UNIFORM ELECTRICAL EXCITATION OF LARGE-VOLUME HIGH-PRESSURE NEAR-SONIC CO2–N2–He FLOWSTREAM

Abstract

Aerodynamic techniques are described whereby continuous electric discharges may be produced uniformly over large volumes in near‐sonic CO₂–N₂–He flowstreams. Experiment shows that discharge input power scales with pressure for the range 30–150 Torr thereby maintaining a fixed specific power load of ≃ 270 kW/lb(mass)/sec, while diffuse discharges at 1‐atm pressure have been achieved at much lower specific power levels. Discharges occupying 4.5‐ and 43‐liter volumes with the corresponding flowrates 2700 and 28 000 cfm are each uniform over their entire volumes, indicating that volume‐flowrate scaling is not affected by wall diffusion. Using these discharge techniques, a closed cycle 28 000‐cfm 5.6 × 76 × 100‐cm³ CO₂ laser amplifier channel has been designed to produce in excess of 20 kW laser power, continuous. In preliminary experiments small‐signal gains reaching 1.9%/cm have been measured transversely across both cold and hot extremities of this device.