Neoclassical toroidal viscous effects on the resonant layer responses to non-axisymmetric magnetic perturbations

Non-axisymmetric magnetic perturbations arising in a tokamak can induce complex plasma responses near the resonant surface. In this region, the plasma will no longer adhere to ideal MHD and will instead demand the reconnection of magnetic field lines which can grow and significantly alter the plasma profile. The resonant layer response can be characterized completely in a linear regime by a single parameter called the inner-layer Δ. Here we apply a two-fluid drift-MHD model to identify the scaling of Δ while including the effects of neoclassical toroidal viscosity (NTV). Previous works have modeled these effects using phenomenological flow damping. We seek to obtain the first order contribution of the effects using the divergence of the stress tensor and to then identify the parameter regimes in which the contribution is most significant on our calculation of Δ, since this will in turn alter the field penetration threshold which is important to understand in MHD stability. The Δ calculations have also been used to predict the field penetration threshold by matching to outer-layer response solutions in general perturbed equilibrium code (GPEC), and validate the predictions over the tokamak error field database.