Excitation of low frequency waves by streaming ions via anomalous cyclotron resonance

The effect of streaming ions on the low frequency Alfvén, magnetosonic, and ion‐cyclotron waves is considered. It is found that excitations of these waves can occur due to the anomalous cyclotron resonance (i.e., ω+Ω i −k ∥ v ∥=0) process. Analytic expressions for the growth rates are derived for the case of a small population of streaming ions, n s /n 0≪1 (where n s and n 0 denote the number densities of the streaming and background ions, respectively). The effects of the Landau and cyclotron damping due to the background plasma are included. Numerical examples are also given for the case of ion‐cyclotron waves.