Title | Turbulence mitigation in maximum-J stellarators with electron-density gradient |
Publication Type | Journal Article |
Year of Publication | 2022 |
Authors | J.H.E. Proll, G.G. Plunk, B.J. Faber, T. Görler, P. Helander, I.J. McKinney, M.J. Pueschel, H.M. Smith, P. Xanthopoulos |
Journal | Journal of Plasma Physics |
Volume | 88 |
Issue | 1 |
Pagination | 905880112 |
Date Published | 02/2021 |
Abstract | In fusion devices, the geometry of the confining magnetic field has a significant impact on the instabilities that drive turbulent heat loss. This is especially true of stellarators, where the density-gradient-driven branch of the "trapped electron mode" (TEM) is predicted to be linearly stable if the magnetic field has the maximum-J property, as is very approximately the case in certain magnetic configurations of the Wendelstein 7-X experiment (W7-X). Here we show, using both analytical theory and simulations, that the benefits of the optimisation of W7-X also serve to mitigate ion-temperature-gradient (ITG) modes as long as an electron density gradient is present. We find that the effect indeed carries over to nonlinear numerical simulations, where W7-X has low TEM-driven transport, and reduced ITG turbulence in the presence of a density gradient, giving theoretical support for the existence of enhanced confinement regimes, in the presence of strong density gradients (e.g. hydrogen pellet or neutral beam injection). |
DOI | 10.1017/S002237782200006X |
Division | FP |
Department | PMT |
PID | 56b59ba74a6482235e8dfb23d8bfcac1 |
Alternate Title | J. Plasma Phys. |
Label | OA |
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