The effect of annealing and surface roughness on the flux harmonic content (domain wall motion) of amorphous ribbons

It is not easy to observe and quantitatively measure the dynamic domain wall motion of amorphous ribbon materials due to the complex nonrepetitive domain wall motion. Therefore the harmonic content of the flux density has been measured under sine H magnetization conditions. From this measurement, it is possible to infer the uniformity of the domain wall motion because the harmonic content of the flux dersity is due to the non-sinusoidal elements of the domain wall motion. In this study the flux harmonic content of amorphous ribbons have been measured for inductions up to saturation at 50 Hz. The effect of annealing on the harmonic content of the flux density of ribbon samples has been ascertained by annealing samples at temperatures in the range 325°C to 385°C. In addition the effect of surface roughness on flux harmonic content has been determined by smoothing Samples and the localised variation of domain wall motion has been investigated. It is concluded that (i) the harmonic content of the flux density and the power loss is reduced by annealing, (ii) there are large differences in the localised domain wall motion, and (iii) the harmonic content of the flux density is reduced by smoothing the ribbons.