Once again on the role of UV illumination in non-chain electric-discharge HF(DF) lasers

The influence of UV illumination of a discharge gap on the stability and homogeneity of a volume self-sustained discharge (VSD) in working mixtures (SF₆ with hydrocarbons) of a non-chain HF laser is studied in broad ranges of the discharge-current duration and the energy deposition. It is shown that the UV illumination in lasers with the cathode area S≤300 cm² and in lasers with the current-pulse duration T≤150 ns stabilises the delay time and the voltage amplitude of the electric breakdown of the gap and leads to the levelling (due to photoeffect) of the VSD current density distribution over the cathode surface. The volume preionisation of the working mixture of a non-chain HF laser by UV radiation is impossible because of strong absorption of this radiation by SF₆. There is no need in UV illumination in wide-aperture, large-volume lasers when small-scale (~50 μm) inhomogeneities are present on the cathode surface.