Weibel instability

The Weibel instability is a plasma instability present in homogeneous or nearly-homogeneous electromagnetic plasmas which possess an anisotropy in momentum (velocity) space. In the linear limit the instability causes exponential growth of electromagnetic fields in the plasma which help restore momentum space isotropy. In the limit of an extremely anisotropic distribution the Weibel instability is related to one- or two-dimensional stream instabilities.

Consider an electron-ion plasma in which the ions are fixed and the electrons are hotter in the y-direction than in x or z-direction.

To see how magnetic field perturbation would grow, suppose a field B = Bzz cos kx spontaneously arises from noise. The Lorentz force then bends the electron trajectories with the result that upward-moving-ev x B electrons congregate at B and downward-moving ones at A. The resulting current j = -eni}ve sheets generate magnetic field that enhances the original field and thus perturbation grows.

References

*wikicite|id=weibelES1959|reference=E.S. Weibel, Phys. Rev. Lett. 2, 83 (1959); http://prola.aps.org/abstract/PRL/v2/i3/p83_1

ee also

* Chromo-Weibel Instability