Modulation of the growth of auroral kilometric radiation by electromagnetic ion cyclotron waves

Abstract

The role of electromagnetic ion cyclotron (EMIC) waves in the stimulation of auroral kilometric radiation is addressed in this study. Observations of the modulation of electron flux and energy due to EMIC/electrostatic ion cyclotron waves within the auroral kilometric radiation (AKR) source region have been reported in the past. These modulations produce in turn oscillations of the electron phase space density and therefore lead to fluctuations of AKR growth rate that may translate along the magnetic field line at the group velocity of the stimulating waves. For a model electron “horseshoe” distribution function, we use the theory of the cyclotron maser instability to investigate how this process might influence the AKR wave spectrum and fine structure.