Electron-beam-initiated chemical laser in SF6–H2 mixtures

Abstract

A 3.5‐cm × 35‐cm planar field emission electron beam diode, producing a total beam current of 4.65 kA of 120‐keV electrons in 26‐nsec pulses was used to initiate the reaction of F with H₂ in SF₆–H₂ mixtures. From an optical volume of approximately 1 liter we observed HF laser pulses of 20–30 nsec duration with a maximum energy of 0.2 J at 450 Torr. The application of a secondary potential, very near the self‐breakdown limit of the gas, to the laser medium increased the laser output by only a factor of 2. Numerical analysis of the experiments without secondary field shows that 2.7 × 10⁴ F atoms are produced by each 120‐keV electron fully stopped in the gas. This corresponds to an energy of 4.5 eV required for the production of one F atom from SF₆ by high‐energy electrons. The conversion efficiency of electron beam energy input to the medium to laser output energy was 5.2%.