GENERALIZED MHD FOR NUMERICAL STABILITY ANALYSIS OF HIGH-PERFORMANCE PLASMAS IN TOKAMAKS

A set of generalized magnetohydrodynamic (MHD) equations is formulated to accommodate the effects associated with high ion and electron temp eratures in high-performance plasmas in tokamaks. The effects of neocl assical bootstrap current, neoclassical ion viscosity, the ion finite Larmor radius effect and electron and ion drift effects are taken into account in two-fluid MHD equations together with gyroviscosity, paral lel viscosity, electron parallel inertia and collisionless ion heat fl ux. The ion velocity is identified as the plasma velocity, while the e lectron velocity is expressed in terms of the plasma velocity and elec tric current. Ion and electron momentum equations are combined to give the plasma momentum equation. The perpendicular (with respect to the equilibrium magnetic held) ion momentum equation is used as perpendicu lar Ohm's law and the parallel electron momentum equation-as parallel Ohm's law. Perpendicular Ohm's law allows for the Hall and ion drift e ffects. Parallel Ohm's law includes the electron drift effect, collisi onless skin effect and bootstrap current. In addition, both perpendicu lar and parallel Ohm's laws contain the resistivity. Due to the quasin eutrality condition, the ions and electrons are characterized by the s ame number density which is described by the ion continuity equation. On the other hand, the ion and electron temperatures are allowed to be different. The ion temperature is described by the ion energy equatio n allowing for the oblique heat flux, in addition to the perpendicular ion heat flux. The electron temperature is determined by the conditio n of high parallel electron heat conductivity. The ion and electron pa rallel viscosities are represented in a form valid for all the collisi onality regimes (Pfirsch-Schluter, plateau, and banana). An optimized form of the generalized MHD equations is then represented in terms of the toroidal coordinate system used in the JET equilibrium and stabili ty codes. The derived equations provide a basis for development of gen eralized MHD codes for numerical stability analysis of high-performanc e plasmas in tokamaks.