Efficient quarter-Joule KrF laser with corona preionization

Abstract

Conventional KrF excimer lasers which are pumped by means of an avalanche discharge use the ultraviolet radiation generated by a series of spark discharges to preionize the discharge region in order to obtain a uniform discharge. This paper describes the design and operating characteristics of a KrF avalanche-discharge laser which uses a corona discharge to preionize the discharge region. Such a preionization technique, along with the unconventional use of Ne rather than He as the buffer gas, has enabled this laser to generate over <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\frac{1}/{4}</tex> J of output energy with an overall efficiency of 1.3 percent while operating at a pulse rate of 2 Hz. This same general technique has enabled us to generate 55 W of average power from a gas transport KrF laser operating at higher pulse rates.