ArbiTER: A Flexible Eigenvalue Solver for Edge Fusion Plasma Applications

Validation and verification (V & amp;V) is an essential part of any large scientific computing effort and of the computational physics component of the international fusion program in particular. To assist in this task, we propose the creation of a flexible eigenvalue solver that can be adapted to fluid and kinetic plasma physics models in a variety of magnetic geometries. This lightweight code can be used (i) to benchmark more complicated nonlinear time-stepping codes by comparing linear growth rates of dominant instabilities, and (ii) as a convenient stand-alone code for linear physics studies for a wide range of problems. In the Phase I project, an eigenvalue solver for partial differential equations with a high degree of flexibility was created. This code has the distinctive feature that equation sets, differential operators, topology, and dimensionality are all determined by input files rather than being fixed by the source code. These features were demonstrated in a number of test cases, showing its capacity to solve simple fluid and kinetic problems in a variety of geometries. In the Phase II project, we plan to expand these capabilities to include richer topological capabilities including unstructured grids, parallel computing capability for large kinetic problems, and source-driven matrix solve capability for perturbed equilibrium problems. We also plan to create utilities to make the entire package easier and more intuitive to use, and to continue verification and benchmarking exercises so as to establish a high degree of confidence in this code prior to its intended use in benchmarking full nonlinear simulation codes. Given its value of such a code to the fusion community, it is anticipated that this code will generate follow-on funding in the form of research grants to maintain the code, as well as subcontracts to apply it to V & amp;V and application driven efforts pertaining to specific simulation codes.