Temperature Relaxation in a Fully Ionized Plasma

The times for relaxation of anisotropic ion or electron temperatures to isotropy, and for relaxation of different ion and electron temperatures to equilibrium, are calculated using the plasma kinetic equation including dynamic shielding. It is shown that, in contradiction to the results (or assumptions) of previous analyses, electron—ion interactions can be more important than interactions between particles of the same species in the relaxation of an anisotropic distribution. The meaning of relaxation time is discussed and a new time for relaxation is introduced for the problem of the relaxation of electron and ion temperatures that are initially greatly different. Detailed numerical computations are presented for various cases of special interest.