Abstract
High-performance fusion plasmas, requiring high pressure β, are not well understood in stellarator-type experiments. Here, the effect of β on ion-temperature-gradient-driven (ITG) turbulence is studied in Wendelstein 7-X (W7-X), showing that subdominant kinetic ballooning modes (KBMs) are unstable well below the ideal MHD threshold and get strongly excited in the turbulence. By zonal-flow erosion, these subthreshold KBMs (stKBMs) affect ITG saturation and enable higher heat fluxes. Controlling stKBMs will be essential to allow W7-X and future stellarators to achieve maximum performance.
| Original language | English |
|---|---|
| Article number | 185101 |
| Journal | Physical Review Letters |
| Volume | 131 |
| Issue number | 18 |
| DOIs | |
| Publication status | Published - 3 Nov 2023 |
Bibliographical note
Publisher Copyright:© 2023 American Physical Society.
Funding
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 No. 101052200—EUROfusion). The 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 supported by the Office of Fusion Energy Sciences, U.S. Department of Energy, under Grant No. DEFG02-89ER53291.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | DEFG02-89ER53291 |
| Euratom Research and Training Programme 2014-2018 | 101052200—EUROfusion |
| European Commission |