Change of a Weibel-type to an Alfvénic shock in pair plasma by upstream waves

M. E. Dieckmann, J. D. Riordan, A. Pe'er

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We examine with particle-in-cell simulations how a parallel shock in pair plasma reacts to upstream waves, which are driven by escaping downstream particles. Initially, the shock is sustained in the two-dimensional simulation by a magnetic filamentation (beam-Weibel) instability. Escaping particles drive an electrostatic beam instability upstream. Modifications of the upstream plasma by these waves hardly affect the shock. In time, a decreasing density and an increasing temperature of the escaping particles quench the beam instability. A larger thermal energy along than perpendicular to the magnetic field destabilizes the pair-Alfvén mode. In the rest frame of the upstream plasma, the group velocity of the growing pair-Alfvén waves is below that of the shock and the latter catches up with the waves. Accumulating pair-Alfvén waves gradually change the shock in the two-dimensional simulation from a Weibel-type shock into an Alfvénic shock with a Mach number that is about 6 for our initial conditions.

Original languageEnglish
Article number062107
JournalPhysics of Plasmas
Issue number6
StatePublished - 1 Jun 2020

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


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