Simultaneous Cross‐Energy Ion Response and Wave Generation After the Impact of an Interplanetary Shock

Interplanetary (IP) shocks have substantial impact on particles and electromagnetic fields when arriving at the Earth's magnetosphere. In this study, we have examined the dynamics of cross‐energy ions and plasma waves observed by Van Allen Probe B near the equator at the noon sector inside the geosynchronous orbit after the impact of an IP shock on 27 February 2014. We found that the Ultra‐Low Frequency (ULF) and electromagnetic ion cyclotron (EMIC) waves are induced, and the differential fluxes of protons of various energies have different responses after the IP shock arrival. The perpendicular flux increased dramatically for low‐energy ions (10–100 eV) due to the electric field drift and betatron acceleration. These adiabatic processes also accounted for the evident proton flux decrease at 30–80 keV energies and increase at energies higher than 100 keV, caused by the positive or negative gradient in phase space density before the IP shock arrival. The short‐lived ULF waves triggered by the IP shock also interacted with the ∼100 keV protons, resulting in the stripes in their pitch angle distribution. The anisotropic distribution of >50 keV protons excited EMIC waves after the shock arrival. This study provides a comprehensive picture of the IP shock effects on the ions of different energies and plasma waves inside the geosynchronous orbit, which shed new lights on the cross‐energy responses of ions and plasma waves in the inner magnetosphere to solar wind discontinuities. Key Points We analyzed simultaneous cross‐energy ion response through adiabatic and non‐adiabatic processes after the impact of an Interplanetary shock Ions with different energies experienced the same adiabatic processes but underwent different evolutions depending on initial distributions Ultra‐Low Frequency and electromagnetic ion cyclotron waves could be generated simultaneously and affect different energy ions