Shearless bifurcation on symplectic maps of magnetic field lines in tokamaks with reversed current

Author(s)

Bartoloni, B. ^[1] ; Schelin, A. B. ^[2] ; Caldas, I. L. ^[3]

Affiliation

^[1] Univ Sao Paulo, Inst Fis, Rua Matao 1371, BR-05508090 Sao Paulo, SP - Brazil

^[2] Univ Brasilia, Inst Fis, Campus Univ Darcy Ribeiro, BR-70910900 Brasilia, DF - Brazil

^[3] Univ Brasilia, Inst Fis, Rua Matao 1371, BR-05508090 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Physics Letters A; v. 380, n. 31-32, p. 2416-2421, JUL 15 2016.
• Web of Science Citations: 1

Abstract

We introduce two-dimensional symplectic maps to describe the Poincare maps of magnetic field lines in large aspect ratio tokamak equilibria with reversed non-monotonic plasma current density profiles. For these maps, we investigate the effect of the symmetry breaking due to the toroidal correction with a peculiar invariant, namely, a magnetic surface with a null rotation number, enclosing a vanishing current. We find that this rotationless invariant surface is surrounded by many small island chains. Furthermore, near such invariant, the symmetry breaking gives rise to two magnetic shearless invariants surrounded by twin island chains. We also find chaotic lines adjacent to all the observed islands created by the considered structurally unstable equilibria. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 12/18073-1 - Symplectic transport in fusion diverted plasmas
• Grantee: David Ciro Taborda
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 11/19296-1 - Nonlinear dynamics
• Grantee: Iberê Luiz Caldas
• Support Opportunities: Research Projects - Thematic Grants