空间电荷效应对X射线条纹相机动态范围影响的研究

Dynamic range of x ray streak camera affected by space charge effect

在惯性约束聚变中,X射线条纹相机是一种诊断图像时空分辨的重要设备,其动态范围反映了条纹相机有效测量入射X射线强度的能力.由于空间电荷效应的存在,电子脉冲在运动过程中会不断展宽,从而限制了条纹相机的动态范围.本文采用一维流体力学模型,利用电子数守恒、动量守恒和Poisson方程等来对电子脉冲的展宽进行推导,最终得到了电子脉冲的密度分布随时间空间的变化情况,从而为条纹相机动态范围的评估提供了依据。

x ray streak camera is an important equipment for time resolved measurement in the field of inertial confinement fusion.Its dynamic range indicates the ability that effectively measuring the intensity of incidence x ray.The photoelectron pulse will be broaden in passing through the photocathode-to-mesh region because of space charge effect.This limits the dynamic range of the streak camera.This paper adopts a fluid model,making use of particle conservation,momentum conservation,and Poisson equations to deduce the widening of the electron pulse and derive the change in the electron density distribution.The results can be used to evaluate the dynamic range of the streak camera.