Single-orifice pulse tubes allow for another kind of this technique that may alternatively use the Gifford-McMahon or Hampson-Linde regenerative cycles.
In a three-stage method for this technique developed by Lounasmaa, the second stage contains a hexagonally symmetric alloy of praseodymium and nickel that has a very small Korringa constant and exhibits hyperfine enhanced van Vleck paramagnetism. The Kapitza boundary resistance limits the effectiveness of one kind of this technique that features a "superleak" membrane and exploits the 6.6 percent minimum solubility of (*) helium-3 in helium-4. Single-orifice pulse tubes allow for another kind of this technique that may alternatively use the Gifford-McMahon or Hampson-Linde regenerative cycles. The most powerful kind of this technique, adiabatic nuclear demagnetization, is based on the magnetocaloric effect. For 10 points, name this technique that enables the creation of extremely low temperatures.
In a three-stage method for this technique developed by Lounasmaa, the second stage contains a hexagonally symmetric alloy of praseodymium and nickel that has a very small Korringa constant and exhibits hyperfine enhanced van Vleck paramagnetism.
cryogenic  refrigeration [or cryogenics; or  cryocooling; prompt on "cooling"]