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GA – A 27954 COMPATIBILITY OF INTERNAL TRANSPORT BARRIER WITH STEADY-STATE OPERATION IN THE HIGH BOOTSTRAP FRACTION REGIME ON DIII-D by
| Content Provider | Semantic Scholar |
|---|---|
| Author | Garofalo, Andrea M. Gong, Xinxin Solomon, Wayne Zeeland, Michael Anthony Van Holcomb, Christopher T. Bravenec, Ron Budny, Robert Vierling Ding, Shidong Grierson, B. A. Lao, Lang L. Qian, J. C. Staebler, G. M. |
| Copyright Year | 2014 |
| Abstract | Recent DIII-D research has increased confidence in the applicability of the high bootstrap current fraction plasma regime for the realization of a steady-state fusion reactor. Fully noninductive plasmas have been sustained for long durations with large-radius ITBs, bootstrap fraction≥80%, βN ≤ 4, βP ≥ 4, and βT ≥ 2%. Building on earlier DIII-D work [P.A Politzer, et al., Nucl. Fusion 45, 417 (2005)], the new experiments utilized an approach to fully noninductive operation based on removing the current drive by transformer induction. The plasmas exhibit excellent energy confinement quality, with H98y2 ~ 1.5. The excellent confinement is associated with the formation of an ITB at large minor radius in all channels (ne, Te, Ti, rotation). The ITB is maintained at large minor radius for ~4 s, more than three times the current profile relaxation time, τCR estimated to be ~1 s. The ITB is maintained at large minor radius despite edge localized mode perturbations, which become particularly large as βN is pushed against the global ideal-wall limit. The transient stored energy drops caused by these coupled edge-core modes have been previously referred to as “relaxation oscillations”. The maximum achievable βN is limited by the stability of these modes, and depends on the plasma-wall separation, which is in turn dictated by the operational need to reduce wall heating by fast ion losses. Using an optimized outer gap waveform has enabled a ~30% βN increase relative to earlier work, and opened the path to further optimizations and performance improvements. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://fusion.gat.com/pubs-ext/IAEA14/A27954.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
