Why does the Maglev train require Superconductivity? (1 Viewer)

[ThreeOne]

Why does the Maglev train require Superconductivity to operate?

 

[Forbidden.]

Because the Maglev is an application of the Superconductor.
You could use magnetic levitation using normal magnets, but the absence of resistance is a desired feature.
That's probably what makes it different, because the power requirements are already enormous.

 

[xiao1985]

That I believe has a point missing.

A crucial point about superconductivity is the meissener effect, where super conducting material generates a magnetic field to oppose any incoming magnetic fields.

This repulsion is what causes the train to levitate.

 

[helper]

The meissner effect does not cause the levitation for the Maglev train. The point is as has been recalled above that large magnetic fields are required. To maintain these they are using superconductors,

 

[Forbidden.]

Don't superconductors also lose superconductivity above the critical magnetic field point ?

 

[zingerburger]

There's a "critical magnetic field point"? I only ever thought there was one critical point - temperature. Once it goes above the critical point of temperature, that's when it starts losing superconductivity?

I don't know. I don't believe there is a critical magnetic field point. But like 'helper' said, superconductors are required to make powerful magnetic fields.

 

[helper]

There is a point where magnetic fields can break down superconductivity.

Link to the japan Maglev site that explains how the superconductors are used as electromagnets. These electromagnets are then used to induce currents in non-superconductors and cause levitation and propolsion.

http://www.rtri.or.jp/rd/maglev/html/english/maglev_frame_E.html

 

[Senrui]

There are three critical parts actually, Critical Temperature, Critical Current and Critical Magnetic field.

The Meissner effect works due the lack of resistance in a superconductor. If you go back to Motors and Generators, you should remember that the magnetic field produced can never fully oppose the motion that created it due to resistance in the conductor. The resistance in the conductor means that the magnitude of the magnetic field will NOT be equal to that of the one that produced it. Because there is no resistance in a superconductor, the magnetic field produced by it due to current flow will always be EXACTLY equal to that of the field that produced it. It’s not actually levitating so much as hovering. As soon as the magnet starts to move towards the superconductor, it induces a current that exactly opposes the motion of the magnet, then the magnet stops dropping, the induced current disappears, then it tries to drop again etc…

Hope that helps.