Equivalent Gap Impedance of TM310-mode in cylindrical coaxial output resonant cavity of klystron

Transverse magnetic TM310-mode in cylindrical coaxial cavity microwave resonator of klystron is investigated. Average gap impedances at the six longitudinal electric field peak value positions, i.e. 1~6 number tubes center where electron beams will pass through, are calculated with microwave equivalent circuit theory and simulated by CST MICROWAVE STUDIO. The average equivalent gap impedances and their 3dB bandwidth are calculated for cavity coupled with empty rectangular waveguide and with inductive diaphragms in waveguide respectively. The results indicates that the high order transverse magnetic TMn10 modes in single gap cylindrical coaxial cavity resonator are suitable for high frequency, narrow-band and high power output circuit of multi beam klystrons (MBK).