Numerical study of threshold intensity dependence on gas pressure in the breakdown of molecular hydrogen induced by excimer laser

作者：Gamal Yosr E E D^*; Nassef Aied

来源：Physics of Plasmas, 2017, 24(10): 103503.

DOI：10.1063/1.4996707

In the present work, a numerical analysis is performed to investigate the threshold intensity dependence on gas pressure in laser spark ignition of the H-2 plasma. The analysis considered the experimental measurements that were carried out by Yagi and Huo [Appl. Opt. 35, 3183 (1996)]. In their experiment, H-2 in a pressure range of 150-3000 Torr is irradiated by a focused excimer laser source using a 96 cm lens at a wavelength of 248 nm and a pulse duration of 20 ns. The study, based on a modified electron cascade model [K. A. Hamam et al., J. Mod. Phys. 4, 311 (2013)], solves numerically a time-dependent energy equation for the distribution of the electron energy as well as a set of rate equations that describe the change in the formed excited molecule population. This model enabled the determination of the threshold intensity as a function of gas pressure. The validity of the model was tested by comparing the calculated thresholds with the experimentally measured ones. Moreover, the calculation of the electron energy distribution function and its parameters justified the role of the electron gain and loss processes in controlling the value of threshold intensity in relation to the gas pressure. The effect of loss processes on the threshold intensity is also presented. Published by AIP Publishing.

• 出版日期2017-10