DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 153: Simultaneous fluctuation amplitudes measured across the plasma radius in L- and H-mode | ||
| Name: | Dave Schlossberg ( |
Affiliation: | University of Wisconsin, Madison |
| Research Area: | Transport | Presentation time: | Requested | Co-Author(s): | G.R. McKee, M.W. Shafer, C. Holland, G. Tynan |
| Description: | Measure the density fluctuation amplitude across the radius of the plasma, both in L-mode and H-mode, and across the LH transition. With the recent upgrades to the BES system, it is possible to obtain fluctuation measurements at 64 spatially-resolved radial locations, spanning up to approximately 50 cm. By simultaneously measuring turbulence amplitudes along much of the plasma�??s entire radius, turbulence dynamics from the core to the edge can be quantified and spreading of turbulence can be measured. Shot-to-shot variation in turbulence behavior can be eliminated since comparisons will be done within a single shot. Radial correlation lengths can also be compared across the radius of the plasma. By investigating both L-mode and H-mode plasmas, a comparison of turbulence amplitudes can be made. Previous measurements show that turbulence is rapidly reduced at the LH transition even in the core region.
The diagnostic arrangement for BES is such that it would be difficult to change the array dimensions during an experiment. Therefore, the BES array would likely be configured as a 1x64 array for the duration of the experiment. | ||
| Experimental Approach/Plan: | Configure the BES array as a 1x64 radial array, spanning the radius of the plasma. Obtain stable L-mode, ELM-free H-mode, and LH-transitioning plasmas, and measure the turbulence amplitudes across the plasma radius. | ||
| Background: | Previous studies have found that turbulence amplitudes decrease at the time of the LH transition. However, it has yet to be determined whether these decreases in turbulence amplitudes propagate from, for example, the edge to the core region, or if they occur simultaneously across the plasma. By recording simultaneous measurements across the entire plasma radius, possible turbulence spreading and suppression front propagation will be measured. Furthermore, turbulence amplitudes in the core region will be compared to values in the edge region in L-mode, H-mode, and near the LH transition time. | ||
| Resource Requirements: | 150L neutral beam | ||
| Diagnostic Requirements: | BES, CER | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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