Helium shortages will impact quantum computer research • Hacker News Board

Re: Helium shortages will impact quantum computer research

#21

Post by astrodust » Sat, Apr 20, 2019, 1:03 AM UTC

jeffwass wrote: post #13

astrodust wrote: post #11

Earlier quoted context omitted.

It's the smallest monatomic gas, so it can wriggle through even the tiniest of holes. Normally you'd liquify a gas to store it, but helium doesn't liquify until you crank it down to 4°K, which is really, really cold. Liquid oxygen and nitrogen have significantly higher boiling points. Now if you do liquify it, the real fun is it's a superfluid so it's going to crawl all over the inside of the container, it won't just…

>Now if you do liquify it, the real fun is it's a superfluid so it's going to crawl all over the inside of the container, it won't just stay at the bottom. Not true. LHe’s boiling point (at atmospheric pressure) is 4.2K. The lambda point when it becomes a superfluid is 2.2K. So there’s a decent temperature range when it behaves as a normal liquid.

Good point but it also means that if you can keep it precisely in the 2.2K to 4.2K range then nothing strange happens.

That's a pretty narrow band to operate in.

Re: Helium shortages will impact quantum computer research

#22

Post by faxi » Sat, Apr 20, 2019, 1:56 AM UTC

askvictor wrote: post #12

MRD85 wrote: post #9

Earlier quoted context omitted.

You could surely store it in a closed container though? Buy a bunch of tanks, weld them closed. Even try putting a thin coat of something over the sealed tank so that it's more leak resistant.

That's harder than it sounds; helium (like hydrogen) has a tendency to leak through anything you put it in due to its tiny molecule size.

Can it go through lots of solid metal, copper for instance?

Re: Helium shortages will impact quantum computer research

#23

Post by jeffwass » Sat, Apr 20, 2019, 6:08 AM UTC

astrodust wrote: post #21

jeffwass wrote: post #13

Earlier quoted context omitted.

>Now if you do liquify it, the real fun is it's a superfluid so it's going to crawl all over the inside of the container, it won't just stay at the bottom. Not true. LHe’s boiling point (at atmospheric pressure) is 4.2K. The lambda point when it becomes a superfluid is 2.2K. So there’s a decent temperature range when it behaves as a normal liquid.

Good point but it also means that if you can keep it precisely in the 2.2K to 4.2K range then nothing strange happens. That's a pretty narrow band to operate in.

It’s a wider range than you think. Temperatures work logarithmically.

The lambda point occurs at roughly half the absolute temperature of the boiling point.

For comparison room temp is roughly 300K, and half of that is 150K or minus 120°C.

Would you call the temperature range between minus 120°C and room temp (call it 20°C) a “narrow band”?

Re: Helium shortages will impact quantum computer research

#24

Post by im3w1l » Sat, Apr 20, 2019, 7:44 AM UTC

RandallBrown wrote: post #20

im3w1l wrote: post #17

Earlier quoted context omitted.

So if we can't store it, then we can't waste it either? So how are we having a shortage?

As far as I know, it's not a shortage of helium, it's a shortage of cheap helium. Back when blimps were a thing, the US stored a shitload of helium in a big cave. In around 2007, the US government was like "We don't need all this helium" and started selling off the reserve at super low prices. Helium is often just vented to the atmosphere when mining natural gas, so we could capture it if we wanted, but right now it'…

So the solution to the contradiction is that it is possible to store helium after all.

Re: Helium shortages will impact quantum computer research

#25

Post by askvictor » Sat, Apr 20, 2019, 9:59 AM UTC

faxi wrote: post #22

askvictor wrote: post #12

Earlier quoted context omitted.

That's harder than it sounds; helium (like hydrogen) has a tendency to leak through anything you put it in due to its tiny molecule size.

Can it go through lots of solid metal, copper for instance?

I would presume so, given that hydrogen (which is bigger in molecular form than helium), leaks out of almost any container you put it in (hence why hydrogen cars have never taken off). But I haven't got any personal experience with it.

There's also the problem of sealing the vessel it's in - since you're almost certainly keeping helium as a gas, it's going to leak through the smallest gap.

Re: Helium shortages will impact quantum computer research

#26

Post by orev » Sat, Apr 20, 2019, 6:11 PM UTC

askvictor wrote: post #25

faxi wrote: post #22

Earlier quoted context omitted.

Can it go through lots of solid metal, copper for instance?

I would presume so, given that hydrogen (which is bigger in molecular form than helium), leaks out of almost any container you put it in (hence why hydrogen cars have never taken off). But I haven't got any personal experience with it. There's also the problem of sealing the vessel it's in - since you're almost certainly keeping helium as a gas, it's going to leak through the smallest gap.

Interesting tidbit, but that’s not why hydrogen cars have not taken off. There’s currently no real infrastructure for producing, distributing, or storing hydrogen, and in-vehicle storage poses safety issues. Even if we put in the effort to solve those issues, we’d wind up with a monoculture like we have for gas now. It’s much better to use electricity as an intermediary, as we already have the infrastructure to handle it and you can use any kind of fuel to generate it.

Re: Helium shortages will impact quantum computer research

#27

Post by NikkiA » Sun, Apr 21, 2019, 5:02 PM UTC

im3w1l wrote: post #24

RandallBrown wrote: post #20

Earlier quoted context omitted.

As far as I know, it's not a shortage of helium, it's a shortage of cheap helium. Back when blimps were a thing, the US stored a shitload of helium in a big cave. In around 2007, the US government was like "We don't need all this helium" and started selling off the reserve at super low prices. Helium is often just vented to the atmosphere when mining natural gas, so we could capture it if we wanted, but right now it'…

So the solution to the contradiction is that it is possible to store helium after all.

You can 'store it', but it leaks over time.

If you were to buy 10 billion cubic metres of helium today as a hedge on prices rising in 10 years, you may well return to find that you have significantly less in 10 years time.

The ways it's 'stored' are

a) in large [very] deep caves, which is the sort of investment an individual cannot generally make as you don't own your property to the centre of the earth.

b) in cryogenic thick walled tanks with the understanding that you will lose helium constantly, but are able to replace it with new helium. This requires a 'constant' resupply of helium, plus energy expenditure in the form of keeping it cryogenically chilled. This isn't a 'long term' storage plan, and assumes that helium prices stay low.

c) by extracting it from the ground - this is how we get helium on earth as it is, we find it in pockets alongside natural gas at reasonably great depths. This is essentially tapping into the planet's own version of method 'a'.

Method 'a' is the only real 'long term storage' we can do, and even then it leaks as long as there is some method to remove it again from the storage.