Comment Re:Dispensing our reserves? (Score 1) 255
[...] Meanwhile, engineers will continue to look at alternate cooling solutions, such as liquid hydrogen. [...]
This doesn't work. There's no viable substitute for helium, not even hydrogen. The reason helium is so useful is that it boils at 4 K (by far the coldest boiling point of any substance), remains liquid all the way down to absolute zero at standard pressure, and becomes superfluid at 2 K (the only bulk superfluid achievable on Earth).
The boiling point is important because that's how cryogenic cooling works: when you use a circulating liquid coolant, the temperature of the (coolant plus apparatus) system cannot exceed the boiling point of the coolant until the coolant has entirely boiled away, so you get a very consistent and predictable temperature (right up until the coolant is gone). 4 K is below the critical temperature of the most common materials for superconducting electromagnets: niobium-titanium (10 K, relatively cheap) and niobium-tin (18 K, highest known T_c for a traditional superconductor). Hydrogen is not a substitute, because it boils at 20 K; that's noticeably too warm for any traditional superconductor, and even if it weren't, superconductors can handle stronger magnetic fields the colder you chill them, so they'd be less useful in an MRI machine. And you can't chill hydrogen much colder than its boiling point before you hit its melting point, 14 K, at which point it stops circulating and becomes much less useful as a coolant.
The superfluidity is not quite as useful day to day, but it's used to study the behavior of other quantum mechanical systems, such as neutron star interiors, that we can't recreate in a lab. It also forms a rigorous analogy with superconductivity, especially in the case of fermionic He-3, so it gives us a chance to play with a bulk fluid that propagates fluid currents in the same way that superconductors propagate electrical currents. Nothing else can replace it for this purpose.
(Side note: helium is not a truly expendable resource. Of the helium present on Earth, not a single gram is left over from the formation of the solar system; Earth doesn't have the mass to retain helium in its atmosphere. All our helium comes from the alpha particle decay of heavier radioactive elements, like radon. When the alpha particles relax and become neutral helium gas, the gas is trapped by the same gas-impermeable rock formations that trap natural gas. However, the natural recharge rate from radioactive decay is much slower than the rate that we're extracting it and venting it, so if we don't curtail our waste we're going to run out regardless.)