RU2824326C1 - Three-component measure of magnetic moment - Google Patents

Abstract

FIELD: measurement.

SUBSTANCE: invention relates to measurement equipment. Three-component magnetic moment measure comprises a coil of magnetic moment (MM) directed along the longitudinal axis of the orthogonal coordinate system (CS) of the coil housing of cylindrical shape from non-magnetic materials, and direct current source I, wherein coil (area – S, number of turns – w) with current I in orthogonal CS with axes X_K, Y_K and Z_K (with centre at point 0_K on diagonal of cube), located in housing cubic shape, creates MM along the Z_K axis, the unit vector of which coincides with the direction of the diagonal of the cube of the measure housing, coming out of one of the vertices of its base, which is simultaneously the centre of the reference orthogonal CS of MM measure with axes X_M, Y_M and Z_M (with centre at point 0_M) along the corresponding edges of the cube, with equal values of components MM (Mx, My, Mz) in the measure CS defined by expression: .

EFFECT: shorter measurement time, higher measurement accuracy.

1 cl, 3 dwg

Description

The invention relates to the field of measurement technology and is intended to create a three-component measure of magnetic moment used as a source of magnetic field for solving various measurement, including metrological, problems.

Sources of magnetic fields can be either ferromagnetic (ferromagnetic masses of the object) or electric (current coils) in their origin. Magnetic moment (MM) is a vector quantity characterizing the source of magnetic field (MF) in the selected coordinate system (CS). Magnetometers with three-component sensors are used to measure the characteristics of MF (magnetic induction - MI) and its source (MM). In this case, the metrological characteristics of magnetometers should be standardized both by the MI value and by the MM value.

To check the quality (verification) of such magnetometers by the measured value of magnetic induction, three-component measures MI are used, and when verifying magnetometers by the measured value MM, three-component measures MM must be used.

The magnetic moment measure EMMM is known [1. State Register of Measuring Instruments. Registration No. 67707-17], developed by Cryomag LLC (2009).

In addition, the MM measures used in the State Primary Standard GET 12-2011 [2. GOST 8.030-2013. State verification scheme for measuring instruments of magnetic induction, magnetic flux, magnetic moment and magnetic induction gradient] are known, in particular - the reference quartz coil of magnetic induction, magnetic flux and magnetic moment KS-4, as well as the reference quartz measure (coil) of magnetic moment EKMM-1.

Measures of MM type EMMM and EKMM-1 differ only in the materials used and technical characteristics.

The main design and technical drawback of these MM measures is their single-component nature, i.e. the direction of the MM vector (M) along one of the designated axes of the device coordinate system, which does not allow measurements of the values of three components of the M vector (M _X , M _Y , M _Z ) to be performed simultaneously. Sequential rotation of the measure for measurements of its remaining components requires additional time, which, in the presence of electromagnetic interference that is non-uniform in time, entails possible unaccounted measurement errors.

In addition, the EMMM measure used as a working standard has fixed dimensions (195×182×182 mm) with a fairly wide range of reproducible MM values (from 0.05 to 30 ^Am2 ), which is not always convenient when reproducing MM values less than 1 ^Am2 .

As a result of the analysis of the above-listed design and technical solutions for the set of essential features, the closest analogue of the claimed device was adopted as the device presented in [1].

The problem that the claimed invention is aimed at solving is the creation of a three-component measure MM that ensures the simultaneous reproduction of the values of the components M _X , M _Y , M _Z of the vector M along the axes of its coordinate system (X _M , Y _M , Z _M ) for the purpose of verifying the measuring instruments MM for the measured value.

The technical result obtained by implementing the claimed invention is that when using a three-component measure MM, a significant reduction in the time of measuring the values of the components of the vector M (M _X , M _Y , M _Z ) is ensured, the elimination of unaccounted measurement errors that arise when using an analog device, as well as the possibility of its manufacture with various overall dimensions taking into account the conditions of the measurement problems being solved.

