Abstract
A spark-gap preionisation system is studied in a laser pumped by a generator with an inductive energy storage and a semiconductor current interrupter. This preionisation system was shown to produce, in addition to UV and VUV radiation, soft X-ray pulses with photon energies higher than 5 keV. The X-ray radiation was recorded from the plasma of a volume discharge in nitrogen, helium, and a NF3–helium mixture. Shortening the rise time of the voltage pulse applied across the spark gaps of the preionisation system and the main gap was demonstrated to increase the radiation pulse duration and to improve the efficiency of exciplex lasers and of several other dense-gas lasers.