Electron Cyclotron Electromagnetic Instabilities in Weakly Relativistic Plasmas

The relativistic dispersion relation of whistlers is solved for weakly relativistic plasmas. The solution takes into account various deviations from a Maxwellian distribution found in laboratory plasmas, namely, pressure anisotropy, loss cone, and cold plasma. The relativistic effects are shown to be strongly stabilizing even for low temperature plasmas when the density is such that ${\omega }_p^2{\mathrm{/\omega }}_c^2\text{≪0.25}$ . The spectrum of unstable waves is also shifted toward smaller frequencies.