I have a pretty large cavity (microwave heating experiment) that I am doing experiments in. It has to hold a high pressure (200 psi), so initially it was design out of steel. But now I find that the energy is not being absorbed so much in the load as I expected, but it is also being simultaneously absorbed by the cavity walls. I either need to plate the cavity walls with some higher conductivity metal, or make the entire cavity out of something like aluminum (not as strong).

My problem is that the process gives off nasty vapors, like sulfuric acid, etc. If I just plate the cavity inside with copper or silver, I am afraid that the acidic environment will cause it to blister/degrage in short time.

So, does anyone know some plating scheme that would give me a higher cavity Q, but uses metals that are relatively immune to acidic fumes?

I once remember silver plated waveguides, with a thin rhodium flash on the exposed surface, as being relatively tough. Any ideas like that?

Alternatively, has anyone experience of adding a reflecting surface plate inside of a large cavity? Maybe a thick (sacrificial) copper plate that would reflect microwave energy that could be hung inside of the larger steel cavity in strategic positions?

Thanks
Rich  

www.MaguffinMicrowave.com

Maguffin Microwave wireless design consulting