Previous months' research papers
June 2011 - New fully superconducting bearing concept using the difference in irreversibility field of two superconducting components
One of the major factors limiting levitation force for existing superconducting magnetic
bearings is the maximum possible remanence of 1.4 T known to exist for rare-earth permanent
magnets. This paper introduces the novel concept of a magnetic bearing which uses the
difference in irreversibility field of two superconducting components to allow one component to
be field cooled in the field originating from the other component which is first magnetized at a
higher temperature. Magnetized (RE)BCO bulks with high trapped fields can be used as one of
the components instead of permanent magnets, giving a significant increase in the levitation
force density that can be achieved between the two components. This paper focuses on using an
MgB2 hollow cylinder for the component which is field cooled. Modelling of the levitation
forces that would exist between magnetized YBCO bulks inside a hollow MgB2 cylinder is
reported as well as modelling of pulsed field magnetization of the pellets to create high field
gradients using MPSC (multi-pulse technique with step-wise cooling). The new design has the
potential to achieve levitation force densities over 100 N cm−2.
Figure shows typical irreversibility field lines for bulk YBCO, MgB2, and Bi2Sr2Ca2Cu3O10+x (Bi-2223). Click on the figure for more detail.
A. Patel, R. Palka and B.A. Glowacki, Superconductor Science and Technology, 24 (1) 015009 (2011)
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