Back Diffusion of Electrons in Ar, $\hbox{SF}_{6}$, and $\hbox{Ar} + \hbox{SF}_{6}$ Binary Mixtures

Abstract

The back diffusion processes in Ar, SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> , and Ar + SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> binary mixtures are analyzed by a Monte Carlo simulation method employing realistic collision cross sections of the respective component gases in the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> range from 50 to 500 Td. The escape factors in pure Ar are always higher than that of those in pure SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> , and as the SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> content in the binary mixture increases, the escape factors decrease accordingly. Furthermore, the number of collisions observed for the backscattered electrons before returning to cathode in SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> are smaller than that of those in Ar, and as the SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> content in the binary mixture increases, the mean number of collisions of the backscattered electrons decrease accordingly.