Studying magnetic field line separation, i.e. how initially close field lines spread from each other,
gives important insights on the chaotic behaviour of a magnetic turbulence. This behavior have
consequences, especially in cosmic ray transport in the case of low energetic particles (small
Larmor radii) around acceleration region such as supernovae remnants (SNR). This separation
depends on the distance along the field lines and the initial distance between neighbor field lines. In
this proceeding, we run 3D synthetic turbulence simulations to characterize field line separation.
We then try to account for the observed regimes with a theoretical model based on Corrsin’s
approximation. The model tends to reproduce the ballistic regime as well as the early stage of a
super-ballistic regime.