Microwave radiometric investigation of the electron velocity distribution in nitrogen plasmas

A microwave radiometric technique has been used to investigate the electron velocity distribution function f(v) during the afterglow of a pulsed N2 discharge. The technique involves comparing radiation temperature measurements taken around electron cyclotron resonance with theoretical computations based on a chosen form for f(v). Non-Maxwellian forms of f(v) displaying either an excess or depletion of high-energy electrons have been observed in the afterglow for different experimental conditions. The technique does not have the necessary sensitivity to determine f(v) during the active discharge.