Effective Field Observation of Magnetic Samples in Pulsed Fields

Abstract

The measurements of the effective coercivity (Hc) of magnets are very difficult to determine as a function of the internal fields in samples with arbitrary shapes. We tried to obtain the exact coercive force, M-H curve in high pulsed magnetic fields up to 20T with an induction method using a triple-fold pick-up coil. The values of Hc were found over-estimated more than 20% for the Nd-Fe-B magnets in comparison with those announced by the company, caused physically by the leakage fields in between the sample and probe. The flux distributions were well simulated with the errors using the software of JMAG. The nature of magnetically isotropic microstructure of the raw material in the sintered Nd-Fe-B samples was also clarified in this study.