IFW-Dresden Superconducting Maglev Train Models
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it as a concrete visual of superconducting levitation, in threads about flux pinning and how levitation height can be changed.
Recommended by 1 people across 1 different months, 2011 to 2014.
What it is
A short 2007 demonstration video from IFW Dresden showing model maglev trains that levitate and glide above a track using superconductors. There is no narration or formal lecture, just footage of the working models.
What people said
Recommends sblair · 2011-10 · Physics Stack Exchange · on “How does quantum trapping with diamagnets work?”
This paper [LINK] describes the effect in some detail. Stable levitation is caused by a combination of the Meissner effect [LINK] , and of flux pinning [LINK] in Type-II superconductors. The Miessner effect is the property of superconductors which prevents magnetic flux from penetrating the superconducting material (beyond the penetration depth [LINK] ). It occurs because the applied magnetic field induces "shielding" currents in the surface of the superconductor, which generates an opposing magnetic field that acts to exactly cancel the applied field. It is as though you've taken two conventional magnets, with the two north poles pointing each other, and suspended one above the other. This
Cites chriddy · 2013-09 · Physics Stack Exchange · on “Effect of strength of magnetic field on the height of a levitating superconductor?”
As you correctly mention, the levitation effect is due to the pinning of magnetic flux lines in a type II superconductor [LINK] . The magnetic flux $\Phi$ that goes through the SC is a function of the external field. This flux is made up of vortices that each carry a flux quantum $\Phi_0$. These vortices are evenly distributed through the SC. If the magnetic field at the SC increases, more flux lines will need to move into the SC. This motion is hindered by pinning of the flux lines. (1) Now in order to levitate, you will need an inhomogeneous magnetic field: If the SC followed gravity, it would move closer to the coil and therefore to a place of higher magnetic field. That would mean vortex
Cites jtmarmon · 2014-07 · Physics Stack Exchange · on “Remotely changing superconductor levitation height?”
Oh. This video [this video] made it seem like you had to physically move the SC to change the levitation height. I was having trouble decoding this thread [LINK] as I'm not an expert on this stuff.