5 ms·

A 4 K dry cryostat’s refrigeration system usually eats about 4-5 kW. Not sure what’s going on here.

• karma_pharmer 2y ago
  4-5kW to extract how many picowatts of heat from the system? You can't quote a number for the cryocooler without knowing how much heat is being injected into the thing it needs to keep below 4.2K.
• boxed 2y ago
  Well, this isn't just going to keep inert matter cold, this will do massive amounts of computation, so it makes sense that it would need to dump a lot of heat.
  • gaze 2y ago
    Such 4 K cryostats have about a 30 W cooling power.
  • bawolff 2y ago
    One presumes a super conducting computer would generate less heat, given the lower resistence due to superconductivity
    • IsTom 2y ago
      Current fastest supercomputer has a little over 1 exaflop and consumes over 20MW. 20 exaflops at 500kW is a lot less power, but it'd probably still generate a substantial amount of heat.
      • breezeTrowel 2y ago
        Superconductors do not generate heat when in their superconducting state. Otherwise they wouldn't be superconductors.
        • boxed 2y ago
          Yea, but just keeping everything in the static superconducting state wouldn't be a computer either.
        • Filligree 2y ago
          Superconductors do not generate heat for a constant DC current. Computers are very, very AC, and you do get heat production anytime the current changes. It is, IMO, a bit dubious whether or not anything is truly flowing in a superconductor at constant current. Electrons don't have identity, so the 'constant flow of electrons' can be rephrased as 'the physical system isn't changing'... and the degree to which you can tell that there are electrons moving about is also the degree to which the superconductor isn't truly zero-resistance.
          • eig 2y ago
            You can tell electrons are flowing in a superconductor by measuring the magnetic field induced around them.
            • Filligree 2y ago
              You can tell there's a magnetic field, certainly. My argument is essentially one of nomenclature; I don't feel a constant electron-field should count as 'flowing'. Of course it isn't actually constant -- there are multiple electrons, and you can tell that the electron field is quantized. But the degree to which that is visible, is the exact degree to which the superconductor nevertheless doesn't superconduct!
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