STUDIES ON MICROSCOPIC STRUCTURES FOR PRODUCTION/DISAPPEARANCE MECHANISMS OF LASER-INDUCED PLASMA AND DYNAMICS DURING LASER-INDUCED DISCHARGE

激光诱导等离子体产生/消失机制的微观结构及激光诱导放电动力学研究

• 批准号: 05402038
• 负责人: AKAZAKI Masanori
• 金额: $ 7.94万
• 依托单位: FUKUOKA INSTITUTE OF TECHNOLOGY (1994)Kyushu Tokai University (1993)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (A)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05402038/
• 关键词: Laser Induced Lightning; Discharge in Atmospheric Air; Laser Diagnostics; Plasma; Electron Temperature; Electron Density

The aim of this research is to find the successful conditions for laser-induced lightning, by understanding (1) the mechanism of ionization by excimer alsers in pure gases and (2) the formation mechanism of plasma produced by CO_2 laser in atmospheric air and (3) processes during laser-induced dicharge. For (1), experiments were done in different kind of ambient gas (air, N_2, O_2 of 100-1000mb in pressure) under an uniform DC electric field using Rogowski electrodes. Through electrical and optical measurements, it was found that oxygen molecules play an important role in characteristics of a laser-induced discharge. For (2) and (3), flashover induction experiments were perfomed for two types of long-gap electrode configurations, plate to rod and plate to plate, with a 50 J TEA CO_2 laser. From the flashover voltage characteristics and interferometric optical measurements on laser-induced plasma, it was found that the delay time for minimum V_<50> defined as 50% flashover voltage, measured from a laser incidence exists in the range of 50 to 200 mus, in laser-induced discharge of plate to rod, the value of V_<50> for negatively biased on the plate are larger than the case of positively biased, and laser-induced discharge does not occur on the surface of shock wave but relates on the low density region in the plasma produced by the laser.

本研究的目的是通过了解(1)准分子激子在纯气体中的电离机制，(2)大气中CO_2激光产生等离子体的机制和(3)激光诱导放电的过程，找出激光诱发闪电的成功条件。对于(1)，采用Rogowski电极在均匀的直流电场下，在不同的环境气体(100-1000 mb压力的空气、N_2、O_2)中进行了实验。通过电学和光学测量，发现氧分子在激光诱导放电特性中起着重要的作用。对于(2)和(3)两种长间隙电极结构，用50J的TEACO2激光器进行了闪络感应实验。从激光诱导等离子体的闪络电压特性和干涉光学测量中发现，定义为50%闪络电压的最小V&lt；50&gt；的延迟时间存在于50-200微秒的范围内。在平板对棒的激光诱导放电中，平板上负偏压的V&lt；50&gt；值大于正偏压的情况，激光诱导放电不发生在冲击波表面，而与激光产生的等离子体中的低密度区有关。

项目成果

C.Honda: "Laser Breakdown Plasmas for Lightning Stroke Studies" Proceedings of The 6th International Symposium on Laser-Aided Plasma Diagnostics. 277-282 (1993)

C.Honda：“激光击穿等离子体用于雷击研究”第六届激光辅助等离子体诊断国际研讨会论文集。

C.Honda: "Laser-Induced Sparkover in Atmospheric Air III" Proc.of 6th Asian Conf.on Electric Discharge. no.C-18. 213-216 (1993)

C.Honda：“Laser-Induced Sparkover in Atmospheric Air III”Proc.of 6th Asian Conf.on Electric Discharge。

C.Honda: "Laser Breakdown Plasmas for Lightning Stroke Studies" Proc.of The 6th Int.Symp.on Laser-Aided Plasma Diagnostics. 277-282 (1993)

C.Honda：“用于雷击研究的激光击穿等离子体”Proc.of The 6th Int.Symp.on Laser-Aided Plasma Diagnostics。

C.Honda: "A Study on Laser-Induced Discharge in Atmospheric Air(II)" Proc.of The 8th Int. Symp.on High Voltage Eng.3-72.02. 289-292 (1993)

C.Honda：“大气中激光诱导放电的研究（II）”Proc.of the 8th Int.

C.Honda: "Laser-Induced Sparkover in Atmospheric Air III" Proceedings of the 6th Asian Conference on Electrical Discharge. 213-216

C.Honda：“大气中的激光诱导火花 III”第六届亚洲放电会议论文集。