Thermal Simulation Of Heater And Cathode In Microwave Tube

Cathode is the core of microwave vacuum electronic device. Every breakthroughon the theory and technology of cathode promotes the progress of the vacuumelectronic device. At presen't, to the cathode, on the one hand, it's necessary toinvestigate deeply in the mechanism of emission continuously, on the other hand, toobtain an excellent-performance cathode or heater-cathode assembly which is highefficiency, high current density, high reliability and long life.People have done lots of research on the cathode as an electronic emission sourcefor a long time. Nevertheless, the discussion is not enough on the effect of heat Sourceof vacuum electronic device. Our Computing results of ANSYS model indicate that thecathode surface temperature of heater-cathode assembly is uniform, and theternperature of support structure is in direct proportion to input power.At first, heater heats up cathode by radiation. Later, people fill up the interspacesbetween heater and cathode with alumina powder and then sinter it to makeheater-cathode assembly, consequently heater heats up cathode of assembly byconduction. We find the following results by computing:Temperature difference between heater and cathode of heater-cathode assembly isvery little. The advantage of non-assembly cathode is that it starts very fast. However,we can increase the undersurface emissivity of cathode to raise cathode temperature, and increase the emissivity of heater to decrease heater temperature. Therefore, thethermal performance of non-assembly will be close to assembly.How to determine the length-diameter ratio of supporting structure is a newproblem in the process of designing and manufacturing heater. From the computingresult, we find that if we keep heater temperature invariable, cathode temperature isinvariable too. At the same time, if length-diameter ratio exceeds 1.5, supportingstructure temperature increases very smoothly.