Barriers in the transition to global chaos in collisionless magnetic reconnection. II. Field line spectroscopy

Abstract

The transitional phase from local to global chaos in the magnetic field of a reconnecting current layer is investigated. The identification of the ridges in the field of the finite time Lyapunov exponent as barriers to the field line motion is carried out adopting the technique of field line spectroscopy to analyze the radial position of a field line while it winds its way through partial stochastic layers and to compare the frequencies of the field line motion with the corresponding frequencies of the distinguished hyperbolic field lines that are the nonlinear generalizations of linear X-lines.

Nonlinear physics and energetic particle transport features of the beam–plasma instability

“…2010; Senatore & Ross 2011) and, more recently, in plasma physics (Borgogno et al. 2011 a , b ). An introductory discussion on the proper operational definition of these structures can be found in Falessi et al.…”

Lagrangian coherent structures and plasma transport processes

“…In two recent works (Borgogno et al. 2011 a , b ) it was shown how the LCS can provide information about the electron transport due to the stochastization of the magnetic field in a collisionless reconnection process.…”

Barriers in the transition to global chaos in collisionless magnetic reconnection. I. Ridges of the finite time Lyapunov exponent field

“…(4) and (18) that the main frequencies that are associated with the radial motion x(z) À x(z 0 ) of a field line near an intermediate rational surface characterized by its value of i are i and (1 À i). 6 We consider subsequent stages of the dynamics of the reconnection process described above, around the Chirikov regime where the transition to global stochasticity occurs, 18 when the size of the islands becomes such that they overlap.…”

“…In order to analyse this system in a companion paper, 6 we will make use of field line spectroscopy. The frequency spectrum of the motion of a field line in a particular time window will be shown to exhibit the frequencies belonging to the specific regular system where it lingers during that time.…”