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Title: Application of ECH to the study of transport in ITER baseline scenario-like discharges in DIII-D

Recent DIII-D experiments in the ITER Baseline Scenario (IBS) have shown strong increases in fluctuations and correlated reduction of confinement associated with entering the electron-heating-dominated regime with strong electron cyclotron heating (ECH). The addition of 3.2 MW of 110 GHz EC power deposited at ρ~0.42 to IBS discharges with ~3 MW of neutral beam injection causes large increases in low-k and medium-k turbulent density fluctuations observed with Doppler backscatter (DBS), beam emission spectroscopy (BES) and phase-contrast imaging (PCI) diagnostics, correlated with decreases in the energy, particle, and momentum confinement times. Power balance calculations show the electron heat diffusivity χe increases significantly in the mid-radius region 0.4<ρ<0.8, which is roughly the same region where the DBS and BES diagnostics show the increases in turbulent density fluctuations. Confinement of angular momentum is also reduced during ECH. Studies with the TGYRO transport solver show that the model of turbulent transport embodied in the TGLF code quantitatively reproduces the measured transport in both the neutral beam (NB)-only and in the NB plus EC cases. A simple model of the decrease in toroidal rotation with EC power is set forth, which exhibits a bifurcation in the rotational state of the discharge.
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [4] ;  [1] ;  [3] ;  [5] ;  [4] ;  [1] ;  [3] ;  [3] ;  [6] ;  [4] ;  [4] ;  [7]
  1. General Atomics, San Diego, CA (United States)
  2. Univ. of Texas at Austin, Austin, TX (United States)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. Univ. of Wisconsin-Madison, Madison, WI (United States)
  6. Univ. of California, Los Angeles, CA (United States)
  7. Columbia Univ., New York, NY (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
EPJ Web of Conferences
Additional Journal Information:
Journal Volume: 87; Journal ID: ISSN 2100-014X
EDP Sciences
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
Country of Publication:
United States