エキシマレーザにより生成した高気圧アルゴンプラズマの特性

Abstract

High pressure argon gases from 2 to 150 atm are irradiated by an intence XeCl excimer laser light with a maximum power of 17MW and a half width of 30ns. A hot and dense plasma is produced in the high pressure gas. The transmitted laser light is observed to study the mechanism of the breakdown and absorption, the breakdown time and the absorption rate are obtained. The breakdown time experimentally obtained agrees with the calculated one based on the cascade ionization. Therefore, in the breakdown process, the cascade ionization is dominant. At a low pressure below 100atm, the laser light is entirely absorbed by the laser-produced plasma. But it is not entirely absorbed at a high pressure. Because the laser-produced plasma decays so fast that the absorption length is shortened even during the laser pulse at a high pressure.