聚焦角度对空气中激光维持爆轰波的影响

 吸气式激光推进的激光能量沉积过程主要发生在激光支持的爆轰波（LSD波）的形成与演化阶段，分析LSD波的传播规律和影响因素对揭示能量沉积机理起到基础性作用。利用纳秒四分幅高速相机和延长光路的纹影系统，拍摄了不同聚焦角度下CO₂激光经透镜聚焦击穿空气流场的纹影照片，结合一维理论公式分析了LSD波速度。结果表明：在本文的实验条件下，吸气式激光推进击穿空气经历了LSD波和激光支持的燃烧波（LSC波）两个阶段， LSD波阶段的持续时间约7.1 μs；3种聚焦角度下LSD波速度与理论公式预测的整体趋势比较吻合；聚焦角度越小，LSD波的初始速度越大，聚焦角度θ=4.29°时实验数据达到约14 km/s。

Effects of Focusing Angle on Laser-supported Detonation Wave in Air

Energy deposition in air-breathing laser propulsion usually occurs during the formation and evolution of laser-supported detonation(LSD)wave.Therefore,analyses of propagation laws and influence factors of LSD wave play a fundamental role in disclosing the mechanism of energy deposition.The schlieren photographs of CO2 laser-induced air breakdown at different focusing angles are taken with a nanosecond framing high-speed camera.During the process,an optical lens is used and ray path of the schlieren system i...