Experimental investigation of a phase-locked harmonic multiplying inverted gyrotwystron

Summary form only given, as follows. The University of Maryland is investigating harmonic multiplication as a means of generating high frequency, large bandwidth, high power microwaves with reduced magnetic fields and high subharmonic injection gain. The current experimental efforts are concentrated on two-stage devices. One of them is the phase-locked, harmonic-multiplying inverted gyrotwystron (phigtron) which uses a MIG produced electron beam (60 kV, 10 A), a combined mode launcher/input coupler, a Ku band fundamental gyro-TWT prebunching section, a radiation-free drift section, and a Ka band special complex cavity as output section. The bandwidth of this phigtron is expected to be improved over that of a gyroklystron since the input cavity is replaced by a traveling wave interaction structure. The second harmonic content of the beam may develop within both the input section and the drift space, and this allows the use of a smaller input signal. For a proof-of-principle experiment, a hot test tube was built. Initial experimental data will be provided in this presentation and will be compared with theoretical predictions. Finally, the feasibility of using a phigtron configuration with second harmonic prebunching and fourth harmonic output to realize a compact, high performance MMW power source at 94 GHz will be discussed.