Generation of the Harmonic Structure of Upper Hybrid and Electron Cyclotron Waves Driven by Energetic Electrons

This is the first report of the harmonic structure of upper hybrid waves (UHWs). Using a one-dimensional electromagnetic particle-in-cell simulation, it is demonstrated that the harmonic structure of UHWs can be generated by energetic electrons through non-linear wave-wave coupling, similar to that of lower hybrid waves by energetic ions. After the saturation of UHWs, furthermore, it is found that electron cyclotron waves (ECWs) gradually grow due to the injection of energetic electrons. The involvement of ECWs in non-linear wave-wave coupling can make the harmonic structure of UHWs more complex.