Experimental evidence of coupling between sheared-flow development and an increase in the level of turbulence in the TJ-II stellarator

Journal Article · Wed Dec 01 04:00:00 EST 2004 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

DOI:https://doi.org/10.1103/PhysRevE.70.067402· OSTI ID:20636919

Hidalgo, C; Pedrosa, M A; Garcia, L; Ware, A ^[1]

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1. Laboratorio Nacional de Fusion, Euratom-Ciemat, 28040 Madrid (Spain)

The link between the development of sheared flows and the structure of turbulence has been investigated in the plasma boundary region of the TJ-II stellarator. The development of the naturally occurring velocity shear layer requires a minimum plasma density. Near this critical density, the level of edge turbulent transport and the turbulent kinetic energy significantly increases in the plasma edge. The resulting shearing rate in the phase velocity of fluctuations is comparable to the one required to trigger a transition to improved confinement regimes with reduction of edge turbulence, suggesting that spontaneous sheared flows and fluctuations keep themselves near marginal stability. These findings provide the experimental evidence of coupling between sheared flows development and increasing in the level of edge turbulence. The experimental results are consistent with the expectations of second-order transition models of turbulence-driven sheared flows.

• OSTI ID: 20636919
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics Journal Issue: 6 Vol. 70; ISSN PLEEE8; ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOUNDARY LAYERS
FLUCTUATIONS
KINETIC ENERGY
PHASE VELOCITY
PLASMA
PLASMA CONFINEMENT
PLASMA DENSITY
PLASMA INSTABILITY
TJ-II HELIAC
TURBULENCE