YBCO & Maglev Trains: Superconductor Properties & Levitation

[randommarble]

I'm interested in the superconductors they use to levitate trains. One of the most talked about high-temp-superconductors seems to be Ytriuum Barium Copper Oxide. I know this has a critical temperature of around 90-93K. Does anyone know any of its mechanical properties, such as Young's Modulus?
Also, I understand that certain magnetic fields can destroy the superconducting properties of a cuprate. What is the critical value (in teslas) of this for YBCO?

You need around 16 teslas to levitate a frog. Does anyone know how many to levitate a train?

I don't think this is the actual superconductor they use in the maglev train tracks. Does anyone know what they use for the tracks and for the undercarriage of the train?

Thanks for any help.

randommarble

 

[f95toli]

The mechanical properties will depend on how the superconductor is used. YBCO is rarely used in "bulk", since it is a ceramic you can't really bend it much. However, a thin film of YBCO cam be depostited on a carrier (such as nickel) and that carrier can then be attached to some flexible material. This is how YBCO cables are made and they are quite flexible.

I am not sure the critical field of YBCO is known (and calculations are not really reliable in this case). However, It is VERY high (probably >40 T) and it don't think we can generate fields that are high enough to acutally test it. I know there have been some high-field work done using field pulses generated with explosives (somewhat akin to EMP pulses are generated) but as far as I remember not even then did they manage to quench YBCO. For obvious reasons this is quite specialized work (it was done at a US Army research centre).

There are various ways to make a Maglev train using superconductors so I don't think there is a general answer to your question. Much of the research is done in China and I know they have even made some rather large prototypes (I've seen some talks and posters and conferences, this is not really my field).
You can probably find quite a few papers if you have access to IEEE transactions on Applied Superconductivity and/or Superconducting Science&Technology

 

[randommarble]

Thanks

Thanks for your help. It is really useful!

 

[Gokul43201]

I don't think this is the actual superconductor they use in the maglev train tracks. Does anyone know what they use for the tracks and for the undercarriage of the train?

Existing commercial maglev technology is based entirely on normal materials (due to obvious temperature concerns, among other things) - no superconductors anywhere.

 

[randommarble]

Existing commercial maglev technology is based entirely on normal materials (due to obvious temperature concerns, among other things) - no superconductors anywhere.

I thought the German trains used ferromagnets, but the Japanese trains use superconducting materials to create electromagnets. Please can you let me know if I'm mistaken.

 

[f95toli]

There is a japanese Maglev train that uses conventional superconductors (presumably niobium or niobium-titanium). Unfortunately, I don't remember where.
AFAIK it hasn't been a success; cooling conventional superconductors is simply too expensive. High-Tc on the other can be cooled using a cheap cryo-cooler in a closed cycle system so the cooling in itself is actually not a big issue anymore. Hence, a YBCO Maglev train might actually be viable.
It seems most problems- mainly the high cost but also the fact that the technology is not compatible with existing infrastructire- are related to the Maglev concept itself (i.e. a levitating train), whether conventional magnets of superconductors are used shouldn't really make that much of a difference.

 

[Gokul43201]

If this is true...wow! I wasn't aware of any trains anywhere that had gotten beyond the development stage.

Edit: Google spat this out just now, when I searched for superconducting maglev: http://jr-central.co.jp/eng.nsf/english/maglev

Pretty neat!

 

[randommarble]

Thanks! That website is useful. Now I know what they use, I can explore that a little more.

 

[Nuage]

Thanks! That website is useful. Now I know what they use, I can explore that a little more.

Hi, I am also researching information on HTC. Since the link doesn't work anymore, could you share what material they use? (Is it superconductive?). Would you like to share what you discovered on superconductors?

Thanks

 

[Vanadium 50]

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