Suppression and saturation of error field-driven tearing mode for different magnetic shears in rotating plasmas

Effects of the equilibrium plasma flow on the error field-driven tearing mode are investigated in a two-dimensional resistive magnetohydrodynamics model. It is found that nonlinear suppression of the tearing mode is dominated by the interaction between the magnetic island and the error field rather than the local flow shear on rational surfaces. For a small magnetic shear case, a modest rigid flow can counteract the driving effect of the error field on the mode in the early nonlinear growth stage and transform the error field-driven mode to a general tearing mode. For a large magnetic shear case, after a fast linear growth, the tearing mode will enter a saturated process quickly before the locked mode occurs, and the mode saturation level is reduced due to the magnetic island and error field pushing each other. The threshold flow strength and its scaling analysis for the saturated modes are also given in this paper.