ELECTRICAL AND LASER DIAGNOSTICS OF AN 80-KW SUPERSONIC CW CO ELECTRIC LASER

Detailed spatial and time-dependent measurements of the electrical parameters and the gas properties have been made on a high-average-power quasisteady supersonic cw carbon monoxide electron-beam-stabilized electric-discharge laser. The electrical and optical measurements show that there are major changes in the current-density distribution and in the supersonic flow field due to the high electric-discharge power input to the gas. A multipin resistor-ballasted electrode has been used to make the current density much more uniform, resulting in a factor-of-2 increase in electrical energy input and in laser power output. Small-signal gain measurements were made on the J=7 to J=13 rotational lines of the V=7 to V=6 CO vibrational transition at various locations in the electrical discharge. The measured rotational temperature showed that only 12% of the discharge power went into gas heating in the supersonic free-stream region. The measured small-signal gain was as high as 0.08 cm-1, the maximum electrical energy density input was 430 J/l amagat, and the maximum laser power density extracted was 120 kW/l.