Flute mode waves near ω _LH excited by ion rings in velocity space

Discrete emissions at the lower hybrid frequency are often seen on the S3‐3 satellite. Simultaneous observation of perpendicularly heated ions suggests that these ions may provide the free energy necessary to drive the instability. Studies of the dispersion relation for k∥ = 0 modes excited by warm ion rings in velocity space show that waves are excited with real frequencies near the lower hybrid frequency and with growth rates ranging from ∼0.01 to 1 times the ion cyclotron frequency. Numerical results are therefore consistent with the possibility that the observed ions are the free energy source for the observed waves.