Generated electric and magnetic fields and particle acceleration results of simulation

The simulation model described above gave the following main result: both the electric and magnetic fields are generated by counter-streaming instability. Fig. 4.28.1 shows the electric field Ex and magnetic field Bz configurations at a)pet =

25.0 generated by this instability.

Fig. 4.28.1. The schematic picture in the top of the figure shows the whole system of this simulation. The dashed square indicates the plotting region for panels (a), (b), (c), and (d). Panels (a) and (b) show Bz and Ex configurations without a background magnetic field; panels (c) and (d) show them with the background magnetic field characterized by aocej aape = 2 at a)pet = 25.0. The vertical dashed line indicates the front of the plasma flow.

According to Saito et al. (2003).

Fig. 4.28.1. The schematic picture in the top of the figure shows the whole system of this simulation. The dashed square indicates the plotting region for panels (a), (b), (c), and (d). Panels (a) and (b) show Bz and Ex configurations without a background magnetic field; panels (c) and (d) show them with the background magnetic field characterized by aocej aape = 2 at a)pet = 25.0. The vertical dashed line indicates the front of the plasma flow.

According to Saito et al. (2003).

The top panel in Fig. 4.28.1 shows the schematic picture which reflects the whole system of this simulation. Saito et al. (2003) plotted the magnetic field and electric field, generated in the region surrounded by dashed square of the schematic picture, in panels (a) and (b) of Fig. 4.28.1 which show Bz and Ex configuration without background magnetic field, and in panels (c) and (d) with the background magnetic field characterized by aQcej ct)pe = 2. The dashed red lines in panels (a),

(b), (c) and (d) show the front of the plasma flow.

When cocejcope becomes large the generation of magnetic field is restrained by the background magnetic field, while the electric field becomes strong and turns into a longitudinal wave from a transverse wave. This means that the wave generated by counter-streaming instability is changed to the electrostatic mode from the electromagnetic mode by the strong background magnetic field.

Fig. 4.28.2 shows the ratio of the generated electric field energy ^Electric and the magnetic field energy £'Magnetic at the linear stage. In Fig. 4.28.2 the horizontal axis shows the ratio Ebo J Eflow of background magnetic field energy Ebo and plasma flow energy EfloW . The ratio EE1eCtric/EMagnetic of energies EE1eCtric and EMagnetic suddenly increase when the ratio EbojEflow exceeds 3 or 4. This means that the generation of electric field is superior than the generation of magnetic field, which indicates that the nature of generated wave becomes electrostatic mode from electromagnetic mode. The generated electrostatic wave accelerates charged particles.

Fig. 4.28.2. The ratio EElectric / EMagnetic of generated electric field and magnetic field energy in dependence on the ratio EBo^/Eflow . According to Saito et al. (2003).

Fig. 4.28.3. shows the electron velocity distribution in the x - direction parallel to both the magnetic field and the counter-streaming. In Fig. 4.28.3 the red (1), green (2), and blue (3) lines indicate the electrons velocity distribution at the initial ( ci)pet = 0), at apet = 200 without the background magnetic field, and at a)pet = 200

with the background magnetic field characterized by aocej mpe = 2, respectively.

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