a2 School of Physics, University of KwaZulu-Natal, Durban 4000, South Africa
We present a dispersion relation for a plane-polarized electromagnetic wave in plasmas composed of cold electrons, relativistically hot electrons and bi-Maxwellian protons. It is shown that the free energy in proton-temperature anisotropy drives purely growing electromagnetic modes in our three-component plasma. Expressions for the growth rates and thresholds of instabilities are presented. The present results are relevant for explaining the origin of spontaneously generated magnetic fields in laboratory and astrophysical plasmas.
(Received June 25 2009)
(Accepted August 28 2009)
(Online publication October 08 2009)
† Permanently at the Department of Physics, Umeå University, SE-90187 Umeå, Sweden; also affiliated with Grupo de Lasers e Plasmas/Instituto de Plasmas Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal.
‡ Also at the Nonlinear Physics Centre and Centre for Plasma Science and Astrophysics, Ruhr-Universität Bochum, D-44780 Bochum, Germany; Department of Physics, Umeå University, SE-90187 Umeå, Sweden; Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching, Germany; Grupo de Lasers e Plasmas/Instituto de Plasmas Fusao Nuclear, Departamento de Física do Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal; STFC Centre for Fundamental Physics, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon 0X11 0QX, UK; Scottish Universities Physics Alliance (SUPA), Department of Physics, University of Strathclyde, Glasgow G 40NG, Scotland, UK.