SF6+H2 laser pumped by a high-current relativistic electron beam

Attention is given to the efficiency of the interaction of the relativistic electron beam with the gas mixture. The apparatus comprises an electron accelerator, a laser cell, an optical resonator, a gas injection system, and a system for detecting the characteristics of the electron beam and laser beam. The energy of the beam electrons in the laser cell is approximately 1.5 MeV; the beam current is approximately 15 kA, and the current pulse length is approximately 40 ns. A figure is included showing the beam currents transported through the chamber at various distances from the injection point. Results are presented for four pressures of the SF6:H2:Ar = 7:1:6 mixture. It is found that above 0.3 atm (the laser output energy being maximized at this pressure) the region of the laser cell filled by the beam begins to contract significantly, causing a decrease in the laser output energy. The electrical efficiency of the system, that is, the ratio of the laser output energy to the energy deposited in the gas by the beam, is 5.6 percent at a maximum output energy of 8.5 J. At pressures below the optimum pressure, the efficiency increases to 8-10 percent for all mixtures.