1,552,408 research outputs found
Superfluidity of Dense He in Vycor
We calculate properties of a model of He in Vycor using the Path Integral
Monte Carlo method. We find that He forms a distinct layered structure with
a highly localized first layer, a disordered second layer with some atoms
delocalized and able to give rise to the observed superfluid response, and
higher layers nearly perfect crystals. The addition of a single He atom was
enough to bring down the total superfluidity by blocking the exchange in the
second layer. Our results are consistent with the persistent liquid layer model
to explain the observations. Such a model may be relevant to the experiments on
bulk solid He, if there is a fine network of grain boundaries in those
systems.Comment: 4 pages, 4 figure
Superconductive magnetic-field-trapping device
An apparatus which enables the establishment of a magnetic field in air that has the same intensity as the ones in ferromagnetic materials is described. The apparatus is comprised of a core of ferromagnetic material and is surrounded by a cylinder made of a material that has superconducting properties when cooled below a critical temperature. A method is provided for producing a magnetic field through the ferromagnetic core. The core can also be split and pulled apart when it is required that the center of the cavity be left empty
Magnetic-flux pump
A magnetic flux pump is described for increasing the intensity of a magnetic field by transferring flux from one location to the magnetic field. The device includes a pair of communicating cavities formed in a block of superconducting material, and a piston for displacing the trapped magnetic flux into the secondary cavity producing a field having an intense flux density
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