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The Race to Seal Helium HDDs (2021)

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Re: The Race to Seal Helium HDDs (2021)

#61
I wanna be this guy when I grow up.

Seriously, how realistic is it to get a job like this guy's? Open ended, no rules, just solving problems... Most days I'm fine with a boring specialized engineering career, but this one got to me...

Re: The Race to Seal Helium HDDs (2021)

#64
post #58

What would happen if you had a rigid structure that helium could permeate, but nothing larger could, and then filled it up with helium and waited? Would most of the helium exit, until it was balanced with just the partial pressure of helium in the atmosphere? That would be nearly a vacuum, wouldn't it?

This is a good question.

I don't know the answer, but this does make me think of atomic sieves like the ones used in oxygen concentrators.

This is an armchair scientist explanation of them, but they "concentrate" oxygen by first having atmospheric air pumped in and then pressurized. The microsieves have holes so small that mostly only oxygen can fit through, the larger CO2 and Nitrogen atoms simply won't fit.

Then, pressure is let off and fresh air brought in. The fresh air scrubs out the oxygen depleted air and refreshes it with standard air.

Then, the pressure decrease allows the oxygen to leak back out of the sieves, leaving you with oxygen enriched air.

I don't know if there are any atomic helium sieves, but if you can find one it might be a start to testing the question.

Re: The Race to Seal Helium HDDs (2021)

#65
post #58

What would happen if you had a rigid structure that helium could permeate, but nothing larger could, and then filled it up with helium and waited? Would most of the helium exit, until it was balanced with just the partial pressure of helium in the atmosphere? That would be nearly a vacuum, wouldn't it?

It would be a vacuum I guess, but generally not in the normal sense because this is the case with most metals. You don't really consider the interstitial space between the atoms in the crystal lattice a vacuum even though there is space for small atoms (He/H) to diffuse through.

Re: The Race to Seal Helium HDDs (2021)

#66
post #58

What would happen if you had a rigid structure that helium could permeate, but nothing larger could, and then filled it up with helium and waited? Would most of the helium exit, until it was balanced with just the partial pressure of helium in the atmosphere? That would be nearly a vacuum, wouldn't it?

Pretty sure it would simply equalize to the external pressure.

Consider it another way. If you have such a device with a vacuum inside, would it not pull in the external helium over time to reduce the vacuum?

Re: The Race to Seal Helium HDDs (2021)

#67

The solution: - They moved all the casing openings to the top of the drive and used a thin metal foil as a second cover. - They adapted laser welding techniques from the satellite industry to seal the foil to the casing without damaging components with excess heat. - They found an aluminum alloy used in aerospace that could withstand the laser welding without cracking. - To get electricity and data in and out without…

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Re: The Race to Seal Helium HDDs (2021)

#68

"Helium is notoriously difficult to contain. Its atoms are some of the tiniest in the universe." It's a good article, and I learned a lot, but every so often it reads like something an 8th grader would write the night before their paper is due.

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Re: The Race to Seal Helium HDDs (2021)

#70

Earlier quoted context omitted.

It won't explode until it's mixed with oxygen.

Hold my beer.

The small amount contained in the HDD would a minimal risk.

Larger amounts handled in the manufacturing process, OTOH...

I'm curious how the shaft seals for generators manage to seal the hydrogen. Perhaps the hydrogen is contained within the the generator and not exposed to the seals, though I thought one of the reasons for its use (along with cooling) was reduced windage losses.

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