Observation and identification of zonal flows in a basic physics experiment

Соколов, В. Г.; Wei, Xiyang; Sen, A. K.; Khare, Avinash

doi:10.1088/0741-3335/48/4/s08

Cited by 24 publications

(24 citation statements)

References 21 publications

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“…The fluctuation level is near the noise level in the center and close to the edge of the plasma, where the ETG is very weak, consistent with the fact that a weak gradient cannot drive the mode. It should be noted that this plot is very similar to the ITG mode we have detected before, 18 which is understandable due to the isomorphism, but the mode width is a little smaller because the electron temperature profile is typically sharper than that in the ion case.…”

Section: -3supporting

confidence: 80%

Experimental production and identification of electron temperature gradient modes

2010

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The electron temperature gradient ͑ETG͒ mode, which is believed to be one of the strongest candidates for the anomalous electron energy transport in plasmas, is difficult to detect in experiments because of its high frequency ͑ϳMHz͒ and short wavelength ͑k Ќ e Յ 1͒. Using a dc bias heating scheme of the core plasma, we are able to produce a sufficiently strong ETG for exciting ETG modes in the Columbia linear machine ͓R. Scarmozzino, A. K. Sen, and G. A. Navratil, Phys. Fluids 31, 1773 ͑1988͔͒. A high frequency mode at ϳ2 MHz, with azimuthal wave numbers m ϳ 14-16 and parallel wave number k ʈ ϳ 0.01 cm −1 , has been observed. The frequency range is consistent with the result of a kinetic dispersion relation of slab ETG modes with appropriate E ៝ ϫ B ៝ Doppler shift. The scaling of its fluctuation level with the temperature gradient scale length and the radial structure are found to be roughly consistent with theoretical expectations. Therefore, this is one of the first direct definitive identifications of ETG modes.

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Section: -3supporting

confidence: 80%

Experimental production and identification of electron temperature gradient modes

2010

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“…Therefore, nonlinear processes among zonal flows/fields and microscale turbulence have been studied experimentally in fusion plasma community. [6][7][8][9][10][11][12][13][14][15][16][17] Bicoherence analysis has contributed to the studies. In addition, studies of nonlinear coupling between secondary instabilities with finite poloidal wave numbers and microscale fluctuations have been also performed.…”

mentioning

confidence: 99%

Observation of the parametric-modulational instability between the drift-wave fluctuation and azimuthally symmetric sheared radial electric field oscillation in a cylindrical laboratory plasma

et al. 2009

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Observation of the parametric-modulational interaction between the drift-wave fluctuation (7–8 kHz) and azimuthally symmetric sheared radial electric field structure (∼0.4 kHz) in a cylindrical laboratory plasma is presented. Oscillation of the sheared radial electric field is synchronized at modulations of the radial wave number and Reynolds stress per mass density of the drift-wave spectrum. Bispectral analysis at the location where the sheared radial electric field has finite radial wave numbers shows that nonlinear energy transfers from the drift wave to the sheared radial electric field occur. Nonlocal energy transfers of fluctuations via “channel of the azimuthally symmetric sheared radial electric field” in spectral space as well as real space are discovered.

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“…47,49 Zonal flows have been observed in some toroidal plasmas, 48,49 but they are hard to identify conclusively 50 and the theoretical generation mechanism is weak. Measured cases in a linear experiment, where the generation mechanism is stronger, also suggest 50,51 weaker effects than predicted. In contrast, zonal flows appear frequently and robustly in GK numerical simulations 49 of toroidal plasmas that use electrostatic or quasi-electrostatic forms for E ʈ .…”

Section: Zonal Flows In a Torusmentioning

confidence: 71%

Guiding center plasma models in three dimensions

Sugiyama

2008

Physics of Plasmas

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Guiding center plasma models describe the fast charged particle gyration around magnetic field lines by an angle coordinate, defined relative to local orthogonal coordinate axes (ê1,ê2,b̂=B∕B) at each guiding center location. In three dimensions (3D), unlike uniform straight two-dimensional (2D) fields, geometrical effects make the small gyroradius expansion nonuniform in velocity phase space in first order O(ρi∕L). At second order, Hamiltonian and Lagrangian solutions may be undefined even when good magnetic flux surfaces exist; existence requires the magnetic field torsion τ=b̂⋅∇×b̂=0 and τg≡b̂⋅(∇ê1)⋅ê2=0, unless the magnetic field has a 2D symmetry, such as toroidal axisymmetry. Keeping complete 3D geometrical effects also requires the magnetic vector potential term to appear in the electric field at the same order as the electrostatic potential. These problems express properties of magnetic vector potentials, Lagrangians, and the curvature of manifolds, and have analogies to attempts to connect small scale Lagrangian theories to higher dimensional, large scale ones in the grand unification theories of physics.

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Observation and identification of zonal flows in a basic physics experiment

Cited by 24 publications

References 21 publications

Experimental production and identification of electron temperature gradient modes

Experimental production and identification of electron temperature gradient modes

Observation of the parametric-modulational instability between the drift-wave fluctuation and azimuthally symmetric sheared radial electric field oscillation in a cylindrical laboratory plasma

Guiding center plasma models in three dimensions

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