RF excited Microgap Discharge in He-Xe-HCl gas mixture

The design of (quasi-) continuous wave excimer lasers remains an ambitious goal for many years. Several approaches are thought to be suitable for that. It was demonstrated recently that in microdischarges the pumping with a very high specific CW power deposition (tens or hundreds kW/cm^3) produces at atmospheric pressure non-thermal plasmas. Still the manufacturing of a sufficiently long array of microdischarges represents a major technical problem. We show that transverse RF sustained discharges at supra-atmospheric pressures can be considered as a serious alternative for to the above mentioned technique. In this work we studied the properties of the RF discharge in He-Xe-HCl (1000:10:1) gas mixture for the gas pressures up to 1.4 bar. RF driven discharges in a frequency range of f = 60-200 MHz were successfully applied for the excitation of fairly long and homogeneous discharges (up to 37 cm). The inter-electrode distance of 160 mm was needed to run stable discharges at pressures of 1.4 bar. Fluorescence signal at 308 nm was measured for different input powers, gas pressures and electrode gaps. The estimated gain value is comparable with those obtained by microdischarge excitation. The experimental data are in a good agreement with the numeric results of the simulation based on our fluid model of the RF discharge. Prospects for further improvement of the design of quasi-CW excimer lasers are discussed.