Relaxation of 2D turbulence to a metaequilibrium near the minimum enstrophy state

Abstract
Relaxation of 2D turbulence has been measured in magnetized electron columns, which follow the same (r,θ) dynamics as 2D incompressible fluids. The turbulence arises from shear instabilities on initially hollow columns, then relaxes to long-lasting, axisymmetric metaequilibria. The measured metaequilibrium vorticity profiles are in close agreement with the minimum enstrophy vortices predicted by the ‘‘selective decay’’ hypothesis.