Electron-molecule collision frequencies in a crossed electric and magnetic field

Abstract

Abstract Electron-molecule collision frequencies in nitrogen obtained from a conductivity method are found to agree well with earlier values obtained by other workers using the same method and with those from our recently developed equivalent pressure-gap procedure. Complete agreement with our theory is obtained at moderate equivalent reduced electric fields, whilst an experimental excess of 9% and a short fall of 27% at low and high (E/p)z respectively can be accounted for. Using the collision frequency values in a corrected formula predicted sparking voltages agree reasonably well with experiment. An error analysis shows that, because the equivalent pressure-gap procedure involves essentially a null method, far greater accuracy can be obtained than with the usual conductivity method, and consequently this should allow the angle, though small, through which an electron avalanche is tilted at atmospheric pressure by a crossed magnetic field to be accurately determined