DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 166: Test theory based models and empirical scaling for intrinsic rotation by changing turbulence modes | ||
| Name: | Edward Doyle ( |
Affiliation: | University of California, Los Angeles |
| Research Area: | Rotation Physics | Presentation time: | Requested | Co-Author(s): | -- |
| Description: | A single experiment is proposed to directly test a key prediction of theoretical and empirical models for intrinsic plasma rotation, and simultaneously provide a key transport model validation test. Leading theories to explain intrinsic plasma rotation predict that the direction of the intrinsic plasma rotation should change sign depending on whether the turbulence mode is in the ion or electron drift direction (Hahm, Diamond, etc). Experiments with balanced NBI (zero net NBI torque) and with/without ECH should be able to directly test this prediction, by changing the plasma from ITG to TEM dominated turbulence. By performing this experiment at constant normalized beta, the current empirical "Rice scaling" can also be tested. In the Rice scaling, the intrinsic plasma rotation is proportional only to beta and q, i.e. at fixed beta (and q), the rotation should be fixed. Finally, this experiment would also provide another route to test the predicted ITG/TEM transition boundary, and thus also provides a transport model validation Performing the experiment with zero net NBI torque will maximize the contribution of the mode dispersion and intrinsic rotation contributions to the measured turbulence rotation, such that ITG/TEM mode transitions should be more easily discerned than in rotating, NBI-driven plasmas. | ||
| Experimental Approach/Plan: | Separately generate ITG and TEM dominated plasmas with zero net NBI torque, at fixed beta. ITG dominated plasma will be balanced NBI only, TEM dominated would add ECH (at fixed beta). The NBI-balance for zero net torque will have to be retuned in the ECH case, both because of ECH induced deposition changes, and also because the NBI power will have to change so as to maintain constant beta. The modulated source NBI technique would also be utilized to determine diffusive and pinch momentum transport terms. ECH could utilize the "swing" technique to modulate profile gradients dynamically. | ||
| Background: | "Rice Scaling" - J. Rice et al, IAEA 2006, and also ITPA talks.
Theoretical models; Hahm et al. POP 14, (2007), and H_mode WS and ITPA talks, Gurcan, et al., POP 14, (2007). | ||
| Resource Requirements: | Co- and counter-NBI. ECH | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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