The specified technical result is achieved by the fact that the claimed three-component measure of magnetic moment, containing a coil (area - S, number of turns - ) with current I in the orthogonal SC with axes X _K , Y _K and Z _K (with the center at the point 0k on the diagonal of the cube), located in the cubic body, creates MM along the Z _K axis, the unit vector of which coincides with the direction of the diagonal of the cube of the body of the measure, emerging from one of the vertices of its base, which is simultaneously the center of the supporting orthogonal SC of the measure MM with axes X _M , Y _M and Z _M (with the center at the point 0 _M ) along the corresponding edges of the cube, with equal values of the components of MM (M _X , M _Y , M _Z ) in the SC of the measure, determined by the expression:

The design of the claimed device is shown in the drawing (Fig. 1), which shows: 1 - cube body; 2 - cube diagonal; 3 - coil; s _г - cube edge thickness; - length of the edge of the case of the measure; d - diameter of the coil; M - vector of the magnetic moment; (0 _M , X _M , Y _M , Z _M ) - SC of the measure; (0 _K , X _K , Y _K , Z _K ) - SC of the coil with current (coordinate Y _K is not shown so as not to obscure the figure). In this case, the center of the SC of the coil with current (point 0 _K ) is the point of application of the vector MM (M), created by this coil, which relative to the center of the SC of the measure (point 0 _M ) has coordinates in the Investigative Committee measures.

The technological feature of the design of the claimed device is to ensure the structural placement of the MM coil in the housing (cubic) of the measure (regardless of the selected methods of winding and fastening the coil, as well as its shape) in such a way that the Z axis _K , which is the magnetic axis of the coil, is at angles to the faces of the cube, which are the coordinate planes of the SC of the MM measure.

Considering that the value of the quantity MM depends on the value of the direct current I [A] flowing in the measure coil with the number of turns w and the area S [ ^m2 ], the dimensions of the measure body (cube), made of a non-magnetic material, as well as the characteristics of the MM coil and the direct current source are calculated based on the requirements for the value of the modulus M of the created (reproduced) vector MM (M) or for the values of its components M _X , M _Y , M _Z .

In particular, to reproduce the vector M with a given value of the modulus M=1 Am ² , it is possible to produce a three-component measure MM with the following main parameters:

- current source with strength I=1.0 A;

- number of turns of the coil

- area (average) of the coil S=0.01 ^m2 .

The values of the components M _X , M _Y , M _Z of the module M of the vector M along the axes of the SC measure are determined by the expression

It should be borne in mind that the values of the components M _X , M _Y and M _Z , taking into account the location of the vector M relative to the axes of the CS measure, in the declared device will be equal to each other, i.e. M _X = M _Y = M _Z .

In this case, expression (2) can be transformed as

where M is any of the components of the vector M.

Thus, for the value of the given vector modulus M=1 Am ² , from (3) we obtain the values of the components M _X , M _Y , M _Z , which in the declared device should be:

The diameter d of the coil, which from the established size of the area S is determined as

is the initial one for establishing the size of the length of the edge of the cube [m], which is determined from the solution of the simplest geometric problem, taking into account the thickness of the cube faces s _g .

For example, for a thickness s _g equal to 5⋅10 ^-3 m (5 mm), the value will be defined as

For the value S=0.01 ^m2 from (4) we obtain the value d=0.1128 m ≅ 11.3 cm. Therefore, from (5) we obtain the value

Accordingly, if requirements are set for the values of the components of the vector M, then by solving the problem in reverse order, the value of the modulus M of the vector M is determined and the main parameters of the MM measure are calculated based on this value.

For example, when setting requirements for the values of components M _i =1 Am ² , the value of the modulus M of the vector M will be

In this case, with the same parameters of the body of the measure and MM coils only the current value will change, which in this case will be I=1.732 A.

In relation to the upper value of the range of the reproduced MM of the selected analog device (M=30 ^Am2 ), using the described calculation procedure, it is possible to produce a three-component MM measure with the specified value of the MM vector modulus, for example, with the following main parameters:

- current source with a strength of /=2.0 A;

- number of coil turns w=150;

- area (average) of the coil S=0.1 ^m2 .

In this case, the value of the length of the device body rib, taking into account the thickness s _g equal to 5⋅10 ^-3 m (5 mm), will be

Based on the calculations provided, it is obvious that it is advisable to manufacture the claimed device in several design modifications for different ranges of MM values reproduced in accordance with [2].

