Physicists Build World’s First “Magnetic Hose” For Transmitting Magnetic Fields | Hacker News Reader

Physicists Build World’s First “Magnetic Hose” For Transmitting Magnetic Fields

technologyreview.com

44 pointsbane18 comments

->these devices could become an important enabling technology for quantum information processing in future

I think they will also be critical for empowering diversity, team cohesion, and synergy; culminating in a forward transition of outside the box, paradigm shifting technology in the cloud.

You're holding your team together with magnets? Please, sir, tell me more about this amazing technology.

You're reading too much into this, he is literally holding them together with magnets.

>Their conclusion is that a “magnetic hose” consisting of concentric tubes of superconducting and ferromagnetic materials ought to do the trick. They say that a tube consisting of 20 concentric rings that is about ten times longer than it is wide, should transmit about 90 per cent of a magnetic field at one end to the other. Indeed, a tube of just 2 concentric rings should transmit about 75 per cent.

"About 75 percent" is a stretch, at least if the article author and I are looking at the same paper. According to the actual paper, in figure 2e, it looks closer to 68 or 69 percent. Not a huge nit pick though.

>These guys have tested this idea with a single superconducting tube 7 cm long (made of BiPbSrCaCuO) and filled with a ferromagnetic alloy (of cobalt and iron).

How much does a superconducting tube of BiPbSrCaCuO that is 10 times as long as it is wide cost to manufacture? How much does it cost to keep it cool enough to superconduct? It's billed as a high Tc (108 K) superconductor from the manufacturer (Can), but there is no price list to be found. Figure 4a in the paper seems to indicate that this effect is indeed only observed with a superconducting tube with a ferromagnet core.

Regardless, it's still a cool effect to see in action! If there's an actual physicist in the room, I'd love to hear more about Chapter four in the paper. It seems that the discretization to more than just a single Superconductor-Feromagnet pair --figure 2e in the paper is the main graph showing the efficiency gains as the number of pairs goes up-- was done using FET, after a brief justification argument that goes over my head, and was not actually produced and measured in lab. I think it'd be a logical extension (if not an expensive one) to produce some of these higher-paired tubes and take more measurements for another paper.

Isn't transmitting magnetic fields over a long distance trivial by converting it to an electric current, sending it down a wire, and then back to a magnetic field?

Unfortunately electric current can only be generated using change in magnetic field. So this won't work with a static magnetic field, as is the case in the article.

Static is relative. Spin a wire loop around a static magnetic field and you get a current, right?

Only if the loop moves, which actually experiences changes in magnetic field

The article says: "They placed a coil at one of the tube that generated a magnetic field of 1.3 mTelsa"

So didn't they generate the magnetic field by running a current through that coil, in which case we're talking about a changing magnetic field?

"So didn't they generate the magnetic field by running a current through that coil"

Yes.

"in which case we're talking about a changing magnetic field?"

No. Why?

Was under the impression that if a changing magnetic field induces a current in a wire then running current through a wire will produce a changing magnetic field around it, but apparently is not the case, it produces a static magnetic field.

Certainly this works, for example this is how any electromagnet works. Skimming the article, it seems they're actually transporting the magnetic field itself, though. For example, you hold a magnet at one end of the pipe, and its field is felt at the other (potentially distant) end.

I guess this is roughly analogous to how a wire hooked up to a high-voltage source will produce an electric field on the other end (relative to common ground). The notion is fundamentally different, however, since there are no magnetic monopoles, and so there's no related notion of "magnetic voltage" or "magnetic ground".

The first use of the term "pals" was OK, but the repeated use of phrases like "these guys", and "and pals" in the anonymous article, in an attempt, I guess, to project a casual tone, got pretty grating pretty fast. Oh, interesting research.

I wonder how much of a break through this is? It seems like anything with controlling and extending magnetic fields could be useful in advancing fusion research, ram scoops? MRI's, wireless power?

I imagine this might be (more) useful on a silicon-wafer scale. Generate/move magnetic fields using a chip - a new way to get highly intense/focussed disk read/write heads?

'Quantum information devices...'.

I just love that we live in a time when that statement is in a science article and not limited to a cool scifi story.

Could this mean that a "magentic hose" built really tall, be used to launch objects into space?

Could we be close to making sonic screwdrivers?

For those who don't get the reference: http://tardis.wikia.com/wiki/Sonic_screwdriver

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