Distinction between electrostatic ion cyclotron waves and ion cyclotron harmonic waves

Two distinctly different plasma wave modes with structure related to the ion cyclotron frequency, ω/sub ci/, have been detected by instruments onboard the S3-3 satellite. The harmonic frequency structure with respect to ω/sub ci/ is different for each mode and the two modes exhibit different values of phase coherence. One referred to as the electrostatic ion cyclotron wave has already been discussed extensively in the literature. The other, the ion cyclotron harmonic mode, is discussed in detail here for the first time. This mode has been produced in the laboratory by a perpendicular ion beam and in fact is found to correlate with energetic ion distributions peaked near 90 degrees (ion conics) in the S3-3 data set. The observations are compared favorably to a theory for electrostatic waves with wave vector nearly perpendicular to the magnetic field, in the presence of a perpendicular ion beam