Development of 200 kV multi-function pulsed radiation system

Abstract

<sec>A multi-functional pulsed radiation system with a peak voltage of 200 kV, an impedance of 2 Ω, and a full width at half maximum (FWHM) of 30 ns is developed. The system can be switched flexibly in two states of generating pulsed electron beam and pulsed X-ray by changing the cathode and anode. It consists of a pulse power driving source, a vacuum diode, and an experimental cavity. A Marx generator, a high energy storage water transmission line, and two pulse compression switches are utilized to generate a high voltage on diode. An effector can be placed in the experimental cavity which has the same vacuum as diode. An insulation structure of transmission line and a diode are optimized to guide in system design. The system can provide a multi-functional experimental platform for investigating pulse power technology, system-generated electromagnetic pulse, biological radiation effect, etc.</sec><sec> The Marx generator generates a high-voltage pulse with hundreds of nanoseconds in FWHM and hundreds of kilovolts in peak value. The pulse is compressed by the main switch and pulse forming switch and then loaded to the diode. Electrons are emitted from diode cathode under the high-voltage pulse and accelerated in the gap. The electrons are extracted directly or converted into X-ray through the anode. Aluminized polyethylene is used as an anode when pulsed electron beam is generated, and tantalum film is used when pulsed X-ray is generated. Working state can be switched by changing the cathode and anode of diode.</sec><sec> The result shows that a current of 83 kA pulsed electron beam and an average energy of 67 keV X-ray are generated. Pulsed X-ray has good uniformity and low electron proportion (0.02%). In order to monitor the operation state and output parameter of the system comprehensively, a complete measurement system is established. Three capacitive voltage dividers are set at the beginning of transmission line, the end of pulse forming line, and the end of output line, while a B - dot current monitor is set at the diode. A Faraday cup is developed to measure the current intensity and the total energy of pulsed electron beam. For energy spectrum, dose and electron proportion, the measurement system composed of pulsed X-ray including spectrometric system, dose system and Rogowski Coil is build.</sec>