On the relation between the diffusion and mobility of gaseous ions moving in strong electric fields

Velocity moments and diffusion coefficients have been calculated theoretically for gaseous ions moving in strong electric fields, assuming ion-neutral interaction potentials of the form V(r) infinity r -n . The calculations confirm the approximate validity of the generalized Nernst-Townsend relations suggested by Wannier in 1953, and further show how the ion temperatures to be used with those relations can be estimated from experimental mobility data. The longitudinal diffusion coefficients predicted by these relations are in very satisfactory agreement with recently published experimental values for K + ions in He, Ne, Ar, N 2 and H 2 .