Output Circuit Of High Order TM Mode In Cylindrical Coaxial Cavity Of Klystron

Klystron is a kind of high power electric vacuum microwave oscillator and amplifierdevice with characteristics of high power, high efficiency and high gain. Its basic principle isby electron beam and standing wave field in the resonant cavity interaction, the DC energybeing changed into high-frequency microwave energy. It is applied widely in radar,communication and accelerator etc. The characteristic of output cavity high frequencysystem influences importantly on power, efficiency, bandwidth and stability.It is important way to increase frequency of klystron by using coaxial output cavity andhigh order mode. Cylindrical coaxial cavity resonator with high order transverse magneticTM310mode in it is designed. The gap impedance of output circuit of klystron is calculatedusing equivalent circuit theory. Characteristic impedances at the positions of six longitudinalelectric field peak values, i.e. shift tubes center, are simulated and calculated. Higher orderTM310mode in single gap coaxial resonator cavity loaded with fundamental mode TE10inoutput rectangular waveguide is analyzed and the gap impedances at six drift tubes center aresimulated and calculated based on the Field-Analysis-Method. External quality factor issimulated and calculated with the group-time-delay method. The results indicate that thistype of circuit is applicable to high-frequency and narrowband klystron. To increase outputbandwidth the transverse filter diaphragm structure in output rectangular waveguide isdesigned，and the output bandwidth is increased as expected.Double gap resonator cavity and overlap mode output circuit can effectively increasethe broadband and power. Combining these two type circuit, gap impedance real part ofdouble gap coupling output cavity is calculated using equivalent circuit theory. In low rangof working frequency band the results obtained with the theory are basically consistent withthe simulation of HF electromagnetic field software CST. The final designed output circuitcan acquire2.54%relative bandwidth.