Momentum-Transfer Cross Sections and Conductivity Ratios for Low-Energy Electrons in He, Ne, Kr, and Xe

Abstract

Conductivity ratios have been measured in weakly ionized afterglows of repetitively pulsed, electrodeless, rf discharges in helium, neon, krypton, and xenon using a microwave resonant cavity (2.7 GHz). Maxwellian electron-energy distributions were obtained at temperatures from 300°K to 10 000°K, as measured with a gated microwave radiometer (4 GHz), Momentumtransfer cross sections for electrons of energy up to 2 eV in neon, krypton, and xenon were determined from the measured conductivity ratios by an iterative procedure. The results in helium support the momentum-transfer cross section determined from the electron-beam experiments of Golden and Bandel. Those for neon indicate a scattering length of + O.2O« 0 . The momentum-transfer cross sections for krypton and xenon agree best with, but are generally lower than, those of Frost and Phelps and indicate a deeper (approximately 2.5 times) Ramsauer minimum. An experimental check of the theoretical electron-ion collision frequency for highfrequency, low-temperature conditions has been made. 1 1 FROST \ \\ \K v\ \ \ J L.

All-order relativistic many-body theory of low-energy electron-atom scattering

“…σ MT [39] 0.249 Phase shift analysis [43] 0.22 Polarized orbital [44] 0.201 Expt. (condctivity ratio, Sashkatchewan) σ MT [45] 0.20 Expt. (drift velocity, ANU) σ MT [40] 0.24 Expt.…”

Momentum Transfer Cross Section for Electrons in Krypton Derived from Measurements of the Drift Velocity in H2?Kr Mixtures

“…7. The cross section of Frost and Phelps (1964) was derived from measurements of drift velocities in pure krypton, while Hoffmann and Skarsgard (1969) used measurements of microwave conductivity ratios. Hunter et al (1987) have suggested that the drift velocity measurements used by Frost and Phelps are in error due to the presence of impurities (Section 2).…”

High Sensitivity Microwave Gated Radiometer for Low Temperature Plasma Afterglow Studies

“…(14). In fact, such a procedure would be very time consuming, owing to the very long integration time, and we prefer to measure T p by linear interpolation between two temperatures Tstd for which l1y is first negative, then positive.1 5…”