Divergence of radiation from an electric-discharge XeCl laser operating in the pulse-periodic regime

Investigations were made of a pulse-periodic electric-discharge XeCl laser with two types of resonator. When an unstable confocal resonator with a magnification of $M$ = 12 was used, the divergence exceeded the diffraction limit by a factor of only 2–3 and there was only a slight ($\lesssim$ 30%) reduction in the output energy relative to that from a laser with a plane–plane resonator. The influence of the pulse repetition frequency on the radiation divergence was investigated for helium- and neon-containing gas mixtures. A dependence of the divergence on the pulse repetition frequency was discovered. A theoretical interpretation is given of the results of the experiments.