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This article describes a modification and an experiment conducted on a solid-state pulsed power modulator (SSPPM) for medical linear particle accelerator (LINAC) applications. Depending on the operating condition of the magnetron, an existing design of an insulated-gate bipolar transistor (IGBT)-based modulator is modified, from a positive pulse generator to a negative pulse generator. The design of the gate driver circuit of the pulse discharging IGBTs is also slightly changed to secure reliability against the arc condition. The developed modulator has the following maximum output—pulse voltage of −40 kV, pulse current of −100 A, pulsewidth of 5 μs, and pulse repetition rate of 250 Hz. By adapting the proposed design to the pulsed power modulator for driving the magnetron, high peak and average power densities of 43 kW/L and 48.9 W/L, respectively, can be achieved. The experimental results from various tests conducted using a resistor load, including a rated operation and an arc protection, verify the robustness and utility of the developed SSPPM for medical LINAC applications. An experiment using a 9.3-GHz 1.7-MW X-band magnetron is also conducted. The developed modulator achieved a successful arc protection operation for the arc generated in the waveguide during the magnetron drive test. [ABSTRACT FROM AUTHOR]

This paper proposes a solid-state pulsed power modulator (PPM) with fast rising/falling time and high repetition rates to drive pockels cells. Since the proposed circuit is based on the modular structure using silicon carbide (SiC) metal–oxide silicon field-effect transistors (MOSFETs) for bypass devices as well as for main switches, it can achieve fast switching speed and high reliability. In addition, by a control scheme employing the voltage difference, the proposed circuit can accomplish a high repetition rate and short pulsewidth. Design and implementation of 1.8-kV PPMs with repetition rate of 1 MHz and rising/falling time below 6 ns are presented. Also, important issues for the practical use of the SiC-based PPM are discussed. Experimental results from the developed PPMs are shown to verify the proposed works. [ABSTRACT FROM AUTHOR]

This paper describes the circuit of a capacitor charger for a solid-state Marx modulator. A high-efficiency LCC resonant inverter is proposed for the simultaneous charging of many capacitors in parallel using a multistage transformer and rectifier. Using a high-voltage insulation cable, the charging loop, which represents the primary winding of transformer, is implemented to transfer the power from the resonant inverter to each stage. In addition to the simultaneous charging of separate capacitors, the advantages of the proposed circuit and structure include compact design and reliable insulation performance against high-voltage pulses. Based on the relevant approximation, the simplified analysis of an LCC resonant converter with a trapezoidal shape of resonant current is provided and a 50-kW high-voltage capacitor charger is designed for a 40-kV solid-state Marx modulator. The power stage, which consists of a transformer with four voltage-doubled rectifiers, is designed, and six power stages are configured for generating a pulse output of 40 kV. The detailed implementation of the multistage transformer and rectifier is presented in accordance with the design requirements of a high voltage modulator. Finally, the developed charger achieves 96% of the maximum efficiency and 0.96 of the maximum power factor. The experimental results verify that the proposed circuit and structure can be effectively used for a solid-state Marx modulator. [ABSTRACT FROM PUBLISHER]

This study presents a simplified design for a solid state pulsed power modulator (SSPPM) based on a power cell structure. Similar to the Marx generator, the power cell structure has advantages such as reliability and modularity. In addition, the proposed SSPPM includes a capacitor charger that is simple and compact. The operating principle of, and the design considerations taken for, the SSPPM are discussed from a practical viewpoint. Based on a reasonable approximation, simplified design equations are developed for a capacitor charger and a high-voltage pulse-switching part, which are comprised of an LCC resonant converter and a power stage, respectively. Accordingly, detailed design procedures are proposed to develop the SSPPM with the following specifications: 40 kV, 20 A, 300 μs, 200 Hz, and 50 kW. The experimental results verify the specifications at the rated operating condition with an efficiency of 92.4%, and also confirm reliable arc-protection performance. Finally, the proposed design methodology, which utilizes simplified equations, can be used for designing an SSPPM based on the power cell structure for extensive applications. [ABSTRACT FROM PUBLISHER]

This paper proposes a new gate driving circuit for the solid-state pulsed power modulator (SSPPM) based on semiconductor devices. The proposed circuit can be easily implemented by applying a short gate signal to the bypass insulated gate bipolar transistor (IGBT), i.e., switches connected in parallel with the load instead of a pull-down resistor. The IGBT_BPs are turned on at the end-point of the pulse. It can quickly discharge the pulse voltage applied to the load. In addition, it can operate as bypass diode, which is used to protect the semiconductor switches when the gate signal malfunctions, by using the antiparallel diode of the IGBT. Moreover, power loss in the pull-down resistor used to achieve fast falling pulses can be eliminated by turning off the IGBT while applying the pulse state. Thus, the proposed circuit can be used for implementing SSPPM with small values of falling time and high efficiency. The circuit configuration, operational principle, relevant analysis results, and a PSpice modeling are presented and verified by the 10-kV SSPPM. [ABSTRACT FROM PUBLISHER]