Cherenkov radiation of an intense relativistic electron beam from corrugated and iris waveguides

The experimental results of microwave Cherenkov generators research, are discussed. The most of Cherenkov generators (with the output of microwave power more than 100 MW) Have the pulse duration not graater than several dozens ns. Therefor we searched the generators which have longer pulse duration of electron current interacted with periodic slow-wave structures. We choozed Cherenkov generators posessing strongly marked resonance features and investigated generators with the corragated and iris waveguides as the slow-wave structures. As we´ll show later on the relativistic generator with the corrugated waveguide worked out in the Gorkey Institute of Applied Physics (IAP) also reveals the resonance properties. This generator has been investigated theoretically in detail in the BWO regime and experimentally using short current pulses in Lebedev Institute (USSR) [1]. It should be mentioned that just this generator has been used for the first time in successful experiments when there were obtained the high microwave radiation power levels and theconversion efficiency achieved the values more than 10%. Recently the authours [2] succeeded in the radiation power 10⁹W with the efficiency more than 25% and the pulse duration 15 ns.