title: How mesoscopic staircases condense to macroscopic barriers in confined plasma turbulence.
abstract: This Rapid Communication sets forth the mechanism by which mesoscale staircase structures condense to form macroscopic states of enhanced confinement. Density, vorticity, and turbulent potential enstrophy are the variables for this model. Formation of the staircase structures is due to inhomogeneous mixing of (generalized) potential vorticity (PV). Such mixing results in the local sharpening of density and vorticity gradients. When PV gradients steepen, the density staircase structure develops into a lattice of mesoscale "jumps" and "steps," which are, respectively, regions of local gradient steepening and flattening. The jumps then merge and migrate in radius, leading to the emergence of a new macroscale profile structure, so indicating that profile self-organization is a global process, which may be described by a local, but nonlinear model. This work predicts and demonstrates how mesoscale condensation of staircases leads to global states of enhanced confinement.
authors.affiliation: Center for Momentum Transport and Flow Organization, Center for Energy Research, and Center for Astrophysics and Space Sciences (CASS) and Department of Physics, University of California San Diego, La Jolla, California 92093, USA.
authors.forename: Arash
authors.initials: A
authors.lastname: Ashourvan
authors.affiliation: Center for Momentum Transport and Flow Organization, Center for Energy Research, and Center for Astrophysics and Space Sciences (CASS) and Department of Physics, University of California San Diego, La Jolla, California 92093, USA.
authors.forename: P H
authors.initials: PH
authors.lastname: Diamond