Active Element Diameter and Uranium Coating Thickness Effect on Nuclear-Pumped Gas-Laser Efficiency

A comparative experimental study is performed of the lasing characteristics of a laser operating on the 2.03 mu m transition of atomic xenon with direct, uranium fission fragment, pumping of the active medium in the form of a mixture of the gases He, Ar, and Xe in cylindrical active elements of two types, differing by the diameter and thickness of the uranium coating. It is shown that a three-fold reduction of the diameter and coating thickness of the active element results in a 1.5-fold increase of the laser efficiency in terms of energy. One possible explanation of this effect is examined: a source of internal losses of laser radiation present in the active medium due to scattering by radial acoustic gas-density waves excited by the pump pulse.