Structures and Zonal Flows in Magnetized Plasmas

Journal Article · Tue Dec 14 00:00:00 EST 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3533182· OSTI ID:21506947

Jovanovic, D ^[1]; Shukla, P K ^[2]

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1. Institute of Physics, University of Belgrade, P. O. Box 57, 11001 Belgrade (Serbia)
2. Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

The numerical study of the zonal flows (transport barriers) in the drift-wave turbulence in magnetically confined plasmas is presented. The existence of two distinct mechanisms for their generation is demonstrated. The evolution of a drift wave-zonal flow system, nonlinearly coupled via the Reynolds stress, is described by a nonlinear equation for the slowly varying envelope of the drift waves, and the nonlinear dispersion relation for the modulational instability of a drift wave pump is derived and analyzed. First, an arbitrary spatial distribution of strictly poloidally propagating drift waves is shown to rapidly decay into the array of localized soliton-like structures moving with different speeds. The corresponding zonal flow potential evolves into the sequence of shocks that produces a strong shearing, with many alternating plasma flows. Next, it is demonstrated that the coherent dipolar vortices, that constitute the building blocks of the strong drift-wave turbulence, are unstable in the presence of an electron temperature gradient. The dipolar vortices (or modons) undergo a qualitative modification by the action of the scalar nonlinearity arising from the magnetic {beta} effect. The modons propagating in the direction of the electron diamagnetic drift rapidly topple, disintegrating into two monopoles that propagate independently and rapidly disperse. Conversely, for the modons that initially moved in the direction of the ion diamagnetic drift, the {beta}-effect produces the change of the direction of the propagation, followed by the stretching in the poloidal direction. On a long time scale, such modons expand to a length equal to the size of the computational box, and essentially an one-dimensional zonal flow is created, whose transverse scale is determined by the initial modon size.

• OSTI ID: 21506947
• Journal Information: AIP Conference Proceedings, Vol. 1306, Issue 1; Conference: Workshop on new frontiers in advanced plasma physics, Trieste (Italy), 5-16 Jul 2010; Other Information: DOI: 10.1063/1.3533182; (c) 2010 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DISPERSION RELATIONS
ELECTRON TEMPERATURE
ELECTRONS
INSTABILITY
IONS
MAGNETOHYDRODYNAMICS
MODIFICATIONS
MONOPOLES
NONLINEAR PROBLEMS
NUMERICAL ANALYSIS
PLASMA
PLASMA DRIFT
REYNOLDS NUMBER
SOLITONS
SPATIAL DISTRIBUTION
STRESSES
TEMPERATURE GRADIENTS
TURBULENCE
VELOCITY
WAVE PROPAGATION
CHARGED PARTICLES
DIMENSIONLESS NUMBERS
DISTRIBUTION
ELEMENTARY PARTICLES
FERMIONS
FLUID MECHANICS
HYDRODYNAMICS
LEPTONS
MATHEMATICS
MECHANICS
QUASI PARTICLES