Are magnetic resonances practical transport controllers in fusion plasmas? The TJ-II experience

15th Latin American Workshop on Plasma Physics; 21st IAEA TM on Research Using Small Fusion Devices

López-Bruna, D.^1 ; Vargas, V.I.^2 ; Romero, J.A.^1

Laboratorio Nacional de Fusión, Ciemat, Madrid, Spain^1

Plasma Laboratory for Fusion Energy and Applications, Cartago, Costa Rica^2

关键词: Electron cyclotron heating;    External control;    Neutral beam heating;    Operational limits;    Rotational transform;    TJ-II stellarators;    Toroidal plasmas;    Transport barrier;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/591/1/012013/pdf
DOI  :  10.1088/1742-6596/591/1/012013

来源: IOP

【 摘 要 】

The TJ-II stellarator is a mid-size Heliac design (high rotational transform, low magnetic shear) that allows for external control of the rotational transform profile. The long experience with locating diverse magnetic resonances at different plasma radii has assessed their reliability as transport controllers: in low density electron cyclotron heating plasmas, a "transport barrier effect" is found in most of the confinement zone accompanying magnetic resonances; in higher density and beta plasmas under neutral-beam heating operation, resonant layers show a clear incidence on the access to the H-mode of confinement or, likewise, on the back transition to L-mode. Moreover, confinement events similar to tokamak phenomenology have been also related with magneto-hydrodynamic activity around the magnetic resonances and are, consequently, amenable to external control. All in all, the TJ-II experience posits magnetic resonances as natural transport and stability controllers in toroidal plasmas. Further studies must either confirm or set operational limits to these findings.