Physical Properties of Dense Plasma Produced by XeCl Excimer Laser in High-Pressure Argon Gases

Abstract

When XeCl excimer laser light was focused in high-pressure Ar gas up to 150 atm, a hot and dense plasma developed not only backward but also forward. The physical properties of the plasma produced by an ultraviolet laser in high-pressure gases have not been studied yet except for the mechanism involved in its development. Interferometric and spectroscopic measurements were carried out. Electron density was measured using a Mach-Zehnder interferometer. When laser intensity was 2×1011 W/cm2 at the focal spot, electron density was proportional to the pressure and a fully ionized state was almost achieved up to 150 atm. Dense plasma with electron density of the order of 1027 m-3 was obtained. Electron density was highest at the focal spot and the forward electron density was higher than the backward one. Electron temperature was estimated from continuous intensities. Electron temperature at the focal spot of the order of 105 K was obtained. The electron temperature distribution differed from the electron density distribution, in which the backward electron temperature was higher than the forward one.