Do you need the purge the oven or can you purge a sample chamber with the gas? Do you need to rotate the sample or can it be stationary? Use a gasinlet that does not absorb microwave energy and drill a small hole for it.

You can try to take the cover of the microwave off, drill a tiny hole in the side of the microwave chamber, enough to accommodate the tip of a 1 ml plastic pipette, stick it a couple of cm in the chamber, drill a corresponding hole on the outer cover so the pipette will stick out and then you can connect it to the glass supply. Plastic is not affected by mycrovawes and the hole that you have to drill in the wall of the chamber will allow only for a small diffusion of energy, plus the exterior body of the apparatus will shield it.Try this operation on the wall on the side of the magnetron or into the opposite wall, otherwise you can damage it!

Thanks for the reply everyone! :)

Hi Dr Boon, my method requires for the microwave oven to be purged with the gas before and during the heating process. I plan on just putting my sample on a quartz tray. I'm not particular if my sample should be rotating or not during the process. Or should I?

Hello Dr Zangani, thanks for the detailed suggestion. I would just like to clarify. Do I drill the hole on the wall opposite from the magnetron, or on the wall beside it?

Hi Bryan, Because microwave oven have always a thicker side on the side that contain all the necessary circuits plus the magnetron, I would, just to avoid damage (the magnetron part is the part that shows inside the oven were you have a space full of holes) to drill the holes in the back of the oven, were the external casing and the inner casing are separated only by a few cm. It will be much easier and there should be no electrical circuits, only may be some insulation and a few wires. It also will make your life easier in sticking in the pipette (because you will not find any kind of impediments and the space to go trough is much shorter)

Dear Bryan, Any way you should protect yourself and environment against microwave leakage. Therefore the holes in the microwave oven in the internal walls should be small enough to be well below cut off frequency of the equivalent wave-guide. The proper solution is to use a metal grid in the hole aperture with the eyes diameters similar to the eyes visible in the grid inside the front door. Best wishes. Piotr

Dear Bryan, you can create a hole on top of microwave oven and assembled the glass assembly as per your need as shown in photograph attached herewith.

but you have to seal the hole properly prier working with the microwave. 

Dr Maldhure, thank you very much!!! It's exactly what I have been looking for. 

but keep in mind that, microwaves should not be leak from the top, 

for that use Teflon caps/adjusters.

You see one schematic of the modified microwave muffle oven given in this paper.

Maybe it will help you.

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