A 650J E-BEAM-PUMPED ATOMIC XENON-LASER

The atomic xenon laser has been scaled from the 80 J per pulse output energy level reported by Basov et at. [1] to 650 J, using a large two-sided e-beam-pumped device. The extraction volume dimensions were 0.5 m · 0.65 m · 3 m. The gas was pumped at a temporally and spatially averaged rate of 70 kW/cm3, and the spatially averaged specific input energy was 115 J/L. An aluminum rear reflector and an uncoated, fused silica output coupler were aligned to form a plane-parallel optical resonator. Output energy measurements were made with a full-aperture calorimeter, and the temporal pulse shape of the 1.73 μm laser radiation was recorded with a spectrally filtered germanium photodiode. The device was operated with argon-xenon gas mixtures at pressures ranging from 20 to 40 psia at a temperature of 23°C, and the xenon mole fraction was empirically optimized. The maximum output energy of 650 J was obtained at an intrinsic efficiency (output energy divided by energy deposited in gas) of 0.57%. A higher efficiency of 0.85% was achieved by using a shorter e-beam pulse, at a reduced laser output energy of 495 J. Laser output which began shortly after the start of the e-beam pulse continued well beyond the termination of that pulse, decaying at an exponential rate with an e-fold time of 1.8 μs. A possible explanation for the observed laser pulse shape which is discussed is the existence of a long-lived metastable state which is populated early in the excitation pulse and serves as an energy reservoir for continued population of the upper laser level during and after the excitation pulse. © 1990 IEEE