Fission-pumped He-Xe and Ar-Xe infrared lasers

Quasi-cw lasing at the atomic-xenon transition during the pumping of He to Xe and Ar to Xe lasers by uranium fission fragments is reported, and some experimental results are shown. The time evolution of the thermal-neutron flux density, of the output power, and of the efficiency of the He to Xe laser at 2 atm is shown. The switch from helium to argon as the primary component of the gas mixture substantially lowers the lasing threshold and improves the energy parameters. The maximum efficiency of the He to Xe laser at 1.732 microns is found to be 2.4 percent, while that of the Ar to Xe laser is 3.6 percent. The practical efficiency found for the Ar to Xe laser is 2.2 percent, not far from the maximum value.