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Article Dans Une Revue Nonlinear Processes in Geophysics Année : 2007

Chaos in driven Alfvén systems: unstable periodic orbits and chaotic saddles

Résumé

The chaotic dynamics of Alfvén waves in space plasmas governed by the derivative nonlinear Schrödinger equation, in the low-dimensional limit described by stationary spatial solutions, is studied. A bifurcation diagram is constructed, by varying the driver amplitude, to identify a number of nonlinear dynamical processes including saddle-node bifurcation, boundary crisis, and interior crisis. The roles played by unstable periodic orbits and chaotic saddles in these transitions are analyzed, and the conversion from a chaotic saddle to a chaotic attractor in these dynamical processes is demonstrated. In particular, the phenomenon of gap-filling in the chaotic transition from weak chaos to strong chaos via an interior crisis is investigated. A coupling unstable periodic orbit created by an explosion, within the gaps of the chaotic saddles embedded in a chaotic attractor following an interior crisis, is found numerically. The gap-filling unstable periodic orbits are responsible for coupling the banded chaotic saddle (BCS) to the surrounding chaotic saddle (SCS), leading to crisis-induced intermittency. The physical relevance of chaos for Alfvén intermittent turbulence observed in the solar wind is discussed.
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Dates et versions

hal-00303053 , version 1 (18-06-2008)

Identifiants

  • HAL Id : hal-00303053 , version 1

Citer

A. C.-L. Chian, W. M. Santana, E. L. Rempel, F. A. Borotto, T. Hada, et al.. Chaos in driven Alfvén systems: unstable periodic orbits and chaotic saddles. Nonlinear Processes in Geophysics, 2007, 14 (1), pp.17-29. ⟨hal-00303053⟩

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