H Kajastie et al 2009 Metrologia 46 298 doi:10.1088/0026-1394/46/3/018
H Kajastie, K Riski and A Satrapinski
Show affiliationsThe method for realization of the kilogram using 'superconducting magnetic levitation' was re-evaluated at MIKES. The realization of the kilogram based on the traditional levitation method is limited by the imperfections of the superconducting materials and the indefinable dependence between supplied electrical energy and the gravitational potential energy of the superconducting mass. This indefiniteness is proportional to the applied magnetic field and is caused by increasing losses and trapped magnetic fluxes. A new design of an electromechanical system for the levitation method is proposed. In the proposed system the required magnetic field and the corresponding force are reduced, as the mass of the body (hanging from a mass comparator) is compensated by the reference weight on the mass comparator. The direction of the magnetic force can be upward (levitation force, when the body is over the coil) or downward (repulsive force, when the body is under the coil). The initial force to move the body from the coil is not needed and magnetic field sensitivity is increased, providing linearization of displacement versus applied current. This new construction allows a lower magnetic induction, reduces energy losses compared with previous designs of electromechanical system and reduces the corresponding systematic error.
84.71.Ba Superconducting magnets; magnetic levitation devices
Issue 3 (June 2009)
Received 19 January 2009, in final form 16 March 2009
Published 27 April 2009
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