Design of a continuous wave Ka-band extended interaction klystron

A continuous wave Ka-band extended interaction klystron producing output power of 3 kW and bandwidth of 100MHz has been designed in Institute of Electronics, Chinese Academy of Sciences (IECAS). The electron beam voltage is 17kV, beam current is 0.9A, tube radius is 0.5mm and beam radius is 0.3mm. Electron optical system has been well optimized because of the continuous operating mode. The beam compression factor is 53:1 and the average emit current density in cathode is 6A/cm². There are six cavities, single gap input cavity and five double gap coupled cavity. Double gap coupled cavities operate in 2pi mode and the efficiency exceeds 20% in required bandwidth. Design considerations and details are addressed in this paper.