Weibel instability beyond bi-Maxwellian anisotropy.

Area of Science:

• Plasma physics
• Astrophysical plasma dynamics
• Laser-plasma interactions

Background:

• The Weibel instability is crucial for generating magnetic fields in plasmas.
• Anisotropic velocity distribution functions (VDFs) are common in astrophysical and laboratory plasmas.
• Standard models often assume Maxwellian VDFs, which may not capture complex plasma behaviors.

Purpose of the Study:

• To investigate the influence of non-Maxwellian VDF shapes on Weibel instability growth.
• To determine how VDF shape affects the self-generated magnetic fields.
• To explore implications for laser-plasma interaction models.

Main Methods:

• Theoretical analysis of VDFs beyond Maxwellian.
• Investigating the wave vector of maximum growth rate for different VDF shapes.
• Simulating laser-plasma interaction scenarios with non-Maxwellian VDFs.

Main Results:

• The direction of the maximum growth rate wave vector is sensitive to the VDF shape.
• Non-Maxwellian VDFs lead to different magnetic field evolution compared to Maxwellian VDFs.
• Specific laser-plasma interaction models exhibit unique Weibel-generated magnetic field characteristics.

Conclusions:

• The shape of anisotropic VDFs is a critical factor in Weibel instability and magnetic field generation.
• Characterizing magnetic fields solely by temperature anisotropy ratio is insufficient for non-Maxwellian VDFs.
• Further investigation into non-Maxwellian VDFs is needed for accurate modeling of laser-plasma and astrophysical phenomena.