Document 
A&A 483, 371-381 (2008)
DOI: 10.1051/0004-6361:20079099
Pitch-angle scattering in pure two-dimensional and two-component turbulence
A. Shalchi1, J. W. Bieber2, and W. H. Matthaeus21 Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
e-mail: andreasm4@yahoo.com
2 Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
(Received 19 November 2007 / Accepted 25 February 2008)
Abstract
Aims. It has been demonstrated that quasilinear theory is inappropriate for describing pitch-angle scattering and parallel
spatial diffusion, if a turbulence model with a strong two-dimensional component is assumed. We aim to revisit this
problem using a more systematic and reliable approach.
Methods. We consider particle transport in pure two-dimensional turbulence, by using a
vector-potential description of pitch-angle scattering.
Results. It is demonstrated that pitch-angle scattering in pure two-dimensional turbulence behaves subdiffusively
and, thus, parallel scattering is expected to behave superdiffusively. In the slab/2D composite model, the
total pitch-angle Fokker-Planck coefficient reaches the slab limit when very long timescales are considered.
Key words: diffusion -- turbulence -- scattering
© ESO 2008