Automated 2D Plasma Edge Grid Generation for Arbitrary Magnetic Topologies

ABSTRACT High quality grids are a crucial ingredient to obtain trustworthy results from any plasma edge simulation code, especially those that employ low order discretization schemes such as SOLPS‐ITER. We present a grid generation algorithm that is able to generate 2D unstructured aligned grids for arbitrary toroidally‐symmetric magnetic field topologies and quasi‐arbitrary wall geometry. Since the algorithm requires only a relatively small set of user inputs that is mainly dependent on machine parameters, it is capable of generating grids for different magnetic topologies automatically. Furthermore, grids extending up to the vessel wall can be generated without additional user intervention. This makes it ideal for remeshing purposes for shape and magnetic field optimization in the future, contrary to existing grid generators. The algorithm consists of two main steps: a magnetic topology mesh generation step and a grid generation step. The first step partitions the domain into topologically rectangular regions, which are used in the second step to apply a block‐structured mesh approach. Several useful features, such as local refinement and boundary layers, are implemented to arrive at high quality grids. The grid generator is currently implemented in the Grid Optimization and Adaptation Toolbox (GOAT) and the resulting grids have been used for plasma edge simulation with SOLPS‐ITER.