短脉冲激光诱导薄膜损伤的等离子体爆炸过程分析

短脉冲激光诱导薄膜材料损伤过程的研究通常止于薄膜材料发生喷溅.超热喷溅物质吸收剩余激光脉冲能量将形成剧烈的等离子体爆炸过程.采用两步数值计算方法处理等离子体微滴的爆炸过程，即在每一个数值计算时间步长内，将爆炸过程分为两步，第一步处理微滴的绝热膨胀及裂解过程；第二步处理微滴对激光脉冲能量的吸收过程.有效地将微滴吸收激光能量的物理学过程与爆炸动力学过程耦合到一起.分析了喷溅物质微滴在剩余激光脉冲作用下，其半径、膨胀（加）速度、裂解（加）速度、电子及离子的密度与温度等参量随时间变化的演化情况.结果表明：材料喷溅 关键词： 光学薄膜 激光损伤 等离子体 爆炸

Investigation of the plasma bursting process in short pulsed laser induced film damage

Investigations on the interaction of short pulsed laser with optical films usually terminate at the ejection of film material. The plasma bursting process will happen, because the superhot ejection will absorb the remainder of laser energy. A two-steps numerical method has been used to deal with this process. In every computation time-step, two phases are used: the first one is the adiabatic expansion and cracking phase; the second one is the phase of absorbing laser energy. By this method, the energy absorption process and the bursting process are effectively coupled. For the thermodynamic parameters of the plasma micro-droplet, such as the radius, expansion speed and acceleration cracking speed and acceleration, densities and temperatures of electronic and ionic systems have been investigated. The results revealed that: the ejection will be atomized to micro-droplets in the early stage, and expansion dominates the latter part. The cracking velocity is cyclic, and the expansion velocity increases all the while. In specific cases, the expansion process may keep a dynamic stable state after the atomization. But it is difficult for this dynamic stable state to form.