微波法诊断激光等离子体研究

【作者】 白顺波；

【导师】 倪晓武； 陆建； 陈建平；

【作者基本信息】 南京理工大学 ， 测试计量技术及仪器， 2006， 硕士

【摘要】 本文研究了微波与激光击穿空气形成的等离子体的相互作用。通过CCD得到了等离子体膨胀过程的图像，根据微波传播原理及等离子体理论分析了微波在等离子体形成过程中不同位置的反射、折射、传输特性，并根据等离子体不同位置物质的运动速度对等离子体反射微波信号的频谱图进行了分析；实验测量和分析了等离子体膨胀速度与激光束能量的关系及与不同频率的微波的关系，以及等离子体轴向速度与径向速度的关系。 基于电磁波传播理论、微波传输线理论、多普勒理论和激光聚焦产生等离子体理论，本文设计了用于测量激光等离子体的微波诊断系统，绘出了等离子体与微波相互作用的示意图。对激光聚焦产生等离子体形成的过程中，以温度达到15，000-20，000K作为等离子体形成的判据，对产生激光支持的燃烧波、爆轰波的过程的不同位置物质的运动进行了描述，根据微波反射的多普勒效应实验测量了等离子体形成过程中不同位置物质的运动速度。 本文的研究结果为进一步研究激光等离子体与微波的相互作用提供了理论和实验借鉴。更多还原

【Abstract】 This paper introduces the interaction between microwave and plasma which is induced by laser breakdown in the air. Based on plasma principle and the theory of transmission of microwave, the reflection, refraction, and transmission characteristics in different time are discussed in this paper. We also discuss the relationship between the plasma velocity and the laser power, as well as the relationship between the plasma velocity and microwave frequency.Based on the theory of electromagnetic wave transmission, theory of plasma induced by laser ionizing, theory of microwave transmitting line and Doppler Effect, a diagnostic system used for measuring laser induced plasma is designed and the sketch map of the interaction between plasma and microwave is depicted. As the temperature reaches 15000-20000K is the criterion of plasma being induced, substance’ s movements of different spots in the process of LSCW and LSDW is described. We also calculated the substance’s velocity in different time by the Doppler Effect.更多还原