Parallelization of JOREK-STARWALL for non-linear MHD simulations including resistive walls (Report of the EUROfusion High Level Support Team Projects JORSTAR/JORSTAR2)

TL;DR

This paper presents the implementation of MPI parallelization in the JOREK-STARWALL code to enable high-resolution non-linear MHD simulations involving resistive walls, significantly reducing memory and computational time.

Contribution

The paper introduces MPI parallelization for JOREK-STARWALL, allowing large-scale, high-resolution simulations of plasma-wall interactions in tokamaks.

Findings

Reduced memory consumption in simulations

Decreased execution time for high-resolution models

Enabled realistic wall structure modeling

Abstract

Large scale plasma instabilities inside a tokamak can be influenced by the currents flowing in the conducting vessel wall. This involves non linear plasma dynamics and its interaction with the wall current. In order to study this problem the code that solves the magneto-hydrodynamic (MHD) equations, called JOREK [Huysmans G.T.A. and Czarny O. NF 47, 659 (2007); Czarny O. and Huysmans G. JCP 227, 7423 (2008)], was coupled [Hoelzl M., et al. Journal of Physics: Conference Series, 401, 012010 (2012)] with the model for the vacuum region and the resistive conducting structure named STARWALL [Merkel P., Strumberger E., arXiv:150804911 (2015)]. The JOREK-STARWALL model has been already applied to perform simulations of Vertical Displacement Events (VDEs), Resistive Wall Modes (RWMs), Quiescent H-Mode, and vertical kick ELM triggering. At the beginning of the project it was not possible to resolve the realistic wall structure with a large number of finite element triangles due to the huge consumption of memory and wall clock time by STARWALL and the corresponding coupling routine in JOREK. Moreover, both the STARWALL code and the JOREK coupling routine were only partially parallelized via OpenMP. The aim of this project is to implement an MPI parallelization to reduce memory consumption and execution time such that simulations with large resolutions become possible.