强脉冲离子束辐照薄金属靶的热力学过程研究

在回顾和总结现有强脉冲离子束诊断技术和能量沉积模型的基础上, 结合红外成像诊断分析, 基于能量平衡, 提出了强脉冲离子束在固体靶中功率密度分布模型, 并采用蒙特卡罗方法对其进行计算. 以该功率密度模型作为源项, 使用有限元分析方法模拟强脉冲离子束入射100 μm不锈钢靶后内部温度场在毫秒时间范围内的分布和演化. 结果显示, 在微秒时间范围内, 热场以存在于近表面区域数倍于离子射程范围内的冲击热场为主要特征; 而在毫秒时间范围内, 靶的前后表面(纵向)已达到温度平衡, 且靶后表面温度场和入射前表面的离子束横截面能量密度具有空间分布的相似性. 这证明了, 在采用具有毫秒响应速度的红外拍摄系统的情况下, 背面红外诊断技术可以实现以较高的精度对强脉冲离子束横截面的能量分布进行诊断和分析.

Distribution and evolution of thermal field induced by intense pulsed ion beam on thin metal target

In this paper, combined with the latest development in relevant diagnostic and modeling techniques, the intense-pulsed ion beam (IPIB) energy deposition model in solid targets is established. The power density distribution induced by IPIB is simulated by Monte Carlo method on the basis of energy balance. By taking the power density as the source term, the thermal field distribution and evolution on a 100 μm stainless steel target irradiated by IPIB are simulated using the finite element method (FEM) in a time scale of several ms. Results reveal that in a time scale of several μups after IPIB irradiation, the main feature in the induced thermal field is a thermal shock within the depth of several times of the ion range. In the time scale of ms, thermal equilibrium can be established between the front and rear surfaces of the target, and the cross-sectional temperature field profile has a similar profile to the cross-sectional energy density distribution of the ion beam. This proves that by the infrared imaging diagnostic method, high resolution cross-sectional energy density diagnostics of IPIB can be achieved with a shooting time delay in ms scale.