In Viktorov et al (2016 Eur. Phys. Lett.116 55001) we reported on chirping frequency patterns that have been observed in the electron cyclotron emission from strongly nonequilibrium plasma confined in a table-top mirror magnetic trap. These patterns were interpreted qualitatively as the first experimental evidence for so-called 'holes and clumps' mechanism acting at such high frequencies (1–10 GHz). In the present paper, we prove this statement on a more rigorous basis, considering the formation of nonlinear phase space structures in proximity of the wave-particle resonances within the framework of the Berk–Breizman theory adopted for a kinetically unstable mirror-confined plasma.
Cyclotron emission spectra from collisionless electrons resonantly heated by cyclotron waves in a magnetic mirror