Transport and radiation of charged particles in chaotic, time dependent, force-free magnetic fields

In regions of low plasma pressure and large currents, such as in solar corona, interstellar space, and gaseous nebulae, the magnetic fields are force-free as the Lorentz force vanishes. The three-dimensional, time-independent, Arnold-Beltrami-Childress (ABC) field is an example of a force-free, helical, magnetic field that is a mix of chaotic and regular field lines. The characteristic motion of particles in the chaotic field lines is chaotic and their transport is super-diffusive in space [1]. Charged particles in the ABC field emit electromagnetic radiation as well. We compare and contrast the radiation emitted by particles exhibiting regular motion with those having chaotic dynamics. For a time-dependent force-free magnetic field, Maxwell’s equations require that there be an associated electric field. Consequently, charged particles not only experience spatial transport but also energy transport. For a time-dependent ABC field, we find that the maximum energy a particle can gain is bounded from above. We will present results on the cross-field diffusion and energization of charged particles, and on the emission of radiation by these particles.. [1] A.K. Ram \textit{et al.}, \textit{Phys. Plasmas} \textbf{21}, 072309 (2014).