Influence of field inhomogeneity in magnetic calibration coils

Calibration of magnetic field detectors in the Helmholtz coil can be performed with an absolute accuracy of some tenths of a percent. This paper presents a correction, verified experimentally, that in some cases can be of the same order of magnitude. The correction, which is due to the inhomogeneity of the magnetic flux density from the Helmholtz coil over the detector coil to be calibrated, is found to exceed 1 percent if the size of the Helmholtz coil is twice the size of the detector coil.