Effects of neutral particle dynamics in the active medium of discharge pumped XeCl lasers

Abstract

A powerful fluid model to study the role of gas dynamics in a glow discharge considered as an excitation medium for XeCl lasers is presented. This model was employed using a numerical code including four strongly coupled parts: electric circuit equations, electron Boltzmann equation, kinetic equations and conservation equations. The theoretical formalism presented here is based on the two-dimensional Euler equations describing the perfect compressible fluid. The numerical calculations have been carried out considering the single shot regime and neglecting the gas flow. The monotonic upstream centred scheme for conservation laws corrections has been used in order to estimate the exchange flow surrounding the control volume walls. We show that the crossing discharge induces a thermal energy density enhancement located principally in the cavity centre.

Propriétés de la zone cathodique d’un plasma pour laser à excimère

“…Ces observations concernent de façon plus générale les décharges haute pression, et mettent en évidence le rôle de la gaine cathodique dans la filamentation du plasma [4,6,7], le développement des instabilités dans le cas des lasers, XeCl [1,3], CO 2 [4,5], ou dans l'hélium [6], mais les mécanismes de propagation de ces instabilités ne sont pas nécessairement les mêmes. Le passage au régime d'arc dans certaines expériences [4,6] est dû à une instabilité thermique, qui se propage sous l'effet du chauffage local [8][9][10]; par contre la filamentation du plasma dans le cas des lasers XeCl est dû à la déplétion d'halogène [1,[11][12][13][14][15].…”

Temperature Characteristics of Cathode Sheath in High-Pressure Volume Discharge Derived from Emanating Shock Wave

“…On the other hand, in the flow field simulation after discharge, the energy deposition process in the cathode sheath is assumed to happen simultaneously with that in the plasma bulk. [6,7] Nevertheless, it is difficult to directly measure the property of cathode sheath, which is thin and transient. As an alternative method, Schröder and Haferkamp [8] have measured the density distribution of the emanating shock wave after discharge by interferometry, and compared it with the gas dynamic model calculations to determine the energy deposition in the sheath.…”

“…To calculate the cathode sheath temperature, the evolution of shock wave in the chamber is simplified by the shock tube model. As the flow field evolution in the chamber is much slower than the transient discharge, [7] we assume that the shock wave is generated after the discharge completely. The differences in energy deposition make the distributions of pressure and temperature much different in cathode sheath and plasma bulk with functions like the driver section and the driven section of shock tube respectively.…”