Monte Carlo Simulation of Electron Swarm Parameters in the SF₆/CF₄ Gas Mixtures

Abstract

We use a binary gas mixture Monte Carlo simulation model to calculate the electron transport parameters in SF 6 /CF 4 mixtures in uniform electric fields. Electron collision cross section sets are assembled on the basis of the critical survey of Christophorou et al. [J. Phys. Chem. Ref. Data 25 (1996) 1341] for CF 4 and Itoh et al. [J. Phys. D 21 (1988) 922] for SF 6 . The electron swarm parameters studied here are electron drift velocity, effective ionization coefficient and the ratio of longitudinal diffusion coefficient to mobility for the density-reduced electric field strength (E=N) in the range of 140 E=N 600 Td (1 Td = 10 À17 V cm 2 ); the SF 6 contents in the gas mixtures are 0, 20, 50, and 100%. The differences between the present calculated and measured values of Urquijo et al. [J. Phys. D 36 (2003) 3132] do not exceed the overall measured uncertainties for the parameters. To our knowledge, only Urquijo et al. [J. Phys. D 36 (2003) 3132] have measured the electron swarm parameters in SF 6 /CF 4 gas mixtures by a pulsed Townsend technique; however, simulation results have scarcely been reported.

SF6-alternative gases for application in gas-insulated switchgear

“…Steady-state Townsend (SST) and pulsed Townsend (PT) are two main experimental methods to measure electron transport parameters of gases, such as the ionization reaction rate coefficient α, the attachment reaction rate coefficient η and the electron drift velocity υ e , at room temperature [100]. Meanwhile, Boltzmann and Monte Carlo methods [29,101,102] are also used in simulation of electron transport parameters and the critical reduced electric field strength (E/N) cr . Generally, according to published studies, it is considered that N 2 or dry air is suitable for MV applications, while CO 2 and its mixtures possess great potential to be used in HV equipment.…”

CF4 Capture and Separation of CF4–SF6 and CF4–N2 Fluid Mixtures Using Selected Carbon Nanoporous Materials and Metal–Organic Frameworks: A Computational Study

“…The recovery and recycle of CF 4 are also highly important in mixtures with SF 6 having significant technological applications. Mixtures of CF 4 with SF 6 are used as insulating and arc-quenching media − at very low temperatures, down to −50 °C, especially in circuit breakers operating at these low temperatures . In these mixtures, CF 4 is added in order to avoid liquefaction of SF 6 gas at low temperatures.…”

Effective ionisation coefficients and critical breakdown electric field of CO2at elevated temperature: effect of excited states and ion kinetics

“…Here α eff is known as the effective Townsend ionization coefficient, expressed in m −1 , and defined as the number of electrons produced by one electron per unit length in the direction of the electric field. Critical reduced breakdown electric field strengths, at which the production and loss of charged species is exactly balanced and the effective ionization coefficient is zero, have been widely studied using both numerical calculations and experiments for various gases at room temperature [6][7][8][9][10][11][12][13][14][15][16][17]. However, detailed experimental investigations for hot gases have rarely been performed because these phenomena are complicated and therefore difficult to treat at elevated temperature.…”