Noise temperature data on low pressure argon discharges

Measured noise temperatures for argon discharges at pressures from 1 to 40 mmHg in tubes with 0.63-cm inner radius are presented. In general, the results agree with theoretical electron temperatures, but disagree with previously published data for similar pressure-radius products. It is suggested that similarity rules should be applied with caution. Large audio-frequency disturbances were found to originate in the anode region at all pressures; variations in the plasma impedance were synchronized with these disturbances.