Propagation of Wave Modes in Ultrarelativistic Magnetoactive Plasma--I

Some results on the propagation of undamped wave modes in fully relativistic, magnetoactive plasma are presented. We introduce a specific isotropic particle distribution function that is uniform in phase space up to a limiting particle energy and zero for higher energies. If only the electrons contribute significantly to the dispersion, it is shown that undamped 'quasi-ordinary' and 'quasi-extraordinary' modes can propagate when the wave frequency is less than the relativistic gyro frequency of the most energetic electrons. When this inequality is reversed, there are limited ranges of field strength and propagation direction for which one quasi-ordinary and two quasi-extraordinary modes can propagate. There are additional propagating modes if the protons contribute significantly to the dispersion.