Optical quality of pulsed electron-beam sustained lasers

The optical quality of a pulsed atmospheric CO(2) electric laser is investigated. The density disturbances in the optical cavity are caused by edge waves originating at the anode and cathode. Volumetric heating effects associated with a nonuniform electric discharge are shown to be negligible. The disturbance propagating from the cathode results from a discontinuity in the spatial heating and the cathode fall. The wave emanating from the anode is associated with the presence of a solid surface that prevents the gas from expanding. As a result, lasers have to be designed with pulse durations much less than the acoustic transit time across the cavity.