Compatibility of internal transport barrier with steady-state operation in the high bootstrap fraction regime on DIII-D
- General Atomics, San Diego, CA (United States)
- Institute of Plasma Physics Chines Academy of Sciences, Anhui (People's Republic of China)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Fourth State Research, Austin, TX (United States)
- Columbia Univ., New York, NY (United States)
- Univ. of California, Irvine, CA (United States)
Recent EAST/DIII-D joint experiments on the high poloidal beta tokamak regime in DIII-D have demonstrated fully noninductive operation with an internal transport barrier (ITB) at large minor radius, at normalized fusion performance increased by ≥30% relative to earlier work. The advancement was enabled by improved understanding of the 'relaxation oscillations', previously attributed to repetitive ITB collapses, and of the fast ion behavior in this regime. It was found that the 'relaxation oscillations' are coupled core-edge modes amenable to wall-stabilization, and that fast ion losses which previously dictated a large plasma-wall separation to avoid wall over-heating, can be reduced to classical levels with sufficient plasma density. By using optimized waveforms of the plasma-wall separation and plasma density, fully noninductive plasmas have been sustained for long durations with excellent energy confinement quality, bootstrap fraction ≥80%, $${{\beta}_{\text{N}}}\leqslant 4$$ , $${{\beta}_{\text{P}}}\geqslant 3$$ , and $${{\beta}_{\text{T}}}\geqslant 2\%$$ . Furthermore, these results bolster the applicability of the high poloidal beta tokamak regime toward the realization of a steady-state fusion reactor.
- Research Organization:
- General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E)
- Grant/Contract Number:
- FC02-04ER54698; AC02-09CH11466; AC52-07NA27344; FG02-04ER54761; SC-G903402
- OSTI ID:
- 1353118
- Alternate ID(s):
- OSTI ID: 1238811; OSTI ID: 1438700
- Report Number(s):
- LLNL-JRNL-741496
- Journal Information:
- Nuclear Fusion, Vol. 55, Issue 12; ISSN 0029-5515
- Publisher:
- IOP ScienceCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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