EVALUATION OF DIFFUSION-COEFFICIENT OF ELECTRONS IN A MERCURY-ARC PLASMA BY MEASUREMENT OF DIFFUSION CURRENT

By measuring the diffusion current and the corresponding diffusion voltage in an arc plasma, a method has been proposed to measure the diffusion coefficient of electrons in mercury vapour utilising the expression of radial distribution function of conductivity as introduced by Ghosal et al.[Int J Electron (GB), 44(1978)404]. Results are reported here for arc current varying from 2 to 5 A and for three pressures 0.075, 0.1 and 0.13 torr. The diffusion coefficient of electrons in mercury vapour is found to be of the order of 10(3) cm2/s which increases with the increase of current and decreases with the increase of pressure. A qualitative explanation for the observed variation has been provided.