Abstract
The sensitivity of magnetic Barkhausen noise (MBN) profile to changes in the excitation field strength and the number of turns of the detection coil was investigated in inhomogeneous material. Generally, the 0.5 mm case depth EN 36 steel specimen shows a double peak profile indicative of inhomogeneity through the detected depth the magnetized landscape. Various excitation field amplitudes were applied to the specimen and the induced MBN emission was analyzed for each magnetizing current. Excitation field at the lowest level induced an MBN emission of two peaks of equivalent heights. The first peak occurs at lower field than the second peak in the magnetization period. As the excitation field increased, the height of both peaks increased but the second peak increased in a higher rate than that of the first peak. Beyond certain excitation level, both peaks began to saturate and no increase in the MBN intensity was observed with increased excitation field strength. However, peak position and the number of Barkhausen events, indicated linearly as a function of the applied field strength. The experiment also establishes that the number of turns in the detection coil is important parameter which controls the height of the first peak. Low field peak height increases as the number of turn of the detection coil increases. The results indicate that the potential difference applied to the electromagnet and the sensitivity of the detection coil, determine the MBN profile characteristics.
Highlights
It is well established that magnetic Barkhausen noise (MBN) devices, irrespective of the variation in their details, consist broadly of two main parts: 1) the generation of an excitation field and provision to the sample and 2) the detection, amplification, filtering, and handling the induced MBN signals
MBN has been attributed to a number of mechanisms, most current thinking associates it with the irreversible movement of domain walls
The variation in the potential difference applied to the electromagnet enhanced the intensity of the high field peak (Peak II) in MBN signal but has lower effect on the height of the low filed peak (Peak I)
Summary
It is well established that MBN devices, irrespective of the variation in their details, consist broadly of two main parts: 1) the generation of an excitation field and provision to the sample and 2) the detection, amplification, filtering, and handling the induced MBN signals. The second part details are important and decide to some extent the induced MBN signal. Both parts function simultaneously and are triggered to each other by the data acquisition card. The applied magnetic field strength, the shape of the magnetizing waveform and the excitation frequency decide the magnetized landscape volume and the detected MBN signal. The number of turns of the detection coil and its diameter together with the magnetization parameters are crucial parameters in controlling the resolution of the induced MBN signal. In spite of various studies in the literature on MBN measurements, the influence of the number of turn of the detection coil and the applied magnetic field strength on the shape of the MBN signal profile is not discussed in detail
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