Particle transport and acceleration in a time-varying electromagnetic field with a multi-scale structure

We present the results of a numerical study of particle transport and acceleration by an ensemble of electromagnetic waves with a multi-scale spatio-temporal structure. We explore the dependence of acceleration and transport on the properties of turbulence. We found that an initially Maxwellian distribution of particle velocities evolves into a heavy-tailed distribution, which resembles the ubiquitous kappa-distribution, often used in non-thermal plasma phenomenology. The results of this study may be used to explain plasma heating and energization in turbulent current sheets such as the current sheets often observed in the Earth's magnetotail and discussed in relation to solar corona.