用于测量激光烧蚀下靶材获得冲量的方法

Method of Impulse Measurement for Laser-Ablated Target

强激光与固体靶物质相互作用产生的等离子体膨胀对靶有强烈的反冲作用,这就是激光等离子体推进的基本思想。固体靶获得冲量大小的测量在研究冲量传递效率过程中有重要作用。采用一种悬摆法和光电测速法相结合的测量方法对激光等离子体膨胀时靶摆动的周期、角速度进行了实验测量,结合测试装置的几何结构和流体力学理论得到了有空气阻力影响下靶的摆动方程,并将实验测量的靶摆动周期与由摆动方程计算的结果进行了比较,两者之间的相对误差小于0．5％,即这一摆动方程能较精确地描述靶的摆动过程,采用此摆动方程和实验测量的靶摆动角速度求得了靶的冲量。理论和实验研究结果表明该测试方法具有结构简单、操作方便、测量精确度高等特点。

The interaction of laser with solid target material can produce plasma called laser-induced plasma, The counteracting force is generated by the expending of laser-induced plasma. That is the foundation of laser propulsion. The measurement of impulse acting on the targets is very important for the impulse imparting from laser beam to target. A new method is presented by combining pendulum with light-electric tachometer, which is adopted in the experiment for measuring the impulse coupling between laser induced plasma and aluminum target, Considering the structure of measurement equipment and the theory of fluid mechanics, the kinetic equation of the pendulum including air damping term is founded, and target impulse is obtained by using the kinetic equation and the measured pendulum angular velocity. The comparison between experimental results and theoretical results testifies that the difference of the period of the pendulum between experimental measurement and kinetic equation is less than 0. 5 %. The experimental operation is simple and the experimental accuracy is high.