Nonlinear calculation of resistive modes in diffuse pinches

Numerical computation on the nonlinear evolution of the resistive tearing modes in diffuse pinch plasmas with the assumption of incompressibility is presented. The model is based on the cylindrical plasma including the effect of finite aspect ratio and the fluctuation quantities in the toroidal direction, which are neglected in the tokamak calculations. The finite difference method is used for the radial derivatives and the Fourier expansion series are used in other two periodic coordinates. The result on the tokamak shows the good agreement with the other work, and the results on the reversed field pinches show that the resistive modes excite the dynamo action for the toroidal flux. (author)