Interpretation of Cyclotron Resonance Line Shapes in Slightly Ionized Gases

Abstract

The cyclotron resonance line shape for the absorption of microwave power by electrons in a slightly ionized gas is analyzed in terms of the energy dependence of the electron-collision frequency for three different electron energy distribution functions. These calculations also include results using measured collision frequencies for collisions between electrons and four netural gases, helium, argon, nitrogen, and oxygen. Moreover, the effects on the deduced collision frequency caused by the presence of admixed broadening agents such as ions is investigated. Because the line shape is strongly influenced by the energy dependence of the collision frequency, the calculation of collision frequencies from linewidth data requires an accurate knowledge of the variation of collision frequency with energy. The examples which are given indicate that extreme care must be exercised if reliable interpretations of experimental data are to be obtained.