Recovering vacuum process gases?

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
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RobertMendelsohn
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Recovering vacuum process gases?

Post by RobertMendelsohn »

Hello! I am wondering if anyone has successfully re-bottled gases they've used in a vacuum system.
I'd appreciate any ideas or experience people have had doing this. This is probably not economic for most applications.
My understanding is you'd use some leak-free diaphragm pump connected to the exhaust of the roughing pump, but I'm not familiar with what you'd call it - a compressor? pump?
The pressures involved are substantial so I'm trying to gain more info before trying it. I'd like to try re-bottling argon and xenon; deuterium would probably necessitate ATEX pumps.
I'd love to hear more about anyone's experience doing this / advice thereof.

-Robert
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Richard Hull
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Re: Recovering vacuum process gases?

Post by Richard Hull »

you are figuring on flowing gases, I assume. Differential pumping as we do it. Why continuously flow and exhaust Argon? Xenon? These ae typically introduced into an evacuated vessel or tube and sealed off at some desired pressure. I view the attempt to reclaim pumped gas as not worth the effort. It has to make economic sense in the first place. Are the gases toxic, corrosive, etc. such gass are often chemically captured and turned into stable compounds.

Exhausted deuterium, with difficulty, might be recovered by conversion to D2O or HDO, but it would take a lot of exhaust to make one drop of chemically reclaimed heavy water to be electrolyzed into the two gases again. Just not really feasible at the amateur level.

Richard Hull
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RobertMendelsohn
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Re: Recovering vacuum process gases?

Post by RobertMendelsohn »

Thank you Richard. Even if it's not economical, how might one do it? What sort of compressors etc. would be necessary to re-bottle gases from a vacuum system? Where could I learn more about this?

It's curious to see that every major vacuum retailer I've used (KJLC, LDS, Ideal, Duniway, Edwards, Pfeiffer etc.) do not offer parts or systems to do this.
It's also curious to think about the compression ratio from the UHV side to the high pressure side...

Sincerely,

Robert
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Rich Feldman
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Re: Recovering vacuum process gases?

Post by Rich Feldman »

Has anyone heard of a commercial or academic vacuum chamber application
that recovers pumped-out process gases for storage and re-use?

Not me, but I am but an amateur scientist.
I expect there are cases where process gases are very toxic, and need to be purged from vacuum pump exhaust stream.
All models are wrong; some models are useful. -- George Box
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Maciek Szymanski
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Re: Recovering vacuum process gases?

Post by Maciek Szymanski »

Tokamaks intended for D-T operation (like JET) have very complex tritium recovery system. First - tritium is very expensive, second - radiation protection issues. Radioactive gases can be dangerous. If you are really interested I can get some information how it is done on JET or how it is planned on ITER.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
RobertMendelsohn
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Re: Recovering vacuum process gases?

Post by RobertMendelsohn »

Thank you all. I think the tritium is handled in a very particular way and not in enough quantity to be bottled in a standard fashion.

I messaged with a rep from Leybold, who said that "leak tight diaphragm compressors" were typically used up to 80 bar, though many gas cylinders are in the ~150 bar range.
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