Abstract of JORSOLV Project

JOREK is the leading non-linear MHD code in Europe for large-scale instabilities in X-point tokamak plasmas with a strong European community and integration into EUROfusion work packages like JET, MST, ENR, etc. The code is applied to many key questions of the fusion roadmap, in particular to disruptions and edge localized modes.

Non-linear MHD simulations require considerable computing resources on Marconi-Fusion and other HPC systems. Any improvement in the code efficiency will reduce the amount of resources required and/or allow to address additional physics aspects which are so far not accessible. Large-scale plasma instabilities are extremely challenging since they are intrinsically multi-scale problems in space and time and are associated with massive fluctuation amplitudes comparable to the background values. Additionally, many of the effects involved are non-linearly coupled such that they cannot be simulated separately, but need to be investigated in an integrated way.

JOREK is a fully implicit code meaning that a large sparse matrix system has to be solved for each time step in which all degrees of freedom are coupled. The matrix construction has been improved successfully in the previous JOKLA project. We propose to optimize the solver part of the code in the present project in several different ways to further enhance code efficiency.