Excitation of Ion Cyclotron Harmonic Waves in a Plasma by a Perpendicularly Injected Electron Beam

抄録

A weak electron beam is injected into a diffused hydrogen plasma perpendicular to the external magnetic field and signals of non-thermal level are observed on the frequency spectra near integral multiples of ion cyclotron frequencies. It is concluded from parameter dependences of these signals that the ion cyclotron harmonic waves, which suffer no Landau damping for perpendicular propagation, are excited as a result of coupling with the electrostatic beam wave. The observed frequency spectra are interpreted to be such grown-up harmonic waves.