Diffusion of charged particles in a stochastic magnetic field
The diffusive motion of charged particles in a stochastic magnetic field is investigated systematically in a model in which the statistics of both the collisions and the magnetic field are described by coloured noises characterised, respectively, by a finite correlation time and finite correlation lengths. An analytic solution is obtained for the basic nonlinear differential equation of the model. It describes asymptotically a pure diffusion process, in which the mean square displacement in the perpendicular direction, Gamma(t), grows proportionally to time. The corresponding diffusion coefficient scales as the fourth power of the magnetic fluctuation intensity. The values obtained are in very good agreement with experimental data in reverse-field pinch experiments. The present result contradicts earlier results predicting subdiffusive behaviour: Gamma(t) approximately t(1/2) or approximately t(1/4). A detailed comparison between these two sets of results is presented.
Bibliographic Reference: Report: EUR-CEA-FC-1463 EN (1992) 46 pp.
Availability: Available from CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Record Number: 199211190 / Last updated on: 1994-11-29
Original language: en
Available languages: en