Electron Kinetics of Weakly Ionized HF Plasmas I. Direct Treatment and Fourier Expansion

Abstract

AbstractIn this paper an analysis of the kinetic quantities of the electrons in the steady‐state HF neon plasma is performed by a time consuming direct solution of the time dependent electron Boltzmann equation up to the establishment of the periodic state. In particular, the reduction of the modulation degree and the phase shift with respect to the HF field of the isotropic distribution function and of some macroscopic electron quantities are systematically determined with increasing field frequency. Furthermore, using the Fourier expansion technique, an equation system for the Fourier coefficients of the isotropic distribution function was derived from the time dependent Boltzmann equation which immediately gives a description of the electron kinetics in the steadystate HF plasma. On the basis of this system the coupling of the harmonics of the isotropic distribution with its dc part was studied for different HF fields. In addition, appropriate conditions could be found which determine a field frequency limit above which the coupling impact of the harmonics on the determination of the dc part of the isotropic distribution may be neglected, making a simplified treatment of the electron kinetics possible. The exact determination of its validity limits and the systematic investigations on the basis of this simplified kinetics will be reported in a second paper.