title: Anomalous cross-field diffusion in a magnetic trap.
abstract: We numerically simulated the diffusion of a charged Brownian particle confined to a plane under the action of an orthogonal magnetic field with intensity depending on the distance from a center. Despite its apparent simplicity, this system exhibits anomalous diffusion. For positive field gradients, radial and angular dynamics are asymptotically subdiffusive, with exponents given by simple analytical expressions. In contrast, when driven by a weakly decaying field, the particle attains normal diffusion only after exceedingly long superdiffusive transients. These mechanisms can be related to Bohm diffusion in magnetized plasmas.
authors.affiliation: Department of Physics, Loughborough University, Loughborough LE11 3TU, United Kingdom.
authors.forename: Sergey E
authors.initials: SE
authors.lastname: Savel'ev
authors.affiliation: Dipartimento di Fisica, Università di Camerino, I-62032 Camerino, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Marchesoni