Fluctuation induced transport of driven drift waves: I. Monochromatic waves

Block, Dietmar; Piel, A.

doi:10.1088/0741-3335/45/4/307

Cited by 7 publications

(13 citation statements)

References 26 publications

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“…Taking the instability of the interchange modes at the LFS and their damping at the HFS into account, these bursts are likely to be just signatures of maximum mode amplitude on the LFS. Hence, the transport features of large scale coherent structures in SMTs might be closer related to those mode dominated transport processes observed in linear devices [34], than to those in fusion devices.…”

Section: Discussionmentioning

confidence: 95%

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Greiner¹,

Block

Piel

2004

Contrib. Plasma Phys.

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The spatio-temporal dynamics of large-scale structures in curved magnetic field of simple magnetized torus (SMT) are presented. The experiments are performed in the SMT BLAAMANN and employ the techniques of conditional averaging (CA) and cross-correlation (CCF) of Langmuir probe data. By means of a detailed comparison of radio-frequency and thermionic discharges, it is shown that general features of the observed large-scale structures are independent of the discharge mechanism. Further, the observed large scale structures have a pronounced spatio-temporal periodicity, which suggests a description as mode-like. The conjectured relationship between the observed coherent structures and the inverse energy cascade is therefore questioned again.

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Section: Discussionmentioning

confidence: 95%

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Greiner¹,

Block

Piel

2004

Contrib. Plasma Phys.

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“…the estimation of the propagation velocity of externally applied signals and possible asymmetries in the signal propagation. A further aspect is motivated by results from laboratory plasma devices: open-loop synchronization of drift-wave turbulence was achieved by externally applied dynamic perturbation signals [11][12][13][14][15]. The frequency and poloidal wave number of the external drive were matched to dominant drift wave modes.…”

Section: Introductionmentioning

confidence: 99%

Active probe experiments at the Wendelstein 7-AS stellarator

Thomsen¹,

Endler²,

Klinger³

et al. 2005

Plasma Phys. Control. Fusion

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The fluctuations in the edge plasma of magnetic fusion experiments play an important role in terms of anomalous energy and particle transport. Experiments on Wendelstein 7-AS (Renner H et al 1989 Plasma Phys. Control. Fusion 31 1579 were conducted to investigate the propagation of actively fed signals driven by electrical probes. The perspective of these investigations is an improved understanding of the turbulence and potentially a method to tailor the edge plasma turbulence. Two moveable poloidal probe arrays were used for the experiments, one located on the inboard side of the vessel and the other on the outboard side. A subset of probe tips was used for actively driving the plasma by different control signals, the remaining probes collected fluctuation data in the plasma boundary. With this set-up it was possible to investigate the signal propagation in the poloidal direction and also parallel to the magnetic field. Poloidally, we find a significant cross-correlation between active and passive probes. From analysis of the cross-coherency and phases of the signal with passive probe tips, a dominant influence of the background plasma rotation on the applied signals is observed. In the case of externally driven waves by several phase-locked active probes, the direction of the wave propagation with respect to the plasma rotation (co-or counter-rotating) is essential for an effective coupling to the turbulence. Also, the signal propagation parallel to the magnetic field depends on co-or counter-rotation with respect to the background plasma rotation. The parallel phase velocity was found to be compatible with the electron thermal velocity.

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“…For this configuration, weak drift wave turbulence is observed inside the midsection [38]. For further details on the plasma equilibrium, drift wave dynamics and related transport we refer the reader to previous investigations [39][40][41].…”

Section: Methodsmentioning

confidence: 88%

Experimental comparison of statistical and spatio-temporal probe diagnostics

Block¹,

Teliban²,

Piel

2007

Plasma Phys. Control. Fusion

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Experiments on plasma turbulence and related transport processes generally require diagnostics with high spatio-temporal resolution. Standard tools for this purpose are statistical methods like cross-correlation analysis or conditional averaging. High spatial resolution is achieved at the expense of an asynchronous recording and a subsequent averaging process. Recently, we had shown that diagnostics arrays in combination with a super-resolution algorithm can achieve a comparably high spatial resolution [1]. This paper compares the results of both techniques applied to identical experimental conditions. It addresses the question of whether the higher efforts for spatio-temporal diagnostics are needed to study the dynamics of large-scale structures in a turbulent system and to what extent the results of statistical approaches are reliable.

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Fluctuation induced transport of driven drift waves: I. Monochromatic waves

Cited by 7 publications

References 26 publications

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Active probe experiments at the Wendelstein 7-AS stellarator

Experimental comparison of statistical and spatio-temporal probe diagnostics

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