is closed through application of positive potential (relative to the plasma) to the control grid, and opened through application of negative potential relative to the plasma to the control grid. The application of negative potential to the control grid creates an ion sheath around the control grid which permits plasma cut-off to the anode region provided the sheath size is larger than the control grid aperture radius.

Abstract: Crossed-field plasma mode electric conduction control device 10 has an interelectrode space 16 between anode 12 and cathode 14 in which is produced a magnetic field 38 by coil 28. Electrons produced at region 46 travel through the crossed-fields to region 48, with cascading ionization to produce an electrically conductive plasma. The electrons are lost at region 48 and plasma density is controlled by magnetic field strength to control magnitude of interelectrode current.

Abstract: Bipolar crossed-field device 10 has outer electrode 12 and inner electrode 18 which define interelectrode space 16. Magnetic field coils 46, 48 operate together to form a magnetic field in the interelectrode space 16 shaped to trap electrons for cascading ionization and plasma formation when viewed from either electrode.

Abstract: A cross-field discharge plasma is used to supply charge carriers for a grid controlled cold cathode discharge device. A dc magnetic field is employed to sustain the crossed-field discharge when the source grid is active. The device comprises an anode, a cathode, a source grid, and in alternate embodiments, additional control grids. Preferably the magnetic field exists only in the source grid-cathode space and penetrates only weakly, or not at all, into other electrode gaps or spaces. The source grid-cathode plasma is effectively a source of charge carriers, electrons or ions, controlled by the source grid current, the anode current being an approximate linear function of source grid current within limits, and/or controllable by adjustment of control grid potentials.

Abstract: A crossed-field switch device is connected in parallel to a load device which may arc. The characteristics of the crossed-field switch device are that it will not conduct when a high voltage is applied, but when the load device arcs, the crossed-field switch device conducts, taking current from the arc so that the arc quenches. The crossed-field switch device thus is a crowbar which is automatically conductive when the applied voltage decreases due to a line or load short.

Abstract: Crossed-field switch device has a continuous elongated closed path active plasma discharge region between adjacent electrodes. A magnet produces a magnetic field at an angle to the electric field to define the elongated active region in the interelectrode space where glow mode discharge occurs. The electrodes and magnetic field are shaped so that the glow mode discharge in the active region is elongated.

Abstract: An auxiliary magnetic field coil is associated with the interelectrode space of a crossed-field switch device for ignition of the crossed-field switch device when high voltage is applied across the interelectrode space. The auxiliary magnetic field coil produces a localized field in which physical conditions cause conduction in the glow mode. Once conduction is started, the interelectrode voltage falls and with the main magnetic field applied to the entire effective interelectrode space, normal glow mode conduction takes place.

Abstract: For off-switching, the magnetic field in a crossed-field switch device is modified by a localized auxiliary field to terminate the previously continuous closed electron path in the interelectrode space to terminate cascading ionization. The auxiliary field and its source can be much smaller in scope than the main field so that off-switching is quickly achieved.

Abstract: Three electrodes define two gaps in the crossed-field tube so that while one gap is holding off high voltage the other can be ignited to turn the tube on with high voltage applied. The three electrodes act as anode, cathode and control electrodes and define the main and ignition gaps. The intermediate electrode is gridded and the control electrode is connected to one of the other electrodes through an impedance to prevent hollow cathode discharge.

Abstract: Plasma chamber maintained ionized by thin wire discharge continuously supplies ionized plasma into the interelectrode space of a low pressure gas discharge device such as a crossed-field switch tube to eliminate dependence on statistical electrons for initiation of discharge.