γ射线在大气中产生康普顿电流的快速计算方法

A fast calculation method for Compton current induced by gamma-ray in uniform atmosphere

康普顿电流是激励核电磁脉冲的主要机制。为了提高核电磁脉冲数值模拟中γ射线产生康普顿电流过程的计算效率,发展了一种γ射线在均匀大气中产生康普顿电流的快速计算方法。首先通过计算康普顿电子在出射方向上的衰减特征,得到在电子出射方向净电子流与其射程和出射距离的拟合关系,然后结合康普顿散射微分截面,给出单能γ射线在大气中产生的康普顿电流密度的解析数值计算方法。和蒙特卡罗程序的计算结果比较,用该方法计算得到的电流密度值差异在10%以内,计算速度提高两个量级以上。该计算方法可用于大气中康普顿电流的快速估算。

Compton current is the main source that generates electromagnetic pulse. To improve the efficiency of calculation of Compton current induced by gamma rays in the atmosphere when the Monte Carlo method is adopted, based on the basic prin ciple of Compton current induced by gamma rays, firstly, this paper calculates the attenuation of the Compton electron in the emit ting direction, then a fitting function is figured out between the net electron current and the travel distance of the electron in a giv en range, finally the analytical and numerical method of calculation of the current density induced by mono energy gamma rays in the atmosphere is given according to the formula of the differential Compton scattering cross section. The analytical and numerical results are compared with the results of the Monte Carlo calculation, the relative difference of the current densities is less than 10%, and the efficiency is increased by two orders of magnitude. The method provided in this paper can be applied in the fast computing of Compton current in the atmosphere.