Study on Load-Side Optimization in Bifrequency MILO Source

In this article, we present an in-depth study of bifrequency magnetically insulated transmission line oscillator (MILO) generating RF output power in S-band with azimuthal partition. It is proposed to optimize the parameters across the load side, inserting gold plate in the collector and tuning the collector cavity depth. The proposal aims at enhancing the power conversion efficiency by employing the concept of a tapered extraction region and implementing four stubs. The stubs help to achieve proper impedance matching, subsequently improving the output power. Further, loss-free FR-4 dielectric is used in extractor vanes which helps to reduce the RF power distribution in other modes. The use of gold plate stimulates space charge near the surface and helps in deflecting the electrons toward the interaction cavities. The presence of FR-4 extractor vane helps to generate spoke current near the collector. The proposed system provides improvised RF coupling of the electron beam to the interaction cavities. The peak power efficiency of ~12.7% is achieved through the device. The beam-wave interaction process is illustrated using space charge instability mechanism. Taking into account the Lagrangian of electrons relationship between angular momentum and torque due to angular force is also derived. This in-depth study helps in the deep understanding of magnetic insulation process inside the device toward developing the proficient MILO source.