Theoretical Advance in Magnetism

7 01 2013

PDF of  research paper.

phys.org reports on a theoretical advance in magnetism:

A general property of magnetic fields is that they decay with the distance from their magnetic source. But in a new study, physicists have shown that surrounding a magnetic source with a magnetic shell can enhance the magnetic field as it moves away from the source, allowing magnetic energy to be transferred to a distant location through empty space.

The basis of the technique lies in transformation optics, a field that deals with the control of electromagnetic waves and involves metamaterials and invisibility cloaks. While researchers have usually focused on using transformation optics ideas to control light, here the researchers applied the same ideas to control magnetic fields by designing a magnetic shell with specific electromagnetic properties.

Although no material exists that can perfectly meet the requirements for the magnetic shell’s properties, the physicists showed that they could closely approximate these properties by using wedges of alternating superconducting and ferromagnetic materials.

The Polywell depends greatly on advances in magnet technology. This approach may be applicable, I don’t know.

A practical realization of a magnetic metamaterial still requires all the inconvenience of superconductors which tempers my enthusiasm. Still, this idea glimmers with potential.

Also, I bet I could build and test one. In fact I have almost all the materials on hand. Submit your ideas for an experiment in the comments.

magnetic_metamaterial

FIG. 4: Enhanced magnetic coupling of two dipoles through free space. In (a), magnetic energy density of two identical cylindrical dipoles separated a given gap. When separating and enclosing them with two of our shells with R2=R1 = 4 [(b)], the magnetic energy density in the middle free space is similar to that in (a). When the inner radii of the shells are reduced to R2=R1 = 10 [(c)], the magnetic energy is concentrated in the free space between the enclosed dipoles, enhancing the magnetic coupling.

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9 responses

7 01 2013
Harvey

Interesting, but isn’t it a diversion of energy away from the Polywell project ?

9 01 2013
Mark Suppes

Sometimes working on the Polywell as a whole feels overwhelming. So I indulge small projects that I enjoy or find interesting. That is how this project got started after all.

There is a chance this idea could be enormously useful to the Polywell. The Polywell depends on powerful magnets for magnetic insulation and electron confinement. So a technology that can transport magnetic fields from their source is super interesting.

Also I don’t think anyone has built a magnetic metamaterial yet (correct me if I’m wrong). So that would be a world’s first.

15 02 2013
Ben

Do what makes you happiest. Worth persueing in my opinion, I can see the application being potentially game changing for electron losses but that’s not based on math just intuition.

22 03 2013
Joe

Any new updates, Mark? I was curious if you and your intern received the new ceramic design yet and if any new testing is planned.

28 03 2013
Jerem

your last article was very teasing, how about meta-materials ?

15 05 2013
Cherd Bud

we have some of the strongest magnets other than mother earth herself here in the sunshine state. Your polywell parallel will come to light w/time.
Your just going to have to fractalize your Ideas. It’s very hard to stay positive when the negativity rules most. You’ll get there. Intuition is what created advanced math.

16 05 2013
Cherd Bud

as I keep looking at those magnets, I can’t help but to notice they are wound with regular copper wire in a regular type coil fashion? And if that is the case, your magnets need redesigned.

28 05 2013
Raelik

It seems to me like this could be leveraged to reduce the necessary magnet drive current for the coils in a Polywell. Since a full-scale Polywell is already going to require superconducting coils, all of the same plumbing for the coolant should be usable for this ‘magnetic shell’. Plus, reducing the necessary drive current may also enable the use of some of the newer high temperature superconductors (which have limited critical current density in pretty much every case), reducing the complexity of the cooling system (i.e. just LN instead of LN/LHe). This could be vastly increase the economic viability of the Polywell, which is already looking to be one of the most cost effective fusion solutions.

14 06 2013
Hazen

Even superconductors have their limits; the issue with superconductors is “magnetic permeability” superconductors do not “take strong magnetic fields well”. Yes superconducting magnets are the strongest on the planet but there’s a bunch of caveats to that. Basically; a superconducting magnet does not behave like a normal electromagnet; you are limited to Type-II and Type-III superconducting materials (Yittrium-Barium-Oxide based ceramics); and these still require liquid nitrogen cryostat to maintain the “High temperature range” at some crazy low tempurature. Getting this next to a “Hot Plasma” means reducing it’s ability to function as any increase in temperature within the magnet reduces the permeability of said magnet; the limit being the temperature at which the ceramic compound becomes non-superconducting. That and a cryostat would mean a re-design of the coils and the chamber.

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