Is magnetic flux quantified only near superconductors?

[Duda Jarek]

Quantization of magnetic flux going through superconducting ring is explained that along this loop, quantum phase (order parameter in this case) has to return to the initial phase, so it makes integer number of full rotations - this number determines the total magnetic flux going through this loop (integer multiplicity of 2.067 833 667(52)×10^-15 Wb), like on this picture:

There appears natural question - why we couldn't take this argument into just a loop in vacuum?

In static picture, we should be able to decrease such abstract loop down to having single flux quant going through it and so they seem to be physical lines in space.

These natural consequences of quantum mechanics are called 'vortex lines' by prof. Bialynicki-Birula (well known in Poland).

 

Very similar concepts are popular in considerations of corona plasma of our Sun.

There is generally a problem for standard MHD models to explain that while the surface has thousands of kelvins, for corona it exceeds million kelvins ('coronal heating problem'). The hope could be the observed magnetic flux ropes (some paper with such explanation, or different Physorg news) - charged particles instead of just repelling each other, gathers in nearly one-dimensional objects along magnetic lines, which carries very large energy released mainly while magnetic reconnections.

 

Such lines should have large energy density per length, so in low temperatures we could expect them rather only in microscopic scales. Quantum rotation operator suggests that such lines should go through fermions along their spin axis - it could explain their tendency to couple (electrons in orbitals, Cooper pairs, nucleons in nuclei), but also suggests how optical photons looks like: topology says that to destroy such couple for e.g. deexcitation, we should twist one of them 180 deg - changing its spin by 1: like from 1/2 to -1/2.

Such twist is angular acceleration then deceleration - angular momentum conservation suggests that there should be created kind of EM wave 'carrying this 180deg rotation' ('have spin 1'), it could also help destabilizing other excited couples (stimulated emission) - we get optical photon candidate:

Accepting such 1D structures also allows for other particle-like constructs, for example if on such vortex line there would be additional 'rotation toward the center of line', it would get charge and it would change it into opposite vortex line (became magnetic dipole) - we would get lepton-like construct (pictures).

 

Could (some?) magnetic flux lines be physical objects?

Is something like corona's magnetic flux ropes observed also in plasma experiments - that against Coulomb repulsion, charged particles have tendency to gather on lines along magnetic field?

Would it affect stability of e.g tokamaks?

[Duda Jarek]

There is extremely interesting yesterday's NASA announcement: http://www.nasa.gov/mission_pages/voyager/heliosphere-surprise.html

Voyager has found bubble-like foam of magnetic field lines (flux ropes/vortex lines?) coming from our Sun:

 

"(...)

"The sun's magnetic field extends all the way to the edge of the solar system," explains Opher. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are now, the folds of the skirt bunch up."

 

When a magnetic field gets severely folded like this, interesting things can happen. Lines of magnetic force criss-cross, and "reconnect". (Magnetic reconnection is the same energetic process underlying solar flares.) The crowded folds of the skirt reorganize themselves, sometimes explosively, into foamy magnetic bubbles.

(...)"

 

ps. Here is recent PRL article about laboratory experiments of magnetic flux ropes: http://prl.aps.org/abstract/PRL/v105/i7/e075005