Numerical model for tearing modes in toroidal plasmas with circular cross section

Numerical model using the implicit difference method for the resistive magnetohydrodynamic (MHD) modes is described. The model without the incompressibility assumption and the expansion with respect to the inverse aspect ratio is applicable to the toroidal plasmas with axial symmetry and the fixed boundary of the circular cross section. The Moebius conformal mapping is used as the coordinates and the Fourier expansions in poloidcal and toroidal angles are employed. The calculations are compared with the results of the reduced set of equations for tokamaks. The method presented is to be extended to the analyses of the nonlinear interactions of the resistive modes in the toroidal plasmas with the finite aspect ratio. (author)