Study of physics and practical applications of laser-driven in-tube accelerator

对组长研制的激光驱动管内加速器进行了基础研究和应用研究。在4m高空垂直发射实验中对其工作原理进行了实验验证。通过激波、膨胀波和激光等离子体之间的相互作用以及伴随的流体动力学不稳定性，对脉冲产生机理进行了实验和数值研究。建立了其推进性能的标度律。实验验证了激光烧蚀对激光脉冲的增强作用。这些对于实际应用都是有用的。在该装置中，由于限制效应和适当设置工作气体种类及其填充压力，动量耦合系数(冲量与激光能量之比)可以增加两倍。动量耦合系数与声速的倒数成正比，并用…进行了实验验证更多的单原子气体，氩、氪和氙气。还得到了它们的电离势对冲量的二次效应。冲量性能用无量纲动量耦合系数、维动量耦合系数乘以声速和无量纲参数、填充压力与有效弹丸体积与激光能量的比率来唯一地表征。通过实验和数值分析，可以从激光等离子体的有效膨胀体积来优化脉冲性能。在激光烧蚀性能实验中，聚缩醛表现出最好的性能，其冲量对环境压力很敏感。在适当的激光注量下，当环境压力低于100pa时，冲量达到最大。这种良好的性能不仅可用于改善该装置的推进性能，而且还可用于其他各种空间应用，包括空间碎片脱轨。较少

Basic and application studies were conducted on the laser-driven, in-tube accelerator which had been developed by the head investigator. The operation principle was experimentally validated in 4-m-high vertical launch experiment. The impulse generation mechanisms were experimentally and numerically studied by highlighting the interactions among shock waves, expansion waves and laser-generated plasma and accompanying fluid-dynamics instabilities. A scaling law of its propulsion performance was established. The impulse enhancement using laser ablation was experimentally demonstrated. Those are useful for practical applications. In this device, the momentum coupling coefficient, which is defined as the ratio of an impulse to a laser energy, can be tripled owing to a confinement effect and with appropriate setting of the working gas species and its fill pressure. The momentum coupling coefficient scales with the reciprocal of the speed of sound, which was experimentally validated using thr … More ee kinds of monoatomic gases, argon, krypton and xenon. The secondary effect of their ionization potential on the impulse was also obtained. The impulse performance is uniquely characterized using a dimensionless momentum coupling coefficient, the dimensional momentum coupling coefficient multiplied by the speed of sound, and a dimensionless parameter, the ratio of the fill pressure multiplied by an effective projectile volume to the laser energy. From the experimental and numerical analysis, it is concluded that the impulse performance can be optimized from the effective expansion volume of the laser plasma. In the laser-ablative performance experiment, polyacetal exhibited the best performance ; its impulse is sensitive to the ambient pressure. At an appropriate laser fluence, the impulse becomes highest at ambient pressures below 100 Pa. This favorable performance can be useful not only for improving the propulsive performance of the device but also for other various space applications including space debris deorbiting. Less