Mechanical Design and Manufacturing of W-Band Sheet Beam Klystron

Development of high frequency, high-average power linear beam devices is hindered by the slow progress in advancement of suitable mechanical design and manufacturing techniques. To compliment the significant progress in electromagnetic modeling and design of high-frequency electronics, the mechanical design and manufacturing approach employed for the development of a 10 kW continuous wave W-band sheet beam klystron is reported. The reported design enabled demonstration of 10-kW, 20-ms duration pulses with 17-dB gain and 97% (hot) beam transmission. This high-average power design was based on the demonstration of a 56 kW short pulse ( $1~\mu \text{s}$ ) device with 54 dB of gain. The high-average power design features a multilayer strengthened material structure with hybrid microcooling and macrocooling circuits for enhanced heat flux handling. Microcooling channels fit between circuit cavities providing heat removal as well as thermal-stress relief for reduced cavity deformation. The design achieves a 1.5-safety factor on yield and less than 2- $\mu \text{m}$ deformation at the cavities. The presented design and manufacturing approach can be applied to the development of other high-average power high-frequency linear beam devices.