X射线分幅相机真空弧放电损害研究

Vacuum-arc discharge damage to X-ray framing camera

基于神光Ⅱ物理实验,研究了X射线分幅相机中真空弧放电对荧光屏和微通道板的损害。通过观测放电点在荧光屏上的位置和输出强度,发现X射线分幅相机存在的3种弧放电形式:散弧、强弧和定弧,由弧点位置和强度的时空变化比较了3种放电形式对器件的损害程度和对相机工作状态的影响。散弧在一定真空度条件下具有很好的稳定性,并且微放电不影响XFC正常性能;强弧的屏输出强饱和,MCP和荧光屏被一次性损害,相机无法正常工作;定弧对相机的正常工作没有影响,放电在两种屏压加载下都表现出稳定的趋向。由场致电子发射理论解释了放电机理,分析了弧放电损坏的稳定性,由实验结果推导了定弧的场增强因子。

Based on the experiment on the Shenguang- Ⅱ ,the damage of the phosphor and the micro-channel plate of the X- ray framing camera, induced by the vacuum-arc discharge, has been investigated. By measuring the position of the arc on the phosphor and the amplitude of the signal, three kinds of the arc discharges have been distinguished, they are scattered arc, strong arc and fixed arc charges. The damage of the imaging tube and the effect of the working state from the three arc discharges have been compared with different intensity and the different position, respectively. The discharge mechanism is explained with the electron field emission theory, and the stability of the damage is analyzed. The field enhanced coefficient of the fixed arc discharge has been deduced from the experiment result.