Establishement of the magnetic flux density standard in the range 100 µT to 1000 µT

The magnetic flux density standard in the range 100 μT to 1000 μT has been established using a standard Helmholtz coil. The ambient magnetic field including earth's magnetic field components inside the room and other noises has been compensated to a level of the order of 100 nT. A circular triaxial Helmholtz coil pair of size nearly 800 mm has been used for compensating the ambient magnetic field. The standard Helmholtz coil of size 300 mm has been placed in the geometrical centre of the triaxial Helmholtz coil pair. The magnetic flux density has been measured using triaxial and single axis fluxgate magnetometers. The coil constant of the standard Helmholtz coil has been found to be 850.6808± 0.0036804 μT/A, which is in good agreement with the manufacture's specification viz, 850 μT/A, with an uncertainly of <; ± 0.5 %.