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78 comments on Goodbye Helium, Goodbye Brainscans

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gregorach on January 16, 2008 - 9:50am Permalink | Subthread | Comments top

For MRI scanning this means the available substitutes can only offer much higher temperatures at which the scanner can operate, implying less conductivity and therefore a less effective scanner.

Haven't we been making rather good progress on high-temperature superconductivity recently? Or did I just imagine that?

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TJ on January 16, 2008 - 2:47pm Permalink | Subthread | Parent | Comments top

AFAIK, it's not used in MRI machines yet. They do use cryocoolers instead of LHe in some machines.

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IrishD on January 18, 2008 - 12:10am Permalink | Subthread | Parent | Comments top

For anyone who cares:

Some cryocoolers (specifically pulse-tube cryocoolers) use pressurized helium instead of liquid He. I installed a cryocooler in a lab a couple of years ago to cool a SQUID chip (superconducting-quantum-interference-device) used for magnetic imaging.

Because the He is in gaseous form and in a closed system, the loss rate is much lower than in traditional coolers where the devices used are basically "bathed" in the liquid form. We could still get this chip down to 3-4K with a power output of under 300mW which is pretty impressive.

Yay science!

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crobar on January 18, 2008 - 5:49am Permalink | Subthread | Parent | Comments top

American Superconductor's 1st gereration superconductor wire operates at around 77K (depending on the local magnetic field, current demsity etc.) and build magnets from this which operate at 20-40K meaning liquid helium cooling is not required. Improvements will no doubt be made on this. I believe HTS magnets will eventually replace rare-earth magnets (such as sintered NdFeB magnets) in wind and wave energy devices, but this is in the distant future.

Richard C

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mdsolar on January 18, 2008 - 12:38pm Permalink | Subthread | Parent | Comments top

I'm not so sure that you need to wait all that long. There are a number of groups working on this.

Chris

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78 comments on Goodbye Helium, Goodbye Brainscans

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