Double Plasma Resonance in Electron–Positron Plasma at the Pulsar Magnetosphere

The electron cyclotron waves instability near the frequencies of electron cyclotron harmonics in an electron–positron plasma is studied under conditions typical for the radio emission source with a quasi-harmonic structure of the pulsar in the Crab Nebula. The increment of instability of longitudinal cyclotron waves is calculated for an electron–positron plasma with a small admixture of energetic electrons and positrons with a “loss cone” distribution function. It is shown that the magnitude of this increment increases significantly for the waves with a frequency close to the frequency of the upper hybrid resonance when the latter is close to the frequency of one of the cyclotron harmonics, similar to the double plasma resonance effect in electron–proton plasma.