Multi-MW 22.8 GHz Harmonic Multiplier

Efforts towards development of a high-gradient warm accelerator structure for a future electron-positron collider require basic experiments to discover the upper limits to radio frequency (RF) electric and magnetic field strengths that can be sustained at material surfaces. The experiments should be carried out at several RF frequencies to explore the wide parameter range to improve understanding of the underlying physical limits. Yet high-power stand-alone RF amplifiers at frequencies above X-band for these experiments only exist at 17.1 and 34.3 GHz, so sources at one or more intermediate frequencies need to be developed. This project addresses this deficiency by constructing a harmonic multiplier, in which multi-megawatt powers can be generated at the 7th, 8th, and 9th harmonics of 2.856 GHz output from a high-power klystron. The 7th harmonic frequency multiplier will be built, tested and evaluated using facilities at Yale Beam Physics Laboratory.