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Using what Liquid gas to cool TYPE I Superconductors?

  1. Jun 27, 2013 #1

    Liquid Nitrogen or Liquid Helium to cool Type I(Lead/Aluminum) superconductor?
    I know its best to use Liquid Helium, but can I use Liquid Nitrogen and go below the BC of those materials?
  2. jcsd
  3. Jun 28, 2013 #2


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    No, because liquid nitrogen boils at 77K, and even if you pump on it the temperature will only go down a few K before it goes solid (I can't remember the exact temperature, 68K or so at 1 Bar?)

    Hence, liquid nitrogen only works for high-Tc superconductors, and they are all type II.

    Also, for aluminium you can't even use liquid helium (bulk Tc=1.2K), you need something more elaborate; you need to e.g. pump on He-3 (or He-3/He-4 mixtures) or use adibatic demagnetization cooling.
  4. Jun 28, 2013 #3

    Hence, another reason why people prefer Type II superconductors.
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