Electromagnetic and electrostatic wavesin a multi-component plasma near the lower hybrid frequency

In propagation perpendicular to the magnetic field, the lower hybrid frequency is the transition between long electromagnetic and short electrostatic waves. Cold, warm and hot plasma theories are applied to the case of a plasma composed of different ion species. For cold and warm (adiabatic) theories, the dispersion curves are not qualitatively different from the single-ion case. In the hot microscopic theory, the dispersion curves, the so-called ‘Bernstein modes’, have a structure mainly related to the lightest ion gyroharmonics, even in concentration as low as 1 %. The theoretical results can explain the ray structure observed in the ISIS II and Electron Echo 1 experiments.