An effective total cross section is calculated for elastic scattering of a monoenergetic beam of test particles in a plasma of arbitrary velocity distribution. Closed-form solutions are obtained for the special case of Maxwellian field particles taking into account small-angle scattering. The result are compared with those obtained using the Debye cutoff technique, and it is shown that such an arbitrary cutoff can lead to erroneous results in the effective cross section and can lead to different conclusions with regard to the relative importance of plasma ions and electrons in test-particle scattering.

• Received 2 April 1970

DOI:https://doi.org/10.1103/PhysRevA.2.2019