Statistical analysis of correlations and intermittency of a turbulent rotating column in a magnetoplasma device.
A statistical analysis of density fluctuations in a cylindrical non-fusion device is performed. The experimental setup is implemented in order to reach a turbulent behavior of the linear plasma column. Two different turbulent regimes are obtained corresponding to two selected sets of values for the discharge parameters. The first regime displays a rotating column characterized by the presence of a shear layer separating the plasma bulk from the tenuous plasma in the shadow of the limiter, the latter showing a strong intermittent behavior and superdiffusion. The second regime corresponds to a weakly rotating column in which coherence is lost in the plasma bulk and a standard diffusive process takes place in the shadow region. These findings are supported by the calculation of the Hurst's exponent using wavelet-analysis techniques. Furthermore the intermittent behavior is characterized and related to the diffusive process. Finally the shape of the probability distribution function of density fluctuations seems to be well described by an analytical form suggested on the basis of Tsallis generalized statistics.
Magni
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Dipartimento di Fisica, Universitá di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy.
Roman
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Barni
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Riccardi
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Pierre
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Guyomarc'h
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