Waves in an Ultra-Relativistic Electron-Positron Plasma

Abstract

Basic equations describing a macroscopic behaviour of ultra-relativistic plasma (T>>mc²) are formulated in a covariant form. Waves in an electron-positron plasma are investigated in a frame of two-fluid model equation. Dispersion relations for electrostatic wave, electromagnetic wave and Alfven wave propagating parallel to a constant magnetic field are shown. In the case that both electron and positron gases have same temperature, there does not exist the slow mode which corresponds to the ion acoustic wave. Right and left circular polarized waves propagate with the same dispersion relation which is different from one of the non-relativistic electron-ion plasma.