DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 290: Develop an L-mode error correction test plasma | ||
| Name: | Michael J. Schaffer ( |
Affiliation: | General Atomics |
| Research Area: | Error Fields | Presentation time: | Not requested | Co-Author(s): | LaHaye, Strait, Scoville (expected) |
| Description: | Test whether plasma toroidal rotation in an L-mode plasma can be used to test magnetic error correction, and if so, develop it. This test plasma might be easier to use than Ohmic, low-density plasmas sensitive to locked modes. | ||
| Experimental Approach/Plan: | Use a DND plasma biased upward, like the present Ohmic error field test plasmas, to avoid easy L-H transition. Begin with just the beam needed for CER toroidal rotation measurement. Apply known error correction and anti-correction fields to see whether rotation is affected enough to be a useful indicator of error status. Try low and moderate densities and NBI. If a useful effect is present, scan the applied non axisymmetric field over a wider range, to verify its usefulness. | ||
| Background: | Error field studies at DIII-D have used low-density, Ohmic test plasmas that are reproducibly sensitive to locked mode onset. As errors have been reduced, operating densities have become inconveniently low. Rapidly rotating, H-mode, high-beta_N, RWM test plasmas have also been used, in which toroidal plasma rotation is maximized by error correction. They require a clean machine and considerable resources to produce. A recent attempt to develop a plainer H-mode test plasma failed, because the plasma evolved too much as correction fields were applied, thus making it unreproducible for error work. L-mode plasmas are easy to run, and they have moderate plasma rotation and CER. It would be helpful for future error field research if a reliable L-mode test plasma could be developed. | ||
| Resource Requirements: | NBI for L-mode and CER toroidal rotation | ||
| Diagnostic Requirements: | CER toroidal rotation | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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