Parametric pulse amplification by acoustic quasimodes in electron-positron plasma

Area of Science:

• Plasma Physics
• Astrophysical Plasmas
• High-Energy Physics

Background:

• Previous studies reported enhanced stimulated Brillouin scattering (SBS) and absent stimulated Raman scattering (SRS) in electron-positron plasmas.
• Discrepancies existed between theoretical fluid models and particle-in-cell (PIC) simulations regarding SBS enhancement.
• A kinetic approach was suggested as necessary for accurate acoustic resonance description.

Purpose of the Study:

• To provide a kinetic calculation for acoustic resonance in electron-positron plasmas.
• To resolve the discrepancy between fluid theory and PIC simulations.
• To analyze the dependencies of Brillouin scattering enhancement on plasma parameters.

Main Methods:

• Kinetic calculation of acoustic resonance.
• Comparison with existing particle-in-cell (PIC) simulation data.
• Analysis of Brillouin enhancement factors and plasma parameter dependencies.

Main Results:

• The kinetic calculation shows good agreement with PIC simulations.
• The enhancement of Brillouin scattering and absence of Raman scattering are confirmed.
• Brillouin enhancement factors are found to depend on electron temperature and particle density.
• Pulse amplification in electron-positron plasmas transitions to strong-coupling regime with increasing pump amplitude.

Conclusions:

• The kinetic approach accurately describes acoustic resonance in electron-positron plasmas.
• Fluid approximation becomes valid again in the strong-coupling regime.
• Findings clarify the behavior of stimulated scattering processes in relativistic plasmas.