Design and cold-testing of two 100 MW gyroklystron amplifiers for collider applications

In this paper we present the design details of both a first harmonic two-cavity coaxial gyroklystron and a second harmonic three-cavity amplifier tube, each of which is designed to produce over 100 MW of output power. Both tubes utilize a fundamental mode TE011 input cavity which is driven by a 150 kW magnetron at 8.56 GHz. The former tube also has an 8.56 GHz TE011 output cavity while the latter system has a buncher cavity and an output cavity that resonate at twice the drive frequency in the TE021 mode. We present details of all system aspects, including the test bed modifications required to produce the enhanced beam characteristics, simulated beam properties, and simulated circuit interactions. HFSS modeling of the drive cavities is also reported and cold test results of both tubes are detailed. Results to date indicate that both systems should be at least 40% efficient.