电子束能量沉积的相对论Fokker-Planck方程的计算方法

Numerical Method of Relativistic Fokker-Planck Equation for Energy Deposition of Fast Electrons

针对相对论电子束在高密度等离子体中的能量沉积过程,建立三维动量空间中快电子能量沉积的相对论Fokker-Planck方程的可计算物理模型,构造数值算法并研制数值模拟程序.通过与解析模型和蒙特卡罗模拟相比较,验证数值方法和程序的可靠性.在二维动量空间的模拟基础上,通过计算能量区间为0.5 MeV^3.5 MeV的快电子在背景密度为300 g·cm^(-3)的氘氚等离子体中的能量沉积过程,发现由于碰撞效应使平均散射角趋近平衡,三维动量空间计算快电子连续射程和穿透深度与二维结果基本一致.

For energy deposition of fast electrons in high density plasma,a relativistic Fokker-Planck equation in three-dimensional momentum space is introduced.It includes both binary collision and contribution from plasma collective response.Numerical method as well as kinetic code of the equation is developed.Typical energy deposition cases are presented with comparison with stopping power model.Energy deposition of fast electrons with energy from 0.5 MeV to 3.5 MeV in 300 g·cm^-3 DT plasma are simulated.It shows that scattering angle Φ plays minor role on range and penetration depth of energy deposition of fast electrons.