Plasma rotation effects on Neoclassical tearing modes

Abstract

The effect of an equilibrium sheared flow on the nonlinear evolution of a neoclassical tearing mode is investigated by estimating the influence it has on the inner and outer layer dynamics of the mode. Two complementary approaches are adopted. A generalized Rutherford model calculation is carried out to estimate the flow contributions to the polarization current term in the inner layer. For the outer layer,flow induced changes in the stability parameter Δ` are estimated with the help of a 3D initial value reduced MHD code (NEAR). For realistic parameters it is found that the outer layer modification is the dominant one and the scaling of Δ` with the flow shear parameter appears to agree with recent experimental observations.