Unusual characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies

摘要: Solution of the linear kinetic dispersion equation shows that cometary new-born ions with large perpendicular energies (large initial angles between solar wind velocity and IMF) can excite a wave mode rest frame frequencies order heavy ion cyclotron frequency which exhibits maximum growth slightly away (6°–15°) from parallel propagation, together high mass density compression ratios almost polarization. The association these properties is relevant to space observations MHD-like waves at comets in planetary foreshocks has not been reported vast literature on possible instability mechanisms. Dilute drifting oxygen photoelectron rings finite thermal spreads model free energy source frame. For interest left-hand circularly polarized, moves direction newborn particles, predominantly fed by ions; as obliquity increases, its polarization change rapidly. Modification parameters (ring density, drift velocity, speed spread) determines their relative influence, defines domain existence mode, it might evolve into nonoscillatory, purely growing structure distinct mirror wave. results are also applicable non-cometary environments.