I am having trouble discovering why temperature fluctuations and magnetic field fluctuations are not a stability concern for superconducting magnetic levitation trains. I am under the impression that liquid helium is expensive and leaks out of containment fairly easily, suggesting higher probability of quenching. The weather naturally induces temperature fluctuations, suggesting possible temperature quenching. The magnetic field fluctuations in the motion of the train could max out the critical field limit, inducing a quench. Why are none of these quenching situations regarded as statistical concerns in maglev trains?

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    $\begingroup$ Without being an actual expert on Maglev trains, I assume the engineers designed the system to operate at a temperature far enough from the quench point that no weather variation could possibly cause a quench (taking into account the insulation). I would also assume their liquid helium containers have sensors of some kind to alert operators if the level drops below acceptable limits. In short, these are all engineering concerns, and I don't see why any of them shouldn't be solvable. $\endgroup$ – Brionius May 6 '15 at 20:55
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    $\begingroup$ I'd add that in my experience, LHe doesn't leak out of containment easily. Above the superfluid transition it behave rather like a normal liquid and there's no problem in keeping it where it should be. $\endgroup$ – LLlAMnYP May 6 '15 at 22:12
  • $\begingroup$ Does anyone know what material is used for the magnets? That would shed light on the practical concerns. $\endgroup$ – DanielSank May 9 '15 at 4:58
  • $\begingroup$ The question asks specifically for superconducting maglev trains, but it might still be worth noting that all currently commercially operational maglevs are not using superconduction but conventional electromagnetism. There are operating superconducting test tracks however. $\endgroup$ – Emil May 11 '15 at 8:52

I know that Wikipedia is not the best source for reference, but according to this page the superconducting parts that are cooled by liquid nitrogen in most cases. Most of the superconductors are High TC ones, which still needs to be cooled.

Here are some links related to this topic:

Toy train Video

Paper on HTS (High Temperature Superconducting) Maglev train

I still can't put this in a comment, so if the admins could move this into a comment that's fine.


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