Collective interactions in rapid theta-pinch

In this work the microwave radiation from the plasma of the rapid thetatron of the electronic cyclotron harmonics series lying lower than the plasma frequency was observed. The intensity of this radiation increased approximately 100 times when the frequency of the higher harmonic of this series coincided with the upper hybrid frequency. The harmonics with numbers 2, 4 and 8 were most easily excited, but radiation was not observed at fundamental frequency. The intensity of the microwave radiation from the plasma was approximately five orders higher than the thermal level. It was shown that this radiation is caused by plasma oscillations which appear in the central discharge region where conditions of continuous acceleration of electrons by a vortex electric field are satisfied.