Breakup of Central Meanders and Outer Shearless Tori in the Standard Nontwist Map

POSTER

Abstract

The standard nontwist map, a simple model for degenerate Hamiltonian systems, e.g., magnetic field lines in toroidal plasma devices with reversed magnetic shear profile, is a useful tool for studying the breakup of shearless orbits in such systems in a numerically feasible way. In the past, the breakup of several shearless orbits with noble winding numbers has been studied for this map. [1,2] Here, we conduct similar breakup studies in a parameter range where a shearless orbit of meander shape is encountered, a type of orbit that is exclusively found in nontwist systems. Further, in contrast to previous studies, multiple shearless orbits can exist for certain winding numbers. The breakup of such additional ``outer orbits'' is examined here as well. \newline \newline [1] D.~del Castillo-Negrete, J.M.~Greene, and P.J.~Morrison, Physica D 91, 1 (1996); [2] A.~Apte, A.~Wurm, and P.J.~Morrison, Chaos 13, 421 (2003)

Authors

  • K. Fuchss

    Fusion Studies, U. of Texas at Austin, Inst. for Fusion Studies, U. of Texas at Austin

  • A. Wurm

    Dept. of Physical and Biological Sciences, Western New England College

  • A. Apte

    Dept. of Mathematics, U. of North Carolina at Chapel Hill

  • P.J. Morrison

    Fusion Studies, U. of Texas at Austin, Inst. for Fusion Studies, U. of Texas at Austin, University of Texas, Austin, University of Texas at Austin