Open AccessRing current proton scattering by low‐frequency magnetosonic waves
Author(s) -
Yu Jiang,
Wang Jing,
Cui Jun
Publication year - 2019
Publication title -
earth and planetary physics
Language(s) - English
Resource type - Journals
ISSN - 2096-3955
DOI - 10.26464/epp2019037
Subject(s) - plasmasphere , physics , ring current , low frequency , proton , scattering , current (fluid) , computational physics , extremely low frequency , van allen probes , atomic physics , optics , nuclear physics , plasma , van allen radiation belt , magnetosphere , magnetic field , astronomy , thermodynamics , quantum mechanics
Magnetosonic (MS) waves are believed to have the ability to affect the dynamics of ring current protons both inside and outside the plasmasphere. However, previous studies have focused primarily on the effect of high‐frequency MS waves ( f > 20 Hz) on ring current protons. In this study, we investigate interactions between ring current protons and low‐frequency MS waves (< 20 Hz) inside the plasmasphere. We find that low‐frequency MS waves can effectively accelerate < 20 keV ring current protons on time scales from several hours to a day, and their scattering efficiency is comparable to that due to high‐frequency MS waves (>20 Hz), from which we infer that omitting the effect of low‐frequency MS waves will considerably underestimate proton depletion at middle pitch angles and proton enhancement at large pitch angles. Therefore, ring current proton modeling should take into account the effects of both low‐ and high‐frequency MS waves.