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Title: Fast-ion transport in qmin>2, high- β steady-state scenarios on DIII-D

The results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high-qminqmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of neutral beam heating power is applied with the intent of maximizing β N and the noninductive current drive. However, in scenarios with q min>2 that target the typical range of q 95= 5–7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reduces the absorbed neutral beam heating power and current drive and limits the achievable β N. Conversely similar plasmas except with q min just above 1 have approximately classical fast-ion transport. Experiments that take q min>3 plasmas to higher β P with q 95= 11–12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high-q min scenario, the high β P cases have shorter slowing-down time and lower ∇β fast, and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, β N,more » and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower-q 95, high-q min plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes.« less
 [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [5] ; ORCiD logo [4] ;  [4] ;  [3] ;  [2] ;  [6] ;  [6] ;  [3] ;  [7] ;  [3] ;  [5] ;  [4]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of California, Irvine, CA (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Plasma Physics
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. Columbia Univ., New York, NY (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1070-664X; PHPAEN
Grant/Contract Number:
AC52-07NA27344; AC02-09CH1146; AC05-00OR22725; FC02-04ER54698; FG02-04ER54761; SCG903402
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 5; Journal ID: ISSN 1070-664X
American Institute of Physics (AIP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States