Particles trajectories in Weibel magnetic filaments with a flow-aligned magnetic field

Abstract

For a Weibel shock to form, two plasma shells have to collide and trigger the Weibel instability. At saturation, this instability generates in the overlapping region magnetic filaments with peak field $B_f$. In the absence of an external guiding magnetic field, these filaments can block the incoming flow, initiating the shock formation, if their size is larger than the Larmor radius of the incoming particles in the peak field. Here we show that this results still holds in the presence of an external magnetic field $B_0$, provided it is not too high. Yet, for $B_0\gtrsim B_f/2$, the filaments become unable to stop any particle, regardless of its initially velocity.

arXiv comment11 pages, 6 figures. To appear in Journal of Plasma Physics

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• Kinetic inhibition of MHD-shocks in the vicinity of a parallel magnetic field
• Density jump as a function of magnetic field for collisionless shocks in pair plasmas: the perpendicular case
• Transport of relativistic jet in the magnetized intergalactic medium
• Particle trajectories in Weibel filaments: influence of external field obliquity and chaos