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Title: Edge turbulence and divertor heat flux width simulations of Alcator C-Mod discharges using an electromagnetic two-fluid model

Journal Article · · Nuclear Fusion
 [1];  [2];  [3];  [4];  [4]; ORCiD logo [4]; ORCiD logo [4];  [4];  [5];  [5];  [5]
  1. Univ. of Science and Technology of China, Hefei (China); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chinese Academy of Sciences (CAS), Hefei (China)
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  5. Univ. of Science and Technology of China, Hefei (China)

The BOUT++ code has been utilized in order to improve the understanding of the role of turbulent modes in controlling edge transport and resulting scaling of the scrape-off layer (SOL) heat flux width. For the C-Mod enhanced Dα (EDA) H-mode discharges, BOUT++ six-field two-fluid nonlinear simulations show a reasonable agree- ment of upstream turbulence and divertor target heat flux behavior: a) The simulated quasi-coherent modes (QCMs) show consistent characteristics of the frequency versus poloidal wave number spectra of the electromagnetic fluctuations when compared with experimental measurements: frequencies are around 60-120 kHz (experiment: about 70-110 kHz), kθ are around 2.0 cm₋1 which is similar to the Phase Contrast Imaging data; b) Linear spectrum analysis is consistent with the nonlinear phase relationship cal- culation which indicates the dominance of resistive-ballooning modes and drift-Alfven wave instabilities; c) The SOL heat flux width λq vs current Ip scaling is reproduced by turbulent transport: the simulations yield similar λq to experimental measurements within a factor of 2. Yet the magnitudes of divertor heat fluxes can be varied, depending on the physics models, sources and sinks, sheath boundary conditions, or flux limiting coefficient; d) Simple estimate by the "2-point model" for λq is consistent with simulation. Moreover, blobby turbulent spreading is confirmed for these relatively high Bp shots.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); National Natural Science Foundation of China (NNSFC)
Grant/Contract Number:
AC52-07NA27344; FC02-99ER54512
OSTI ID:
1566032
Alternate ID(s):
OSTI ID: 22925908
Report Number(s):
LLNL-JRNL--722400; 868467
Journal Information:
Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 11 Vol. 57; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English

References (26)

Multi-parameter scaling of divertor power load profiles in D, H and He plasmas on JET and implications for ITER journal July 2011
Turbulent transport regimes and the scrape-off layer heat flux width journal April 2015
Parallel heat flux limits in the tokamak scrape-off layer journal October 2005
Concept Design of CFETR Tokamak Machine journal March 2014
Scaling of the tokamak near the scrape-off layer H-mode power width and implications for ITER journal August 2013
Confinement and Transport Research in Alcator C-Mod journal April 2007
Comparison of theoretical models for scrape-off layer widths with data from COMPASS-D, JET and Alcator C-Mod journal February 1999
Inter-ELM Power Decay Length for JET and ASDEX Upgrade: Measurement and Comparison with Heuristic Drift-Based Model journal November 2011
Models, assumptions, and experimental tests of flows near boundaries in magnetized plasmas journal March 2016
Observations and empirical scalings of the high-confinement mode pedestal on Alcator C-Mod journal July 2002
Divertor heat flux footprints in EDA H-mode discharges on Alcator C-Mod journal August 2011
Chapter 4: Power and particle control journal June 2007
Heuristic drift-based model of the power scrape-off width in low-gas-puff H-mode tokamaks journal December 2011
Experimental divertor physics journal June 1997
Transport into and across the scrape-off layer in the ASDEX Upgrade divertor tokamak journal May 2002
Convective transport by intermittent blob-filaments: Comparison of theory and experiment journal June 2011
Scaling of the power exhaust channel in Alcator C-Mod journal May 2011
Comparison of scrape-off layer profiles in outboard-versus inboard-limited plasmas in Tore Supra journal March 2010
Experimental and Theoretical Study of Quasicoherent Fluctuations in Enhanced D α Plasmas in the Alcator C-Mod Tokamak journal November 2002
Analysis of a multi-machine database on divertor heat fluxes journal May 2012
Physics Design of CFETR: Determination of the Device Engineering Parameters journal March 2014
Modeling of tokamak divertor plasma for weakly collisional parallel electron transport journal August 2015
New insights on boundary plasma turbulence and the quasi-coherent mode in Alcator C-Mod using a Mirror Langmuir Probe journal May 2014
Impact of inward turbulence spreading on energy loss of edge-localized modesa) journal May 2015
Divertor heat flux scaling with heating power and plasma current in H-mode discharges in the national spherical torus experiment journal June 2007
The Plasma Boundary of Magnetic Fusion Devices book January 2000

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