Self-organization in sheared drift-wave turbulence

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859956· OSTI ID:6397360

Scott, B D ^[1]; Biglari, H ^[2]; Terry, P W ^[3]; Diamond, P H ^[2]

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1. Max Planck Institut f uer Plasmaphysik, D8046 Garching bei Muenchen, Federal Republic of Germany (DE)
2. Department of Physics B-019, University of California at San Diego, La Jolla, California 92093 (USA)
3. Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (USA)

Turbulent drift-wave dynamics in a sheared magnetic field are studied using direct numerical simulations. Self-consistent nonadiabatic electron and parallel ion dynamics are both retained in a 2-D sheared-slab model. Magnetic shear causes division of the system into two physically distinct regions with differing cascade dynamics. In a hydrodynamic layer centered upon the mode resonant surface, linear coupling between the density and potential is weak, and the density gradient acts to force spontaneous nonlinear alignment of density fluctuations with the turbulent flows. Further away, shear-induced collisional dissipation constrains the density fluctuations to respond adiabatically, so that the density cannot vary on flow streamlines. The dynamics of the interregion spatial energy flow leads to strong phase coherence between modes at scales larger than the hydrodynamic layer width. Concurrently, the alignment between flows and density fluctuations at scales comparable to the layer width becomes even stronger, increasing the energy input at those scales. This self-organizing tendency is sufficiently robust as to survive competition with a linear external drive. Because of its greater structural freedom, the full nonadiabatic system is much more likely than an adiabatic model with a linear density response to support saturated turbulence below the threshhold for linear instability.

• OSTI ID: 6397360
• Journal Information: Physics of Fluids B; (USA), Vol. 3:1; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COLLISIONAL PLASMA
TURBULENCE
ADIABATIC APPROXIMATION
DRIFT INSTABILITY
ELECTRON DRIFT
ENERGY LOSSES
FLUCTUATIONS
ION DRIFT
MAGNETIC FIELDS
NUMERICAL SOLUTION
SCALING LAWS
SHEAR
SIMULATION
SLABS
TWO-DIMENSIONAL CALCULATIONS
INSTABILITY
LOSSES
PLASMA
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
VARIATIONS
640430* - Fluid Physics- Magnetohydrodynamics