Article
The effects of electron cyclotron heating and current drive on toroidal Alfven eigenmodes in tokamak plasmas
Author/s | Sharapov, S. E.
García Muñoz, Manuel Zeeland, M. A. van Bobkov, B. Classen, I. G. J. Galdón Quiroga, Joaquín González Martín, Juan de Dios Rodríguez Ramos, Mauricio Sanchís Sánchez, Lucía |
Department | Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear |
Publication Date | 2018-01 |
Deposit Date | 2020-07-21 |
Published in |
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Abstract | Dedicated studies performed for toroidal Alfvén eigenmodes (TAEs) in ASDEX-Upgrade (AUG)
discharges with monotonic q-profiles have shown that electron cyclotron resonance heating (ECRH)
can make TAEs more unstable. In ... Dedicated studies performed for toroidal Alfvén eigenmodes (TAEs) in ASDEX-Upgrade (AUG) discharges with monotonic q-profiles have shown that electron cyclotron resonance heating (ECRH) can make TAEs more unstable. In these AUG discharges, energetic ions driving TAEs were obtained by ion cyclotron resonance heating (ICRH). It was found that off-axis ECRH facilitated TAE instability, with TAEs appearing and disappearing on timescales of a few milliseconds when the ECRH power was switched on and off. On-axis ECRH had a much weaker effect on TAEs, and in AUG discharges performed with co- and counter-current electron cyclotron current drive (ECCD), the effects of ECCD were found to be similar to those of ECRH. Fast ion distributions produced by ICRH were computed with the PION and SELFO codes. A significant increase in Te caused by ECRH applied off-axis is found to increase the fast ion slowing-down time and fast ion pressure causing a significant increase in the TAE drive by ICRH-accelerated ions. TAE stability calculations show that the rise in Te causes also an increase in TAE radiative damping and thermal ion Landau damping, but to a lesser extent than the fast ion drive. As a result of the competition between larger drive and damping effects caused by ECRH, TAEs become more unstable. It is concluded, that although ECRH effects on AE stability in present-day experiments may be quite significant, they are determined by the changes in the plasma profiles and are not particularly ECRH specific. |
Project ID. | 633053
P012450/1 |
Citation | Sharapov, S.E., García Muñoz, M., Van Zeeland, M.A., Bobkov, B., Classen, I.G.J., Galdón Quiroga, J.,...,Sanchís Sánchez, L. (2018). The effects of electron cyclotron heating and current drive on toroidal Alfven eigenmodes in tokamak plasmas. Plasma Physics and Controlled Fusion, 60 (1), 1-10. |
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