DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 350: Giant Sawtooth control with Alfven Eigenmodes in ITER | ||
| Name: | Gerrit J. Kramer ( |
Affiliation: | Princeton Plasma Physics Laboratory |
| Research Area: | Energetic Particles | Presentation time: | Not requested | Co-Author(s): | G.J. Kramer, R. Nazikian, M. van Zeeland, B. Heidbrink, N.N. Gorelenkov |
| Description: | Sawteeth in DIIID can be stabilized by a combination of NBI and ICRF heating.
The stabilization occurs when the fast particle pressure inside the q=1 surface is sufficiently high. Such fast particle pressures are created by accelerating NBI ions with on-axis ICRF heating. The sawtooth stabilization period, however, does only last for up to about 200 ms ending with a giant sawtooth. In the period before the giant sawtooth energetic particle modes (EPMs) or core-localized TAEs (C-TAE), localized inside the q=1 surface, are often observed. When the ICRF power is increased not only C-TAEs but also global TAEs (G-TAE), localized outside the q=1 surface, are excited. It has been found that in discharges where core-localized and global TAEs are observed simultaneously, the stored energy is reduced. It was made plausible that the combination of C-TAEs and G-TAEs was an efficient way to expel fast particles from the core, thereby reducing the fast-particle pressure and setting of the sawtooth. | ||
| Experimental Approach/Plan: | We propose to study the influence of C-TAEs and G-TAEs on the fast-ion
transport by varying the the q at the edge between 3 and 5 with otherwise identical plasma conditions. By varying q_edge the alignment of the TAE gap is changed which in turn influences the spectrum of the TAEs which are thought to be responsible for fast-ion transport. | ||
| Background: | -- | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | This experiment is well suited for DIIID because of the increased
capability of measuring part of the fast-ion distribution in the plasma with the D_alpha diagnostic. | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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