“晨光号”加速器二极管辐照面积和寿命提升技术

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

“晨光号”强流脉冲电子束加速器是我国最早的脉冲功率装置之一,当前该加速器承担的课题日益多元,机时愈发紧张。为拓展实验用途,着眼于提升辐照面积、阴阳极寿命和实验频次,以“晨光号”油介质传输线为前级,采用弱箍缩设计、Ta-Al复合叠靶等方法,研制了一种工作于0.90~2.00 MV的长寿命弱箍缩二极管。该二极管具有良好的抗热-力学损伤特性,工程稳定性好、维护工作量小。与原二极管相比,辐射场由聚焦型变为前向型,在维持峰值剂量率量级(108 rad/s)不变的情况下,辐照面积由10 cm^(2)提升至80 cm^(2),不换靶连续工作炮数由2~4发提升至70发,且30 min即可进行1次实验。

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^(2)0Ωto 30Ω,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 cm^(2) to 80 cm^(2),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 andeconomic benefits are significantlyimproved.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 from2 9.53Ωto 25.65Ω,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.