Abstract: An electron acceleration system includes a first RF cavity, and a second RF cavity whose center is located at a distance not more than 1.5 inch from the center of the first RF cavity, along an axis. The first RF cavity has a length less than about 0.25 inches. The on-axis coupling between the first and second RF cavities along the axis, which is primarily electric, is cancelled out by an off-axis coupling between the RF cavities off the axis, which is primarily magnetic. In this way, the net RF coupling between the RF cavities is zero. The phase and amplitude of the first and second RF cavities are each independently adjustable.

Abstract: A system comprises: an RF cavity; a main emitter; a floating grid configured to capture a portion of the electron current emitted by the main emitter; and a discharging emitter in electrical contact with the floating grid and configured to discharge the floating grid. The floating grid and the discharging emitter are electrically insulated from the main emitter and from the RF cavity, when the RF cavity is not in operation. The DC bias of the floating grid is adjusted so that the ending emission phase of the electron beam from the floating grid occurs earlier than the starting phase of back-bombardment of the electrons in the RF cavity, thereby suppressing the back-bombardment of the electrons. A floating grid can be also placed between the RF drive grid and the cathode in an IOT, thereby suppressing arcing of the cathode in the IOT.

Abstract: A photocathode enhancement system includes a cathode plate that is movably positioned relative to an incident optical beam. The emission surface of the cathode plate has an area between about 0.5 cm2 to greater than 100 cm2. The system includes a motion controller that is configured to control the movement of the cathode plate relative to the optical beam, so that the optical beam successively strikes non-overlapping portions of the emission surface, and may reach substantially the entire emission surface over a time period of about 10 seconds to about 100 seconds. The movement of the cathode plate is controlled so that on average, the heat from the optical beam is uniformly distributed over the emission surface of the cathode plate.

Abstract: A photocathode system includes a plurality of photocathodes, and at least one combining device. The photocathodes have individually adjustable voltages, and each photocathode generates an individual electron bunch at an emission period. The combining device combines the individual electron bunches, generated at each emission period, into a combined bunch along a combined axis. The timing of the individual electron bunches is independently adjustable, so that an electron bunch with a lower energy arrives at the combined axis earlier in time compared to another electron bunch with a higher energy, thereby allowing the combined beam of electron bunches to be longitudinally compressed. The photocathodes may be distributed along a 1D column, or a 2D array, or a 3D array, or any arbitrary configuration. A linac is located near a longitudinal focusing point to boost beam energy and therefore freeze bunch length and emittance.

Abstract: A photocathode system includes a plurality of photocathodes, and at least one combining device. The photocathodes have individually adjustable voltages, and each photocathode generates an individual electron bunch at an emission period. The combining device combines the individual electron bunches, generated at each emission period, into a combined bunch along a combined axis. The timing of the individual electron bunches is independently adjustable, so that an electron bunch with a lower energy arrives at the combined axis earlier in time compared to another electron bunch with a higher energy, thereby allowing the combined beam of electron bunches to be longitudinally compressed. The photocathodes may be distributed along a 1D column, or a 2D array, or a 3D array, or any arbitrary configuration. A linac is located near a longitudinal focusing point to boost beam energy and therefore freeze bunch length and emittance.

Abstract: A photocathode enhancement system includes a cathode plate that is movably positioned relative to an incident optical beam. The emission surface of the cathode plate has an area between about 0.5 cm2 to greater than 100 cm2. The system includes a motion controller that is configured to control the movement of the cathode plate relative to the optical beam, so that the optical beam successively strikes non-overlapping portions of the emission surface, and may reach substantially the entire emission surface over a time period of about 10 seconds to about 100 seconds. The movement of the cathode plate is controlled so that on average, the heat from the optical beam is uniformly distributed over the emission surface of the cathode plate.

