Time-of-flight observation of electron swarm in methane

Abstract

This paper reports on the evolution of an isolated electron swarm, which is experimentally observed as spatial distributions at every moment. This observation is assumed to directly correspond to the conventional time-of-flight theory. We have measured the spatial distribution of electrons using a double-shutter technique in the drift tube, where a shutter electrode to collect electrons can be slid along the field ͑E / N͒ direction in order to capture a relative electron number at a certain range of location. As a typical parameter defined by this spatial distribution, the center-of-mass drift velocity ͑W r ͒ is determined for methane gas. The result is compared with the mean-arrival-time drift velocity ͑W m ͒ defined from the arriving electron number at fixed positions. We have also performed a theoretical analysis in which a Fourier transformed Boltzmann equation is solved to deduce both of the drift velocities from a dispersion relationship. The difference between W r and W m at high E / Ns ͑above 200 Td͒ is clearly ascertained in the experimental and theoretical investigations, which is attributable to the occurrence of ionization events.

Study of electron transport in hydrocarbon gases

“…4), the exact definition of some parameters and their measurement methods have been established. 21 Our study presents experimental parameters for the mean arrival-time drift velocity (W m ) and the Townsend effective ionization coefficient ( a) (including the separate result for the ionization coefficient a and the attachment coefficient g over a low range of E/N). The resultant data for the swarm parameters in the organic gases treated here can be used to predict quantitative properties of electron transport in the gases under the action of electric fields.…”

Data-driven discovery of electron continuity equations in electron swarm map for determining electron transport coefficients in argon

“…When the values of Q L and high-order transport coefficients are small, equation (36) indicates W r > W m when α T > 0. Such a relationship was observed in the electron swarm experiment in methane [33] as well as in the MCS in real gases [34,35] and model gases [36].…”

Electron Transport Properties in HSi(OC2H5)3Vapor

“…The experimental apparatus and procedure for the SST method are the same as those by Yoshida et al 21) After the experiments, the electron collision cross sections for TRIES were estimated by the Boltzmann equation analysis, referring to the cross sections of SiH 4 (Ohmori et al 22) ) and TEOS (Morgan et al 23) ), where the parameters appearing in both eqs. (1) and ( 2) are computed by solving the Fourier transformed Boltzmann equation with the Legendre polynomial six-term approximation (e.g., Hasegawa et al 24) ). The cross sections are determined by feedback procedures so as to fit the calculated parameters to the experimental ones within a certain degree of difference.…”