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.





Hot Cathode Electron V2

29 04 2012

All photos.

Today I’m taking some small steps toward building hot cathode electron gun v2.

Here is a physical diagram and schematic:

This is the hot cathode intended for  an electron beam welder. It has 34 mΩ resistance:

The parts of the electron gun will be arranged like this:

This is more simple than most electron guns. I don’t need a carefully focused beam, I just want to shoot a crude beam of electrons into the Polywell.

The next step is to design and build a simple armature to hold the pieces together.





CERN / Large Hadron Collider Visit

29 02 2012

All photos.

Last week I was in Geneva doing a talk at LIFT 2012, which I will post when it goes online. As part of the conference I was invited to tour CERN and the Large Hardron Collider. Despite a hungover 7AM wakeup I managed to make the train to CERN. What an amazing experience!!

A cutaway showing how the beam line section are connected. The beam line tubes contract several centimeters as they are cooled with liquid helium, so bellows and sliding joins are used:

This is the main testing facility for beam line tubes:

This is a cavity resonator used in the Large Electron Positron Collider – the predecessor to the LHC:

Here we see the control room for the Large Hadron Collider. SO COOL.

James Bridle , who spoke at LIFT, wrote a nice post on our CERN visit.








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