Weibel instability

Both populations have a rest frame temperature corresponding to a thermal velocity / //, = 0.01c. In order to be able to resolve both electron and ion dynamics the ion-electron mass ratio is Mi/me = 16. This is clearly a strong assumption but it allow us qualitatively to understand how particles with different mass affects the Weibel instability. In these experiments both populations are initially unmagnetized. 

When the simulation runs and the plasma populations stream through each other, we observe how the Weibel instability collects particles into current filaments (Medvedev and Loeb, 1999). First the electrons go through the instability and then further downstream the electrons thermalize to one single population and the heavier ions goes through the instability. 

We have performed numerical experiments of relativistic collisionless plasma shocks using a self-consistent three dimensional particle-in-cell code. We find that the Weibel instability is capable of generating turbulent magnetic fields with a strength up to percents of equipartition. The magnetic field is induced around ion current filaments. These filaments also accelerates electrons to power law distributions. The suggested acceleration scenario does not rule out ion Fermi acceleration but might overcome some of the problems pointed... 

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