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Science Forum

  1. Standard member DeepThought
    Losing the Thread
    28 Jul '13 20:49
    http://www.youtube.com/watch?v=VyOtIsnG71U

    Fun to watch, they show a superconductor locked to a magnetic track to a classical theme tune. Trains for tomorrow?
  2. Standard member DeepThought
    Losing the Thread
    30 Jul '13 00:52
    By posting here I ensure I've posted in 7 threads which is more lucky than other numbers of posts I could make.
  3. Standard member sonhouse
    Fast and Curious
    30 Jul '13 14:33 / 2 edits
    Originally posted by DeepThought
    By posting here I ensure I've posted in 7 threads which is more lucky than other numbers of posts I could make.
    It will be fantastic if and when they finally figure out room temperature + superconductors. THAT will rewrite the entire transportation book. Till then, we have to use industrial refrigeration to keep even the high temp ones somewhat below the temperature of liquid nitrogen which is pretty cheap compared to having to use liquid helium at 3 or 4 degrees Kelvin.

    Did you know there is now a US navy ship powered by superconducting motors? They are a LOT smaller, a lot more quiet and consumes about 30% less energy for the same traditional ships at the same speed.

    They still have to depend on a constant supply of liquid nitrogen though.

    http://www.powermag.com/issues/departments/global_monitor/Superconductor-Motor-for-Navy-Passes-Full-Power-Test_1759.html

    This puppy is rated at nearly 50,000 horsepower! 39 megawatts!
  4. Standard member DeepThought
    Losing the Thread
    30 Jul '13 17:06
    Originally posted by sonhouse
    It will be fantastic if and when they finally figure out room temperature + superconductors. THAT will rewrite the entire transportation book. Till then, we have to use industrial refrigeration to keep even the high temp ones somewhat below the temperature of liquid nitrogen which is pretty cheap compared to having to use liquid helium at 3 or 4 degrees Kel ...[text shortened]... sses-Full-Power-Test_1759.html

    This puppy is rated at nearly 50,000 horsepower! 39 megawatts!
    Is there an upper bound on the transition temperature at normal pressure? At room temperature and pressures of the order of 5,000,000 atmospheres hydrogen is believed to be superconducting.

    The boiling point of nitrogen, 77 kelvin corresponds to around 0.0064 eV, room temperature is 0.025 eV. The record highest transition temperature is 132K (so ~0.01eV). So for all known superconductors the band gap is <~ 0.01 eV, for a room temperature superconductor one would need a gap about 2.5 times bigger. I've no intuition as to how feasible this is. According to the Wikipedia page a few groups have reported on this, but no one's managed to make anything reproducible.

    The engine is interesting, but what happens if they get a magnet quench? Are they going to get the kind of mess they got at LHC - which wouldn't be good on a warship.
  5. Standard member sonhouse
    Fast and Curious
    30 Jul '13 17:54
    Originally posted by DeepThought
    Is there an upper bound on the transition temperature at normal pressure? At room temperature and pressures of the order of 5,000,000 atmospheres hydrogen is believed to be superconducting.

    The boiling point of nitrogen, 77 kelvin corresponds to around 0.0064 eV, room temperature is 0.025 eV. The record highest transition temperature is 132K (so ~0. ...[text shortened]... Are they going to get the kind of mess they got at LHC - which wouldn't be good on a warship.
    I think they incorporate copper windings in parallel with the superconductors so the copper takes the brunt of that kind of failure. They did not do that at the LHC. That is the technique talked about for superconducting energy storage rings to prevent explosions.