Excitation of high-order harmonics in a plasma

It is shown theoretically and experimentally that high-order harmonics of an applied periodic electric field will be excited in a plasma subjected to this field. Theoretical calculations are made for the formation of instabilities in the plasma and the excitation of high harmonics of the external field. In the experiment, a high-frequency (150 MHz) discharge was created in a longitudinal, static, homogeneous magnetic field around a quartz tube, and oscillations were detected in the plasma. Excitation of harmonics (up to the 77th harmonic of the discharge frequency) was recorded.