An inward-emitting magnetically insulated line oscillator

Magnetically insulated line oscillator (MILO) can generate microwave of GW-class without external magnetic field. The main disadvantage of the device is that part of the input power is used to maintain the insulating magnetic field, which limits the power conversion efficiency significantly. In order to increase the power conversion efficiency, a novel MILO with an inward-emitting cathode is presented. Compared with the typical outward-emitting MILO where the magnetic field is provided by the load current, the electron beam in the inward-emitting MILO is collected at a specially designed inner conductor, and the returning spoke current contributes substantially to the insulating magnetic field. The inward-emitting MILO is investigated in detail by particle-in-cell simulation and a high efficiency has been obtained.