Simulation of electron swarms in SF₆in uniform E*B fields

Abstract

Reports electron swarm parameters in SF6 in uniform E*B fields employing a Monte Carlo simulation technique. The parameters studied are transverse and perpendicular drift velocities, magnetic deflection angle, collision frequency, mean energy and effective ionization coefficients for 30<or=E/p<or=200 V cm-1 Torr-1 and 0<or=B/p<or=6*10 T Torr-1. At a given E/p, application of a magnetic field causes decreases in the transverse drift velocity, the mean energy and the effective ionization coefficient. The validity of the effective reduced electric field concept is also investigated for the evaluated collision frequency, mean energy and effective ionization coefficient.

Transport Coefficients in Crossed E and B Fields: Empirical Relations and Nonconservative Collisional Effects

“…The generalisation of Tonks' theorem (i.e., the drift speed in the E × B direction is equal to the drift speed in an electricfield-only situation, with E = E e [38,39]) to nonconservative processes follows directly. The utility of the effective electric field concept has been justified by Dincer [6] using Monte Carlo simulation in the case of electron swarms in SF 6 . We note, however, that in the case of spatial inhomogeneity, no such simple relation as (23) exists, as is shown in the following section.…”

“…Ness [16] gave the first comprehensive theoretical prescription applicable to nonconservative collisions and there have been subsequent investigations of nonconservative effects for crossed fields in both model and real gases [18,19]. Dincer [6] investigated electron transport in SF 6 in the crossed field configuration, where both attachment and ionization processes are operative in spatially homogeneous condition using Monte Carlo simulation. Petrovic et al [23, 40a, 40b] have studied nonconservative collision effects on electron transport parameters in spatially uniform conditions in an orthogonal field configuration using momentum transfer theory [15].…”

The drift velocity vector of electron swarms in crossed electric and magnetic fields

“…The deviation is attributed rather to the fact that the collision frequency of each electron is actually energy-dependent although the macroscopic collision frequency which is the integrated value over the swarm seems constant. Dincer (1993) showed that the ionization coeécient in SF 6 is a function of the eãective reduced electric åeld (E=N ) eã = (E=N ) cos í , where í is the Hall angle. A similar situation is found also in F 2 .…”

“…Dincer and Gokmen (1992) measured electrical breakdown properties of SF 6 , and subsequently Dincer (1993) and Milsom (1993) calculated electron transport coeécients in SF 6 employing a Monte Carlo method. Shimura and Makabe (1993) analyzed the electron velocity distribution in Ar using a Boltzmann equation technique.…”

The behavior of N/sub 2/ + SF/sub 6/ gas mixtures subjected to orthogonal electric and magnetic fields

“…Because the model for the electron swarm and the Monte-Carlo technique used for calculating the critical fields have been described by the authors elsewhere [11,15,17,18], only a brief description of the method is in order. The technique is based on a free-flighttime approach in which the three-body collisions and Coulomb interactions are neglected based on the assumption that the gas is weakly ionized.…”