DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 118: NTM stabilization and RMP in high li, high betaN discharges | ||
| Name: | John Ferron ( |
Affiliation: | General Atomics |
| Research Area: | Core Integration (Steady-State Scenario) | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | Apply ECCD stabilization of NTMs to help maximize the beta in high li discharges. Use RMP to reduce the pedestal height in order to reduce the edge bootstrap current. | ||
| Experimental Approach/Plan: | Off-axis ECCD was applied in the 2007 discharges in order to avoid sawteeth. This seemed to be effective. To stabilize NTMs, the toroidal field and aiming of the ECCD would be adjusted for preemptive stabilization. ECCD could be used effectively in discharges in which we attempt to maximize betaN. This use of the ECCD will also have a good likelihood of stabilizing sawteeth by slightly raising q(0) as was observed in 2007. The application of RMP fields is known to reduce the pedestal height, particularly when the edge q is at the most resonant value. The new method for forming a high li discharge allows the toroidal field and plasma current to be chosen in order to produce the resonance condition required for most effective use of the RMP. In order to develop the technique, RMP would probably first be applied in a discharge with a relatively steady value of betaN (about 4). Then the application could be extended to higher betaN, more transient discharges in order to attempt to extend the period of high betaN. | ||
| Background: | Some of the high betaN, high li discharges produced in 2007 were limited by NTMs. The NTMs provided a rather soft limit to beta. So, if the NTMs could be avoided then higher values of beta might be accessible. Another feature of the high li discharges is that after the H-mode transition the edge bootstrap current increases resulting in a decrease in li. It is desirable to reduce the edge bootstrap current. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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