Abstract
The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is the high-confinement mode. In this regime, however, periodic relaxations of the plasma edge can occur. These edge-localized modes pose a threat to the integrity of the fusion device. Here we reveal the strong impact of energetic ions on the spatio-temporal structure of edge-localized modes in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between the fast ions at the plasma edge and the electromagnetic perturbations from the edge-localized mode leads to an energy and momentum exchange. Energetic ions modify, for example, the amplitude, frequency spectrum and crash timing of edge-localized modes. The simulations reproduce some observations that feature abrupt and large edge-localized mode crashes. The results indicate that, in the International Thermonuclear Experimental Reactor, a strong interaction between the fusion-born alpha particles and ions from neutral beam injection, a main heating and fast particle source, is expected with predicted edge-localized mode perturbations. This work advances the understanding of the physics underlying edge-localized mode crashes in the presence of energetic particles and highlights the importance of including energetic ion kinetic effects in the optimization of edge-localized mode control techniques and regimes that are free of such modes.
| Original language | English |
|---|---|
| Pages (from-to) | 43-51 |
| Number of pages | 9 |
| Journal | Nature Physics |
| Volume | 21 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2025 |
Funding
We thank A. Kallenbach, H. Zohm, K. Ichiguchi, A. Loarte, M. Hoelzl and M. Dunne for fruitful discussions and for their valuable input. This work received funding from the Spanish Ministry of Science (grant nos. FPU17/05703 and PID2020-116822RB-I00). This work received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 805162). This work was supported by the NINS programme of Promoting Research by Networking among Institutions. This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (grant agreement no. 101052200 – EUROfusion). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. This work was co-funded by the European Regional Development Fund (Andalusian Operational Programme 2014–2020) and by the Ministry of Economic Transformation, Industry, Knowledge and Universities of the Junta de Andalucía within the framework of the PAIDI project with reference P18-FR-3812. We acknowledge the computer resources of RES (Spanish Supercomputing Network) at MareNostrum and the technical support provided by Barcelona Supercomputing Center (BSC) and the support from Marconi-Fusion, the High Performance Computer at the CINECA headquarters in Bologna (Italy) for its provision of supercomputer resources. We acknowledge PRACE for awarding us access to ARCHER2-HPC hosted by EPCC, UK. This work was carried out (partially) using JFRS-1 supercomputer resources at the Computational Simulation Centre of International Fusion Energy Research Centre (IFERC-CSC) in Rokkasho Fusion Institute of QST, provided under the EU-JA Broader Approach collaboration.