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Title: Compatibility of internal transport barrier with steady-state operation in the high bootstrap fraction regime on DIII-D

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 2 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%, β N ≤ 4 , β P ≥ 3 , and β T ≥ 2%. Finally, these results bolster the applicability of the high poloidal beta tokamak regime toward the realization of a steady-state fusion reactor.
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  1. General Atomics, San Diego, CA (United States)
  2. Institute of Plasma Physics Chines Academy of Sciences, Anhui (People's Republic of China)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Fourth State Research, Austin, TX (United States)
  6. Columbia Univ., New York, NY (United States)
  7. Univ. of California, Irvine, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0029-5515
Grant/Contract Number:
FC02-04ER54698; AC02-09CH11466; AC52-07NA27344; FG02-04ER54761; SC-G903402
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 12; Journal ID: ISSN 0029-5515
IOP Science
Research Org:
General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; steady state; ion transport barrier; wall stabilization; high beta; 70 PLASMA PHYSICS AND FUSION
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1238811; OSTI ID: 1438700