Electrostatic ion cyclotron and ion acoustic waves in a multi-ion cometary plasma

The electrostatic ion cyclotron and ion acoustic waves are investigated in a five component cometary plasma consisting of hydrogen and positively and negatively charged oxygen ions and kappa described hot solar and slightly colder cometary electrons. A linear dispersion relation for the system is derived and studied numerically. It is found that at larger propagation angles the separation between acoustic and cyclotron modes increases, which indicate a weak coupling between the two modes. For perpendicular propagation, the ion acoustic mode nearly vanishes and only the cyclotron mode exists. The influence of various parameters such as superthermality, densities of ions, charge numbers and temperature ratios of pair ions on the dispersion characteristics is extensively investigated. (author)