Variation with Electron Energy of the Collision Cross Section of Helium for Slow Electrons

The method of interaction of microwaves in gaseous discharge plasmas has been applied to a determination of the variation of the effective collision cross section for momentum transfer, qₘ, of helium atoms with electrons having energies from 0.04 to 0.4 ev. Under our experimental conditions with electron densities {}10¹⁰ electrons/cc, appropriate charge interactions have been considered. The mean fraction of excess energy loss of slow electrons upon collision, G, was found to be {~}2.7×{}10^-4, the expected 2m/M value.