skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Mean flows and blob velocities in scrape-off layer (SOLT) simulations of an L-mode discharge on Alcator C-Mod

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4953419· OSTI ID:1256738

Two-dimensional scrape-off layer turbulence (SOLT) code simulations are compared with an L-mode discharge on the Alcator C-Mod tokamak [M. Greenwald, et al., Phys. Plasmas 21, 110501 (2014)]. Density and temperature profiles for the simulations were obtained by smoothly fitting Thomson scattering and mirror Langmuir probe (MLP) data from the shot. Simulations differing in turbulence intensity were obtained by varying a dissipation parameter. Mean flow profiles and density fluctuation amplitudes are consistent with those measured by MLP in the experiment and with a Fourier space diagnostic designed to measure poloidal phase velocity. Blob velocities in the simulations were determined from the correlation function for density fluctuations, as in the analysis of gas-puff-imaging (GPI) blobs in the experiment. In the simulations, it was found that larger blobs moved poloidally with the ExB flow velocity, vE , in the near-SOL, while smaller fluctuations moved with the group velocity of the dominant linear (interchange) mode, vE + 1/2 vdi, where vdi is the ion diamagnetic drift velocity. Comparisons are made with the measured GPI correlation velocity for the discharge. The saturation mechanisms operative in the simulation of the discharge are also discussed. In conclusion, it is found that neither sheared flow nor pressure gradient modification can be excluded as saturation mechanisms.

Research Organization:
Lodestar Research Corp., Boulder, CO (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Contributing Organization:
Enter names of organizations that provided significant assistance but not direct funding
Grant/Contract Number:
FG02-97ER54392; AC02-09CH11466; FC02-99ER54512; S013429-U
OSTI ID:
1256738
Alternate ID(s):
OSTI ID: 1256535
Journal Information:
Physics of Plasmas, Vol. 23, Issue 6; Related Information: (Provide citations for supplementary items published with journal articles, or any other citation directly supporting the document you are submitting. Or, see the Related DOIs field below.); ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

References (50)

Effects of E×B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices journal May 1997
Suppression of turbulence and transport by sheared flow journal January 2000
Dynamics of L–H transition and I-phase in EAST journal September 2014
Nonlinear transfer in heated L-modes approaching the L–H transition threshold in Alcator C-Mod journal June 2015
The role of zonal flows and predator–prey oscillations in triggering the formation of edge and core transport barriers journal April 2014
Low-to-high confinement transition simulations in divertor geometry journal May 2000
Physics of Stimulated L H Transitions journal May 2013
Mechanisms and dynamics of the external transport barrier formation in non-linear plasma edge simulations journal June 2015
Flux-driven simulations of turbulence collapse journal March 2015
L to H mode transition: on the role of Z eff journal January 2014
H-mode transitions and limit cycle oscillations from mean field transport equations journal November 2014
Plasma turbulence in the scrape-off layer of tokamak devices journal January 2013
Turbulent regimes in the tokamak scrape-off layer journal September 2013
Reduced model simulations of the scrape-off-layer heat-flux width and comparison with experiment journal January 2011
Numerical investigation of edge plasma phenomena in an enhanced D-alpha discharge at Alcator C-Mod: Parallel heat flux and quasi-coherent edge oscillations journal August 2012
Numerical scalings of the decay lengths in the scrape-off layer journal June 2013
Modeling the effect of lithium-induced pedestal profiles on scrape-off-layer turbulence and the heat flux width journal September 2015
Theory-based scaling of the SOL width in circular limited tokamak plasmas journal November 2013
Theory of the scrape-off layer width in inner-wall limited tokamak plasmas journal March 2014
Effect of the limiter position on the scrape-off layer width, radial electric field and intrinsic flows journal July 2014
Turbulent transport regimes and the scrape-off layer heat flux width journal April 2015
Comparison of edge turbulence imaging at two different poloidal locations in the scrape-off layer of Alcator C-Mod journal July 2013
Edge transport studies in the edge and scrape-off layer of the National Spherical Torus Experiment with Langmuir probes journal April 2014
New insights on boundary plasma turbulence and the quasi-coherent mode in Alcator C-Mod using a Mirror Langmuir Probe journal May 2014
High-speed imaging of edge turbulence in NSTX journal December 2003
Observations of the turbulence in the scrape-off-layer of Alcator C-Mod and comparisons with simulation journal May 2003
On physical interpretation of two dimensional time-correlations regarding time delay velocities and eddy shaping journal December 2012
Zonal flow production in the L–H transition in Alcator C-Mod journal May 2014
Experimental studies of edge turbulence and confinement in Alcator C-Mod journal May 2010
Fast 2-D camera control, data acquisition, and database techniques for edge studies on NSTX journal May 2014
Derivation of time-dependent two-dimensional velocity field maps for plasma turbulence studies journal October 2006
Comparison of velocimetry techniques for turbulent structures in gas-puff imaging data journal February 2016
Recent theoretical progress in understanding coherent structures in edge and SOL turbulence journal October 2008
Convective transport by intermittent blob-filaments: Comparison of theory and experiment journal June 2011
20 years of research on the Alcator C-Mod tokamaka) journal November 2014
Saturation mechanisms for edge turbulence journal December 2009
Two-dimensional modelling of blob dynamics in tokamak edge plasmas journal April 2006
Magnetic field dependence of the blob dynamics in the edge of ASDEX upgrade L-mode plasmas journal June 2014
The influence of finite ion temperature on plasma blob dynamics journal November 2014
Effects of the parallel electron dynamics and finite ion temperature on the plasma blob propagation in the scrape-off layer journal November 2008
The influence of finite Larmor radius effects on the radial interchange motions of plasma filaments journal November 2011
Filament velocity scaling laws for warm ions journal October 2013
Role of ion temperature on scrape-off layer plasma turbulence journal April 2013
Radial convection of finite ion temperature, high amplitude plasma blobs journal September 2014
Finite ion temperature effects on scrape-off layer turbulence journal January 2015
Drift-ordered fluid equations for field-aligned modes in low-β collisional plasma with equilibrium pressure pedestals journal December 2003
Status and verification of edge plasma turbulence code BOUT journal June 2009
Effects of parallel electron dynamics on plasma blob transport journal August 2012
Modeling of particle and energy transport in the edge plasma of Alcator C-Mod journal July 1999
Kinetic effects on ballooning modes in mirror machines journal January 1981

Cited By (2)

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices journal April 2017
Blob-hole correlation model for edge turbulence and comparisons with NSTX gas puff imaging data journal June 2018