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Comment by hydrogen7800 | Hacker News Reader

BepiColombo [0] uses 581 kg of Xe gas for its electric propulsion. I remember reading at the time this was being built that it consumed a measurable portion of the global xenon production for that year. This post reminded me to look that up, and it seems to be only ~1% of the ~50 tons, which is quite a bit less than I remember but still quite significant for a single application to use a non-trivial amount of the supply.

[0]https://sci.esa.int/web/bepicolombo/-/60642-bepicolombo-mtm-...

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Given that ~100 million tons of oxygen are produced annually, extracting all the xenon from that air would yield about 170 tons/year. So there's a bit of room for growth.

The BepiColombo number is similar, I think, to the amount of xenon made annually in nuclear reactors (where it occurs in spent fuel as the result of fission.)

I think it might have taken a larger percentage of high-grade ultrapure xenon, a narrower market than the global bulk supply. A 1% impurity is fine if you are using xenon for welding, not so much if you are firing zenon plasma at a grid carrying a few hundred volts. A little bit of o2 in there and your grid would be rust very quickly.

Does anyone use xenon for welding? Argon, yes, but xenon is five orders of magnitude less common in air.

You could. It is heavier and so can carry more heat. There may be some specific metal/tool combo where that might be needed.

Inert gas in welding isn't used to carry heat, it's used as shielding to prevent oxidation, nitridation, and ingress of hydrogen. In any case, the heat capacity of the noble gases are almost identical. What xenon might do is reduce diffusion of heat away from the weld, as its thermal conductivity is just 1/3rd that of argon.

In practice I think a combination of argon and CO2 is typically used for inert gas welding of steel.

It depends on the process. Argon/CO2 is used for MIG welding, while TIG generally uses pure argon. In some situations that justify the expense, helium is used instead as it allows deeper weld penetration.

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