Numerical methods for stellarator simulations in BOUT++

TL;DR

This paper discusses recent improvements to the BOUT++ simulation framework for modeling the stellarator SOL in realistic geometries, exemplified by Wendelstein 7-X, enhancing grid generation, physics models, and software capabilities.

Contribution

It introduces new features and improvements in BOUT++ for more accurate stellarator SOL simulations in complex geometries.

Findings

Enhanced grid generation for realistic geometries

Improved physics modeling capabilities

Application to Wendelstein 7-X stellarator

Abstract

Modeling the Scape-off layer (SOL) of stellarator fusion devices is challenging due to the complicated magnetic topology, requiring numerical tools to solve transport equations for realistic geometries. Previously the flux coordinate independent (FCI) method has been successfully applied to model the SOL in simplified geometries. The current work presents some of the recent improvements for the BOUT++ modeling implemented to simulate the SOL in realistic geometries with the example of Wendelstein 7-X. The changes include improvements for the grid generation tool, the physics model as well as the BOUT++ library itself. A short outlook is given on current modeling work using the new features.