Abstract: A rapidly tunable RF cavity includes a cavity body, and at least one ferroelectric element disposed within a hollow interior region of the cavity body. A biasing system provides a nominal DC electric field bias across the ferroelectric element so as to induce a rapid change in dielectric permittivity of the ferroelectric element, and a corresponding change in resonant frequency of the RF cavity. A change in dielectric permittivity of up to about 20% can be induced within a response time of less than 10 nanoseconds, with a biasing field strength of less than 50 kV. In some embodiments, the ferroelectric element is made of BST (barium-strontium titanate). The ferroelectric element may be cylindrically shaped, and coaxial with the cavity body. The biasing system may include one or more copper cylinders supported by supporting rods.

Abstract: A solid mixture of fullerene and titanium hydride, a method of its formation, and a method of its use to rapidly produce a gaseous mixture of molecular hydrogen and fullerene on demand. The solid mixture may be resistively heated by discharge of a high power electrical current from a capacitor bank through the mixture to produce the mixture of hydrogen and fullerene within a few tens of microseconds. The resulting gaseous mixture of hydrogen and fullerene may be ionized and accelerated for the purpose of mitigating electromagnetic disruptions in a magnetically confined plasma.

Abstract: A pair of cavities defined within a hollow elongate accelerator body include a first resonant cavity having a first resonant slot through an outer wall thereof, and a second resonant cavity having a second resonant slot through an outer wall thereof. The first resonant slot and the second resonant slot are separated by a void region that extends between the outer wall of the first cavity and the outer wall of the second cavity and is bounded in part by an inner surface of the hollow elongate member. The first and second cavities are coupled to each other through a dual slot coupling structure that includes the first resonant slot, the void region, and the second resonant slot.

Abstract: A slot resonance coupled, linear standing wave particle accelerator. The accelerator includes a series of resonant accelerator cavities positioned along a beam line, which are connected by resonant azimuthal slots formed in interior walls separating adjacent cavities. At least some of the slots are resonant at a frequency comparable to the resonant frequency of the cavities. The resonant slots are offset from the axis of the accelerator and have a major dimension extending in a direction transverse to the radial direction with respect to the accelerator axis. The off-axis resonant slots function to magnetically couple adjacent cavities of the accelerator while also advancing the phase difference between the standing wave in adjacent cavities by 180 degrees in addition to the 180 degree phase difference resulting from coupling of the standing wave in each cavity with the adjacent slot, such that the signals in each cavity are in phase with one another and each cavity functions as a live accelerating cavity.

Abstract: A method and apparatus for producing soft x-ray laser radiation. A low pressure plasma column is created by electric discharge or by laser excitation inside a rotating containment tube. Rotation of the plasma is induced by viscous drag caused by rotation of the tube, or by magnetically driven rotation of the plasma as it is created in a plasma gun in the presence of an axial magnetic field, or both. A high power electrical discharge is then passed axially through the rotating plasma column to produce a rapidly rising axial current, resulting in z-pinch compression of the rotating plasma column, with resultant stimulated emission of soft x-ray radiation in the axial direction. A rotating containment tube used in combination with magnetically driven rotation of the plasma column results in a concave electron density profile that results in reduced wall ablation and also reduced refraction losses of the soft x-rays.

Abstract: Disclosed is a diagnostic resonant cavity for determining characteristics of a charged particle beam, such as an electron beam, produced in a charged particle accelerator. The cavity is based on resonant quadrupole-mode and higher order cavities. Enhanced shunt impedance in such cavities is obtained by the incorporation of a set of four or more electrically conductive rods extending inwardly from either one or both of the end walls of the cavity, so as to form capacitive gaps near the outer radius of the beam tube. For typical diagnostic cavity applications, a five-fold increase in shunt impedance can be obtained. In alternative embodiments the cavity may include either four or more opposing pairs of rods which extend coaxially toward one another from the opposite end walls of the cavity and are spaced from one another to form capacitative gaps; or the cavity may include a single set of individual rods that extend from one end wall to a point adjacent the opposing end wall.