PROJECT TITLE :

Coils and the Electromagnet Used in the Joule Balance at the NIM

ABSTRACT:

In the joule balance developed at National Institute of Metrology, the dynamic section of a watt balance is replaced by the mutual inductance measurement in an try to supply an alternative methodology for the kilogram redefinition. However, for this method a rather large current within the exciting coil, is required to offer the mandatory magnetic field within the force weighing section, and also the coil heating becomes an vital uncertainty source. To reduce coil heating, a replacement coil system, in that a ferromagnetic material is employed to extend the magnetic field was designed recently. However, adopting the ferromagnetic material brings the difficulty from the nonlinear characteristic of material. This problem can be removed by measuring the magnetic flux linkage distinction of the suspended coil at 2 vertical positions directly to exchange the mutual inductance parameter. Some systematic effects of this magnet are discussed.