Electron Density Measurements in UV-Preionized XeCl and CO₂ Laser Gas Mixtures

Abstract

A Langmuir probe technique has been used to measure electron densities and temperatures in UV-preionized XeCl excimer and CO 2 laser gas mixtures in a laser tube. For this experiment, only pin electrodes (preionization sparks) were operated with no discharge between the main electrodes. The measured electron densities were about 10 8 cm -3 in both the excimer and CO 2 laser gases, compared with 10 10 cm -3 in pure He gas. The electron density was found to increase due to the proximity of the main electrodes. The coefficients of absorption for excimer and CO 2 laser gas were obtained from the characteristics of the electron densities vs the distance from the UV source. Based on the absorption coefficient for XeCl, 0.9 cm -1 atm -1 , we propose pin-electrode arrangements for spatially uniform preionization.