Normal Doppler effect in experiments on the interaction of relativistic electron beams with plasma: Plasma relativistic microwave amplifier

Plasma relativistic microwave amplifier with smooth frequency tuning from 2.4 to 3.2 GHz

“…Experiments with ampli fiers operating on lower frequencies, 2-3 GHz [3][4][5], allowed one to measure the output radiation spectra and study the phase stability of the electric field in each microwave pulse, i.e., to obtain a more complete picture of the physical phenomena occurring in the amplifier. Thus, in [5], it was proven that the plasma wave reflected from the collector can be suppressed due to the normal Doppler effect, as was earlier observed in [6]. In [4], the effect of noise suppression at high intensities of the output signal was revealed.…”

“…After the plasma wave is con verted into the vacuum mode Н 11 in mode transformer 4, the amplified radiation is emitted from horn 6 into free space, the electric field at the axis of the output microwave beam being directed vertically. Microwave generation is suppressed due to the normal Doppler effect [6], as well as by placing microwave absorbent 7 in the plasma waveguide. The output radiation is received by a 2 cm long rod antenna placed vertically on the axis of the microwave beam at a distance of 70 cm from the horn.…”