GYRORESONANT. “Several wave modes interacting with the electrons at resonant energies can scatter them to the atmospheric loss cone hence leading to increased precipitation and loss of electrons from the magnetosphere. Plasmaspheric hiss is a wave mode confined within the plasmasphere, driven unstable by gyroresonant interaction with energetic electrons.”
https://link.springer.com/article/10.12942/lrsp-2007-1