DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 16: Expand the dimensionless similarity database on intrinsic rotation | ||
| Name: | John Degrassie ( |
Affiliation: | General Atomics |
| Research Area: | Rotation Physics | Presentation time: | Not requested | Co-Author(s): | W. Solomon, K. Burrell, J. Rice |
| Description: | *A prioritized plan will be developed to explore the scaling of intrinsic rotation with beta, q95, nustar, and rhostar to see to what extent it can be described by the dimensionless variables. A first experiment should simply be redoing dimensionless parameters from previous LSN H-mode discharges in USN and DND shapes to see whether there is a significant effect on intrinsic rotation. The experiment will be greatly facilitated by having the near-balanced NBI tool operational (proposal 14). Accommodation of turbulence measurements should be given thought in this plan, since there are now theories that predict intrinsic rotation arising from turbulence, and the profile of turbulence activity. This is a multi-day effort. | ||
| Experimental Approach/Plan: | *Execute the experimental plan that is developed. A first priority should be to get some data on the effect of shape on intrinsic rotation; X-point up/down, DND and triangularity. Then the next priorities would seem to be scans in Beta and q95, followed by nustar and eventually rhostar. This is a multi-day experiment.
*The balanced-NBI (proposal 14) is an enabling capability here. | ||
| Background: | *Rice-s C-Mod scaling of intrinsic toroidal rotation increasing with W/Ip is seen in a number of tokamaks, as described in his 2006 IAEA paper. This is an engineering scaling. We see this same scaling in DIII-D in the outer ¾ region in minor radius, in ECH H-modes, while the interior velocity profile appears to be modified by ECH details.
We need to turn this into a dimensionless scaling in order to have an empirical extrapolation to ITER. There is clearly some size scaling in this Rice engineering scaling. The slope of the scaling in DIII-D is about a factor of 10 less in DIII-D than in C-Mod, smaller machines have greater intrinsic rotation velocities perhaps. *Cross machine similarity experiments between DIII-D and C-Mod are underway. JET will hopefully join this effort in 2008. *We need to push a search for a similarity law in many directions, beta, q95, nustar, rhostar, and investigate the effect of shape, for which we have little information. The near-balanced beam tool (proposal 14) will be important to facilitate these scans. *The effect of shape is largely unknown. If there is a significant effect, it will greatly expand the data landscape, but would then provide another knob and more opportunity to narrow down explanations. | ||
| Resource Requirements: | NBI: 21R/L, 30L, 33L/R needed. 15L/R desired.
ECH: more is better | ||
| Diagnostic Requirements: | standard for intrinsic rotation experiments | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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