High efficiency Klystron design and test result in TETD

The efficiency of the klystrons is great interest at large particle accelerators, in terms of power consumption and performance of accelerators. To increase the efficiency, TETD (Toshiba Electron Tubes & Devices co., ltd.) introduced core oscillation and smooth bunching approach into a TETD's commercial model klystron for early evaluation by minimal changes. The efficiency of the design result was 59% at 6MW peak output RF power, and that of test result was 58%. It was proved that new approach was useful, and expansion to other conventional models could be expected due to simple structure and minimal modification.