Comment by jeffwass
7 years ago
It gets worse than that when your cryo equipment has a “cold” helium leak. Ie, something leaking on the dilution fridge only at helium temperatures (4.2K) and lower, but no trace of a leak at room temp.
Repeated bouts of guessing where the leak might be and trying to plug it (usually by welding or re-machining some part), cooling down, checking if it worked, warming up, ripping some more of your hair out, repeat.
Yeah I had that as well, in that case it was best to replace all the Indium seals right away as like you said it takes 24 hours to do a full cooldown/warmup cycle anyway, so spending a day to make new seals is often faster. That's a part of low-temperature physics I definitely don't miss!
I worked on a system where I needed to reach and maintain pressures of 10^-3 tort, and that was hard enough. I can’t imagine having to deal with helium sensitivity.
10^-3 tort is very low. That will cause lawyers to explode.
Just having fun with your typo...
It's why companies that do stuff with ultra-low-temperature pressure vessels typically dramatically overengineer the devices.