Articles | Volume 30, issue 2
Ann. Geophys., 30, 427–431, 2012
Ann. Geophys., 30, 427–431, 2012

ANGEO Communicates 28 Feb 2012

ANGEO Communicates | 28 Feb 2012

A note on the Weibel instability and thermal fluctuations

R. A. Treumann1,2 and W. Baumjohann3 R. A. Treumann and W. Baumjohann
  • 1Department of Geophysics and Environmental Sciences, Munich University, Munich, Germany
  • 2Department of Physics and Astronomy, Dartmouth College, Hanover NH 03755, USA
  • 3Space Research Institute, Austrian Academy of Sciences, Graz, Austria

Abstract. The thermal fluctuation level of the Weibel instability is recalculated. It is shown that the divergence of the fluctuations at long wavelengths, i.e. the Weibel infrared catastrophe, never occurs. At large wavelengths the thermal fluctuation level is terminated by the presence of even the smallest available stable thermal anisotropy. Weibel fields penetrate only one skin depth into the plasma. When excited inside, they cause layers of antiparallel fields of skin depth width and vortices which may be subject to reconnection.