一种用于产生高强度大面积中等脉冲X射线的两级串联二极管。

A two-stage series diode for intense large-area moderate pulsed X rays production.

作者信息

Lai Dingguo, Qiu Mengtong, Xu Qifu, Su Zhaofeng, Li Mo, Ren Shuqing, Huang Zhongliang

机构信息

State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 701124, China.

Department of Engineering Physics, Tsinghua University, Beijing 100084, China.

出版信息

Rev Sci Instrum. 2017 Jan;88(1):013506. doi: 10.1063/1.4974102.

DOI:10.1063/1.4974102

PMID:28147662

Abstract

This paper presents a method for moderate pulsed X rays produced by a series diode, which can be driven by high voltage pulse to generate intense large-area uniform sub-100-keV X rays. A two stage series diode was designed for Flash-II accelerator and experimentally investigated. A compact support system of floating converter/cathode was invented, the extra cathode is floating electrically and mechanically, by withdrawing three support pins several milliseconds before a diode electrical pulse. A double ring cathode was developed to improve the surface electric field and emission stability. The cathode radii and diode separation gap were optimized to enhance the uniformity of X rays and coincidence of the two diode voltages based on the simulation and theoretical calculation. The experimental results show that the two stage series diode can work stably under 700 kV and 300 kA, the average energy of X rays is 86 keV, and the dose is about 296 rad(Si) over 615 cm area with uniformity 2:1 at 5 cm from the last converter. Compared with the single diode, the average X rays' energy reduces from 132 keV to 88 keV, and the proportion of sub-100-keV photons increases from 39% to 69%.

摘要

本文提出了一种由串联二极管产生中等脉冲X射线的方法，该二极管可由高压脉冲驱动，以产生强的大面积均匀的低于100keV的X射线。为Flash-II加速器设计了一种两级串联二极管，并进行了实验研究。发明了一种紧凑的浮动转换器/阴极支撑系统，额外的阴极在电气和机械上是浮动的，通过在二极管电脉冲前几毫秒拔出三个支撑引脚来实现。开发了一种双环阴极以改善表面电场和发射稳定性。基于模拟和理论计算，对阴极半径和二极管间距进行了优化，以提高X射线的均匀性和两个二极管电压的一致性。实验结果表明，两级串联二极管在700kV和300kA下能稳定工作，X射线的平均能量为86keV，在距离最后一个转换器5cm处，615cm²面积上的剂量约为296rad(Si)，均匀性为2:1。与单二极管相比，X射线的平均能量从132keV降低到88keV，低于100keV光子的比例从39%增加到69%。