Trapping and Amplification of Unguided Mode EMIC Waves in the Radiation Belt

Electromagnetic ion cyclotron (EMIC) waves can cause the scattering loss of relativistic electrons in radiation belt. They be classified into guided mode and unguided mode, according to wave's propagation behavior. The have been widely investigated belt, but observation not expected. Based on observations Van Allen Probes, we demonstrate for first time existence intense L-mode EMIC belt polarization characteristics. Growth rate analyses indicate that hot protons with energies a few hundred keV may provide free energy wave growth. reflection interface formed by spatial locations local helium cutoff frequencies nearly parallel equatorial plane when proton abundance ratio decreases sharply -shell. This structure combined lead trapping significant amplification waves. These results help understand nature their dynamics