Parametric investigation of the small-signal gain in a large aperture e-beam controlled CO2 laser

In an e-beam controlled CO2 laser unit the spatial, temporal and spectral properties of the small-signal gain were investigated in a single pass geometry. A smooth spatial distribution was found with peak values of 2.9 %/cm near the cathode at 112.5 J/(1 bar). No reduction in the gain value was monitored up to repetition rates of 60 Hz when circulating the laser gas with a gas flow velocity of 100 m/s. A HeNe laser probe beam, being collinear to the CO2 laser beam, was used to monitor shock waves or mechanical vibrations by measuring its deflection. This investigation showed, that the small-signal gain measurements were not interfered by any disturbances.