Free-Boundary 3D Equilibria and Resistive Wall Instabilities with M3D-C1

A resistive wall model has been implemented in the two-fluid, 3D MHD code M3D-C1. This capability allows M3D-C1 to be applied to several new applications that were not possible with conducting wall boundary conditions, including vertical displacement events, resistive wall modes, and free-boundary equilibria. Examples of each for both DIII-D and NSTX are presented. This also permits direct comparison of M3D-C1 results with magnetic probe data. Generally good agreement with magnetics data and qualitative agreement with soft x ray imaging is found in simulations of the non-axisymmetric response to applied 3D fields. It is found that the response can be sensitive to the treatment of the open field-line region. The boundary conditions and treatment of the open field-line region are especially important for the n = 1 response. In M3D-C1, the resistive wall and the external vacuum region are included within the computational domain, which allows good implicit scaling, walls of arbitrary thickness, and the evolution of wall conditions.

Supported in part by the US Department of Energy under DE-FG02-95ER54309 and DE-FC02-04ER54698.