A Parametric Study of Locally Generated Magnetosonic Waves by Ring-Beam Hot Protons in the Martian Heavy Ion-Rich Environment

Magnetosonic (MS) waves with frequencies above the proton gyrofrequency can be locally generated by ring-beam protons in the Martian heavy ion-rich ionosphere. In this study, we conduct a parametric analysis to investigate the effects of heavy ion concentrations, energy (E_rb), and angle (α_rb) of ring-beam protons, and wave normal angle on the excitation features of Martian ionospheric MS waves. We find the growth rates and frequency range of MS waves decrease by including O⁺ and O₂⁺ ions but are insensitive to their relative concentrations. With increasing E_rb or α_rb, the growth rates of MS waves show a general dropping tendency. Meanwhile, their frequency and wavenumber range are almost unaffected by increasing E_rb but shrink to a narrower range mainly distributed in high frequencies by increasing α_rb. Unstable MS waves expand to a wider wavenumber range but shrink to a narrower frequency range as they become more oblique.