Simulations of a 100 KW CW, 650 MHz gridded magnetron

Summary form only given. Calabazas Creek Research Inc. (CCR) has examined the feasibility of a grid to control the magnitude and phase of magnetrons. A 650 MHz 100 kW CW magnetron was the focus of the study. Simulations were performed using VSIM, a Particle-in-Cell (PIC) code from Tech-X [1], and the trajectory code Beam Optics Analyzer (BOA) from CCR [2]. VSIM gave moderate resolution simulations of the self-consistent interaction of the electrons with the RF fields. BOA was used to examine grid interception and heating. With VSIM, stable operation was achieved over a range of power of almost an octave through variation of the grid voltage. However, even after a thorough examination of parameter space, phase locking was not observed. BOA was used in its quasi-electrostatic PIC mode, along with its adaptive meshing, to determine grid loading. In this mode, the RF electric field was imported from VSIM. As expected, heating of the grid was a serious issue. A shadow grid was used to limit heating from electrons coming directly off the cathode. But, even with this geometry, heating from recirculating electrons limited the duty cycle to about 1%. Details of the simulations will be presented.