Electric Field Correlation and Plasma Dynamics

The correlation function for the electric field in a fully ionized plasma is derived, and its application to the problem of finding the force on a charge moving slowly through a plasma is described. The correlation function is evaluated for a plasma with and without a magnetic field, and this function is then converted to the spectrum of the mean-square fluctuation in the random electric field. The application of the generalized fluctuation-dissipation theorem gives the mean force on a slowly moving test charge. The relation of this to other treatments is briefly discussed.