Minimisation of the radiation divergence in an XeCl laser with a 12 × 16 cm aperture

An experimental investigation was made of the spatial and energy characteristics of an XeCl laser with a 12 cm × 16 cm aperture, excited by an electron beam. It was found that the laser radiation divergence was minimal only when the amplified spontaneous radiation fluxes were reduced in an unstable cavity with generalised parameters g_1,2 ≥ 1. A laser beam with an energy 10 J and a divergence less than 5 × 10^–5 rad at half the energy was obtained. For a part of the beam 75 mm in diameter, the proportion of the energy in the diffraction core was 50%.