Abstract:
The coupling of electrostatic ion cyclotron and ion acoustic waves is examined in three component
magnetized plasma consisting of electrons, protons, and alpha particles. In the theoretical model
relevant to solar wind plasma, electrons are assumed to be superthermal with kappa distribution
and protons as well as alpha particles follow the fluid dynamical equations. A general linear
dispersion relation is derived for such a plasma system which is analyzed both analytically and
numerically. For parallel propagation, electrostatic ion cyclotron (proton and helium cyclotron) and
ion acoustic (slow and fast) modes are decoupled. For oblique propagation, coupling between the
cyclotron and acoustic modes occurs. Furthermore, when the angle of propagation is increased, the
separation between acoustic and cyclotron modes increases which is an indication of weaker
coupling at large angle of propagation. For perpendicular propagation, only cyclotron modes are
observed. The effect of various parameters such as number density and temperature of alpha
particles and superthermality on dispersion characteristics is examined in details. The coupling
between various modes occurs for small values of wavenumber.
