Method for Reducing the Amplitude Error of the Magnetic Comparator

Abstract

The output signals of sensors when testing ferromagnetic materials using the Barkhausen effect method (a non-destructive testing method based on recording the parameters of magnetization jumps arising from the Barkhausen effect) represent a stream of EMF pulses from Barkhausen jumps. It is of a statistical nature (the so-called "magnetic noise"). With a large number of them, the moving average process takes place during the half-cycle of magnetization reversal.

In bistable ferromagnets, fluctuations of the sensor output signals (and the latter represent two pulses of different polarity per magnetization reversal cycle) cannot be averaged without loss of information, which reduces the metrological characteristics of the entire device. Such parameters as amplitude, duration, and start field fluctuate. This limits its use in precise measurements.

To develop a method for increasing the stability of the sensor output signal, the hypothesis of complete switching of a bistable sample of a ferromagnetic material with a Barkhausen jump was used. The hypothesis is based on new physical data obtained in the study of bistable ferromagnets by the authors Baranov S. A., Lomaev G. V., Akhizina S. P. and
 others.

A method is proposed to reduce fluctuations in the amplitude of the EMF pulse at the output of the magnetic comparator, which consists in converting the volt-second area into a pulse proportional to the amplitude. A simple and reliable circuit has been developed that implements this method. A series of experiments was carried out. It is shown that the fluctuation of the output signal decreases by almost an order of magnitude when using the developed method.

The approbation of the method was carried out on cores made of vikalloy 2 (Co52Fe38V10) alloy subjected to plastic deformation to form plasticity according to the technology developed at the Department of instruments and methods of measurement, control and diagnostics of Kalashnikov ISTU.