Particle energization through timeperiodic helical magnetic fields
Abstract
We solve for the motion of charged particles in a helical timeperiodic ABC (ArnoldBeltramiChildress) magnetic field. The magnetic field lines of a stationary ABC field with coefficients A =B=C=1 are chaotic, and we show that the motion of a charged particle in such a field is also chaotic at late times with positive Lyapunov exponent. We further show that in timeperiodic ABC fields, the kinetic energy of a charged particle can increase indefinitely with time. At late times the mean kinetic energy grows as a power law in time with an exponent that approaches unity. For an initial distribution of particles, whose kinetic energy is uniformly distributed within some interval, the probability density function of kinetic energy is, at late times, close to a Gaussian but with steeper tails.
 Publication:

Physical Review E
 Pub Date:
 April 2014
 DOI:
 10.1103/PhysRevE.89.042919
 arXiv:
 arXiv:1306.0151
 Bibcode:
 2014PhRvE..89d2919M
 Keywords:

 05.45.a;
 94.20.wc;
 96.50.Pw;
 98.70.Sa;
 Nonlinear dynamics and chaos;
 Plasma motion;
 plasma convection;
 particle acceleration;
 Particle acceleration;
 Cosmic rays;
 Astrophysics  High Energy Astrophysical Phenomena;
 Nonlinear Sciences  Chaotic Dynamics;
 Physics  Space Physics
 EPrint:
 uses Revtex 4 instead of Revtex 41