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arXiv · 1201.3549

Effective transport barriers in nontwist systems

J. D. Szezech Jr·I. L. Caldas·S. R. Lopes·P. J. Morrison·R. L. Viana
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Abstract

In fluids and plasmas with zonal flow reversed shear, a peculiar kind of transport barrier appears in the shearless region, one that is associated with a proper route of transition to chaos. Using a symplectic nontwist maps, which model such zonal flows, we investigate these barriers. In particular, the standard nontwist map, a paradigm of nontwist systems, is used to analyze the parameter dependence of the transport through a broken shearless barrier. Varying a proper control parameter, we identify the onset of structures with high stickiness that give rise to an effective barrier near the broken shearless curve. Several diagnostics are used: stickiness is measured by escape time and transmissivity plots, while barriers that separate different regions of stickiness are identified by employing two indicators in the phase space, the finite-time rotation number and the finite-time Lyapunov exponent.

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J. D. Szezech Jr, I. L. Caldas, S. R. Lopes, P. J. Morrison, R. L. Viana. 2012-01-17. Effective transport barriers in nontwist systems. https://doi.org/10.1103/physreve.86.036206

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