DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 116: Access to betaN = 5 in a high li scenario | ||
| Name: | John Ferron ( |
Affiliation: | General Atomics |
| Research Area: | Core Integration (Steady-State Scenario) | Presentation time: | Requested | Co-Author(s): | -- |
| Description: | Build on the promising results (betaN = 4.5) achieved in 2007 that used a new high li discharge formation technique in order to improve the discharge operation, increase the value of li at the peak of betaN, reach betaN = 5, and extend the duration of the high li phase. | ||
| Experimental Approach/Plan: | Further analysis of the 2007 data is required in order to decide the best approach for new experiments. Since we quickly tried quite a number of variations on the details of the discharge evolution, there wasn't any opportunity to choose the approach giving the best results and pursue it further. The focus would be on achieving 4li above 5 at the time of the peak betaN. The issues are the relative time evolution of beta and li, the choice of time for the H-mode transition and whether the rate of decrease of li after the H-mode transition can be reduced such as by reducing the edge pedestal height. Also, it isn't clear that the optimum plasma current and toroidal field were used. There is a long list of ideas for changing details of the experiment including operating with type 3 ELMs at high-density, operating at extremely low squareness, and going back to a discharge closer to what was used in the ITER startup experiments which reached higher values of li. In addition, we need to get data with the counter-beam viewing mse channels in order to improve the q profile measurement. | ||
| Background: | During 2007, a new approach to formation of a high li discharge was tested based on the constant q95 ITER startup scenario. This discharge formation technique is much simpler and more versatile than the current ramp or kappa ramp techniques used previously; toroidal field and flattop plasma current can be varied over a significant range allowing tuning of the discharge to meet various constraints. BetaN = 4.5 was achieved with high normalized confinement. During this one-day experiment a number of methods for operating the discharge were tested rather quickly with varying results for the betaN achieved and the beta limiting phenomenon. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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