激光与固体靶面烧蚀等离子体的能量耦合计算

Simulation of Energy Coupling of Laser and Ablated Plasma at Target Surface

强激光辐照下固体靶表面迅速汽化产生靶蒸气等离子体,激光穿过等离子体区到达固体靶表面的过程就是激光束与等离子体的能量耦合与交换过程。采用具有五阶精度的WENO差分格式和简易等离子体状态方程模型对激光与等离子体相互作用的复杂物理过程进行了数值计算,分析了激光束能量在等离子体区中的吸收、屏蔽效应等动态耦合规律以及激光支持等离子体前驱冲击波传播。数值模拟结果表明:激光能量是支持靶面等离子体运动的唯一原因,能量屏蔽效应对激光与等离子体能量耦合有很大影响,通过控制激光脉冲宽度,可以合理调节屏蔽效应的影响。

Under the irradiation of power laser,the material of solid target surface evaporated instantly and then the vapor plasma of target generated, coupling the energy of laser beam with plasma during the laser go through the plasma field to arrive at the target surface were the main physical process of laser interaction with plasma. A general Godunov finite difference schemes-WENO（Weighted Essentially Non-Oscillatory）schemes which have fifth-order accuracy is used to perform a numerical calculation for 2-dimensional axis symmetrical laser-supported plasma flow field under laser ablated solid target. The models for the calculation of ionization degree of plasma and the interaction between laser beam and plasma and the simplified EOS（equation of state） of plasma are considered in the simulation, the energy of laser absorbed in the plasma and the shielding effect of plasma were analyzed. Simulation results showed that the main portion of laser energy Was used to drive the plasma flow,the shielding effect played an important role in the coupling of laser and plasma,the variation of the duration time of laser pulse could adjust the shielding effect which influenced the coupling of laser energy and plasma.