A new matching method for linear stability analysis of MHD modes close to the ideal MHD marginal stability

摘要

A new matching method has been invented for linear stability analysis of magnetohydrodynamics (MHD) modes for plasmas marginally stable against ideal MHD. An inner region with a finite width is utilized as in our previous study M. Furukawa, S. Tokuda, and L.-J. Zheng, Phys. Plasmas 17, 052502 (2010). An ordering scheme for the outer region has been newly developed, thereby it succeeds to include effects of small plasma inertia and resistivity perturbatively in the outer region. The corresponding boundary condition requires direct, not asymptotic, matching of the outer and inner solutions, which assumes nothing special for the behavior of parallel electric field across the matching points. The union of the ordering scheme and the boundary condition enables us to apply our matching method even for plasmas marginally stable against ideal MHD. Because our matching method is not asymptotic, it is easy to implement numerically. The stability analysis of resistive MHD modes, such as internal kink and tearing modes, is satisfactory.