There are many kinds of high power microwave devices.According to the phase and frequency characteristics of the output microwave,they can be divided into the phase and frequency locking high power microwave (HPM) devices and HPM oscillator.Among them,the frequency and phase of HPM devices with locked frequency and phase can be adjusted by the injecting microwave,which has achieved great progress of the HPM research.In this paper,the latest progress of HPM devices with locked frequency and phase which have been developed by the Institute of Applied Electronics,China Academy of Engineering Physics in recent years are reviewed,covering relativistic klystron amplifier (RKA) and relativistic backward-wave oscillator (RBWO) with injection-locked.Aiming at the problems encountered in the research of high power and long pulse RKA,in this paper we briefly introduce the key technologies in design and experiment,including the beam-wave interaction merits,the suppression of multi-frequency oscillation,pulse shortening, high frequency and high power operation,high gain,etc.The performances of RKA,such as power,phase stability and gain,have been improved remarkably.High-power output with stable frequency and phase has been realized by single-annular beam RKA in S-band,whose output power reaches more than 1 GW with a pulse width of 165 ns and phase fluctuation of 18 at a repetitive pulse of 25 Hz/1 s.The high gain RKA also achieves a similar output power and phase stability under the condition of injected microwave power of several kW.In X-band RKA,a structure of coaxial multi-beam has been used to break through the limitations of high frequency and high power capacity,which generates more than 1 GW output power with an input power of 30 kW,the beam-wave conversion efficiency is 34% and the phase fluctuation is 15 with a pulse width of 140 ns.On the basis of an in-depth understanding of RBWO technology, and using the advantages of high efficiency and compact structure,the RBWO research of injection modulated electron beam is proposed and carried out.More than 1 GW output microwave with locked phase is realized by 100 kW seed microwave.These results not only extend scientific and technological research of a large family of HPM devices,but also make it possible for HPM devices to be used in power synthesis,particle acceleration,high-performance radar,etc.
