Oscillations of frequency ν≈100 kHz were detected in a plasma created by an electron beam in a magnetic field. The amplitude of these oscillations depends on the strength of the external field of frequency ω≫ν The high-frequency field is in turn modulated by the low frequency, and this produces combination frequencies (ω±ν). The oscillation amplitudes at the combination frequencies ω+ν and (ω–ν are not equal; as in the case of the Raman effect, this may be related to the effectiveness of the interaction of various frequencies and to the direction of energy transfer.