Theoretical and experimental study of low-temperature, capacitively coupled, radio-frequency helium plasmas

Abstract

A comparison is made of one-dimensional theoretical simulations with measured densities of electrons and He metastables in a Gaseous Electronics Conference Reference Cell. The theory attempts to be as ab initio and complete as necessary for describing a He plasma. The basic theoretical description incudes the time-dependent, electric-field-consistent Boltzmann equation for the electrons, inertial fluid equations for the heavy particles, and a multilevel model of the He excitations. The novel numerical algorithms are rapidly convergent. The experimental and theoretical absolute number densities are generally within a factor of 2 for both the electron plasma density and the metastable densities. In addition the spatial variation of the metastable populations (singlet and triplet) between the electrodes is well reproduced.