Anomalous cross-field diffusion in a magnetic trap
journal contributionposted on 19.08.2015, 13:44 by Sergey SavelievSergey Saveliev, Fabio Marchesoni
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.
S.E.S. acknowledges support from the Leverhulme Trust; F.M. acknowledges support from the European Commission, under the Seventh Framework Programme (256959, NanoPower).