DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 424: Test of thermal ion ripple loss as key parameter for L-H transition | ||
| Name: | T. C. Luce ( |
Affiliation: | General Atomics |
| Research Area: | Transport | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | Lots of dependencies have been observed for the L-H threshold that do not appear in the scalings derived from the international database. For example, the rise in threshold power at low density, the higher threshold with EC, the variation with co-NBI vs. balanced, the ion grad-B drift direction, and variation with current ramp up or ramp down have all been observed on DIII-D. The hypothesis here is that the true hidden parameter is the ripple cone loss of thermal ions, which, when large enough, leads to an L-H transition. | ||
| Experimental Approach/Plan: | The experiment would vary plasma shape and plasma parameters to change the ripple loss of the thermal ions and look for correlation with the L-H threshold power variation. It is essential to find the threshold by bracketing the L-H threshold in near stationary conditions. The sawtooth pulses would be minimized by operation at high q95. | ||
| Background: | -- | ||
| Resource Requirements: | Need EC power, co-NBI, and ctr-NBI. | ||
| Diagnostic Requirements: | Full edge diagnostics desirable, but not mandatory for exploratory experiment. Only filterscopes mandatory for transition info. | ||
| Analysis Requirements: | Need intensive analysis using model equilibria to examine thermal ion loss dependence on shape and other parameters (collisionality, ion grad(B) direction, etc.). | ||
| Other Requirements: | -- | ||
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