Tunable plasma relativistic microwave amplifier

A stable regime of the amplification of a slow plasma wave in a plasma waveguide during the injection of a high-current relativistic electron beam is obtained. For an input-signal frequency of 9.1 GHz, there exists a range of plasma densities in which the spectrum of the output microwave radiation lies in a 0.5-GHz-wide band. For a 40-kW input power at a frequency of 9.1 GHz, the maximum output power is 8 MW. It is shown experimentally for the first time that the beam-plasma amplifier can operate at frequencies of 9.1 GHz and 12.9 GHz. The range of plasma densities in which the regime of amplification is observed agrees with the results of calculations based on linear theory.