Electron Ionization, Attachment and Effective Ionization Coefficients, Drift Velocity in CF3I

Abstract

Trifluoroiodomethane ($CF_{3}I$) has high dielectric strength, at the same time reduced potential for global warming. The gas mixtures of $CF_{3}I$ has the greatest possibility to replace SF6 gas, such as with N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> . This paper selected a group of initial electron collision cross sections and modified them. In uniform electric field the path of movement of electrons in $CF_{3}I$ was simulated by Monte Carlo method. This paper calculated and analyzed electron drift velocity (Ve), the density-normalized ionization coefficients ($\alpha$/N), attachment coefficients ($\eta$/N) and effective ionization coefficients ($\alpha-\eta$)/N of $CF_{3}I$ by Monte Carlo method from 200 Td and 700 Td, 1 $Td =10^{-17} Vcm^{2}$. A group of final electron collision cross sections of $CF_{3}I$ are determined with little modifications. The values of Ve, $\alpha$/N, $\eta$/N and ($\alpha-\eta$)/N of $CF_{3}I$ are calculated by the formulas of a Pulsed Townsend discharge. From the calculation curves of ($\alpha-\eta$)/N for the $CF_{3}I$, the limiting field $(E/N)_{lim}$ value is $\alpha$/N equal to ($\eta$/N), the $(E/N)_{lim}$ of $CF_{3}I$ is about 441Td, higher than that of SF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> . The values of Ve, $\alpha/N, \eta/N, (\alpha-\eta)/N$ and $(E/N)_{lim}$ were good consistency with experiment and simulation data.