DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 119: Study of moderate beta, high li transport and stability | ||
| Name: | John Ferron ( |
Affiliation: | General Atomics |
| Research Area: | Core Integration (Steady-State Scenario) | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | Produce a high li discharge that runs without beta collapse at significant betaN (for example, about 4). Use MHD spectroscopy to look for the no wall beta limit as li evolves, particularly as it decreases at constant betaN. Evaluate the confinement in the absence of large dW/dt and the dependence of confinement on rotation. Evaluate the effect of the toroidal rotation velocity on the measured stability limit. | ||
| Experimental Approach/Plan: | In 2007 it was relatively easy to make a discharge with betaN above 4. So, it seems reasonable that we could make a discharge that regulates at betaN = 4 while li evolves to lower values after the H-mode transition. If the no-wall stability limit is above 4 at the higher values of li, then it ought to be possible to observe the discharge passing through the no wall limit as li decreases (using MHD spectroscopy). In addition, a discharge with relatively constant betaN would facilitate the study of confinement and the dependence on rotation that could be obtained by using the counter beams. A change in the stability limit could be observed at lower rotation. | ||
| Background: | MHD spectroscopy is an excellent tool for diagnosis of the low-n no-wall stability limit. In 2007 experiments, it didn't appear that, even at betaN = 4.5, the no-wall stability limit was exceeded. The 2007 high li discharges that reached high betaN had H factor about 3, but there was also still a large dW/dt. It would be good to establish that the confinement is still high in conditions with more steady state stored energy. Also, the normalized confinement increases significantly as the beam power is increased suggesting that perhaps there is a strong dependence of confinement on rotation. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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