Microwave Oven Magnetron Squirrel Cage Cathode

Cathode is the most important part of magnetron. The lifetime of magnetron, the output power and stability are all determined by the quality of cathode. It is crucial to determine the structure and types of cathode.This dissertation focus on the effect of spiral, pillar and squirrel cathode structure on the output property of magnetron, employing the three dimension MAGIC simulation software. The model is built up according to the practical structure and size of 2M219 magnetron of Media Company. The spiral cathode, which is presently used in microwave oven, is simulated. A suggestion of replacing spiral cathode with squirrel structure is proposed, which employ multi-strips cathode structure in ten-cavity microwave oven magnetron to improve output property of magnetron. The simulation results show that this structure can achieve fast start-up toπmode and efficient suppressing mode competition and reducing noise especially in the center work frequency.Three kinds of cathode structures are investigated: (1) spiral cathode; (2) pillar cathode structure; (3) squirrel structure. Due to the specialty of the spiral cathode, the output of spiral cathode used nowadays in microwave oven magnetron has the problems on start-up slowly, mode competition, noise disturb. The structure of cathode needs to be improved to get rid of these drawbacks. Pillar cathode structure is like a solid cylinder. The purpose of studying this structure is to analysis the effect of hollow and solid cathode on output property of magnetron. The simulation results show that the noise is suppressed in pillar cathode structure near the centre working frequency, but a serious mode competition is observed. The results of simulation of the cathode strip number and strip angle show that the squirrel cathode can accelerate start-up speed, efficiently suppress mode competition, stably work atπmode and reduce noise near centre working frequency.