Simulation Investigation of High-Efficiency L-Band MILO Using Reflector Stubs

A magnetically insulated line oscillator (MILO) is a renowned crossed-field high-power microwaves (HPMs) device with an intrinsic property of self-insulation against electrical breakdown, which corroborates its gigawatt range operation. This article presents an idea of a reflector in MILO for efficiency enhancement. Reflectors are placed symmetrically in the beam dump region. Effects of reflector radius and positioning on output power are also studied, and it is observed that a matched reflector causes a drastic improvement in efficiency. The presented reflectors in conventional MILO enhance the axial electric field (Ez) in the slow-wave structure (SWS) region, which reinforces the beam-RF wave interaction. An eigenmode analysis is done to determine the dominant frequency of MILO. Simulation results show that the device is operating in the L-band at 1.82 GHz. The dominant mode is T M01 with an average output power of 7.55 GW. The average power efficiency is 18.6%. The applied input voltage is 680 kV and current of 59.7 kA. While the conventional MILO only generates an average power of 5.2 GW at the same input power. PIC simulation results reveal that the efficiency of MILO with reflector configuration is 45% higher than that of conventional MILO with a commonly used beam stub position of lambda g/4 from the extractor cavity.