The plasma dispersion relation near the two-ion hybrid resonance

The dispersion relation of a deuterium -hydrogen plasma is investigated near the ion cyclotron frequency of hydrogen at varying hydrogen temperatures. It is found that at low hydrogen-to-deuterium temperature ratios, only the fast mode and the ion Bernstein mode are coupled around the hybrid layer. Above a certain critical temperature ratio T_h< T_hc, these two modes become coupled also to a third mode. Around and above T_hc, the wave equation is of sixth order rather than of the fourth order previously discussed.