Plasma turbulence. II

Presents the major theories of plasma turbulence and points out the differences and similarities in the mathematical formulations. The theories of Rudakov-Tsytovich and Weinstock-Dupree seems to be to some extent identical, at least in this operator formulation, except for the methods of solution of the final equations. The theory of Balescu-Misguich contains additional terms by explicit introduction of memory effects. Their effect upon diffusion coefficients for various spectra (and thus on the evolution of the distribution function) is being investigated and will be published elsewhere. Although formally they are capable of handling strong turbulence, mathematical difficulties limit their applicability to weak turbulent fields. Also the time scale of their validity is not always clear and one can think of weak fields acting for a long time giving rise to density fluctuations and trapping of the waves, an effect which belongs more properly to strong turbulence. Strong turbulence, at this time, is, however, only a partially explored subject. (Auth.)