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Experimental characterization of drift-wave turbulence in the sheared, cylindrical slab

Plasma turbulence on a uniform density gradient with unfavorable magnetic curvature is investigated extensively in the Helimak device. The turbulence is strong with density and electrostatic potential fluctuation levels in excess of 40%. Measurements of the dispersion relation, k[subscript z], and k[subscript parallel lines] identify the the fluctuations with drift-waves, which propagate in the poloidal direction at the diamagnetic drift velocity and have a small, but nite parallel wavenumber. A non-zero phase shift between the density and potential fluctuations gives rise to turbulent cross-eld particle transport, which is measured using spectral techniques. In addition, the electrostatic drift-wave fluctuations have a small magnetic component that is driven by the turbulent parallel current [scientific symbols]. An examination of nonlinear processes associated with the plasma turbulence uncovers high levels of intermittency near the plasma edge and long-time persistence of the density fluctuations on the order of the parallel confinement time. An analysis of the bispectrum conrms the existence local and nonlocal three-wave interactions between unstable drift-waves although the turbulent saturation of the density fluctuation spectrum is likely due nonlinear processes acting in the time domain. / text

Identiferoai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/10671
Date24 March 2011
CreatorsLee, Kevin Michael
Source SetsUniversity of Texas
LanguageEnglish
Detected LanguageEnglish
Formatelectronic
RightsCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.

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