A microwave generated plasma in a tunable resonant cavity for studies of turbulence in weakly ionized gases

A microwave plasma in argon is generated inside a pyrex tube by a 3-kW power supply in combination with a magnetron, wave guide, and a resonant cavity. The gas pressure is varied from 200 to 2000 mtorr, and the microwave output power is varied from 600 to 1200 W. Plasma parameters are determined by using a single Langmuir probe. Bias voltage and current characteristic curves are analyzed for the determination of electron temperature, density, and plasma potential. Electron density is found to be in the range of 1.4-7.6 /spl times/ 10/sup 11/ cm/sup -3/, electron temperature 4.2-6.2 eV, and plasma potential 22.6-35.6 volts. Turbulence in plasma emissions can now be studied in these various regimes using Ar I lines.