Saturated tearing modes in toroidal geometry

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Abstract
A quasilinear method is developed for determining saturated tearing mode magnetic island widths in axisymmetric toroidal plasmas with arbitrary cross‐sectional shape, aspect ratio, or plasma pressure (beta). The method is applied to compute magnetic island widths in force‐free toroidal plasmas with aspect ratio as low as 2.0 and elongation between 1.0 and 2.0. It is found that current suppression within the magnetic island strongly increases the saturated width while current peaking reduces width. The effects of current profile, geometry, and harmonic mixing are also studied.