Center for Tokamak Transient Simulations
This project will develop simulation tools to provide a better understanding of the behavior and consequences of plasma disruptions in tokamaks and will use those tools to investigate methods to better control them.
The Center is developing and applying simulation software to improve the understanding of, and ability to predict and control, transient events in tokamak discharges. Simulation tools are being developed to model disruptions that are caused by violating ideal MHD stability criteria, vertical displacement events, resistive wall modes, and tearing modes. The modeling of disruption mitigation techniques, particularly by shattered pellet injection (SPI), will also be developed. The Center is built around two extended MHD codes: NIMROD and M3D-C1. These codes are being extended as required by the demands of disruption modeling. The codes will be coupled to the FronTier code for state-of-the-art modeling of SPI. The objectives of the center are to: (1) develop better understanding and improved predictive capability for plasma disruptions; (2) provide a tool for calculating vessel forces for worst case VDE and other disruptions in tokamaks; (3) develop increased understanding and improved predictive capability for locked mode disruptions and how best to avoid them; (4) develop, verify, and validate 3D models for disruption mitigation by shattered pellets that can be used to design and optimize a system for future tokamaks; and (5) increase the efficiency and scalability of the M3D-C1 and NIMROD codes.
FASTMath is providing solver, unstructured mesh infrastructure, unstructured mesh generation and adaptation tools for use in this project. The Parallel Unstructured Mesh Infrastructure (PUMI) is supporting the unstructured mesh operations through to the assembly of the global system matrix in the M3D-C1 code. Solver developments are focused on first determining optimal ordering to most effectively support the physics and scale aware hierarchical matrix preconditioners to be developed for this project. The newly developed STRUMPACK package will be used in the development of the new solver technologies. Improved mesh adaptation methods and methods to support mesh-to-mesh solution transfer for coupling to other fusion codes (e.g., XGC edge plasma) will be developed. Multiscale coupling of continuum mesh and particle tracking methods will be developed for M3D-C1.