关键参数对空气中激光引致热核特性的影响规律研究

针对纳秒脉冲激光能量在空气中沉积的等离子体热核演化问题，利用两种不同分辨率的高速相机，搭建了高分辨率的纹影系统。所获得的纹影实验结果很好地展示了激光能量沉积初始时刻的演化过程，并研究了激光能量大小和透镜焦距这两个关键参数对激光引致等离子体热核演化过程的影响规律。实验结果表明激光沉积能量越大，等离子体热核的尺寸越大，但是可能存在激光能量沉积的饱和现象。另外，激光能量越高、透镜的焦距越短，激光能量沉积之后环境冷空气穿透热核的时间就越晚，意味着等离子体热核维持稳定的高温低密度气团的时间越长，这可以为激光致等离子体主动流动控制的相关研究提供充足的反应时间。

Influence of key parameters on laser-induced hot core in air

In order to understand the phenomenon of plasma hot core evolution in air deposited by nanosecond-pulsed laser energy, a high-resolution schlieren system was set up by using two cameras with different resolution. The experimental results obtained from schlieren system showed a good illustration of the initial moment of laser energy deposition, and then the law of the two key parameters of pulse energy and lens focal length on the evolution of laser-induced plasma hot core were studied. The experimental results show that the higher the energy of laser deposition, the larger the size of the plasma hot core, but there may be saturation of the laser energy deposition. In addition, the higher the laser energy and the shorter the focal length of lens, the later the external air penetrates the plasma core after laser energy deposition, which means the plasma core can maintain a steady state of high temperature and low density for a long time, and provides sufficient reaction time for the relevant research on plasma active flow control from the laser energy.