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Astron. Astrophys. 337, 558-564 (1998)

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On the cosmic ray cross field diffusion in the presence of oblique MHD waves

G. Michalek and M. Ostrowski

Obserwatorium Astronomiczne, Uniwersytet Jagielloski, ul.Orla 171, PL-30-244 Kraków, Poland

Received 1 April 1998 / Accepted 17 June 1998


The process of particle cross-field diffusion in the presence of finite MHD amplitude wave fields is considered using the Monte Carlo particle simulations. We derive the cross-field diffusion coefficient [FORMULA] and the parallel diffusion coefficient [FORMULA] for the flat and the Kolmogorov wave spectra, including the waves propagating oblique to the mean magnetic field [FORMULA]. We note a substantial difference in the cross-field diffusion efficiency between the considered turbulent fields. Much larger values of [FORMULA] appear in the presence of fast-mode waves in comparison to the Alfvén waves and we reproduce the expected increase of [FORMULA] with the growing power of waves propagating perpendicular to [FORMULA]. We interpret these results in terms of the particle drifts in non-uniform magnetic fields.

Key words: magnetohydrodynamics – turbulence – waves – ISM: cosmic rays

Send offprint requests to: G. Michalek, (michalek@oa.uj.edu.pl)

© European Southern Observatory (ESO) 1998

Online publication: August 17, 1998