Hybrid simulation of space plasmas: Models with massless fluid representation of electrons. III. Shockless discontinuities

This is the third article in a series of reviews on hybrid simulation of low-frequency processes in space plasmas. It deals with shockless (contact, tangential, and rotational) discontinuities. A hybrid model is described with ions represented by particles and electrons by a massless fluid. The Hamiltonian scheme for the numerical implementation of this model is discussed in detail. The first part of the article provides basic background information, which covers MHD models (ideal, resistive, and Hall models) as well as a classification of shockless discontinuities and their main properties. The review part of the article surveys the literature on simulation of the structure and properties of nonpropagating (contact and tangential) discontinuities and the structure of the magnetopause as a complex domain consisting of multiple discontinuities and waves. We also review the literature on hybrid simulation of rotational discontinuities and the structure of the reconnection layer-the configuration of the reconnecting magnetic forcelines in the dayside magnetopause and in the distant magnetotail. The concluding sections examine studies on hybrid simulation of the penetration of plasma inhomogeneities from the solar wind into the magnetosphere. The following issues are considered: the interaction of the bow shock with interplanetary discontinuities; the "hot flow anomaly"; the interaction of pressure pulses with the bow shock; impulsive plasma penetration through a tangential discontinuity (the magnetopause) as a result of a "collision" of a magnetosheath plasmoid (plasma current sheet) with the magnetopause. Copyright 2001 Plenum Publishing Corporation.