The expression for the Coulomb collision term in Fokker-Planck form is revised and generalized to the case of interaction of trace impurity ions with a fluid-like background plasma. The velocity distribution of the background ions is assumed as a Maxwellian in the 13 moment expansion, with parameters determined from a fluid consideration. The impurities are described in the framework of a linear drift kinetic test particle model. The new Coulomb term is suitable for linear Monte Carlo procedures and provides both a correct treatment of thermalization of the test particles and an accurate kinetic description of velocity distribution effects on the thermal and frictional forces.
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