强流脉冲离子束辐照铜靶热效应数值研究

Research on Thermo Effects of Cu Modified by Intense Pulsed Ion Beam

摘要: 为了研究强脉冲离子束辐照改性铜靶的行为，建立了基于靶室中法拉第杯检测的离子束流密度和离子加速电压时空分布模型；采用蒙特卡罗方法计算了束流在铜靶中的能量沉积，并将这随时间变化的非线性沉积能量作为热传导方程的热源项，计算得到了脉冲期间靶材内部温度场的演化规律。一次脉冲后与液化烧蚀相比，靶材表面较小区域的物质气化烧蚀掉，辐照中心处熔化的厚度最大；气、液化烧蚀厚度随偏离中心位置而减小。当束流密度为300 A/cm2时，中心区域气化烧蚀和液化烧蚀的厚度分别达到0.2微米和1.3微米；脉冲期间热量延纵深方向的传播距离小于2微米。

Abstract: A modification method for Copper target by intense pulsed ion beam (IPIB) irradiation has been reported. Based on the temporal and spatial distribution models of the ion beam density detected by Faraday cup in the chamber and the ions accelerating voltage, the energy deposition of the beam ions in Cu is calculated by Monte Carlo method. Taking this time-dependent nonlinear deposited energy as the source term of two-dimensional thermal conduction equa- tion, the temporal and spatial ablation process of metal Cu during a pulse time was obtained. Only a little area of mate- rial is ablated off due to the vaporization compared with the melting ablation area on the surface after a shot. The most deep melting depth is in the irradiation centre. The melting and vaporizing thicknesses decrease with the increasing dis- tance from the irradiation centre. The top-layer Copper material in thickness of about 0.2 μm is ablated by vaporization and the layer in thickness of 1.3 μm is melted after one shot under the ion beam density of 300 A/cm2. The thermal transportation along the longitudinal direction in the specimens is less than 2.0 μm during a pulse.