Statistical properties of turbulence in a toroidal magnetized ECR plasma

Yu, Yijun; Lu, Rengui; Wang, Zhijiang; Yao, Wen; Changxuan, Yu; Wan, Shude; Liu, Wandong

doi:10.1016/j.physleta.2007.07.006

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…Like several fusion experimental devices [74], also in the Thorello [75] SMT long range correlations and non-Gaussian PDFs have been detected; moreover intermittency is clearly present in the signals [76]. Analogously, in the KT5D SMT the investigation of the statistical properties of intermittency were carried out [77].…”

Section: Bursts and Structuresmentioning

confidence: 86%

Coherent structures and transport properties in magnetized plasmas

Serianni

Agostini

Antoni

et al. 2007

Plasma Phys. Control. Fusion

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A common feature of magnetized plasmas is the presence of fluctuations, which can lead to fully developed turbulence. Often large events-called bursts-emerge from the remaining low-level turbulence, giving an intermittent character to fluctuations; namely the statistical properties of fluctuations are found to depend on the temporal scale over which the investigation is conducted.In magnetized plasmas, the bursts are generally believed to be due to the presence of magnetic-field-aligned structures. Moreover, it has been experimentally shown that the intermittent events detected in the signals are associated with a relevant contribution to the loss of particles from the plasma.All these observations are common to plasmas spanning a wide range of temperature and density and magnetically confined both in linear and toroidal devices. In particular, in high-temperature plasmas for thermonuclear fusion, research aims at devising suitable ways to control transport by acting on the plasma structures, for instance by biasing the plasma edge using electrodes.This paper gives a characterization of the structures found in magnetized plasmas and of their contribution to the particle transport; moreover, the effect of the velocity shear on structures is addressed. Emphasis will be laid on to the most advanced diagnostics allowing the reconstruction of turbulent structures by optical and electrostatic techniques.

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Section: Bursts and Structuresmentioning

confidence: 86%

Coherent structures and transport properties in magnetized plasmas

Serianni

Agostini

Antoni

et al. 2007

Plasma Phys. Control. Fusion

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“…However, it should be noted that the absolute value of the plasma density is nonsense here, and all that we are concerned about are the relative distributions of the density and the density fluctuation. In low temperature plasmas, except for the cases where the phase angles of electron temperature play an important decisive role [24] , this approximation is usually suitable. The key to judge the superiority or inferiority of this kind of approximation is the degree of evenness in the electron temperature.…”

Section: Discussion Of the Probe Datamentioning

confidence: 99%

A 57-Pin Langmuir Probe Array for Two-Dimensional Diagnosis in the Toroidal KT-5D Steady-State Plasma

He¹,

Yu²,

Xu³

et al. 2013

Plasma Sci. Technol.

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In this article, the design idea of a 57-pin Langmuir probe array is presented, together with some experimental results. The manufacture technique of the probe array is discussed. Twodimensional distributions of the plasma density, the floating potential and their fluctuations in the poloidal cross section are obtained. The blobs, which move radially and poloidally, cause great particle and energy transport. The charge neutralization by the poloidal movement of particles greatly decreases the vertical electric field in the helimak plasma. This leads to a confinement time which is two orders of magnitude larger than the theoretical prediction.

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A study of self organized criticality in ion temperature gradient mode driven gyrokinetic turbulence

et al. 2014

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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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Statistical properties of turbulence in a toroidal magnetized ECR plasma

Cited by 3 publications

References 24 publications

Coherent structures and transport properties in magnetized plasmas

Coherent structures and transport properties in magnetized plasmas

A 57-Pin Langmuir Probe Array for Two-Dimensional Diagnosis in the Toroidal KT-5D Steady-State Plasma

A study of self organized criticality in ion temperature gradient mode driven gyrokinetic turbulence

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