Comparative study of charged particle dynamics in time-stationary and time-varying spatially chaotic magnetic fields...

The first step in understanding charged particle dynamics is based on the development of relevant three-dimensional models for the fields and using a test particle approach in the presence of prescribed electromagnetic fields. In this paper, first, we investigate the dynamics of charged particles in spatially inhomogeneous time-stationary Beltrami magnetic fields. The field lines of stationary three-dimensional Beltrami magnetic fields are chaotic. Characterization of dynamical behavior of charged particles moving in such fields is provided through Lyapunov exponents and the exponent associated with the transport law. The main motive of this study is to relate the spatial properties of magnetic field lines over the entire space to the chaotic behavior and transport properties of charged particles. Later, the same idea is applied to the charged particles in the presence of time-periodic Beltrami magnetic fields, and it is found that unlike the previous case with time-stationary magnetic fields, here, a clear understanding of anomalous diffusion cannot be achieved from the knowledge of particle dynamics through Lyapunov exponents.