Particle energization through time-periodic helical magnetic fields

Dhrubaditya Mitra, Axel Brandenburg, Brahmananda Dasgupta, Eyvind Niklasson, Abhay Ram
2014 Physical Review E  
We solve for the motion of charged particles in a helical time-periodic ABC (Arnold-Beltrami-Childress) 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 time-periodic ABC fields, the kinetic energy of a charged particle can increase indefinitely with time. At late times the mean kinetic
more » ... ergy 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 PDF of kinetic energy is, at late times, close to a Gaussian but with steeper tails.
doi:10.1103/physreve.89.042919 pmid:24827325 fatcat:3mw3me6knbhs7fsgn3vkjt6joa