Development of a C-Band Klystron With a 360-MHz Instantaneous Bandwidth

This paper presents the design considerations, the simulation results, and the test results for a C-band klystron design with a 360-MHz instantaneous bandwidth, which was developed from March 2005 to June 2008. Five klystrons were built and tested. Over 800 kW peak output power with a 400-MHz instantaneous bandwidth (constant RF input drive over frequency) was measured at a 0.525% RF duty cycle. The measured electron beam-to-RF conversion efficiency is 30%, and the output power fluctuation over frequency is less than ±0.75 dB. The technological problems, including gain/power dip over frequency and low electron-beam transmission, are also discussed.