DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 236: Grad-Ti/Stiffness scan for transport validation studies | ||
| Name: | Christopher Holland ( |
Affiliation: | University of California, San Diego |
| Research Area: | Transport Model Validation | Presentation time: | Requested | Co-Author(s): | G. R. Tynan, G. R. McKee, M. W. Shafer, A. E. White, T. Rhodes, J. DeBoo, R. Prater, G. Staebler, J. Kinsey, R. E. Waltz, J. Candy |
| Description: | The goal of this experiment would be to carry out a deviation from criticality scaling study, to validate gyrokinetic simulations of �??deep core�?� ITG turbulence and its scaling | ||
| Experimental Approach/Plan: | TBD. Basic idea is to scan grad-Ti or some other parameter (using a reference point at r/a=0.5-0.6), while holding rest of plasma as constant as feasible. For each value of grad-Ti, carry out multiple repeat discharges to obtain radial profiles of ne and Te fluctuations. Up-down symmetric plasmas would be preferable. The real test here is to do a scan of deviation from critical gradient for ITG modes. If we cant push on grad-Ti, could try varying a parameter to push on what the critical gradient is, with grad-Ti fixed. | ||
| Background: | Gyrokinetic simulations of plasma turbulence are believed to be most successful in predicting the ion heat flux due to long-wavelength ion temperature gradient (ITG) transport. However, to the author�??s knowledge there has been no systematic validation study of this effect using modern gyrokinetic simulations and detailed fluctuation measurements. Because grad-Ti is the dominant parameter in setting ITG dynamics, a series of experiments in which it is systematically varied would provide extremely useful data in quantifying the success of these codes in predicting core ion heat flux. More generally, stiffness can be quantified by delta = grad-Ti - grad-Ti_crit, where grad-Ti_crit is the critical temperature gradient for ITG instability. Thus the essential parameter to scan is actually delta, rather than grad-Ti. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | complete profile and fluctuation measurements | ||
| Analysis Requirements: | TGLF/GYRO/fluctuation and transport analysis | ||
| Other Requirements: | -- | ||
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