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Author: Nate M Ferraro
Requested Type: Poster
Submitted: 2017-03-14 08:47:26

Co-authors: D.Pfefferle, S.C.Jardin, C.E.Myers, Q.Teng, M.T.Beidler

Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Road
Princeton, NJ   08543-0
United States

Abstract Text:
A successful tokamak reactor will require robust methods for avoiding and withstanding disruptions. Achieving this will require considerable progress in understanding both the causes and dynamics of disruptions. Here we describe present research and future directions in extended-MHD modeling, in particular with the M3D-C1 code, to address these issues. Nonlinear MHD modeling is necessary to understand how some linearly unstable modes develop into disruptions while others saturate or cycle without causing disruptions. For example, the nonlinear evolution of the tearing mode may result in locking—one of the most common causes of disruptions—or may saturate benignly, as in “hybrid” operation. Macroscopic linear instability is therefore not a sufficient condition for disruption prediction and avoidance schemes. We present results of M3D-C1 modeling of mode locking and Resistive Wall Tearing Mode stability as a step towards understanding how linearly unstable modes may develop into disruptions. In order to characterize the dynamics of a disruption, we also present M3D-C1 simulations of vertically unstable plasmas in toroidal geometry. In these simulations, the plasma drifts toward the wall and the plasma current quenches, leading to large halo currents and eddy currents in the surrounding conducting structures. We consider the effect of breaks in the resistive wall on the evolution of the current quench and the wall currents.

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