[Table of Contents]

Plasma and Fusion Research

Volume 4, 012 (2009)

Regular Articles


Spectrally Condensed Fluid Turbulence and L-H Transitions in Plasma
Michael SHATS and Hua XIA
Research School of Physics and Engineering, The Australian National University, Canberra, ACT, 0200, Australia
(Received 19 August 2008 / Accepted 31 January 2009 / Published 4 June 2009)

Abstract

Recent experimental and theoretical studies of two-dimensional (2D) turbulence reveal that spectrally condensed turbulence which is a system of coupled large-scale coherent flow and broadband turbulence, is similar to plasma turbulence near the L-H transition threshold. Large condensate vortices fed via the turbulent inverse energy cascade, can control both the level of the broadband turbulence by shear decorrelation, and the energy injected into turbulence at the forcing scale via sweeping of the forcing-scale vortices. The interaction between these ingredients of spectrally condensed fluid turbulence is in many aspects similar to the interactions in the zonal flow-GAMs-turbulence system in plasma. In this paper we overview recent results on condensed 2D turbulence and present evidence of interaction between its three components: condensate structures, turbulence and forcingscale vortices. This is compared with the modifications in the spectra of plasma electrostatic potential during L-H transitions. It is shown that mean zonal flows are spatially and temporally correlated with both the broadband turbulence and with the narrow spectral range identified as the spectral range of the underlying instability.


Keywords

two-dimensional turbulence, spectral condensation, inverse energy cascade, spectra, zonal flow, H-mode, shear suppression

DOI: 10.1585/pfr.4.012


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This paper may be cited as follows:

Michael SHATS and Hua XIA, Plasma Fusion Res. 4, 012 (2009).