High power CW magnetrons can be used widely in industrial heating and other aspects
and long-anode magnetrons could reach higher power because of their larger thermal capacitance and longer interaction distance than convntionalmagnetrons. In this paper
a preliminary design of a long-anode resonator for 2450 me operation was given and its charcteristics including mode dispersion and characteristic impedance etc. for different arrangement of output structure and straps werecalculated using MAFIA package. Higher axial modes
which do not exist in ordinary magnetrons were found by the study ofthe field patterns. At last
a good mode separation has been obtained for π-mode oscillation by prope straps arrangements.