激光驱动飞片加速特征分析

Acceleration characteristics of flyers driven by pulsed laser beams

在激光驱动飞片研究中,飞片的加速特征是需要认识的关键问题之一。设计了强激光作用金属膜驱动飞片实验,采用聚偏氟乙烯(PVDF)压电薄膜测量了飞片到达不同距离的时间,计算得到飞片速度和加速度,分析激光能量对飞片加速性能的影响。基于Gurney能理论,建立了激光驱动飞片速度的计算模型,根据实验结果获得了激光能量损失系数和有效吸收系数,分析了激光能量和膜体厚度对飞片速度的影响。实验结果表明:不同激光能量下飞片的加速特征基本相似,激光能量变化对飞片的加速时间影响较小;激光能量较大的情况下,膜体厚度对飞片最大速度、能量耦合系数的影响更显著;当膜体超过一定厚度时,能量耦合系数不再增加。

The acceleration characteristics of flyers are critical parameters for laser-driven flyer study. In this paper, a laser- driven flyer experiment was designed. The PVDF piezoelectric film sensor was employed to measure the flight time of flyers trav- eling different distances, also flyer velocity and acceleration were calculated. The effects of laser energy on flyer acceleration per- formances were analyzed. Based on the Gurney energy theory, a calculation model of laser-driven flyer velocity was established.According to experimental results, laser energy loss and effective absorption coefficient were determined, and the eitects ot laser energy and metal film thickness on flyer velocity were obtained. The results show that the acceleration characteristics of flyers driven by different laser energies are similar. Moreover, laser energy has little influence on acceleration time. At high laser ener- gy, the influences of metal film thickness on flyer maximum velocity and coupling coefficient are obvious. When the metal film is thicker than a certain value, the counlin~ coefficient could not increase again.