
Author(s):
A. Ito, N. Nakajima

Title:
Equilibrium and Stability of Highbeta Toroidal Plasmas with Toroidal and Poloidal Flow in Reduced Magnetohydrodynamic Models

Date of publication:
Nov. 2010

Key words:
22 IAEA Fusion Energy Conference, THC/P503

Abstract:
Effects of flow, finite ion temperature and pressure anisotropy on equilibrium and stability of a highbeta toroidal plasma are studied in the framework of reduced magnetohydrodynamics (MHD). A set of reduced equilibrium equations for highbeta tokamaks with toroidal and poloidal flow comparable to the poloidal sound velocity is derived in a unified form of singlefluid and Hall MHD models and a twofluid MHD model with ion finite Larmor radius (FLR) terms. Pressure anisotropy is introduced with equations for the parallel heat flux which are closed by a fluid closure model. It is solved analytically for the singlefluid model and the solutions shows complicated characteristics in the region around the poloidal sound velocity due to pressure anisotropy and the parallel heat flux. Numerical solutions are found by using the finite element method for the twofluid model with FLR effects in the case of isotropic, adiabatic pressure and indicate the following features of twofluid equilibria: the isosurfaces of the magnetic flux, the pressure and the ion stream function do not coincide with each other, and the solutions depend on the sign of the radial electric field. Reduced singlefluid MHD equations with time evolution that are consistent with the above equilibria are also derived in order to study their stability. They conserve the energy up to the order required by the equilibria.
