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arXiv · 2012.10611

Potential Vorticity Transport in Weakly and Strongly Magnetized Plasmas

Chang-Chun Chen·Patrick H. Diamond·Rameswar Singh·Steven M. Tobias
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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 $β$-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.

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Chang-Chun Chen, Patrick H. Diamond, Rameswar Singh, Steven M. Tobias. 2020-12-19. Potential Vorticity Transport in Weakly and Strongly Magnetized Plasmas. https://doi.org/10.1063/5.0041072

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