Potential Vorticity Transport in Weakly and Strongly Magnetized Plasmas

Abstract

Tangled magnetic fields, often coexisting with an ordered mean field, have a major impact on turbulence and momentum transport in many plasmas, including those found in the solar tachocline and magnetic confinement devices. We present a novel mean field theory of potential vorticity mixing in $\beta$-plane magnetohydrodynamic (MHD) and drift wave turbulence. Our results show that mean-square stochastic fields strongly reduce Reynolds stress coherence. This decoherence of potential vorticity flux due to stochastic field scattering leads to suppression of momentum transport and zonal flow formation. A simple calculation suggests that the breaking of the shear-eddy tilting feedback loop by stochastic fields is the key underlying physics mechanism. A dimensionless parameter that quantifies the increment in power threshold is identified and used to assess the impact of stochastic field on the L-H transition. We discuss a model of stochastic fields as a resisto-elastic network.

arXiv comment11 pages, 10 figures

References in corpus (5)

• A general theorem on angular-momentum changes due to potential vorticity mixing and on potential-energy changes due to buoyancy mixing
• Effect of magnetic perturbations on turbulence-flow dynamics at the L-H transition on DIII-D
• Potential Vorticity Mixing in a Tangled Magnetic Field
• Effect of Rossby and Alfvén waves on the dynamics of the tachocline
• Impact of Resonant Magnetic Perturbations on the L-H Transition on MAST

Cited by in corpus (5)

• Feynman rules for forced wave turbulence
• Instability and Turbulent Relaxation in a Stochastic Magnetic Field
• On statistical zonostrophic instability and the effect of magnetic fields
• Turbulent transport regimes in the presence of an X-point magnetic configuration
• Ion Heat and Parallel Momentum Transport by Stochastic Magnetic Fields and Turbulence