Power combiner with high power capacity and high combination efficiency for two phase-locked relativistic backward wave oscillators

摘要

To realize power combination of two phase-locked relativistic backward wave oscillators (RBWOs), a compact power combiner is designed and investigated by 3-D particle-in-cell (PIC) simulation and experiment. The power combiner consists of two TM_(01)-TE_(11) serpentine mode converters with a common output. When the two incident ports are fed with TM_(01) modes with a relative phase of 180° and power of 2.5 GW at each port, the conversion efficiency from the incident TM_(01) modes to the combined TE_(11) mode is 95.2% at 9.3 GHz, and the maximum electric field in the combiner is 714kV/cm. The PIC simulation shows that the output power from the common port is 4.2 GW when the power combiner is connected to the two RBWOs with input signals, both producing 2.2 GW microwave, corresponding to a combination efficiency of 95.4%. In the high power microwave test, a method is proposed to obtain the combination efficiency without breaking the vacuum, which is 94.1% when the two phase-locked RBWOs output 1.8 GW and 2.2 GW. The power capacity of multi-gigawatts has been demonstrated.