Forschungszentrum Jülich (FZJ)
Neutral gas physics and its interactions with the plasma is a key aspect of edge plasma and divertor physics in a fusion reactor. The proposal foresees the development, verification and validation of a Neutral Gas Module (NGM) based on the existing EIRENE code to establish a flexible, efficient and reliable computational tool. The NGM will provide efficient use of high-performance computing (HPC) resources including domain decomposition and demonstration of good speedup scaling for hybrid OpenMP-MPI parallelisation in a view of significant volumes and numbers of traced Monte-Carlo particles. The NGM will be employable in any 2D or 3D integrated modelling approach for simulation of fusion reactor regimes with (semi)detached divertor on ITER and DEMO scale. The interfaces to other codes will be adopted for IMAS (Integrated Modelling and Analysis Suite platform) and liaised with other TSVVs, in particular, TSVV-3&4.
The physics improvements will include refined and extended collisional-radiative models (CRMs) for molecules including resolving the rotational and vibrational states, adding reactions types (e.g. for photon absorption) and treatment of isotope effects for H2, D2, T2, DT and molecular ions. A significant focus will be given to building a hierarchy of models including advanced fluid neutrals and various fluid-kinetic hybridisations (FKH), which are to approach the accuracy of the full-kinetic runs, while providing an efficient treatment of highly collisional regions (HCR). These models will enable efficient simulations for ITER and DEMO.
The task includes significant modernisation of the EIRENE basic structure: modulisation will allow segregating the numeric core from all branching, data pre-processing and interfaces; new models and features will be provided, including a finite element model (FEM) for the divertor target (W) and its proxy at MAGMUM-PSI (the FEM will also be able to treat first wall (FW) elements); modifications providing time-dependent simulations and the use of the adjoint approach for sensitivity studies and uncertainty quantification (UQ) are foreseen. The proposed NGM infrastructure conform with up-to-date standards includes version control, continuous integration and repository for the simulated data for the selected simulation base cases.
The task contains a strong validation part with experiments at JET-ILW, MAGNUM-PSI and PSI-2. Predictive power and computational performance will be demonstrated for ITER (focus on semi-detached divertor scenario) and DEMO (focus on usability and advantages of FKH for HCR). The validation effort will be focused on detachment physics including improved CRMs and photon trapping (spectroscopy for well-characterised plasma conditions) as well as on testing of improved coupling to plasma-surface interaction physics including transients utilizing the target/FW FEM.
IEK-4, FZ Juelich, 52425 Juelich, Germany