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Title: Role of density gradient driven trapped electron mode turbulence in the H-mode inner core with electron heating

In a series of DIII-D [J. L. Luxon, Nucl. Fusion 42 614 (2002)] low torque quiescent H-mode experiments show that density gradient driven TEM (DGTEM) turbulence dominates the inner core of H-Mode plasmas during strong electron cyclotron heating (ECH). By adding 3.4 MW ECH doubles Te/Ti from 0.5 to 1.0, which halves the linear DGTEM critical density gradient, locally reducing density peaking, while transport in all channels displays extreme stiffness in the density gradient. This then suggests fusion -heating may degrade inner core confinement in H-Mode plasmas with moderate density peaking and low collisionality, with equal electron and ion temperatures, key conditions expected in burning plasmas. Gyrokinetic simulations using GYRO [J. Candy and R. E. Waltz, J. Comp. Phys. 186 545 (2003)] (and GENE [F. Jenko et al., Phys. Plasmas 7, 1904 (2000)]) closely match not only particle, energy, and momentum fluxes, but also density fluctuation spectra from Doppler Backscattering (DBS), with and without ECH. Inner core DBS density fluctuations display discrete frequencies with adjacent toroidal mode numbers, which we identify as DGTEMs. GS2 [W. Dorland et al., Phys. Rev. Lett. 85 5579 (2000)] predictions show the DGTEM can be suppressed, to avoid degradation with electron heating, by broadening themore » current density profile to attain q0 > qmin > 1.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [3] ;  [7] ;  [2] ;  [1] ;  [8] ;  [2] ;  [1] ;  [4] ;  [4] ;  [9] ;  [4]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
  2. General Atomics, San Diego, CA (United States)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. Univ. of California, Los Angeles, CA (United States)
  5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  6. Fourth State Research, Austin, TX (United States)
  7. Univ. of California, San Diego, CA (United States)
  8. Univ. of Wisconsin, Madison, WI (United States)
  9. Univ. of Colorado, Boulder, CO (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698; FC02-08ER54966; AC02-09CH11466; FG02-08ER54984; SC-0006957; FG02-08ER54999; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 5; Related Information: D. R. Ernst, K. H. Burrell, W. Guttenfelder, T. L. Rhodes, A. M. Dimits, R. Bravenec, B. A. Grierson, C. Holland, J. Lohr, A. Marinoni, G. R. McKee, C. C. Petty, J. C. Rost, L. Schmitz, G. Wang, S. Zemedkun, L. Zeng, and the DIII-D Team; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Orgs:
the DIII-D Team
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY TEM; fluctuations; turbulence; ECH; tokamak; gyrokinetic
OSTI Identifier:
1372301
Alternate Identifier(s):
OSTI ID: 1372301