Magnetospheric Plasma Instabilities
“Instabilities of the internal magnetospheric plasma distributions can be another mechanism for the generation of the ULF pulsations. …consider now kinetic instabilities which result in the generation of MHD and ion-cyclotron waves in the frequency range of Pc1, Pc2, and Pi1 pulsations. In a linear approximation the ion-cyclotron instability arises from the energy exchange between the wave field and charged particles. This interaction becomes most effective under the resonance condition [the equation used] … wave frequency … projection of the thermal velocity of particles on ambient magnetic field … the same projection of wave vector … the gyro frequency of ions … the integer … The kinematic meaning of this condition can be understood in a local reference frame fixed at the Larmor center of the particle. … Depending on the plasma particle distribution of the velocities the interaction between the MHD wave and the resonant particles may result in either enhancement or damping of the magnetic oscillation.”
Does any of this appear ‘natural’ to you?