Electrostatic solitons and Alfvén waves generated by streaming instability in electron-positron plasmas

Area of Science:

• Plasma Physics
• Astrophysical Plasmas
• Computational Physics

Background:

• Electron-positron plasmas are relevant to laboratory experiments and astrophysical environments.
• Debates exist regarding the formation of nonlinear electrostatic solitons in electron-positron plasmas compared to electron-proton plasmas due to inertia symmetry.

Purpose of the Study:

• To investigate the formation of electrostatic solitons and electromagnetic Alfvén waves in magnetized electron-positron plasmas.
• To analyze the role of streaming instabilities in generating these plasma phenomena.
• To provide a unified theoretical framework for their formation mechanisms.

Main Methods:

• Electromagnetic particle-in-cell simulations were employed to model an extensive magnetized electron-positron plasma system.
• Fluid theory analyses were used to complement simulation results and validate instability growth rates and wavelengths.

Main Results:

• The formation of interlacing electron and positron solitons was observed in the early stages of the simulation (t<20ωₚ⁻¹).
• Large-amplitude Alfvén waves were generated in the later phase (t>150ωₚ⁻¹).
• Magnetic-field perturbations arose from beam and firehose-type instabilities driven by temperature anisotropy (T∥>T⊥).

Conclusions:

• The study confirms the development of electrostatic solitons and electromagnetic Alfvén waves in electron-positron plasmas.
• The coexistence of these electrostatic and electromagnetic waves with significant magnetic field fluctuations is a unique characteristic of these plasmas.
• Simulation results and growth rates align with fluid theory predictions, supporting the proposed unified formation mechanisms.