P-10 · The influence of edge viscosity on plasma instabilitiesLudwig, Gerson1) Abstract The interface between the plasma edge and its surroundings affect both the structure of plasma instabilities and the quality of confinement. According to well established procedures in MHD theory, the boundary conditions for the analysis of free-boundary instabilities is set by the flow of energy, mass, or flux across the boundary. However, ideal MHD disregards the role of viscosity in fluid motion. Even considering that viscosity effects are negligible for large scale instabilities in the core of high temperature plasmas, the effect of viscosity in the boundary is similar to surface tension, having a strong influence on high order modes of oscillation near the plasma edge. In water the balance between the forces of gravity and surface tension marks the transition from gravity waves to capillary waves. This paper reports two instances where edge viscosity may be important in the behavior of natural as well as laboratory plasmas.
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