Figure 6: PIC simulations of the leptonic beam dynamics in a background electron-ion plasma
From: Generation of neutral and high-density electron–positron pair plasmas in the laboratory
Simulation results of the propagation of an e−/e+ plasma through an e−-ion plasma. The first row depicts the results for a perfectly neutral beam (50% electrons and 50% positrons). (a) Electron (blue) and positron (red) density isosurfaces showing growth of the Weibel instability at the back of the bunch. (b) Magnetic field (Bθ) filaments due to the Weibel instability, where the Bθ lies on the plane transverse to bunch propagation direction. (c) Fireball bunch density slice taken at the position of the dashed line in a. (d) Corresponding magnetic Bθ filaments taken at the same location. The insets in c,d show the electron density and magnetic field corresponding to the propagation of a purely electronic beam showing no onset of filamentation. Frames (e,f) depict the results for an analogous simulation, with the only difference that now the positrons account only for 45% of the beam. The frames show slices of the electron (blue) and positron (red) spatial distribution, similar to frame a. (g) Comparison between the magnetic field growth for the case of a purely neutral beam (blue) and a slightly asymmetric beam (45% of positrons, red). For what concerns the plasma dynamics, the two cases are virtually undistinguishable.
