INGRID: An interactive grid generator for 2D edge plasma modeling

Abstract

A fusion boundary-plasma domain is defined by axisymmetric magnetic surfaces where the geometry is often complicated by the presence of one or more X-points; and modeling boundary plasmas usually relies on computational grids that account for the magnetic field geometry. The new grid generator INGRID (Interactive Grid Generator) presented here is a Python-based code for calculating grids for fusion boundary plasma modeling, for a variety of configurations with one or two X-points in the domain. INGRID first performs partitioning over the domain consisting of a small number of patches conforming to the magnetic field and wall geometry; then it generates a subgrid on each of the patches and joins them into a global grid. This domain partitioning strategy makes possible a uniform treatment of various configurations with one or two X-points in the domain. This includes single-null, double-null, and other configurations with two X-points in the domain. The INGRID design allows generating grids either interactively, via a parameter-file driven GUI, or using a non-interactive script-controlled workflow. Results of testing demonstrate that INGRID is a flexible, robust, and user-friendly grid-generation tool for fusion boundary-plasma modeling. Program summaryProgram Title: INGRID: Interactive Grid Generator for Tokamak Boundary RegionCPC Library link to program files:https://doi.org/10.17632/w3hbdgbndk.1Developer's repository link:https://github.com/LLNL/INGRIDLicensing provisions: MITProgramming language: PythonNature of problem: Modeling of tokamak boundary edge plasma physics is essential for the design and optimization of future fusion reactors. A crucial component of certain edge transport modeling codes is the computational grid representing the magnetic topology and plasma facing components within a tokamak. Generation of grids can be a tedious process that requires frequent intervention from the user of the grid generator. Despite their importance, robust simple-to-use grid-generation tools are nonexistent. The creation of a grid generator capable of both modeling and automatically identifying advanced divertor configurations is of great importance.Solution method: INGRID utilizes user-provided MHD equilibrium data and the target plates and limiter geometry to automatically identify magnetic topology, and generate the appropriate computational grid in block structured manner. First, the magnetic topology identification algorithm decides how the computational domain is partitioned. Within each partition, a local subgrid is generated which is used to construct the global grid ready for export.