Determination of the non-ideal response of a high temperature tokamak plasma to a static external magnetic perturbation via asymptotic matching

Asymptotic matching techniques are used to calculate the response of a high temperature tokamak plasma with a realistic equilibrium to an externally generated, non-axisymmetric, static, magnetic perturbation. The plasma is divided into two regions. In the outer region, which comprises most of the plasma, the response is governed by the linearized equations of marginally stable, ideal-magnetohydrodynamics (MHD). In the inner region, which is strongly localized around the various rational surfaces within the plasma (where the marginally stable, ideal-MHD equations become singular), the response is governed by Glasser-Greene-Johnson linear layer physics. For the sake of simplicity, the paper focuses on the situation where the plasma at one of the internal rational surfaces is locked to the external perturbation, whereas that at the other surfaces is rotating.