Model Calculations of Negative Differential Conductivity in Gases

Abstract

Negative differential conductivity in gases has been studied using simple models of elastic and inelastic collision cross sections for electron scattering. The use of such models has demonstrated features of the cross sections that lead to the phenomenon, and shown that it can occur without a Ramsauer-Townsend minimum (and even without a sharply rising momentum-transfer cross section) or a special combination of inelastic cross sections.

Multiterm solution of a generalized Boltzmann kinetic equation for electron and positron transport in structured and soft condensed matter

“…This phenomenon has also been observed in other electron calculations [17]. In contrast to other forms of NDC for electron transport in dilute gases [39][40][41], this form does not require inelastic scattering processes or nonconservative processes such as annihilation and attachment [12,13]. In [14], the following condition for the existence of structure-induced NDC was presented:…”

A Monte Carlo study of photoelectron extraction efficiency from CsI photocathodes into Xe–CH4 and Ne–CH4 mixtures

“…Although the cross-sections used in the present work may not guarantee the completeness established by the so called swarm method as usually required in gas discharge and plasma physics [77][78][79][80][81], figures 2 to 4 show that in the low E/N range relevant for the present work (drift fields E/N~<20Td near the photocathode), our calculations give sufficiently accurate drift parameters. In particular, they reproduce well known characteristic effects very sensitive to cross-sections, namely the anisotropy of diffusion when electrons drift under an electric field [36,[82][83][84][85], and negative differential conductivity [81,[86][87][88][89][90]. The NDC effect -a decrease of drift velocity with increasing E/N -may be observed for instance in some mixtures of noble gases with molecular additives (e.g.…”

Electron attachment properties of c-C4F8O in different environments

“…The same effect was observed in [36] for small admixtures about 0.5% of octafluorocyclobutane c-C 4 F 8 in Ar. This decrease of the drift velocity, often referred to as negative differential mobility or negative differential conductivity, has been studied extensively [37,38,39] and is considered common for diluted mixtures of molecular gases in Ar.…”