Efficient preionisation in XeCl lasers

It is shown that preionisation in XeCl lasers with different pumping system s is most efficient near the instant of the ionisation-attachment equilibri um when the electron concentration varies in the prebreakdown stage of the discharge. The influence of the rate of increase in the discharge voltage o n the duration of the optimum time interval and on the preionisation effici ency was determined. Under optimised conditions in an XeCl laser with an ac tive volume of 1 litre, it was sufficient to introduce an energy of 25 mJ i nto 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 dis charge was developed to provide an average radiation power of similar to 50 0 W for different combinations of the energy, duration, and repetition rate of the pump pulses.