Parallel and perpendicular turbulence correlation length in the TJ-II Stellarator

Long-range correlations were measured using two remote reciprocating Langmuir probe systems at TJ-II. The influence of the rotational transform on the correlation was studied by scanning the magnetic configuration. A simple drift-wave correlation model, assuming an exponential decay of the correlati...

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Published inNuclear fusion Vol. 53; no. 9; pp. 93025 - 7
Main Authors van Milligen, B.Ph, Fraguas, A. Lopez, Pedrosa, M.A., Hidalgo, C., Martín de Aguilera, A., Ascasíbar, E.
Format Journal Article
LanguageEnglish
Published IOP Publishing and International Atomic Energy Agency 01.09.2013
Subjects
Correlation
Correlation analysis
Decay
Density
Drift
Mathematical models
Reciprocating
Turbulent flow
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Summary:Long-range correlations were measured using two remote reciprocating Langmuir probe systems at TJ-II. The influence of the rotational transform on the correlation was studied by scanning the magnetic configuration. A simple drift-wave correlation model, assuming an exponential decay of the correlation with different correlation lengths in the directions parallel and perpendicular to the field lines, was found to describe the observations well at low densities. The experiment was repeated at gradually higher densities, and an additional correlation was detected at a critical value of the density. In accordance with previous work, this additional correlation was ascribed to zonal flows associated with a confinement transition. Thus, the total long-range correlation is found to be a sum of the drift wave and zonal flow contributions.
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ISSN:0029-5515
1741-4326
DOI:10.1088/0029-5515/53/9/093025