Identification of Low-Frequency Zonal Flow in a Linear Magnetic Plasma Device

Chen, Ran; Xie, Jinlin; Changxuan, Yu; Liu, Adi; Lan, Tao; Zhang, Shoubiao; Hu, Guanghai; Li, Hong; Liu, Wandong

doi:10.1088/0256-307x/28/2/025202

Cited by 3 publications

(5 citation statements)

References 27 publications

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“…Here, the plasma is in the weak-turbulence state with a wide frequency spectrum, together with some drift wave (DW) eigenmodes (f ' several kHz) inside, driven by density gradients. 47 From Fig. 2, high coherency and cross power in the low-frequency (f < 3 kHz) region are observed between the two potential fluctuations with a large separation in azimuthal direction, as exhibited in (a) and (b), respectively.…”

Section: Experimental Set-upmentioning

confidence: 75%

“…This potential structure is the ZF theoretically-predicted in previous work and identified by a complete direct measurement of spectral characteristics of the mode. 47 From Fig. 2(c), note that the values of the relative phase angle spectrum, while almost zero below 1 kHz, deviate slightly from zero over f % 1-3 kHz.…”

Section: Experimental Set-upmentioning

confidence: 91%

“…Detailed descriptions of the LMPD can be found in previous work. 46,47 In our experiment, helium is chosen as working gas at pressure P % 0:47 Pa. A fixed uniform axial magnetic field (B ¼ 940 G) provides plasma confinement.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Also, as shown in Fig. 1, a triprobe located at r ¼ 4 cm, where the electron density gradient rapidly steepens with the deployment of a ring-like limiter, 47 is used to measure the local fluctuation-induced flux. Two tips of the triprobe, which are symmetrically positioned either side of the midplane with a slight azimuthal separation dl h ¼ 3 mm, are used to measure the floating potential fluctuations (/ f 1 and / f 2 ).…”

Section: Experimental Set-upmentioning

confidence: 99%

“…47 In this article, the authors focus on the properties of ZF-induced modulations of the fluctuation-driven particle flux. Furthermore, we clarify for the first time the contributions from the suppression of fluctuation intensities and cross-correlation terms between the azimuthal electric field and the density fluctuating quantities to this flux reduction induced by the shearing effect of ZF in a cylinder plasma.…”

Section: Introductionmentioning

confidence: 99%

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Observation of fluctuation-driven particle flux reduction by low-frequency zonal flow in a linear magnetized plasma

et al. 2015

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Low-frequency zonal flow (ZF) has been observed in a linear magnetic plasma device, exhibiting significant intermittency. Using the conditional analysis method, a time-averaged fluctuationinduced particle flux was observed to consistently decrease as ZF increased in amplitude. A dominant fraction of the flux, which is driven by drift-wave harmonics, is reversely modulated by ZF in the time domain. Spectra of the flux, together with each of the related turbulence properties, are estimated subject to two conditions, i.e., when potential fluctuation series represents a strong ZF intermittency or a very weak ZF component. Comparison of frequency-domain results demonstrates that ZF reduces the cross-field particle transport primarily by suppressing the density fluctuation as well as decorrelating density and potential fluctuations. V C 2015 AIP Publishing LLC.

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Section: Experimental Set-upmentioning

confidence: 75%

Section: Experimental Set-upmentioning

confidence: 91%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observation of fluctuation-driven particle flux reduction by low-frequency zonal flow in a linear magnetized plasma

et al. 2015

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Suppression of drift wave turbulence and zonal flow formation by changing axial boundary conditions in a cylindrical magnetized plasma device

Thakur

Mänz

et al. 2013

Physics of Plasmas

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For drift wave turbulence, due to charge conservation, the divergence of the parallel current is coupled to the divergence of the perpendicular polarization current, which determines the effective radial momentum flux, i.e., the Reynolds stress. Changes in the current flow patterns also affect the nonlinear energy transfer from smaller to larger scales. Here, we show that by changing the end plate boundary conditions in a cylindrical plasma device, the radial currents through the plasma and hence the net momentum transport and the nonlinear coupling for the inverse energy transfer are strongly modified. The transition to drift wave turbulence and the formation of low frequency zonal flows can be either suppressed with conducting boundaries or enhanced with insulating boundaries.

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Analysis on the azimuthal velocity fluctuation of drift-wave turbulence and zonal flow via dynamic programming based time-delay estimation technique in a linear magnetized plasma device

Chen¹,

Liu²,

Lin-Ming³

et al. 2014

Acta Phys. Sin.

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The effective measurement of plasma turbulence flow field is of great help for better understanding the turbulence in magnetically confined plasmas, and experimentally verifying the theoretically predicted phenomenon such as zonal flows. In this article, the dynamic programming based time-delay estimation technique is employed for the first time to estimate azimuthal velocity fluctuation of drift-wave turbulence in a linear magnetized plasma generated via a hot cathode plasma source. Analysis results clearly reproduce the zonal flow structure which is spontaneously generated by nonlinear energy transfer from the drift-wave turbulence. Moreover, via the comparison among the zonal flow (ZF) characteristics estimated respectively by the turbulent fluctuations of plasma located in different frequency regions, we further evaluate the dependences of accuracy and response for estimating ZF property using this newly developed time-delay estimation algorithm on the level of relative incoherent noise in the carrier waves. This work provides an example and reference value for deeper exploration on plasma turbulence and in particular the relevant flow field with the help of the dynamic programming based time-delay estimation technique.

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Identification of Low-Frequency Zonal Flow in a Linear Magnetic Plasma Device

Cited by 3 publications

References 27 publications

Observation of fluctuation-driven particle flux reduction by low-frequency zonal flow in a linear magnetized plasma

Observation of fluctuation-driven particle flux reduction by low-frequency zonal flow in a linear magnetized plasma

Suppression of drift wave turbulence and zonal flow formation by changing axial boundary conditions in a cylindrical magnetized plasma device

Analysis on the azimuthal velocity fluctuation of drift-wave turbulence and zonal flow via dynamic programming based time-delay estimation technique in a linear magnetized plasma device

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