New experimental techniques in the study of electron swarms in gases and their impact on the determination of low energy electron scattering cross sections

Abstract

A new generation of experiments to study the transport of electron swarms in gases has been developed to enable transport coefficients in pure electric and crossed electric and magnetic fields to be measured with a precision and completeness not previously achieved. The basic concepts and strengths of these new techniques are presented in this paper. The application of the new techniques to the study of electron transport in hydrogen and the subsequent Boltzmann analysis of the newly measured transport coefficients has led to a more refined and detailed understanding of elastic and inelastic low energy electron scattering for this elementary system. The availability of a new set of cross sections for hydrogen has made possible a study of transport coefficients in mixtures of hydrogen with argon, krypton and xenon. We have checked the compatibility of the published elastic momentum transfer cross sections for the heavy noble gases with the present measurements and derived new and much more reliable cross sections. A precise knowledge of these elementary systems is of the greatest importance as the heavy noble gases can be used as powerful probes for deriving the low energy cross sections for more complex molecules from swarm experiments.