DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 398: RMP pedestal transport and stability at normal density | ||
| Name: | Ilon Joseph ( |
Affiliation: | University of California, San Diego |
| Research Area: | ELM Control & Pedestal Physics | Presentation time: | Not requested | Co-Author(s): | TE Evans, ME Fenstermacher, RA Moyer, TH Osborne |
| Description: | Compare pedestal transport in an ELMing plasma versus an RMP plasma at the SAME density. The two major goals are to determine: 1. WHERE transport changes occur, and 2. HOW the ELM stability boundary is affected.
Reconstruct diffusivity profile to determine WHERE local transport changes have occurred: at the top of the pedestal, or only near the separatrix and SOL. Directly measure HOW the ELM stability boundary changes in RMP plasmas with the same density. | ||
| Experimental Approach/Plan: | Move plasma far enough away from pump to achieve the same line-averaged density before and after application of the I-coil pulse. Characterize pedestal transport by using edge breathing to develop high-resolution TS and CER profiles across the pedestal. | ||
| Background: | Attempts to understand changes in RMP transport and stability have been frustrated by the significant changes of temperature and density profiles between the original ELMing plasma and the final low density RMP plasma. A simple method to mitigate such changes is to move the strike point far enough away from the pump to maintain the same density before and after the I-coil is applied. The pedestal profiles of the before and after states can then be directly compared. If the diffusivities are shown to change at the top of the pedestal, one could conclude that effects deeper in the plasma such as the production of an island, or stochastic region, or in a model with complete shielding: by neoclassical transport in the resonant components of delta B^2 due to a perfectly ideal mode (compare to EHO). If, however, transport is only changed near the separatrix and SOL, one would need to assume that only a small of the plasma is sensitive to RMP induced transport changes.
By working in plasmas at relatively similar density and temperatures, one will be able to directly determine the effect of the RMP on the ELM stability boundary. | ||
| Resource Requirements: | n=3 I-coil, edge breathing to develop high resolution TS and CER edge profiles. | ||
| Diagnostic Requirements: | Turbulence diagnostics. | ||
| Analysis Requirements: | ONETWO, TRANSP | ||
| Other Requirements: | -- | ||
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