Abstract: Devices, methods and techniques related to the suppression of electrical transients are disclosed. In one example aspect, an electrical transient protection device includes a sensor configured to monitor power transmission on a transmission line of a power system, a controller configured to generate a control signal in response to a detection of one or more electrical transients by the sensor, and a controller transient suppression unit comprising at least a switch that exhibits a changeable impedance. The controllable transient suppression unit configured to impose a load to the power system. The load has a substantially same impedance as a characteristic impedance associated with a part of the power system.

Abstract: Methods, devices and systems for ultra-high dose radiotherapy are described that rely in-part on active switching control of a photoconductive switch when the accelerator is accelerating charged particles to produce output radiation at desired dose rates. One example method for producing output radiation in a flash radiotherapy system includes receiving, at a particle accelerator, a charged particle beam, where the particle accelerator system also includes a photoconductive switch coupled to the particle accelerator. The photoconductive switch can operate in a linear mode and includes a doped crystalline material that receives a voltage to establish an electric field across the crystalline material.

Abstract: Methods, devices and systems for ultra-high dose radiotherapy are disclosed. The described techniques rely in-part on active switching control of a photoconductive switch during the time the accelerator is accelerating charged particles to produce the output radiation at the desired dose rates. One flash radiotherapy system includes an induction accelerator, and a controllable switch coupled to the induction accelerator. The switch is operable to produce a plurality of voltage pulses to drive the induction accelerator. The radiotherapy system also includes a radiation measurement device to measure output radiation produced by the radiotherapy system and provide feedback to the controllable switch. The controllable switch is operable to, based on the received feedback, modify an amplitude, shape, spacing, number or width of the voltage pulses that are supplied to the particle accelerator to deliver the desired output radiation.

Abstract: Methods, devices and systems for ultra-high dose radiotherapy are disclosed. The described techniques rely in-part on active switching control of a photoconductive switch during the time the accelerator is accelerating charged particles to produce the output radiation at the desired dose rates. One radiotherapy system includes a particle accelerator configured to receive charged particles from a pulsed source. The particle accelerator includes a pipe configured to allow the charged particles to pass through as a beam, a magnetic core positioned proximate to the pipe and coupled to the pulsed source, and at least one multilayer insulator positioned adjacent to the pipe and the magnetic core. The system also includes a photoconductive switch coupled to the particle accelerator and configured to supply the particle accelerator with a plurality of voltage pulses.

Abstract: Methods, devices and systems for ultra-high dose radiotherapy are disclosed. The described techniques rely in-part on active switching control of a photoconductive switch during the time the accelerator is accelerating charged particles to produce the output radiation at the desired dose rates. One flash radiotherapy system includes an induction accelerator, and a controllable switch coupled to the induction accelerator. The switch is operable to produce a plurality of voltage pulses to drive the induction accelerator. The radiotherapy system also includes a radiation measurement device to measure output radiation produced by the radiotherapy system and provide feedback to the controllable switch. The controllable switch is operable to, based on the received feedback, modify an amplitude, shape, spacing, number or width of the voltage pulses that are supplied to the particle accelerator to deliver the desired output radiation.

Abstract: Devices, methods and techniques are disclosed to interrupt a fault current in a high-voltage direct-current circuit. In one example aspect, a device includes a mechanical switch including a pair of contacts configured to be positioned apart upon activation of the circuit breaker, and a photoconductive component connected in parallel with the mechanical switch. The photoconductive component is configured to establish a current upon activation of the circuit breaker. The photoconductive component comprises a crystalline material positioned to receive a pulsed light signal from a laser light source, and a pair of electrodes coupled to the crystalline material and configured to allow an electric field to be established across the crystalline material to generate the current.

Abstract: A multi-stage electric voltage converter is disclosed. The converter comprises a voltage source and multiple stages. Each stage of the multiple stages comprises a first and a second and a third switch, and a capacitor, wherein the capacitor is coupled to the voltage source by the first and the second switches and each stage is coupled to a different stage or to an output of the multi-stage electric voltage converter by the third switch so as to allow the capacitor to be charged by the voltage source when the first and the second switches are closed and the third switch is open, and to allow the capacitor to be connected to the output of the multi-stage electric voltage converter when the first and the second switches are open and the third switch is closed.

Abstract: A photoconductive switch consisting of an optically actuated photoconductive material, e.g. a wide bandgap semiconductor such as SiC, situated between opposing electrodes. The electrodes are created using various methods in order to maximize reliability by reducing resistive heating, current concentrations and filamentation, and heating and ablation due to the light source. This is primarily accomplished by the configuration of the electrical contact geometry, choice of contacts metals, annealing, ion implantation, creation of recesses within the SiC, and the use of coatings to act as encapsulants and anti-reflective layers.

