• ⁴He liquefies at 4.2K and remains a liquid down to absolute zero.
• ⁴He undergoes a superfluid phase transition at 2.17K known as the lambda transition.
• As a superfluid, this liquid can flow without dissipation (zero viscosity!) through very small holes, long narrow paths, and sinters. Just like superconductors, currents can persist in loops indefinitely.
• Experimentally, it is observed that superflow is stable for currents less than some critical current. The value of this critical current is fixed for a given experimental setup. However, this critical current does not have a universal value and depends on the details of each particular experiment.

• Back to previous page

Updated October 25, 1999

Send comments or questions to: Richard Packard