Magnetron simulations and experiments

Summary form only given, as follows. Simulations and experiments are underway at UM to investigate the characteristics of GW-level, cold cathode, relativistic magnetrons versus kW-level, thermionic cathode magnetrons. The goal of the research is to understand why kW magnetrons exhibit 50-80% efficiencies, but relativistic (>100 MW) magnetrons are limited to /spl sim/30% efficiency. We present simulations relevant to relativistic magnetron experiments beginning at the University of Michigan. Planned MELBA experimental relativistic e-beam parameters are: voltage=-500 kV, current=1-10 kA, and pulselength from 100-500 ns. The main relativistic magnetron under study is the Maxwell Physics International L-band magnetron. Commercial oven magnetrons are also being studied. Mode competition and mode hopping are being addressed by utilizing time-frequency-analysis of the heterodyned microwave signals, we are planning to explore the effects of the vastly different impedances and space charge densities that characterize each device.