Numerical Analysis of Corona Pre-Ionization for High-Power Discharge-Pumped XeCl* Excimer Lasers

Abstract

The working gas of discharge-pumped excimer lasers is generally a mixture of rare gases and monohalide. Typically, the working gas is preconized to generate reproducible uniform glow discharge. In high-power (more than 100 W) excimer lasers, this pre-ionization is achieved through spark discharge in the discharge chamber. In this study, a high-power discharge-pumped XeCl* excimer laser with corona preionisation was designed to investigate the feasibility of applying corona preionisation in high-power excimer lasers as well as analyse the correlation of corona discharges characteristics with laser discharge properties. The electron avalanche triggered by ultraviolet preionisation in the laser was numerically studied by creating 2D models. The simulation results revealed that the additional ionisation induced by the secondary electron emission of the cathode together with the dielectric constant of the corona bars significantly affect the discharge current of the principal electrodes. Under the condition of the design values, the peak preionisation electron density between electrodes was approximately 108 cm−3, and the laser discharge was quite uniform, which theoretically proved the feasibility of using corona preionisation instead of spark discharge preionisation in high-power practical devices.