Study of a Photoswitched Discharge for Excimer Laser

Abstract

Since their discovery (Searles and Hart, 1975, Ewing and Brau, 1975), the rare-gas halide lasers have been developed rapidly.In discharge-pumped systems, many improvements in preionization (Lin and Levatter, 1979), laser mixture (Sze, 1979), impedance matching between the driving circuit and the discharge (Sarjeant et al., 1978, Long et al.,1983) and high repetition rates (Christensen, 1978) have led to systems delivering multi-joules pulses with an efficiency of a few percent, usable as industrial tools in such fields as microelectronics, photochemistry or material processing. For the most part of excimer lasers, first the high pressure mixture is preionized, and then a high voltage pulse is applied across the electrodes. In such classical schemes, good performances require to switch a large amount of current in a very short time. As a result, the limited lifetime of the switching component, usually a thyratron, induces an important problem of reliability.