Ambipolar Diffusion Measurements in Low Pressure Rare Gas Afterglows

Microwave resonant cavity techniques have been used to investigate the afterglows of low pressure pulsed discharges in argon, helium and neon. The values for the reduced mobilities of the various ions in their parent gases, derived from the ambipolar diffusion coefficients, disagree with previous microwave measurements but are in close agreement with the accepted drift tube values which cover a wide range of E/p . The mobilities of the various ions in their own gases were found to be He + , 10.2; He 2 + , 20.3; Ne + , 3.9; Ne 2 + , 7.5; Ar + , 1.4; Ar 2 + , 2.6 cm 2 v -1 sec -1 . The average energy of electrons and ions, during measurement, was 0.04 ev. Finally, diffusion cooling was observed in argon and neon.