For example, for the range of MM values from 0.05 Am ² to 1.0 Am ² , it is possible to produce a three-component MM measure, for example, with the following main parameters:

- current source with a power of Ш in the range from 0.05 A to 1.0 A;

- number of turns of the coil

- area (average) of the coil S=0.01 ^m2 ;

- length of the device body edge

For the range of MM values from 1.0 Am ² to 30.0 Am ² , it is possible to produce a three-component MM measure, for example, with the following main parameters:

- current source with a strength I in the range from 1.0 A to 30.0 A;

- number of turns of the coil

- area (average) of the coil S=0.1 ^m2 ;

- length of the device body edge

The examples described also show:

- the declared three-component measure MM provides the possibility of obtaining different values of the modulus M of the reproduced vector M and the values of its components (M _X , M _Y , M _Z ) by changing the values of the current strength specified by the current source, without additional costly procedures (rotations of the measure);

- based on the requirements of a specific measurement task, the overall dimensions of the measure body during its manufacture can vary in the range of values from (100×100×100) mm to (300×300×300) mm.

Control of the angles of the Z _axis of the coil relative to the axes of the measure is the most important procedure in the manufacture of the device and must be carried out in two stages.

Stage 1 - control of the position of the plane of the measuring coil relative to the measuring SC carried out by linear measurement methods.

As an example, the drawing (Fig. 2) shows the location of the plane on which the measure coil is placed. The indicated plane intersects the corresponding edges of the cube at points AF, dividing the intersected edges of the cube into two equal segments In this case, at the points of intersection of the plane of the coil of the edges of the cube, the condition of equality of these segments is controlled.

Stage 2 - control of the condition of equality of the moduli of the MI values at the control points of the measuring stand using the magnetometric method.

The layout of the magnetometer sensors on the control stand is shown in the drawing (Fig. 3).

Sensors D ₁ and D ₂ are placed on the plane (X _M 0 _M Y _M ) of the lower face of the cube of the measure body on the axes of the measure X _M and Y _M at equal distances from the beginning of the SC (0 _M ).

In this case, the X axis of the SC of the sensor D ₁ is directed along the X _M axis, and the Y axis of the SC of the sensor D ₂ is directed along the Y _M axis of the SC of the measure.

The condition for the equality of the angles of the Z axis _of the coil SC relative to the axes of the SC of the measure are the relations:

where: B _X1 , B _Z1 are the values of the corresponding components of magnetic induction measured by sensor D ₁ ; B _Y2 and B _Z2 are the values of the corresponding components of magnetic induction measured by sensor D ₂ .

Relation (6) is valid since in this design of the proposed measure MM the values of the components of the vector M are equal to each other (M _X = M _Y = M _Z ), and sensors D ₁ and D ₂ are located at the same distance from the center of the SC of the measure (0 _M ).

If necessary, it is possible to install additional sensors and mechanical “closers” to achieve the most accurate control conditions for the equality of the angle of the Z axis _of the coil SC relative to the axes of the SC of the measure.

The error in measuring the current in the coil, as well as the differences in the design and technological implementation of the three-component MM measure from its geometric construction are sources of errors in the measure, which are determined during its metrological certification.

Thus, the implementation of the claimed device, taking into account the technological features of its design and control, will allow the creation of a three-component measure of MM and ensure the verification of three-component magnetometers by the measured value - MM.

Claims (2)

A three-component measure of magnetic moment, containing a magnetic moment (MM) coil directed along the longitudinal axis of the orthogonal coordinate system (SC) of the cylindrical coil body made of non-magnetic materials, and a source of direct current I, characterized in that the coil (area - S, number of turns - ) with current I in the orthogonal SC with axes X _K , Y _K and Z _K (with the center at the point 0 _K on the diagonal of the cube), located in the cubic body, creates MM along the Z _K axis, the unit vector of which coincides with the direction of the diagonal of the cube of the body of the measure, emerging from one of the vertices of its base, which is simultaneously the center of the supporting orthogonal SC of the measure MM with axes X _M , Y _M and Z _M (with the center at the point 0 _M ) along the corresponding edges of the cube, with equal values of the components MM (Mx, M _Y , Mz) in the SC of the measure, determined by the expression:

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