Nonlinear absorption of cyclotron waves in a plasma

The increment of the decay of an electromagnetic wave, at an arbitrary harmonic of the electron or ion cyclotron frequency, into two potential Bernstein modes, efficiently absorbed by the plasma, is obtained. The condition on the amplitude of the incident wave is given for which the optical depth of the plasma due to the decay instability becomes greater than the optical depth of the zone of direct cyclotron absorption. The process under consideration is possible in cyclotron heating of a plasma by powerful radiation