Statistical analysis of the turbulent Reynolds stress and its link to the shear flow generation in a cylindrical laboratory plasma device

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2985836· OSTI ID:21269045

Yan, Z; Yu, J H; Holland, C; Xu, M; Mueller, S H; Tynan, G R ^[1]

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1. Center for Energy Research, University of California, San Diego, La Jolla, California 92093 (United States)

The statistical properties of the turbulent Reynolds stress arising from collisional drift turbulence in a magnetized plasma column are studied and a physical picture of turbulent driven shear flow generation is discussed. The Reynolds stress peaks near the maximal density gradient region, and is governed by the turbulence amplitude and cross-phase between the turbulent radial and azimuthal velocity fields. The amplitude probability distribution function (PDF) of the turbulent Reynolds stress is non-Gaussian and positively skewed at the density gradient maximum. The turbulent ion-saturation (Isat) current PDF shows that the region where the bursty Isat events are born coincides with the positively skewed non-Gaussian Reynolds stress PDF, which suggests that the bursts of particle transport appear to be associated with bursts of momentum transport as well. At the shear layer the density fluctuation radial correlation length has a strong minimum ({approx}4-6 mm{approx}0.5C{sub s}/{omega}{sub ci}, where C{sub s} is the ion acoustic speed and {omega}{sub ci} is the ion gyrofrequency), while the azimuthal turbulence correlation length is nearly constant across the shear layer. The results link the behavior of the Reynolds stress, its statistical properties, generation of bursty radially going azimuthal momentum transport events, and the formation of the large-scale shear layer.

• OSTI ID: 21269045
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 9 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
COLLISIONS
DISTRIBUTION FUNCTIONS
PLASMA
SHEAR
TURBULENCE