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Title: Modelling enhanced confinement in drift-wave turbulence

Authors:
; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1363708
Grant/Contract Number:
FG02-04ER54738; SC0008378
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 6; Related Information: CHORUS Timestamp: 2018-02-14 21:07:48; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English

Citation Formats

Hajjar, R. J., Diamond, P. H., Ashourvan, A., and Tynan, G. R. Modelling enhanced confinement in drift-wave turbulence. United States: N. p., 2017. Web. doi:10.1063/1.4985323.
Hajjar, R. J., Diamond, P. H., Ashourvan, A., & Tynan, G. R. Modelling enhanced confinement in drift-wave turbulence. United States. doi:10.1063/1.4985323.
Hajjar, R. J., Diamond, P. H., Ashourvan, A., and Tynan, G. R. 2017. "Modelling enhanced confinement in drift-wave turbulence". United States. doi:10.1063/1.4985323.
@article{osti_1363708,
title = {Modelling enhanced confinement in drift-wave turbulence},
author = {Hajjar, R. J. and Diamond, P. H. and Ashourvan, A. and Tynan, G. R.},
abstractNote = {},
doi = {10.1063/1.4985323},
journal = {Physics of Plasmas},
number = 6,
volume = 24,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on June 12, 2018
Publisher's Accepted Manuscript

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  • This Letter predicts, on the basis of the structure of mode-coupling equations, that if the plasma ..beta.. exceeds the square of the inverse aspect ratio, (a/R)/sup 2/, the cross-magnetic-field diffusion is greatly enhanced by the appearance of convective cells even in the presence of magnetic shear.
  • Low-..beta.. tokamaks have drift-wave density fluctuations (n/n) with the characteristics of strong turbulence. To describe their spectra, earlier work (Phys. Fluids 26, 169 (1983)) with simple wave--wave nonlinear coupling models in two dimensions is extended to more physical electrostatic models for drift waves in three dimensions. The electrons are treated with a linear nearly Boltzmann response. The cold ions have nonlinear cross-field drift motion and linear parallel motion. Numerical methods based on the direct interaction approximation are applied to both wave--wave and wave--particle nonlinear effects, and the spectral intensity I/sub k//sub x/k/sub y/k/sub parallel/..omega.. (n/n = (rho/sub s//L/sub n/)I/sup 1//supmore » ///sup 2/) for a sheared slab is calculated. The shear causes a linear coupling of adjacent k/sub x/ and k/sub parallel/ modes. A suggested extension to toroidal geometry is made. Many similarities with experiments are found: Iperpendicular is nearly isotropic in k/sub perpendicular/ and peaked at k/sub perpendicular/rho/sub s/« less
  • Scattering experiments in tokamaks show a broad drift wave frequency spectrum ..delta omega../..omega..approx.O(1) at fixed wavenumbers indicating a strong turbulent state with unstable drift modes strongly decorrelated at a rate ..delta omega.. by nonlinear wave--wave coupling to stable modes. In this paper a two-dimensional study of homogeneous stationary drift wave turbulence with simple models of the wave--wave coupling is described. It shows that linearly driven-damped stationary states exist and demonstrates that approximate weak coupling theories based on the direct interaction approximation (DIA) can provide a faithful and practical description of the turbulence. In addition, it is found that simple modelsmore » which include nonlinear E x B as well as nonlinear polarization drift coupling are in rough agreement with the experimental turbulence levels, transport coefficients, and decorrelation rates.« less
  • A study on the amplification of ion acoustic wave in an inhomogeneous plasma has been made on the basis of a nonlinear wave-particle interaction process called plasma maser effect. The drift wave instability, which is a universal phenomenon of an inhomogeneous confined plasma system, is found to be strongly in phase relation with thermal particles and may transfer its wave energy nonlinearly through a modulated field to ion acoustic wave. Considering a Maxwellian distribution function model for inhomogeneous plasmas under the standard local approximation, we have estimated the growth rate for ion acoustic wave, which is obtained by using themore » nonlinear dispersion relation. It has been found that amplification of ion acoustic wave is possible at the expense of drift wave turbulent energy. This result may be particularly important for stability of various drift modes in magnetically confined plasma as well as for transport of momentum and energy in such inhomogeneous systems.« less