SU917146A1 - Device for determination of barkhausen jump amplitude distribution - Google Patents

Description

(S) DEVICE FOR DETERMINING AMPLITUDE DISTRIBUTIONS OF BARKGAUSEN SWITCHES

t -

This invention relates to a magnetic measuring technique and is intended to build amplitude distributions of Barkhausen jumps.

A device for studying the amplitude-amplitude distribution of Barkhausen jumps, which includes a series-connected rotating potentiometer, a magnetizing amplifier, a magnetizing magnet and a measuring coil, a measuring amplifier, a threshold device with a tunable trigger level, and a counter I.

The disadvantages of this device are low accuracy and high complexity of constructing the amplitude distributions of Barkhausen jumps, due to the need to repeatedly re-magnetize the sample and re-adjust the trigger level of the threshold device.

A device is also known for constructing amplitude distributions of pa-parameters of Barkhausen jumps containing a series-connected linearly-varying voltage generator, a magnetizing amplifier, a magnetizing and measuring windings, a measuring amplifier, the output of which is connected to n strings containing successively connected threshold device and counters, counters containing counters connected to the output circuit, and counters connected to each other. .

ten

The disadvantage of this setup is the low accuracy of the construction of the amplitude distributions of the Barkhausen jumps from the pulse counter readings.

15

The closest to the present invention is a device, comprising a series-connected DC voltage source, a magnetization unit, a magnetizing winding and

20 reference resistor, as well as series-connected measuring winding amplifier, threshold device, driver, and three integrating 3 circuits, the inputs of which are connected to the inputs of the amplifier itself, the threshold device and driver, and outputs through a switch connected to the input of an analog divider 3. The disadvantage of the known device is low. The accuracy of determining the amplitude distributions of the Barkhausen jumps from the dependences of the density of the jump distribution over the field, the registration of which provides a device. The purpose of the invention is to improve the accuracy of building the amplitude distributions of Barkhausen jumps. The goal is achieved in that a device for determining the amplitude distributions of Barkhausen jumps containing a series-connected magnetization unit, a magnetizing winding and a reference resistor and a series-connected measuring winding, amplifier, threshold unit, as well as two integrating circuits, whose inputs are connected to the outputs, respectively the amplifier and the threshold unit, the series-connected subtraction unit and the integrator, whose output is connected to the magnetization unit, are entered, and moves the subtraction unit to connect us to a source of constant voltage and an integrating chain connected to the amplifier, respectively. The drawing shows the functional scheme of the proposed device. The device contains a constant voltage source t, a subtraction unit 2, an integrator 3, a magnetization unit k, sample 5 with a magnetizing winding 6 and measuring winding 7.J measuring amplifier 8, a threshold unit 9 integrating chains 10 and 11, and a reference resistor 12. Device works as follows. When the magnetizing field voltage in the measuring winding 7 placed on the test sample 5 slowly changes, EMF pulses are induced proportional to the speed of the magnetic moments of the Barkgausen jumps clmg (t) CgCt) –k, -, r-, k, - coefficient proportionality; fflgCt) is the magnetic moment of the Barkhausen jump. Thus, the voltage on the extinguishing chain 10 is defined. 2 m .. «rk (G-, (t)% - rZ f -i. ztBsr (ODN (1) / M, CO k, kj are the proportionality coefficients; An is the number of Barkhausen jumps on the averaging interval of the integrating chain j - respectively, the start T and the duration; K-th jump; - the magnetic moment of the Barkhausen jumps, averaged over the AT interval. The averaging of the magnetic field in the brain 5 varies in accordance with relation 1. (t) -; (2).. K is the coupling coefficient between the input signal of the magnetization unit k and the voltage: the magnetic magnetic field in,,. Difference 5; -;,.:, -: t - the integration constant iintegrator 3 $ and output voltage iprchni;. 1: -.;, that means dHj4t- (dH / dBB) x (W Bg is a component of magnetic induction caused by discontinuous processes of magnetization reversal; - magnetic permeability of vacuum; / dB differential magnetic sample permeability; due to jump-like processes of magnetization reversal; sample cross-section plots. We differentiate expression (2), -U, (t) -te6 (t) / jl / ,.

Thus, if the coefficient k is large enough, then

, and u, (t),:

and therefore according to

to f boil (I) 1BSr () - dG

(, (3)

 t

8cp (t) y,

faith where with const. bsrlbsr. respectively, the duration: the Barkhausen skv.rkrv amplitude, averaged over the interval & T, the output voltage of the integrating chain 10 is determined by the expression u, Ct) k5utgep) tt) AN (t) / AT, (4) where kj is the proportionality factor ; U is the amplitude of the rectangular pulses at the output of the threshold block 9.I; Thus, taking into account the expressions 3) and (k VJ u., (Tc / u ,, p. (T). When you connect one channel of the coordinate of the recorder to the output of the integrating chain P, and the other to the reference resistor 12 by the recorder at The amplitude distribution of the Barkhausen jumps according to the magnetic field strength in the ISSL € 5 test specimen c / Uep. (t) (H) was recorded on the specimen. The use of the proposed device allows an increase in the accuracy (the distribution

917tA $

jerkily, and not to points), reduce the duration (distribution is built during the half-cycle of the magnetization reversal) and automate the registration of 5 amplitude distributions of Barkgausen jumps. The registration error does not exceed (in known devices no less).

Claims (3)

SUMMARY OF THE INVENTION A device for determining the amplitude distributions of Barkhausen jumps containing a series-connected magnetization unit, a magnetizing winding and a reference resistor and series-connected measuring & (drop, amplifier, threshold unit, as well as two integrating circuits whose inputs are connected to the outputs, respectively an amplifier and a threshold unit, so that in order to increase the accuracy of the construction of amplitude distributions, j These are the subtraction unit and the integrator, whose output is connected to the magnetization unit, and the inputs of the subtraction unit are connected respectively to a constant voltage source and an integrating circuit connected to the amplifier. Sources of information taken into account in the examination of 1 Ore to B. M. The Barkgausen Effect / Advances in Physical Sciences, Vol. 101, 1970, Issue 3. 2. Merzlkov Yu. M. Apparatus for the study of the Barkhausen effect. Collection. The use of computing and engineering. Izhevsk, 1971. 3. USSR author's certificate №, cl. G 01 R 33/00, 1975.