Jumps and bi-stabilities in electron energy distribution in Ar-N2post discharge plasma

Abstract

The electron energy distribution function (EEDF) in an afterglow ofa pulsed direct current discharge has been measured in an Ar:N2mixture by means of a time-resolved Langmuir probe technique. The vibrationaltemperature, Tv, of N2 molecules has also been experimentallyestimated. The results show that a correlation between an effective electrontemperature, Te, and Tv strongly varies with experimental conditions. Inparticular the conditions exist under which the rapid decrease from high tolow Te values is observed at some moment after the discharge pulse, whilethe vibrational temperature remains almost constant.The theoretical study of the EEDF in Ar:N2 afterglow plasma hasalso been made by the numerical solution of an appropriate Boltzmann equationby taking into account electron-electron collisions as well as superelasticvibrational and superelastic electronic collisions. Calculations show that fora given Tv the value of Te depends on the electron concentration, ne.Moreover, the ranges of ne and Tv exist, where two different solutions ofBoltzmann equations can be obtained.Finally, the comparison of the theoretical and experimental results isperformed and an explanation of the experimentally observed phenomenon is given.