“…Lastly, although so‐called sideband waves can grow spontaneously very close to a main (sufficiently intense) wave in an inhomogeneous magnetic field (Costabile et al., 2017 ; Nunn, 1974 , 1986 ), it is worth noting that (a) such sideband waves are not generated independently from the main wave but are instead directly generated by cyclotron resonance with particles trapped by the main wave (they are a by‐product of the nonlinear growth of this main wave), and (b) their growth rate is largest for a frequency difference with the main wave Δ ω * ≃ ω tr /(1 − v res / v g ) ≃ ω tr /(1 + Ω ce /2 ω ) (Dowden, 1982 ; Nunn, 1986 ). Accordingly, a sideband wave reaching a sufficiently high amplitude, similar to the main wave amplitude, is expected to produce wave amplitude modulations corresponding to relatively long packets with β * = ω /Δ ω * > β tr , min 2 > β tr , min , similar to the trapping‐induced modulations already considered in Section 2.1 .…”