An Approach to Monitoring of Magnetic Parameters of Cores of a Chain of Spheres. Diagnostics of Different Chain’s Length and Core’s Radius

The basic structural elements of the magnetized granular medium (effectively used, in particular, in apparatus of thin magnetic separation) are granule chains (according to channel-by-channel model), in connection with which there is a need to detail the features of their magnetization. The purpose of the work is to develop and implement an approach to measuring magnetic (micro)flows along the cores of different radius r in the chain of granules using a specially developed (by printed circuit board technology) sensor, with high radius R (15 and 20 mm) spheres available for such measurements.

From the data of measuring magnetic (micro)flows data of average induction in each of the quasi-continuous cores of the spheres chain are obtained, as well as data of magnetic permeability and susceptibility of these cores, their magnetization for different values of the intensity of the magnetizing field. It is shown that dependences of mentioned magnetic parameters from number n spheres in a chain are generalized on r /R for different R.

These relationships, increasing as n increases due to a decrease in the demagnetizing factor N of any of the cores and the chain as a whole, demonstrate the achievement of individually limiting values of magnetic parameters and corresponding auto-model regions where N→0. At the same time, the transition to each of these regions, manifesting almost independently of r /R and intensity, falls on the value of n = 10–12 = [n]. Thus, in fact, such a criterion value [n] distinguishes chains by sufficiently “long” – when n ≥ [n] and “short” – when 2 ≤ n ˂ [n]. Data of demagnetizing factor for different cores of “short” chains of spheres are obtained and phenomenologically described.

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