M3D-C1 is a code that solves the extended-magnetohydrodynamic (MHD) equations, which is a model that describes plasma as electrically conducting fluids of ions and electrons. This code is primarily used for calculating the equilibrium, stability, and dynamics of fusion plasmas, but has also been used for a variety of other applications, including astrophysical applications. In particular, M3D-C1 is designed to address some of the most critical challenges confronting tokamak plasmas: large-scale instabilities, which significantly degrade thermal confinement; and disruptions, which cause complete loss of energy confinement and which may cause damage to reactor-scale tokamaks.
M3D-C1 builds upon some of the design principles pioneered by the M3D code, but the two codes are developed independently and do not share source code. The "C1" in M3D-C1 refers to the C1 property of its finite elements, which ensures that both the value and the derivatives of fields are continuous across mesh element boundaries.
Advanced numerical methods are employed in M3D-C1 to permit the efficient solution of its model equations over a broad range of temporal and spatial scales. These methods include the use of high-order finite elements on an unstructured mesh; fully implicit and semi-implicit time integration options; physics-based preconditioning; and parallelization via domain decomposition and the use of scalable parallel sparse linear algebra solvers.
M3D-C1 is an open-source code, hosted on github. Public installations are available on NERSC Perlmutter and Princeton University's Stellar computer. For descriptions of how to build and run the code, or how to access the public installations, please refer to the documentation.
The development of M3D-C1 is funded by the U.S. Department of Energy, primarily through contract DE-AC02-09CH11466. Projects that have supported significant development of this code have included the Center for Extended MHD Modeling (CEMM) SciDAC, the Center for Tokamak Transient Simulations (CTTS) SciDAC, the U.S. DOE Early Career Research Program, the INFUSE program, PPPL Lab-Directed Research and Development (R094 and R150), and the Mitigating Risks from Abrupt Confinement Loss (MiRACL) FIRE collaborative.