Position and velocity space diffusion of test particles in stochastic electromagnetic fieldsS. Perri1, F. Lepreti1, 2, V. Carbone1, 2 and A. Vulpiani3
1 Dipartimento di Fisica, Università della Calabria - Via P. Bucci 31/C, I-87036 Rende (CS), Italy
2 Consorzio Interuniversitario per le Scienze Fisiche della Materia (CNISM), Unità di Cosenza - Via P. Bucci 31/C, I-87036 Rende (CS), Italy
3 Dipartimento di Fisica and INFN, Università di Roma "La Sapienza" - Piazzale A. Moro 2, I-00185 Roma, Italy
received 5 January 2007; accepted in final form 10 April 2007; published May 2007
published online 3 May 2007
The two-dimensional diffusive dynamics of test particles in a random electromagnetic field is studied. The synthetic electromagnetic fluctuations are generated through randomly placed magnetised "clouds" oscillating with a frequency . We investigate the mean square displacements of particles in both position and velocity spaces. As increases the particles undergo standard (Brownian-like) motion, anomalous diffusion and ballistic motion in position space. Although in general the diffusion properties in velocity space are not trivially related to those in position space, we find that energization is present only when particles display anomalous diffusion in position space. The anomalous character of the diffusion is only in the non-standard values of the scaling exponents while the process is Gaussian.
05.40.Fb - Random walks and Levy flights .
05.45.-a - Nonlinear dynamics and chaos .
05.60.Cd - Classical transport .
© Europhysics Letters Association 2007