Electromagnetic and Particle-in-Cell Simulation Studies of a High Power Strap and Vane CW Magnetron

This paper presents electromagnetic and particle-in-cell (PIC) simulation studies of ring strapped vane resonator of a 2.45 GHz 1-kW magnetron using Computer Simulation technology microwave studio and MAGIC-3-D. The aim was to gain design understanding through the analysis of constituent parts of the resonant system and to deduce results having significant engineering value. The electromagnetic analysis includes modeling the effect of the end-gap length, the straps, the coupling antenna, and the surface roughness of cavity wall on resonant frequency. It was found that a clearance of 4 mm and beyond between cavity resonator and end plate have negligible effect on resonance frequency. Straps influence the resonant frequency of the π mode maximum, and can be used to control and fine tune the resonant frequency of the desired π mode. A surface roughness of 1 μm or more affects the unloaded Q of the resonator cavity adversely. Coupling antenna height is found to play an important role to achieve desired Q
_l
and Q
_ext
for the segment loaded axial extraction of power. The PIC simulation study predicted that the hot resonant frequency differ from cold resonant frequency by ~9 MHz. The computed frequency, power, and efficiency were found to be 2.462 GHz, 1.3 kW, and 70%, respectively.