Articles | Volume 21, issue 1
Nonlin. Processes Geophys., 21, 143–148, 2014
Nonlin. Processes Geophys., 21, 143–148, 2014

Brief communication 22 Jan 2014

Brief communication | 22 Jan 2014

Brief Communication: Weibel, Firehose and Mirror mode relations

R. A. Treumann1,2 and W. Baumjohann3 R. A. Treumann and W. Baumjohann
  • 1Department of Geophysics and Environmental Sciences, Munich University, Munich, Germany
  • 2International Space Science Institute, Bern, Switzerland
  • 3Space Research Institute, Austrian Academy of Sciences, Graz, Austria

Abstract. Excitation of Weibel magnetic fields in an initially non-magnetized though anisotropic plasma may trigger other low-frequency instabilities fed by pressure anisotropy. It is shown that under Weibel-like stable conditions the Weibel-like thermal fluctuation magnetic field allows for restricted Firehose-mode growth. In addition, low-frequency Whistlers can also propagate in the plasma under certain anisotropic conditions. When the Weibel-like mode becomes unstable, Firehose instability ceases but Mirror modes take over. This will cause bubble structures in the Weibel-like field in addition to filamentation.