DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 467: NTM (de)stabilization by co-/ctr-ECCD in island O-/X-point | ||
| Name: | Francesco Volpe ( |
Affiliation: | ORAU |
| Research Area: | NTM Stabilization | Presentation time: | Not requested | Co-Author(s): | R. La Haye |
| Description: | Drive current in the O-point or X-point of a neoclassical island in the co- or ctr-direction (4 cases). Compare NTM stabilization efficiency and characterize (de)stabilization mechanisms. | ||
| Experimental Approach/Plan: | Begin as #230 (Mirnov-controlled MECCD), #382 (oblique ECE-controlled MECCD) or #385 (MECCD on entrained mode) as far as co-CD in the O-point is concerned. Repeat with ECCD modulation out-of-phase for co-CD in the X-point. Tilt gyrotrons in the opposite direction for ctr-CD in the X-point. Repeat with O-point phasing for ctr-CD in the O-point. | ||
| Background: | The capability of modulating the ECCD power in a controlled manner in order to selectively drive current in the O- or X-point of a rotating island is relatively recent. Experiments of this type have been carried out at Asdex Upgrade (AUG) and are under preparation at DIII-D (see proposals #230, #382, #385). AUG results clearly showed that co-CD in the O-point has a stabilizing effect and co-CD in the X-point is destabilizing, although not as much as expected. The aims of this proposal are: a) to confirm such co-CD observations; b) to compare with ctr-CD in the O- and in the X-point, which is similar but not identical to co-CD in the X- and O-point, respectively. One possible difference is that ctr-CD might give rise to a 4/2 component that would make the 2/1 island narrower and thus easier to stabilize. Similar considerations apply to a 6/4 distortion of the 3/2 island. Further differences between co- and ctr-CD stabilization might be unveiled by the experiment, in particular by magnetic probe and ECE measurements of the island width evolution and of the poloidal and toroidal mode numbers. MSE measurements of the total local current and ONETWO and TORAY calculations of the Bootstrap and EC-driven currents will also be essential in the analysis. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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