Power loading and extraction on a large CW CO2 atmospheric EDL

The performance of a large atmospheric, subsonic, continuous wave, carbon dioxide, electric discharge laser sustained by an electron beam is presented. For power loadings as high as 210 kJ/lb mass flow, into the 8:7:1:0.3 (He:N2:CO2:O2) gas, small signal gain and lasing efficiency were improved with different cathode arrangements by reducing the discharge spreading. More than 100 kW can be routinely extracted for cavity power loadings of 2.0 MW. The 100% modulation by flux output oscillations of 10 to 200 kHz has been documented for different cathode and resonator configurations. Due to the large flux oscillations, direct electrical efficiencies of only 3 to 7% have been measured. Farfield beam quality measurements imply a 1.04 times an ideal, diffraction limited beam, despite the flux oscillations.