# Treatment of Advanced Divertor Configurations in the Flux-Coordinate Independent turbulence code GRILLIX

## TL;DR

This paper extends the GRILLIX turbulence code to handle advanced divertor magnetic geometries, enabling detailed studies of turbulence effects in complex edge and SOL plasma configurations.

## Contribution

The paper introduces modifications to the FCI turbulence code GRILLIX for generalized magnetic geometries, facilitating turbulence analysis in advanced divertor configurations.

## Key findings

- Successful implementation of magnetic geometry modifications in GRILLIX.
- Initial validation with Snowflake magnetic scenario tests.
- Enhanced boundary condition handling for complex geometries.

## Abstract

Advanced divertor configurations modify the magnetic geometry of the diverter to achieve a combination of strong magnetic flux expansion, increased connection length and higher divertor volume - to improve detachment stability, neutral/impurity confinement and heat-channel broadening. In this paper, we discuss the modification of the Flux-Coordinate Independent (FCI) turbulence code GRILLIX to treat generalised magnetic geometry, to allow for the investigation of the effect of magnetic geometry on turbulent structures in the edge and SOL. The development of grids and parallel operators from numerically-defined magnetic equilibria is discussed, as is the application of boundary conditions via penalisation, with the finite-width method generalised to treat complex non-conformal boundaries. Initial testing of hyperbolic (advection) and parabolic (diffusion) test cases is presented for the Snowflake scenario.