SIMULATION STUDY OF A HIGH-ORDER MODE BWO WITH MULTIPLE INCLINED RECTANGULAR ELECTRON BEAMS

A backward wave oscillator (BWO) operating at the high-order mode (HOM) with multiple inclined rectangular electron beams (IRBs) is presented in this article. The BWO operating at the HOM with multiple IRBs (HOM IRB BWO) is driven by multiple IRBs. Compared with typical BWOs, the slow wave structure of the HOM IRB BWO is an overmoded metal-grating rectangular waveguide (OGRWG). The mode competition of the slow-wave device operating at the HOM is analyzed according to the ohmic losses of different modes of the OGRWG slow wave structure and multiple beams exciting. The analysis is verified by simulation. Two kinds of HOM-fundamental mode converters (MCs) are designed for converting the HOM generated by the HOM IRB BWO into the fundamental mode. The beam-wave interaction of the HOM IRB BWOs with the HOM-fundamental MC is studied. The results show that the mode competition does not occur; frequency spectrums of output signals are pure; and the HOM is converted into the fundamental mode effectively.