Simulation of a 41 cavity MILO

Summary Form only given, as follows. The MILO high-power microwave device consists of a cylindrical cathode surrounded by a vaned anode. Between them flows a magnetically self-insulated electron beam, which interacts with the anode structure to produce microwave oscillations. The current consists of two parts, that which flows within the AK gap and that which flows in the cathode, ultimately crossing in a load region away from the anode structure. Most of the current flowing in the gap reaches the anode in electron spokes similar to those seen in magnetrons. Earlier MILO designs contained ten cavities. In this configuration, 20% of the current flowed in the gap while 80% remained in the cathode, expending its energy uselessly (except for providing the required magnetic field) in the load region. Simulations predict that about 40% of the energy of the beam flowing in the gap could be converted to microwaves, giving an overall efficiency of 8%. Simulations of MILO with 41 cavities show that three-quarters of the current crosses in the spokes, leaving only one-quarter to be dumped in the load. Furthermore, the 40% conversion efficiency appears to be maintained, giving an overall efficiency of 30%.<>