SU1679424A1 - Vibration magnitometer - Google Patents

Abstract

The invention relates to magnetic measurements, in particular to magnetometers with vibrating measuring coils, designed to determine the magnetic characteristics of samples of magnetic materials. The aim of the invention is to increase the sensitivity. The plates 4, 5 are summed by a constant Do and a variable Dm voltage, and 2U0 Um. As a result, the oscillations of the elastic element 9 and the measuring coil 6 occur with a larger amplitude, and the output emf 2 and increases.

Description

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Phases. 2

The invention relates to magnetic measurements, in particular to magnetometers with vibrating measuring coils, intended to determine the magnetic characteristics of samples of magnetic materials.

The purpose of the invention is to increase the sensitivity of the magnetometer.

Figure 1 shows the functional diagram of the magnetometer; Figure 2 shows the construction of a magnetometer vibration system.

Adjustable constant current source 1 is connected to coils 2, creating a magnetic field that compensates for a constant magnetic field of interference, including the earth's field, the coil axis is located in the plane of the drawing (two other pairs of the same coils are not shown in figure 1, creating a compensating the magnetic field in the other two directions, mutually perpendicular to the axis of the coils 2, also fed from regulated DC sources). The output of the alternating voltage generator 3 is connected to movable 4 and fixed 5 plates through an adder. The terminals of the measuring coil b are connected by flexible conductors to the input of the amplifier 7, the output voltage of which is fed to the input of the indicator 8, graduated in units of magnetic moment.

The measuring coil 6 and the movable plates 4 are rigidly fastened to the middle of the non-ferromagnetic elastic element 9 clamped by the ends in the supports 10. The fixed plates 5, as well as the tested ferromagnetic sample 11 are rigidly fastened to the base of the vibrating system 12, which includes all the elements shown in FIG .one. A pair of coils 13, creating a magnetizing-demagnetizing field, is fed from a controlled source 14 by the floor. The output of the constant voltage source 15 is connected to the input of the adder 16, which can be configured as MOUNTING OR.

The magnetometer works as follows.

Before starting the determination of the magnetic moment or induction (magnetization) and field strength at the points of the hysteresis loop of samples of magnetic materials include a compensating field.

An alternating voltage generator 3 and a constant voltage source 15 are turned on.

Under the action of these stresses, mobile 4 and fixed 5 plates are attracted or repelled with force.

F KS () (U0 + Um sin CDlf

dl d§

KS (-3 - -L) (uS + 2U0Um sin 0) t -f Um sin2 0) t), SP d2

where F is the force of electrical interaction;

Um is the amplitude of the alternating voltage;

S is the area of the plates 4 and 5;

di is the greater distance between adjacent plates of different sections;

d2 is the shorter distance; (a is the oscillation frequency;

K - coefficient of proportionality;

Do constant voltage value.

When this occurs, the component force is proportional to 2U0Umsin cat. The amplitude of the oscillations at the fundamental frequency is proportional to 2UoUm, and the amplitude of the oscillations at the even harmonics of the alternating voltage is proportional to Um, and the ratio of the amplitudes of the oscillations is proportional to 2U0

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five

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onally

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Setting 2U0 Um, it is possible to increase the amplitude of oscillations at the fundamental frequency as compared to the amplitude of oscillations at even harmonics, and therefore, to increase the signal-to-noise ratio.

In the proposed magnetometer, the ratio is 1–2. Considering also that the elastic

Um

0

0

five

the system has mechanical resonance and non-linear properties both in the initial part of the characteristic and in the saturation region; the amplitude of vibrations of the vibrating conductors at the fundamental frequency increases dramatically; the measuring coil, which is rigidly connected with the elastic system, at the fundamental frequency, reduces the parasitic EMF and, consequently, increases the sensitivity of the magnetometer in comparison with the known , Vibratory system which operates in a nonlinear initial region.

Claims (1)

Vibration magnetometer comprising magnetizing and compensation systems in the form of a series-connected current source and coils, each connected in series measuring coil, amplifier and indicator, as well as an alternator voltage and vibration drive, made in the form of insulated moving and fixed sections of non-magnetic conductive overlapping plates and mechanically connected to the measuring coil and elastic element, characterized in that, in order to increase the sensitivity, it is equipped with a constant voltage source and a totalizer, and the output alternating voltage generator co2 There is a dinene with the first input of the adder, the outputs of which are connected to the sections of the vibrodrive, and the second input of the adder is connected to the output of the source of direct voltage, the value of which is selected from the ratio 2U0 Um, where Do is the value of constant voltage; Um is the amplitude of the output signal of the alternating voltage generator. eight NO and eleven 13 1