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Electron Weibel instability in relativistic counterstreaming plasmas with flow-aligned external magnetic fields
A Grassi1,2,3, M Grech4, F Amiranoff4
1LULI, UPMC Université Paris 06: Sorbonne Universités, CNRS, Ecole Polytechnique, CEA, Université Paris-Saclay, F-75252 Paris Cedex 05, France.
Physical Review. E
|March 17, 2017
Summary
The Weibel instability in relativistic electron plasmas is weakly affected by magnetic fields during saturation. External magnetic fields slightly increase saturation levels for large wavelengths but not small ones.
Area of Science:
- Plasma Physics
- Astrophysical Plasmas
- Relativistic Plasma Dynamics
Background:
- The Weibel instability, or current-filamentation instability, is crucial in high-energy astrophysical phenomena.
- Understanding its behavior in magnetized plasmas is essential for modeling these environments.
Purpose of the Study:
- To investigate the linear and nonlinear stages of the Weibel instability in relativistic electron plasmas under an external magnetic field.
- To analyze the saturation mechanisms and the influence of magnetic fields, multimode interactions, and temperature.
Main Methods:
- Analytical modeling of plasma behavior.
- Particle-in-cell (PIC) simulations for detailed kinetic analysis.
- Relativistic cold fluid framework for saturation mechanism investigation.
Main Results:
- The external magnetic field has a weak effect on the saturation stage of the Weibel instability.
- Large wavelengths show a slight increase in saturation level with an external field, while small wavelengths are unaffected.
- At high temperatures, saturation is independent of the magnetic field; at low temperatures, the magnetic field can lower the saturation level due to mode competition.
Conclusions:
- The Weibel instability's saturation is robust against external magnetic fields, particularly at small scales.
- Temperature and multimode interactions significantly influence the saturation level in magnetized plasmas.
- Findings are relevant for understanding particle acceleration and magnetic field generation in astrophysical plasmas.
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