Three-component non-symmetric counter-streaming instabilities: oblique propagation case

The effects of the background plasma as well as of the non-resonant plasma-cyclotron and cyclotron-cyclotron interactions on the oblique unstable electrostatic waves generated by resonant plasma-cyclotron (P-C) and cyclotron-cyclotron (C-C) interactions in magnetized non-symmetric two-stream plus background plasma systems are theoretically investigated. Two main effects are reported: (a) preferential increase or decrease of the maximum growth rates of certain m-modes for appropriate plasma parameters and (b) an additional contribution to the frequency shift from the integer multiple values of half the cyclotron frequency. Closed analytical expressions for the maximum growth rates and frequency shifts of both plasma-cyclotron and cyclotron-cyclotron unstable interactions are presented and discussed. The theoretical results obtained in this paper are supported by recent experimental results on electron counter-streaming instabilities in the presence of significant background plasma concentrations in which dominant electric field emissions at 3Ω_e/2 have been observed to occur.