**Abstract:**
The M3D code [1] has proven itself to be an invaluable tool for the simulation and understanding of global nonlinear phenomena in magnetic fusion confinement devices. However, the structure of M3D is not optimal for computing in regimes where two-fluid (2F) effects dominate, or for times that are very long compared to the Alfven transit time. We have built upon many of the favorable features of the M3D approach to construct the M3D-C1 code [2], which is based on high-order, compact conformal finite elements with C1 continuity on an unstructured adaptive grid. The efficient split-implicit time advance is shown to be closely related to the ideal MHD energy principle, and allows time steps several orders of magnitude in excess of the Courant condition based on the Alfven or whistler waves. The full model consists of 8 3D scalar variables. Nontrivial, energy conserving, subsets of the full equations exist including 2-variable 3D reduced MHD which is a toroidal generalization of [3] and a 4-variable 3D reduced model which is a toroidal generalization of [4]. The structure of the code makes linear calculations exceptionally efficient. Illustrative results in 2F toroidal equilibrium, 3D linear stability and 2F magnetic reconnection are given. Future capabilities including a surrounding resistive wall and a scalable full 3D nonlinear time evolution are discussed.

___________________________________ [1] W. Park, et al., Phys Plasmas 6, 1796 (1999) [2] S. C. Jardin, J. Breslau, N. Ferraro, J. Comput. Phys, 226 (2007) 2146 [3] H. Strauss, Phys. Fluids 19 (1976) 134 [4] R. Hazeltine et al, Phys Fluids 28 (1985) 2466, R. Fitzpatrick et al, Phys Plasmas 11 (2004) 4713

Steve Jardin Last modified: Wed Feb 13 11:03:55 EST 2008