Mode analysis of an overmoded extended interaction cavity in terahertz EIK

The extended interaction klystron (EIK) operating at high order mode has many advantages compared with conventional EIK in high frequency band for its oversized structure. A five-gap cavity operating at the TM31-2π mode with resonant frequency of 0.34 THz is investigated in this paper. Resonant modes in the overmoded cavity are analyzed for mode selection and stable operation. Finally, the cavity is theoretically approved stable operation at the TM31-2π mode without self-oscillation and mode competition under 15 kV beam voltage and 300 mA beam current.