Abstract: A multi-stage electric voltage converter is disclosed. The converter comprises a voltage source and multiple stages. Each stage of the multiple stages comprises a first and a second and a third switch, and a capacitor, wherein the capacitor is coupled to the voltage source by the first and the second switches and each stage is coupled to a different stage or to an output of the multi-stage electric voltage converter by the third switch so as to allow the capacitor to be charged by the voltage source when the first and the second switches are closed and the third switch is open, and to allow the capacitor to be connected to the output of the multi-stage electric voltage converter when the first and the second switches are open and the third switch is closed.

Abstract: A photoconductive switch consisting of an optically actuated photoconductive material, e.g. a wide bandgap semiconductor such as SiC, situated between opposing electrodes. The electrodes are created using various methods in order to maximize reliability by reducing resistive heating, current concentrations and filamentation, and heating and ablation due to the light source. This is primarily accomplished by the configuration of the electrical contact geometry, choice of contacts metals, annealing, ion implantation, creation of recesses within the SiC, and the use of coatings to act as encapsulants and anti-reflective layers.

Abstract: Apparatus, systems, and methods that provide an X-ray interrogation system having a plurality of stationary X-ray point sources arranged to substantially encircle an area or space to be interrogated. A plurality of stationary detectors are arranged to substantially encircle the area or space to be interrogated, A controller is adapted to control the stationary X-ray point sources to emit X-rays one at a time, and to control the stationary detectors to detect the X-rays emitted by the stationary X-ray point sources.

Abstract: A photoconductive switch and optical transconductance varistor having a photoconductive region e.g. a wide bandgap semiconductor material substrate between opposing electrodes. An optical waveguide is arranged to surround the photoconductive region for directing conduction-inducing radiation into the photoconductive region. And an optical diffusion element is arranged to diffuse/disperse the radiation prior to entering the optical waveguide and into the substrate, for uniformly illuminating the substrate for conduction.

Abstract: Apparatus, systems, and methods that provide an X-ray interrogation system having a plurality of stationary X-ray point sources arranged to substantially encircle an area or space to be interrogated. A plurality of stationary detectors are arranged to substantially encircle the area or space to be interrogated, A controller is adapted to control the stationary X-ray point sources to emit X-rays one at a time, and to control the stationary detectors to detect the X-rays emitted by the stationary X-ray point sources.

Abstract: In a structure or device having a pair of electrical conductors separated by an insulator across which a voltage is placed, resistive layers are formed around the conductors to force the electric potential within the insulator to distribute more uniformly so as to decrease or eliminate electric field enhancement at the conductor edges. This is done by utilizing the properties of resistive layers to allow the voltage on the electrode to diffuse outwards, reducing the field stress at the conductor edge. Preferably, the resistive layer has a tapered resistivity, with a lower resistivity adjacent to the conductor and a higher resistivity away from the conductor. Generally, a resistive path across the insulator is provided, preferably by providing a resistive region in the bulk of the insulator, with the resistive layer extending over the resistive region.

Abstract: A photo-conductive switch package module having a photo-conductive substrate or wafer with opposing electrode-interface surfaces, and at least one light-input surface. First metallic layers are formed on the electrode-interface surfaces, and one or more optical waveguides having input and output ends are bonded to the substrate so that the output end of each waveguide is bonded to a corresponding one of the light-input surfaces of the photo-conductive substrate. This forms a waveguide-substrate interface for coupling light into the photo-conductive wafer. A dielectric material such as epoxy is then used to encapsulate the photo-conductive substrate and optical waveguide so that only the metallic layers and the input end of the optical waveguide are exposed. Second metallic layers are then formed on the first metallic layers so that the waveguide-substrate interface is positioned under the second metallic layers.

Abstract: A system and method for producing modulated electrical signals. The system uses a variable resistor having a photoconductive wide bandgap semiconductor material construction whose conduction response to changes in amplitude of incident radiation is substantially linear throughout a non-saturation region to enable operation in non-avalanche mode. The system also includes a modulated radiation source, such as a modulated laser, for producing amplitude-modulated radiation with which to direct upon the variable resistor and modulate its conduction response. A voltage source and an output port, are both operably connected to the variable resistor so that an electrical signal may be produced at the output port by way of the variable resistor, either generated by activation of the variable resistor or propagating through the variable resistor. In this manner, the electrical signal is modulated by the variable resistor so as to have a waveform substantially similar to the amplitude-modulated radiation.

Abstract: An improved photoconductive switch having a SIC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

Abstract: An improved photoconductive switch having a SIC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

Abstract: An improved photoconductive switch having a SiC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

Abstract: A compact accelerator system having an integrated particle generator-linear accelerator with a compact, small-scale construction capable of producing an energetic (˜70-250 MeV) proton beam or other nuclei and transporting the beam direction to a medical therapy patient without the need for bending magnets or other hardware often required for remote beam transport. The integrated particle generator-accelerator is actuable as a unitary body on a support structure to enable scanning of a particle beam by direction actuation of the particle generator-accelerator.