Efficient preionisation in XeCl lasers

It is shown that preionisation in XeCl lasers with different pumping systems is most efficient near the instant of the ionisation-attachment equilibrium when the electron concentration varies in the prebreakdown stage of the discharge. The influence of the rate of increase in the discharge voltage on the duration of the optimum time interval and on the preionisation efficiency was determined. Under optimised conditions in an XeCl laser with an active volume of 1 litre, it was sufficient to introduce an energy of 25 mJ into the surface discharge of a preioniser in order to obtain a laser output energy of 3 J. A compact XeCl laser with UV preionisation by a surface discharge was developed to provide an average radiation power of ~ 500 W for different combinations of the energy, duration, and repetition rate of the pump pulses.