Mirror instability: From quasi-linear diffusion to coherent structures

P. Hellinger (1) , E. Kuznetsov (2) , T. Passot (3) , P.L. Sulem (3) , P.M. Trávnícek (1)

1 IAP - Institute of Atmospheric Physics [Prague]
2 LPI RAS - P. N. Lebedev Physical Institute of the Russian Academy of Sciences [Moscow]
3 CASSIOPEE - Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides

A model for the nonlinear dynamics of mirror modes near the instability threshold is presented. By matching the quasi-linear theory for the space-averaged distribution function with a reductive perturbative description of the mirror modes, the model reproduces the early-time flattening of the distribution function and the development of magnetic humps from an initial noise, in agreement with Vlasov-Maxwell numerical simulations. It suggests a possible mechanism at the origin of the mirror structures observed in planetary magnetosheaths and in the solar wind.

Domaines: Planète et Univers [physics]

P. Hellinger, E. Kuznetsov, T. Passot, P.L. Sulem, P.M. Trávnícek. Mirror instability: From quasi-linear diffusion to coherent structures. Geophysical Research Letters, 2009, 36, pp.L06103. ⟨10.1029/2008GL036805⟩. ⟨hal-00387941⟩