Supraluminous waves in a relativistic anisotropic plasma

The linearized relativistic Vlasov equation is used to investigate supraluminous waves in a field-free two-component plasma. The ions are immobile; the electrons are described by a spatially- homogeneous equilibrium distribution f 0 (p) which is anisotropic in momentum space but which satisfies f 0 (p)=f 0 (-p). For a given wavenumber k there are in general three supraluminous normal modes, all of which propagate without growing or damping. One mode remains transverse for all degrees of anisotropy; the other two are mixed in that they are neither purely longitudinal nor purely transverse. Each mode satisfies a different dispersion relation, the different depending on k, the degree and direction of anisotropy, and the relativistic properties of f 0 (p). The resulting 'dispersive' effects are discussed for both a plane wave and a pulsed signal.