The Friction and Diffusion Coefficients with Maxwellian Scatters

Abstract

The Fokker-Planck coefficients for Coulomb interaction, or the friction coefficient (the average change in velocity) and the diffusion coefficient , are evaluated by an appropriate variable change technique. This approach reduces the five-fold integral expressions of the Fokker-Planck coefficients to one-fold integral without meeting the divergence difficulties. A new Debye cutoff parameter , instead of the customary cutoff avoids the error incurred through the customary neglecting of velocity dependence of the Coulomb logarithm. The dominant terms of the new results are similar to Chandrasekhar's results. A non-dominant term, which can exceed the dominant one in the case of is added for .