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| helium II | |
|---|---|
| Name | Helium II |
| Caption | Superfluid helium film demonstrating film flow |
| Phase | Liquid (superfluid) |
| Formula | He |
| Molar mass | 4.002602 g/mol |
| Boiling point | 4.22 K (at 1 atm) for helium I–II lambda transition at 2.17 K |
| Density | ~0.145 g/cm3 (at 1.8 K) |
| Notable properties | Superfluidity, zero viscosity component, quantized vortices |
helium II Helium II is the low-temperature phase of the isotope Helium-4 that exhibits macroscopic quantum phenomena including frictionless flow, persistent currents, and quantized vortices. Observed below the lambda point at 2.17 K at saturated vapor pressure, it underpins research in condensed matter physics, low-temperature engineering, and quantum turbulence, and has been studied by communities associated with Royal Society, Nobel Prize, Cambridge University and Princeton University laboratories. Experimental investigations linking helium II to theories developed by figures at University of Göttingen, University of Leiden, and Harvard University have shaped modern understanding of superfluidity.
Helium II displays anomalous thermophysical properties such as high thermal conductivity (the "second sound"), extremely low viscosity in one component, and a density and specific heat anomaly at the lambda transition, studied at facilities like CERN, Argonne National Laboratory, Los Alamos National Laboratory, Rutherford Appleton Laboratory and Kamerlingh Onnes Laboratory. Its two-component nature leads to temperature-dependent properties measured in experiments at Bell Labs, Max Planck Institute for Physics, MIT, Stanford University and California Institute of Technology. Macroscopic observables such as fountain effect, film creep, and the lambda peak were characterized in apparatus developed by researchers collaborating with Royal Society of London and institutes in Leiden, Heidelberg, Moscow State University and Kyoto University.
The phenomenological two-fluid model, formulated by theorists connected to University of Cambridge, Niels Bohr Institute, University of Göttingen and Landau Institute for Theoretical Physics, decomposes helium II into an inviscid superfluid component and a viscous normal component, a framework refined in correspondence between scientists at Imperial College London, Princeton University and University of Chicago. Landau’s treatment was integrated into curricula and research at institutions such as Moscow State University, Leningrad State University and later discussed at conferences organized by International Union of Pure and Applied Physics and American Physical Society. The model predicts phenomena like the fountain effect and second sound, which were experimentally verified in laboratories affiliated with École Normale Supérieure, Soviet Academy of Sciences and University of Oxford.
Quantized vortices in helium II were predicted and observed in experiments linked to groups at ENS Paris, University of Illinois Urbana-Champaign, University of Tokyo and Royal Institution. Vortex dynamics, reconnection events, and quantum turbulence intersect research programs at Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, Duke University and Yale University that compare superfluid turbulence with classical turbulence studied by researchers from Princeton University and Cambridge University. Excitation spectra including phonons and rotons were introduced in theories developed by scholars associated with Landau Institute for Theoretical Physics and Institute for Advanced Study, and measured in neutron scattering experiments at facilities such as ISIS Neutron and Muon Source and Oak Ridge National Laboratory.
The lambda transition of helium II is a continuous phase transition exhibiting a sharp specific heat peak, explored in precision experiments at NIST, Physikalisch-Technische Bundesanstalt, University of Leiden and aboard microgravity experiments coordinated with European Space Agency and NASA. Critical exponents and renormalization group interpretations were advanced by researchers connected to Princeton University, Harvard University and Stanford University and debated at meetings of International Centre for Theoretical Physics and Royal Society. Studies of finite-size scaling and critical phenomena used cryostats and torsional oscillators housed in laboratories at Cornell University, Johns Hopkins University and University of California, Berkeley.
Production of helium II requires liquefaction of helium gas produced by suppliers such as Air Products and Chemicals, Inc., Linde plc, Air Liquide and containment in cryostats, Dewars and dilution refrigerators engineered by groups at Cambridge University Engineering Department, Brookhaven National Laboratory, Fermi National Accelerator Laboratory and CERN. Containment challenges include film leakage, heat ingress, and materials compatibility addressed in collaborations involving National Institute of Standards and Technology, Sandia National Laboratories and industrial partners in Germany, France and United States. Transport and storage infrastructures developed by Royal Dutch Shell and national laboratories support helium supply chains studied in policy contexts at European Commission and United States Department of Energy.
Helium II is used in cooling superconducting magnets in accelerators at CERN and Brookhaven National Laboratory, in low-temperature detectors and quantum devices at MIT Lincoln Laboratory, Bell Labs and IBM Research, and in fundamental physics experiments at Lawrence Berkeley National Laboratory and SLAC National Accelerator Laboratory. It enables technologies in Magnetic Resonance Imaging systems developed by companies like GE Healthcare and Siemens Healthineers and underpins research in quantum fluids relevant to programs at Max Planck Institute for Quantum Optics and Institute of Quantum Optics and Quantum Information. Spaceflight cryogenics and microgravity studies have been conducted in cooperation with NASA Glenn Research Center and European Space Agency payload teams.
The discovery and characterization of helium II involved experimentalists and theorists from institutions including Leiden University, Kamerlingh Onnes Laboratory, Moscow State University and University of Cambridge. Early liquefaction and anomalous behavior were reported in publications associated with Heike Kamerlingh Onnes, and theoretical explanations advanced by figures linked to Lev Landau, Pyotr Kapitsa and collaborators at Moscow State University and Cavendish Laboratory. Nobel recognitions and awards followed contributions from researchers at Royal Swedish Academy of Sciences, and subsequent international collaborations at École Normale Supérieure, University of Leiden and University of Oxford expanded the experimental and theoretical foundations of the field.
Category:Helium Category:Superfluids