Operating characteristics of a high pressure DF-CO2CW chemical transfer laser

Interest in the DF-CO2transfer chemical laser (TCL) is stimulated by its potential to yield high specific efficiencies and high gain coefficients at high optical cavity pressures. Previous technology studies of the DF-CO2TCL for the most part have been limited to operation at cavity pressures of 100 torr or less. Recently, high pressure operation (233 torr) of a supersonic TCL has been achieved. Analytical predictions have indicated that a high velocity subsonic TCL could be operated at cavity pressures as high as 200 torr. Based upon these predictions, a small subsonic device has been designed and constructed specifically for operation at 200 torr. Parametric scanning gain and power extraction experiments have been conducted on this device at cavity pressures of 100, 140, and 200 torr. Parametric analytical studies at these cavity pressures have also been completed. The emphasis in the present work was placed on achieving flow conditions yielding the highest gain distributions. The device is found to produce 500 W of closed cavity power under optimum flow conditions. The performance of the device is well represented by the analysis with peak gains of 1.5 percent/cm being attained in typical experiments.