In most microwave heating systems, we use waveguides and certain TE mode. I am designing a MW heating system where use of waveguides reduces heat consumption by the subject material. It's because of the heating technique entirely depends on the field pattern incident on the object. Is a limitation and if we could use the magnetron without waveguide of certain design, we can surely build more efficient MWH system.
I do not follow you? your waveguides get hot? The field pattern will always influence your heating of objects? The trouble of using Magnetrons without waveguides is in fact not having the isolator/circulator in the setup, which means that if your object do not want to absorb the wave in some conditions, you may have power back into the magnetron which it does not like too long.
In microwave ovens for the kitchen, there are mode mixers.. to homogenise the field patterns. What material in to be heated? be careful about runaways.. depending on your application, you may heat more stable suceptors and indirectly heat your substrat.
Thank you Lucas for you answers and interest into this topic. Actually, if I am going to heat a thin material, then the incident field strength and pattern become an issue because somewhere the working field is strong (hot) and somewhere it is weak (cold).
Now, this variation of EM field is primarily caused by how we deliver EM wave into the metal cage (via waveguide) and size of the cage which generates specific standing wave pattern. Somehow, can we get rid of conditions for specific mode generation inside the heating chamber and efficiently distribute EM energy for more efficient heating? or, more importantly, can we determine a efficient wave and energy distribution of EM field and try to generate it using devices (lens or something to guide the EM wave) and techniques?
I was doing some MWH modelling and I came across this question. I don't even know whether it's possible or not. I need some references of similar/helpful studies so that I can move forward. If you/anyone can suggest some good reading material, please post here or send me email at [email protected]. Thanks a lot...
http://www.gobookee.org/metaxas-industrial-microwave-heating/
some references.. general books..
it will depend a lot on how your material behaves in the microwave..
I have a plasma, there it is easy, since the plasma just locally saturates so that the energy can be automatically distributed (surface wave kind of plasma).
All other material I know of, will heat, their tan(delta) (the imaginary part of the dielectric) normally raises, they absorb more, heat faster and locally burn.. they do not self limit theirselves.. which makes it very difficult to heat homogenously.
so some inline method is appropriate, several pathes under the microwave until it is done.. all the cavities will have their standing wave pattern..
i do not know exactly how much budget you have..
thin materials are anyway very difficult..
Puschner in Germany can help you.. Muegge GmbH also..
if it is for fun, I would like to know if a thin plasma can do the susceptor job.
I know of some roll2roll heater for plastic foils.. (developed by Horst Muegge, now retired, for .. i forgot) two antennas in two cavities such as the one cavity has shifted standing waves of lambda/4, narrow exit slits and the foil passes very close to the slits.. one can have 2/4/6 of those applicator..
good luck.
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