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Comment by pavel_lishin | Hacker News Reader

> “The technical difficulty in manufacturing such a magnet is staggering,” says Brookhaven Lab physicist David Morrison, co-spokesperson for PHENIX, one of RHIC’s two main experiments. “The technology may be similar to an MRI—also a superconducting solenoid with a hollow center—but many times larger and completely customized. These magnets look very simple from the outside, but the internal structure contains very sophisticated engineering. You can’t just order one of these beasts from a catalogue. ”

Can someone go into more detail about this? What makes it so sophisticated? At the end, it's just a pipe made out of ferrous metals, right? So is it just a very evenly distributed alloy, or what?

Edit: Also, how do you transport something like that along the highway without arriving with three smart cars and a geo metro stuck to the trailer?

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Also, how do you transport something like that along the highway without arriving with three smart cars and a geo metro stuck to the trailer?

It's not charged up, of course.

Moving heavy things that will fit on a standard truck is not difficult. Moving things larger than that is. Some magnet about 20 feet across was moved last year, and they had to close off a roads at night to get the thing to a barge port.

> Some magnet about 20 feet across was moved last year, and they had to close off a roads at night to get the thing to a barge port.

For fun stuff of that sort, there was moving OXCART (the future A12/SR-71) from the Lockheed SkunkWorks assembly plant to Area 51 (a ~750 miles journey with the package being wider than many road at the time) for testing: http://www.roadrunnersinternationale.com/transporting_the_a-...

And the A380 parts moving through a small french village to reach the assembly plant: http://www.cnet.com/news/the-giant-airbus-a380-and-the-tiny-... Because it's a pan-european project the A380 route is pretty extensive and varied, on the final part of the water journey they actually have to play with the tides as some barge sections need high tide to go through, but bridges require low tide to get under.

Hm, I assumed it was a permanent magnet, not an electromagnet. I'm not sure why.

The fine tolerance coil made of kilometers of superconducting wire. All the care and material considerations needed for tight tolerance device that has to survive being cooled to a few degrees kelvin. On top of that the safety considerations of storing energy in the gigajoule realm.

The stronger a magnet the stronger the internal forces that it needs to withstand. Tap a ceramic magnet with a hammer at the wrong angle and the whole thing explodes (I found this out the hard way when trying to recycle a bunch of strong magnets that were attached with two sided tape to a chunk of metal, yay safetyglasses).

Any kind of deformation that stresses the structure in a way unforeseen during engineering and the whole thing will collapse, then explode outward as the pieces hit each other and rebound. Not pretty. So the stronger the magnet that harder it becomes to keep the thing from selfdestruction when you activate it, or in the case of a superconducting magnet, quench it.

https://www.youtube.com/watch?v=1R7KsfosV-o

Coil positioning and geometry is critical for field homogeneity. And the coil materials must be very consistent.

Add to that you have to withstand heating/cooling cycles down to a few Kelvin -- the whole thing needs to withstand a lot of stress so it's heavy.

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