Microinstabilities and anomalous transport

Abstract

The role of microinstabilities in producing dissipation and anomalous transport in collisionless shock waves is reviewed. Particular emphasis is placed on quasiturbulent magnetosonic shocks. The review follows the historical development of anomalous transport and the incorporation of the coefficients into multifluid and hybrid models. A general formalism is presented which describes in a self-consistent manner, the macroscopic transport produced by short wavelength microinstabilities. Similarities and differences with models incorporating classical transport are emphasized. The important instabilities and their transport properties are summarized. It is shown that multifluid simulations with anomalous transport explain many features of the experimental observations. The relevance of ion reflection and the necessity for kinetic ion description for supercritical shocks along with state of the art numerical studies are also discussed. The review concludes with a brief discussion of the piston shock problem and of quasi-parallel turbulent shocks.