Radially propagating fluctuation structures in the scrape-off layer of Alcator C-Mod

Journal Article · Sat Jan 14 23:00:00 EST 2006 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2164991· OSTI ID:20782437

Grulke, O; Terry, J L; LaBombard, B; Zweben, S J ^[1]

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1. MPI for Plasma Physics, EURATOM Association, D-17491 Greifswald (Germany) and Ernst-Moritz-Arndt University, D-17489 Greifswald (Germany)

Radially propagating spatiotemporal fluctuation structures are observed in the scrape-off layer of Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1 (1994)] using the combination of electric probes, a radial array of views measuring D{sub {alpha}} emission, and two-dimensional imaging of D{sub {alpha}} emission. For a specific magnetic-field configuration the electric probe and the D{sub {alpha}} array measured plasma density and potential fluctuations along the same magnetic-flux tube. Calculations of the cross-correlation functions of D{sub {alpha}} intensity fluctuations with ion saturation current fluctuations and floating potential fluctuations, respectively, reveal that the potential associated with fluctuation structures is of dipole type, consistent with fundamental models for radial blob propagation. Radial and poloidal velocities of fluctuation structures are obtained by two-dimensional spatiotemporal turbulence imaging using an ultrafast framing camera observing the D{sub {alpha}} emission intensity in the poloidal plane. In the poloidal direction the fluctuation structures are predominantly propagating in direction of background ExB velocity. Measured radial velocities are directed outwards with a magnitude of typically 1% of the ion sound speed.

• OSTI ID: 20782437
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 1 Vol. 13; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
CHARGED-PARTICLE TRANSPORT
CORRELATION FUNCTIONS
DIPOLES
ELECTRIC PROBES
ELECTROMAGNETIC FIELDS
EMISSION
FLUCTUATIONS
IONS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FLUX
PLASMA
PLASMA CONFINEMENT
PLASMA DENSITY
PLASMA POTENTIAL
PLASMA SCRAPE-OFF LAYER
RADIAL VELOCITY
SOUND WAVES
TURBULENCE