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Author: Ryan L White
Requested Type: Poster
Submitted: 2016-02-15 08:18:09

Co-authors: B. Coppi

Contact Info:
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge, MA   02139

Abstract Text:
The Glasser-Greene-Johnson equations, which govern the dominant behavior of a resistive mode in the viscinity of a resonant surface, are generalized to include toroidal flow. In toroidal geometry, flow can affect stability by modifying the equilibrium density profile as well as the shape of the magnetic surfaces, and these effects are not captured in a cylindrical model. Indeed, the loss of pressure as a flux function is part of what makes the derivation nontrivial. Moreover, recent results [R. L White and R. Fitzpatrick, Phys. Plasmas 22, 102507 (2015)] extrapolated from a cylindrical model suggest that toroidal corrections are essential for capturing the stabilizing effect of sufficiently weak velocity shear for tearing modes. By solving the layer equations numerically over a much larger parameter space, we are able to investigate this effect beyond the weak-shear limit, as well as the transition to velocity-shear-induced instability for sufficiently large shear.