DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 466: ECCD stabilization of non-rotating mode in high beta, low-torque plasmas | ||
| Name: | Holger Reimerdes ( |
Affiliation: | Columbia University |
| Research Area: | RWM Physics | Presentation time: | Not requested | Co-Author(s): | F. Volpe |
| Description: | Use ECCD stabilization as mean to probe the nature of the high-beta, low-rotation non-rotating mode. Any success of ECCD in reducing the mode amplitude or even stabilizing the mode would be an indication of the tearing character. Moreover, complete stabilization would allow for a further increase of beta in order to test the RWM/plasma mode beta limit. | ||
| Experimental Approach/Plan: | Use a low torque high beta RWM target and apply co-ECCD at the o-point of an assumed 2/1 island (see proposals 384 and 385 by F. Volpe). The ECCD is triggered using the locked mode detector. The position of the island o-point is estimated from the typical toroidal phase with which the mode grows and mapping the field line to the ECCD location. Since this mapping has some uncertainties the location has to be varied when looking for an effect on the mode magnitude. If the mode can be indeed stabilized we plan to increase beta in order to investigate the next beta-limiting instability. | ||
| Background: | The n=1 modes in high beta, low-rotation plasmas have been classified as "tearing modes" and "RWMs" depending on whether they exhibit a rotating precursor. However, an analysis of the magnetic perturbation measurements at the low-field-side yields the same helicity suggesting that the "RWM" could be a tearing mode that is born locked. This conjecture is further supported by recent rotation scans of the NTM betaN threshold by Buttery and La Haye. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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