Impact of Warm Plasma Cloak Ions on EMlC Waves and Detached Auroral Arc

It is well known that the presence of cold dense ions significantly enhances electromagnetic ion cyclotron (EMIC) wave activity. A warm plasma cloak is a structure that contains these dense ions in the magnetosphere. However, the detailed effects of dense ions from the warm plasma cloak on EMIC waves and their subsequent influence on magnetosphere‐ionosphere coupling remain unclear. Utilizing conjugate data from the RBSP‐A and DMSP satellites, we present observations of the current presence of dense ions from the warm plasma cloak and the enhancement of He + ‐band EMIC waves in the afternoon sector's plasmasphere boundary layer. Further investigation reveals an abundance of H + and He + in these dense ions, which explains the enhanced EMIC waves' band. These enhanced EMIC waves also lead to increased proton precipitation and intensified detached aurora arcs. These findings reveal the details of the impact of dense ions from the warm plasma cloak on the EMIC waves and magnetosphere‐ionosphere coupling.