Abstract
Alpha particles with energies on the order of megaelectronvolts will be the main source of plasma heating in future magnetic confinement fusion reactors. Instead of heating fuel ions, most of the energy of alpha particles is transferred to electrons in the plasma. Furthermore, alpha particles can also excite Alfvénic instabilities, which were previously considered to be detrimental to the performance of the fusion device. Here we report improved thermal ion confinement in the presence of megaelectronvolts ions and strong fast ion-driven Alfvénic instabilities in recent experiments on the Joint European Torus. Detailed transport analysis of these experiments reveals turbulence suppression through a complex multi-scale mechanism that generates large-scale zonal flows. This holds promise for more economical operation of fusion reactors with dominant alpha particle heating and ultimately cheaper fusion electricity.
| Original language | English |
|---|---|
| Pages (from-to) | 776-782 |
| Number of pages | 7 |
| Journal | Nature Physics |
| Volume | 18 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jul 1 2022 |
Funding
We thank M. Baruzzo and F. Nave for the preparation and execution of JET experiments discussed in this paper; E. de la Luna for support in detailing the experimental diagnostics of JET; A. Ho for assistance in processing the experimental data; T. Görler for providing essential advice to ensure the correct numerical setup for the GENE modelling reported in this paper; Y. Camenen, X. Garbet and A. Bierwage for fruitful discussions about the gyrokinetic analyses; G. Giruzzi for valuable suggestions on the article strategy. The simulations were performed on the IRENE Joliot-Curie HPC system, in the framework of the PRACE projects IONFAST and AFIETC, led by J. Garcia, and on the CINECA Marconi HPC within the project GENE4EP, led by D. Zarzoso. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement no. 633053. The views and opinions express herein do not necessarily reflect those of the European Commission. Part of the work by Ye. O. Kazakov and J.Ongena was also carried out in the framework of projects done for the ITER Scientist Fellow Network (ISFN). We thank M. Baruzzo and F. Nave for the preparation and execution of JET experiments discussed in this paper; E. de la Luna for support in detailing the experimental diagnostics of JET; A. Ho for assistance in processing the experimental data; T. Görler for providing essential advice to ensure the correct numerical setup for the GENE modelling reported in this paper; Y. Camenen, X. Garbet and A. Bierwage for fruitful discussions about the gyrokinetic analyses; G. Giruzzi for valuable suggestions on the article strategy. The simulations were performed on the IRENE Joliot-Curie HPC system, in the framework of the PRACE projects IONFAST and AFIETC, led by J. Garcia, and on the CINECA Marconi HPC within the project GENE4EP, led by D. Zarzoso. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement no. 633053. The views and opinions express herein do not necessarily reflect those of the European Commission. Part of the work by Ye. O. Kazakov and J.Ongena was also carried out in the framework of projects done for the ITER Scientist Fellow Network (ISFN).
