【作者】 朱金荣；

【导师】 陆建； 倪晓武； 沈中华；

【作者基本信息】 南京理工大学 ， 计量测试技术与仪器， 2007， 硕士

【摘要】 本文对激光等离子体冲击波的测试方法和特性进行了研究，对激光支持爆轰波的点燃阈值、激光支持爆轰波的冲量耦合过程及其激光吸收区内气态粒子和离化粒子的组分进行了实验、理论、数值模拟的分析工作。提出了一种采用了波长为1064nm的激光作用在铝靶表面，产生的等离子体声波的峰值声压与作用激光功率密度间存在跃变阶段，并进行了理论分析和实验验证，取得了激光支持爆轰波的点燃阈值。针对激光与靶材相互作用过程中存在的冲量传递问题，提出了悬摆法和光电测速法相结合的测量方法，用于激光支持爆轰波对靶冲量耦合作用的实验测试研究。应用该测试方法测量了不同激光功率密度下的激光支持爆轰波对靶产生的冲量，得到了聚焦透镜焦点附近的靶获得的冲量、冲量耦合系数随作用激光功率密度变化的关系，进而根据有关理论对实验测试结果进行了解释。在对激光与靶材相互作用时伴生的纵向稀疏波和横向稀疏波对激光支持爆轰波的影响的基础上，提出了利用稀疏波与冲击波作用时间为时间标度，进而通过数值模拟计算了激光作用于靶的冲量，并将该冲量与实验测试的结果进行了比较。最后根据不同功率密度的激光束作用于靶材时比热比的差异，确定了激光吸收区内气态粒子和离化粒子的组分。本文结果对于金属表面处理、激光加工的自动控制、激光推进技术的研究均有一定的参考价值。更多还原

【Abstract】 Testing methods and properties of the laser plasma shock wave is studied in this paper by analyzing the experimental, data simulation and theoretical result in the lit threshold , the mechanism of action between Laser-Supported Detonation Wave and component of plasma and gas with the variation of laser power densityBased on the phenomena of laser supported combustion or detonation wave occurs because of the interaction between the high-intensity laser and material, a new method is present for diagnosing the ignition threshold of laser supported detonation wave by measuring the jump of the sound peak pressure of laser-target plasma. The ignition threshold can be obtained by analyzing the jump stage between laser power density and the sound peak pressure of laser-target plasma, which generates on the surface of target due to interaction between Nd: YAG laser whose wavelength is 1064 nanometer and aluminum target. The test results are largely in accord with those form other methods。For solving the impulse coupling between laser and target, a new method of combining pendulum with light electric tachometer was presented, which was adopted in the experiment to measure the impulse of laser supported detonation wave impacting target at a series of laser power density. The target’s impulse near the focal spot and the relation between impulse coupling coefficient and the laser power density were obtained. Furthermore, the experimental result was explained base on the relational theory. Considering the two direction influence between rarefaction and shock that include lateral and forward directions in the interaction between laser and target, the time scale of shock and rarefaction is founded. Furthermore, the result from the data simulation, which calculates the impulse on the target, is compared with the experimental result. Finally, the difference of specific heat ratio with variation of laser power density, the component in the shock region can be determined.These research results will provide the theoretical, numerical simulation references metal surface treatment and laser propulsion.更多还原