1. Onset of internal transport barriers in tokamaks
- Author
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Yves Elskens, L. A. Osorio, Marisa Roberto, Iberê L. Caldas, Ricardo L. Viana, Instituto de Fisica, Universidade de Sao Paulo (INSTITUTO DE FISICA, UNIVERSIDADE DE SAO PAULO), Universidade de São Paulo (USP), Instituto Tecnológico de Aeronáutica [São José dos Campos] (ITA), Departamento de Física, Universidade Federal do Paraná, 81531-980 Curitiba, Paraná, Brazil, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Instituto de Fisica da Universidade de São Paulo (IFUSP), and Universidade de São Paulo = University of São Paulo (USP)
- Subjects
Physics ,Work (thermodynamics) ,Tokamak ,ELETROSTÁTICA ,Chaotic ,FOS: Physical sciences ,Plasma ,Mechanics ,Condensed Matter Physics ,01 natural sciences ,Charged particle ,Physics - Plasma Physics ,010305 fluids & plasmas ,law.invention ,Shear (sheet metal) ,Maxima and minima ,Plasma Physics (physics.plasm-ph) ,Nonlinear Sciences::Chaotic Dynamics ,Amplitude ,law ,[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph] ,0103 physical sciences ,[NLIN.NLIN-CD]Nonlinear Sciences [physics]/Chaotic Dynamics [nlin.CD] ,010306 general physics - Abstract
Barriers have been identified in magnetically confined plasmas reducing the particle transport and improving the confinement. One of them, the primary shearless barriers are associated to extrema of non-monotonic plasma profiles. Previously, we identified these barriers in a model described by a map that allows the integration of charged particles motion in drift waves for a long time scale. In this work, we show how the existence of these robust barriers depends on the fluctuation amplitude and on the electric shear. Moreover, we also find control parameter intervals for which these primary barriers onset and break-up are recurrent. Another noticeable feature, in these transitions, is the appearance of a layer of particle trajectory stickiness after the shearless barrier break-up or before its onset. Besides the mentioned primary barriers, we also observe sequences of secondary shearless barriers, not reported before, created and destroyed by a sequence of bifurcations as the main control parameters, the fluctuation amplitude and electric shear, are varied. Furthermore, in these bifurcations, we also find hitherto unknown double and triple secondary shearless barriers which constitute a noticeable obstacle to the chaotic transport., 12 pages, 28 figures. This article has been accepted by the Journal Physics of Plasmas. It can be found at: https://doi.org/10.1063/5.0056428
- Published
- 2021