Nonlinear instability of electromagnetic drift waves

A pair of electromagnetic drift waves is shown to be excited simultaneously by an induced Cerénkov emission by electrons. The instability is shown to be explosive. However, its property is different from the ordinary explosive instability involving three wave interactions with a negative energy wave pump. The instability here is excited by the inverted population of electrons (inverse Landau damping) and is less sensitive to the frequency mismatch or dissipation. The nonlinear growth rate is shown to exceed the linear growth rate at a reasonably small level of wave amplitude. A magnetic field perturbation is essential for this process.