Elementary Study on Pulsed CO_2 Laser Induced Electrical Discharge through Plasma Produced by Linear Focused Beam Method in Atmospheric Air

§ 1.引言从理解激光诱导闪电方法的基本知识的角度出发，我们重点研究了大气中具有非均匀直流电场的激光诱导放电（LIED）对聚焦点处的激光功率密度（LPD）和气溶胶颗粒的依赖性。§ 2.脉冲激光产生等离子体（PLPP）特性的研究我们用三个具有相同表面积和高响应度的环形芯片的三探针方法测量了PLPP的电子温度（T_e）和离子密度（n_i），并与实验结果进行了比较。1μs。结果表明，在点聚焦位置，照明PLPP的T_e为4.4eV，n_i为100 μ <21>m <-3>~ 2，在不照明的情况下，等离子体状态保持在100μs以上。§ 3.含气溶胶粒子的LIED特性研究用熏香烟雾模拟大气中的气溶胶粒子，对非均匀直流电场下的LIED特性进行了实验研究。用激光散射法测量了气溶胶粒子在放电间隙中的密度分布。相对增加的密度为6x10^5。结果表明，即使在模拟气溶胶条件下，激光功率密度为空气击穿阈值的1/700时，LIED也会发生，并且LIED的放电路径接近线性。

§1.Introduction From the view point of understanding elementary knowledge about the laser induced lightning method, we focused on the dependences of laser power density (LPD) at focused points and aerosol particles on laser induced electrical discharges (LIED) with non-uniform DC electric filed in an atmospheric air. We studied on experimentally (1) inner plasma energy and (2) characteristics of LIED by using of the LPD difference between point-focused and linear-focused methods with aerosol conditions.§2.Study on the behavior of pulsed laser produced plasma (PLPP) We measured electron temperature (T_e) and ion densitie (n_i) of a PLPP by a triple probe method of three ring chips with same surface area and high responsiveness-1μs. As the results, T_e was 4.4 eV and n_i was 〜10^<21> m^<-3> an illuminative PLPP at a point-focused position, and the plasma state was maintained more than 100μs without illuminating.§3.Study on the characteristics of LIED with aerosol particles We studied on experimentally the characteristics of LIED with non-uniform DC electric filed in an atmospheric air with aerosol particles simulated by incense smog. The density distribution of simulated aerosol particles in a discharge gap was observed to be nearly uniform by a laser scattering method. The relative increased density was 6x10^5. As the results, the LIED occurred even though the laser power density was 1/700 compared with the threshold of air breakdown in a simulated aerosol condition, and the discharge path of LIED was nearly linear.