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Title: Transport barriers with and without shear flows in a magnetized plasma

Different ways of producing a transport barrier in a toroidal magnetized plasma are discussed and the properties of the barriers are analyzed. The first mechanism is associated with the presence of a sheared plasma flow that is present in a limited region of the plasma, which creates a zonal flow. In contrast to the usual paradigm stating that the sheared flow reduces the turbulence correlation length and leads to suppression of the fluctuation driven transport in the region of highest shear, it is shown that from the perspective of chaotic transport of plasma particles in the fluctuation fields, the transport barrier is formed in the region of zero shear and it can be destroyed when the fluctuation level is high enough. It is also shown that finite gyroradius effects modify the dynamics and introduces new conditions for barrier formation. The second mechanism considers a method in which radio-frequency waves injected into the plasma can stabilize the drift waves and therefore the anomalous transport is reduced, creating a barrier. This process does not involve the presence of sheared flows and depends only on the effect of the RF wave field on the drift waves. The stabilizing effect in this case ismore » due to the nonlinear ponderomotive force which acts in a way that offsets the pressure gradient destabilization. Finally, a mechanism based on the ponderomotive force of RF waves is described which produces poloidal plasma rotation around the resonant surface due to the asymmetry of induced transport; it creates a transport barrier by shear flow stabilization of turbulence.« less
Authors:
 [1]
  1. Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A. Postal 70-543, Mexico D.F. (Mexico)
Publication Date:
OSTI Identifier:
22264065
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1578; Journal Issue: 1; Conference: 5. Leopoldo Garcia-Colin Mexican meeting on mathematical and experimental physics, Mexico City (Mexico), 9-13 Sep 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; FLUCTUATIONS; NONLINEAR PROBLEMS; PLASMA; PONDEROMOTIVE FORCE; PRESSURE GRADIENTS; SHEAR; WAVE PROPAGATION