Improvement of Radiation Area and Lifetime of “Chenguang” Accelerator Diode

The “Chenguang” high-current pulsed electron beam accelerator is one of the earliest and most valuable pulsed power devices in China. At the meantime, tasks of the accelerator are becoming increasingly diverse, and the experiment time is running out. Based on a TaAl stacked target and weaklypinched design, a longlife radiation diode with a high level of engineering stability and a low maintenance workloadwas designed and employed under 0.902.00 MV and 3545 kA to expand the accelerator's experimental use. The diode operates from 20 Ω to 30 Ω, with an adjustable AK gap of 2050 mm, and was equipped with measurement interfaces for voltage, current, and optical windows. The longlife weaklypinched diode was developed through calibration law calculations, particleincell simulations, Monte Carlo simulations and experimental tests, successfully achieving the goal of improving both the radiation area and lifetime of the accelerator diode. When compared with the original diode, the radiation field shifted from concentrating to forward. Under the condition that the peak dose rate order (108 rad/s) remains constant, the radiation area is increased from 10 cm2 to 80 cm2, and the number of continuous shots without replacing the target is increased from 24 to 70. With this configuration, the “Chenguang” could shoot repetitively at the rate of one shot every 30 min, and the experimental efficiency and economic benefits are significantly improved. The data of diode voltage, current, and radiation field dosage rate are given for 70 shots of continuous operation without adjusting the target. This series of data shows that under continuous operation, even when the diode operating impedance declines from 29.53 Ω to 25.65 Ω, the dose rate stays essentially consistent and meets the experimental index. Under continuous tests, the change in impedance was induced by a change in diode gap caused by deformation of the anode target surface to some extent. It is proposed to improve the structure and process of the anode target in order to raise the diode’s dose rate and lifetime even more.