SU1285418A1 - Device for measuring magnetic susceptibility of low-magnetic materials - Google Patents

Abstract

The invention relates to the testing of weakly magnetic materials. The goal is to improve measurement accuracy. In the device for measuring the magnetic susceptibility of weakly magnetic materials, the rocker arm (K) 1 is mounted on the pad 3 by means of the supporting element 2. The insulating mechanism 4 is designed to transfer K 1 from the non-working position to the working position and back. On one of the shoulders K 1 suspended

Description

(L

with

tsD

00

sd

one

the transducer element 5 is the deviation and the sample under study 6, placed in the inhomogeneous magnetic field of the electromagnet 7 (EM) of direct current. The goal is achieved by introducing a low-frequency generator 10, a modulator 9 and a power amplifier 1, and an electromagnetic compensator 13 in the device.

18

de stationary EM 14 AC and core (C) 15, made from a set of paramagnetic plates and suspended from K 1, with one end of C 15 placed in the center of the gap between the poles of EM. The device is used in conditions of increased magnetic interference to the compensating mechanism. 1 silt

one

The invention relates to the testing of weakly magnetic materials and can be used to measure the sensitivity of samples of materials and materials by means of silometric methods, for example, Farad or Gun.

The purpose of the invention is to improve the accuracy of measuring the magnetic susceptibility of samples under the conditions of increased magnetic interference to the compensating mechanism.

The drawing shows a device for measuring the magnetic susceptibility of samples.

In the device, the rocker 1 with the support element (support; prism) 2 is installed on the cushion 3: The insulating mechanism 4 is designed to transfer the rocker 1 from. non-working position in the working and back. On one of the arms of the rocker arm 1, a movable element of the deflection converter 5 is suspended and sample 6, located in the non-uniform magnetic field of the constant-current electromagnet 7. The DC amplifier 8 through the modulator 9, the control input of which is connected to the low-frequency generator 10, the power amplifier 11 and the recorder 12 is connected to an electromagnetic compensator 13, made in the form of fixed AC electromagnet 14 and the core 15, made from a set of paramagnetic plates and suspended from the yoke 1 so that one end is placed in the center of the gap between the poles of the electromagnet 14 AC. The set-up of a set of paramagnetic plates is oriented per

five

0

five

0

five

0

pendicular to the direction of the power lines of the magnetic field generated by the electromagnet 14 of alternating current. A cup 16 is also suspended from the beam 1; it is designed for placing weights on it.

A device for measuring the magnetic susceptibility of the samples works as follows.

In the initial position, the sample 6, suspended from the beam 1, is placed on the line of symmetry between the poles of the magnetizing electromagnet 7, direct current. Using the insulating mechanism 4, the yoke 1 is transferred into working life and the mass (weight) of the test sample is balanced with 6 weights, placing them on the cup 16. The DC electromagnet 7 and the autocompensation circuit are turned on (deflection converter 5, DC amplifier 8, modulator 9, low-frequency generator 10, power amplifier 11, recorder 12, electromagnetic compensator 13).

Under the action of the force acting on the test sample 6 from the magnetizing field, the rocker 1 deviates from the equilibrium position, which leads to the displacement of the moving element of the deflection transducer 5. At the output of the transducer 5, a deflection signal appears, proportional to the deflection angle of the rocker arm 1, which is amplified by the direct current amplifier 8 and fed to the modulator 9. The latter converts the direct current signal to an alternating current signal,; whose frequency is determined by the frequency of the modulating signal, coming in .1.1

 On the control input of the modulator 9 from generator 10 of low frequency. The alternating current signal is amplified by the power amplifier 11 and through the recorder 12 is supplied to the winding of the electromagnet 14 of the alternating current of the compensator 13. An alternating magnetic field arises between the poles of the electromagnet 14 of the compensator 13. The core .15 of the compensator, made from a set of paramagnetic plates, has the shape of an elongated parallelepiped. One end is placed in the center of the gap between the poles in the zone of a uniform alternating magnetic field with the value of induction B «-, and the other outside the poles, where the value of induction B2 is 5-10 times smaller. A core located in this way from the side of an alternating magnetic field will be affected by a force along the line of the gradient field, i.e. vertically, downward, as the paramagnetic is drawn into the field. Since the inertia of the yoke 1 of the balance is sufficiently high, and the natural frequency is the fraction of hertz, a periodic change in the value of the force FC, which occurs without changing the direction of its action with a frequency of several tens of hertz, does not cause the swing of the yoke 1. the interaction of the core 15 with the variable magnetic field of the electromagnet 14 of the compensator 13 of the balance arm 1 returns to its original position. The value of the force acting on the sample 6 from the magnetic field of the electromagnet 7 of direct current, and consequently, the magnetic susceptibility of sample 6, is judged by the effective values of the alternating current flowing through the winding of the electromagnet 14 of the compensator 13, which Recorded using recorder 12..

The transition from the direct current signal at the output of the transducer 5 to the alternating current signal at the output of the modulator 9 is used to eliminate the influence of the hysteresis, the frame material of the electromagnet 14 of the compensator 13 on the counterbalancing force. The use of alternating current provides an unambiguous relationship between the value of alternating current flowing through the winding.

18

an electromagnet 14, and the value of the force acting from the alternating magnetic field on the core 15 of the compensator 13, made in the form of a parallelepiped from the set. plates made of brass, which is a paramagnetic and having a bulk magnetic susceptibility of about 10 in SI units (8C is a dimensionless quantity). The intrinsic magnetic moment of the core does not exceed 2–10 A.m. , which is at least several tens of thousands of hours smaller than the magnetic moment of the compensator core, of known weights. The yoke of the electromagnet AC compensator is made of a set of electrical steel plates. The winding of the electromagnet consists of two coils wound on frames. The force acting on the paramagnetic core from the side of the magnetic field, reaching a maximum value in the gap between the poles of the electromagnet of the compensator, is sufficient to automatically compensate for the change in weight of the sample under study. The balance beam deflection converter consists of a generator coil, two receivers, aligned coaxially with the generator, and a core, made in the form of a hollow cylinder of nonmagnetic conductive material and placed in an annular gap between the generator and receiver coils.

Claims (1)

Formula A device dp for measuring magnetic susceptibility of weakly magnetic materials, containing a direct current electromagnet, rocker with an insulating mechanism, mechanically coupled through a deflection transducer with a direct current electromagnet, a direct current amplifier connected to the output of a deflecting transducer, an electromagnetic compensator, and a registrator, t l and - since, in order to increase the measurement accuracy, it is additionally equipped with series-connected low-frequency generator, the modulator ohm and power amplifier, the output of which is connected to the recorder, the second input of the modulator is connected to the output of the dc amplifier, and the output of the recorder is connected to the electromagnetic 51285418f compensator, made in the video guide beam, with ptiph pdip end fixed electromagnet of change-core is located in the center current and core, from a set of gaps between poles of electric paramagnetic plates, a suspended magnet.