DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 15: Intrinsic rotation in helium H-mode discharges. | ||
| Name: | John Degrassie ( |
Affiliation: | General Atomics |
| Research Area: | Rotation Physics | Presentation time: | Requested | Co-Author(s): | W. Solomon, K. Burrell |
| Description: | *Obtain a set of intrinsic rotation measurements with helium as the bulk ion, so that we can measure the bulk ion intrinsic toroidal and poloidal velocities. ECH H-modes will be the starting point, but we need to add the near balanced NBI capability in order to increase BetaN (see proposal 14) . It is tbd whether or not the beams must be dominantly helium also (excluding some of the standard diagnostic beams). | ||
| Experimental Approach/Plan: | *We will use our developed experimental techniques to measure the bulk ion toroidal and poloidal velocities in helium discharges. The near balanced NBI extraction of intrinsic rotation (proposal 14) will be an important tool to increase BetaN and follow the change in intrinsic poloidal velocity with plasma energy. Matched discharges will be taken to measure the carbon intrinsic velocities as we did in the past. | ||
| Background: | *We have made intrinsic velocity measurements in ELMing H-mode discharges with helium as the bulk ion. This 2004 one day experiment has been most important in giving confidence that the carbon velocity typically measured is not misleading us in inferring intrinsic rotation of the plasma as a whole.
*The standard methodology to go from carbon velocity to bulk deuterium velocity utilizes the neoclassical theory for the bulk ion poloidal rotation, since it is not measured. However, the experiments of Solomon et al have shown that the carbon poloidal velocities do not agree with this neoclassical theory, throwing into confusion any attempt to compute the bulk ion toroidal velocity from the carbon impurity toroidal velocity. This affects any comparisons of intrinsic rotation experiments with theory. *We must measure the bulk ion intrinsic poloidal velocity as well as toroidal velocity to establish a known data set against which all proposed theories can be scrutinized. In companion matched discharges the carbon velocities will also be measured, as we did before. *Near balanced NBI will be an important tool since we believe that the poloidal velocity will increase with plasma stored energy, bringing it well out of the error bars. | ||
| Resource Requirements: | NBI: all beams no doubt. It may be necessary to have 21R/L and 15L/R in helium.
ECH: max power. Entry level is probably 3 gyrotrons to make a LSN H-mode in the good direction. | ||
| Diagnostic Requirements: | Standard set for intrinsic rotation experiments | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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