DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 95: RMP Effect on Location of P-B Stability Boundary | ||
| Name: | Max E. Fenstermacher ( |
Affiliation: | Lawrence Livermore National Laboratory |
| Research Area: | ELM Control & Pedestal Physics | Presentation time: | Not requested | Co-Author(s): | M.E. Fenstermacher |
| Description: | Test possibility that n=3 RMP from I-coil can change the location of the stability boundary in P-B alpha-J space without affecting any change on the edge pedestal plasma profiles (Leonard idea). | ||
| Experimental Approach/Plan: | Use slowly oscillating I-coil current (as suggested by Wade - vis 50 Hz, +- 1 kA about centroid of 4 kA, ala shot 129208 in Moyer experiment in 2007) to vary the RMP within a plasma with fixed pedestal profiles. Apply this technique to the ELM suppressed phase of a standard ISS ELM suppression scenario. Since the effective particle confinement time in the ELM suppressed pedestal is about 250 ms, this oscillation should not produce any variation in the pedestal density or pressure, but will produce a variation in perturbed magnetic field strength in the pedestal. If there is an effect on the ELM suppression then this will suggest that the RMP changes the location of the stability boundary in P-B space. If changes seen in edge plasma profiles, try different oscillation frequencies (ie. probably higher up to allowable hardware limit). | ||
| Background: | This is a reminder to follow-up on the one interesting shot run in 2007 using this technique. Whether or not the RMP affects the location of the stability boundary in P-B alpha-J space is a critical question for our interpretation of the mechanism for RMP ELM suppression. Understanding in this are might geneate ideas for RMP ELM suppression at higher pedestal parameters than currently obtained. | ||
| Resource Requirements: | Same resources as used for 2007 ISS ELM control experiments, see for example shot 128374 etc. I-coil maximum current with C_supplies with capability for slow oscillation at intermediate currents, C-coil for optimum error field correction, 5 co-beams. | ||
| Diagnostic Requirements: | All pedestal and lower divertor diagnostics. Edge current measurements (especially simultaneously) with the Li-beam and co- plus counter-beam MSE would be highly desirable as would fast divertor IRTV. | ||
| Analysis Requirements: | Control room island overlap analysis with SURFMN. Post experiment kinetic EFIT analysis including edge current measurements, field line trajectory analysis with TRIP3D and other 3D modeling. | ||
| Other Requirements: | -- | ||
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