Numerical simulation of Ne-like Ar plasma dynamics and laser beam characteristics of 46.9 nm laser excited by capillary discharge

摘要

In this work, we performed computer modeling of high electrical discharge in an Ar filled alumina capillary in order to investigate the parameters of the discharge system that may lead to achieve an intense laser beam. One-dimensional magnetohydrodynamics (MHD) simulations were used to study the parameters of discharge produced Ar plasma. The radial evolution of plasma parameters such as electron temperature, electron density, and Ne-like argon density was estimated from MHD simulations. Additionally, the influence of the main discharge current on the pinching time and plasma radius was analyzed with the one-dimensional MHD model. The active medium for lasing is created by a high amplitude main pulse and pre-pulse. Specifically, we investigated the optimum main discharge current and Ar filling pressure. The main discharge current of 30 kA was declared as the best current to obtain the 46.9 nm laser with a 4 mm alumina capillary. The influence of the main discharge current and lasing pressure on laser beam intensity and beam characteristics has been studied theoretically and experimentally. The saturated laser intensity was obtained with a main discharge current of 30 kA. A severe reduction in laser intensity was observed above the main discharge current of 30 kA due to capillary wall ablation. The laser beam divergence was observed to be less than 3.5 mrad. The theoretical results obtained from MHD simulations are in good agreement with the experimental results of laser intensity and laser beam characteristics.