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A study of self organized criticality in ion temperature gradient mode driven gyrokinetic turbulence
被引:5
|作者:
Mavridis, M.
[1
]
Isliker, H.
[1
]
Vlahos, L.
[1
]
Goerler, T.
[2
]
Jenko, F.
[2
]
Told, D.
[2
]
机构:
[1] Aristotle Univ Thessaloniki, Sect Astrophys Astron & Mech, Dept Phys, GR-54124 Thessaloniki, Greece
[2] Max Planck Inst Plasma Phys, D-85748 Garching, Germany
关键词:
TRANSPORT;
DYNAMICS;
PARADIGM;
D O I:
10.1063/1.4900767
中图分类号:
O35 [流体力学];
O53 [等离子体物理学];
学科分类号:
070204 ;
080103 ;
080704 ;
摘要:
An investigation on the characteristics of self organized criticality (Soc) in ITG mode driven turbulence is made, with the use of various statistical tools (histograms, power spectra, Hurst exponents estimated with the rescaled range analysis, and the structure function method). For this purpose, local non-linear gyrokinetic simulations of the cyclone base case scenario are performed with the GENE software package. Although most authors concentrate on global simulations, which seem to be a better choice for such an investigation, we use local simulations in an attempt to study the locally underlying mechanisms of Soc. We also study the structural properties of radially extended structures, with several tools (fractal dimension estimate, cluster analysis, and two dimensional autocorrelation function), in order to explore whether they can be characterized as avalanches. We find that, for large enough driving temperature gradients, the local simulations exhibit most of the features of Soc, with the exception of the probability distribution of observables, which show a tail, yet they are not of power-law form. The radial structures have the same radial extent at all temperature gradients examined; radial motion (transport) though appears only at large temperature gradients, in which case the radial structures can be interpreted as avalanches.
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页数:13
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