Excitation frequency effects in a fast axial flow laser with a narrow gap slab RF discharge

A rectangular cross-section flow tube has been used in the fast axial gas flow configuration to investigate the excitation of the CO, laser with narrow electrode gap RF discharges. Stable discharges at a power density of 80 W.cm(-3) have been obtained, and the influence of excitation frequency in the range 27 to 125 MHz investigated. No localised thermal instability has been detected, and discharge shrinkage at high frequency is the main frequency dependent effect found. A beam power of 132 W.cm(-2) per discharge section has been obtained. Current density measurements have confirmed that conditions similar to planar waveguide, diffusion cooled CO2 lasers are attained.