-
-
-
Service Support
-
-
Magnetic measurement mainly refers to the measurement of which quantity?
Release time:
2019-08-17
Source:
Www.fe2100.com
Magnetic measurement mainly refers to the measurement of basic magnetic parameters such as magnetic field strength, magnetic induction strength, magnetic flux, magnetic conductivity, hysteresis loss and eddy current loss of the medium. The magnetic flux density in space is proportional to the magnetic field strength, and the measurement of the magnetic field strength in space is also a measurement of the magnetic flux density in essence.
Magnetic measurement mainly refers to the measurement of basic magnetic parameters such as magnetic field strength, magnetic induction strength, magnetic flux, magnetic conductivity, hysteresis loss and eddy current loss of the medium.
The magnetic flux density in space is proportional to the magnetic field strength, and the measurement of the magnetic field strength in space is also a measurement of the magnetic flux density in essence. Therefore, what is actually measured by the magnetometer is the magnetic flux density. Magnetic field measurement is mainly carried out using magnetic measuring instruments. According to the nature of the measured magnetic field, magnetic field measurement is dividedconstant magnetic field measurementandchanging magnetic field measurement.
constant magnetic field measurement
For the measurement of DC magnetic fields that do not vary with time. There are 7 commonly used measuring instruments.
① Torque magnetometer: magnetometer for short. The strength of a magnetic field or the magnetization of a material is measured using the force effect of a magnetic field.
② Flux meter and impact galvanometer (see galvanometer): used to measure magnetic flux and magnetic flux density in impact method (see soft magnetic material measurement). During the measurement, the magnetic flux in the detection coil must be artificially changed.
③ Rotating coil magnetometer: In the measured constant magnetic field, place a small detection coil and make it rotate at a constant speed. By measuring the electromotive force of the coil, the magnetic flux density or magnetic field strength can be calculated. The measurement range is 0.1 mts to 10 ts. The error is 0.1 ~ 1%. The detection coil can also be suddenly turned over or quickly moved to the field-free area, and the magnetic flux density can be measured according to the principle of impact method.
④ fluxgate magnetometer: the iron core made of high permeability soft magnetic material is subjected to alternating and constant magnetic fields at the same time. Due to the nonlinearity of the magnetization curve and the work of the iron core in the asymmetric region of the curve, the voltage induced by the detection coil wound on the iron core contains even harmonic components, especially the second harmonic. This harmonic voltage is proportional to the strength of the constant magnetic field. By measuring the harmonic voltage of the detection coil, the magnetic field strength is calculated. The principle structure of the fluxgate magnetometer is shown in the figure. The two cores in the probe are made of a high permeability soft magnetic alloy. Each iron core is wound with an AC excitation coil, and the detection coil is wound on the two iron cores. After the two AC excitation coils are connected in series, the power is supplied by the oscillator, and the magnetic field strength generated in the two cores is H ~, but the direction is opposite. Thus, the fundamental wave and the odd harmonic voltages induced in the detection coil cancel each other. When the probe is in the measured constant magnetic field with strength H0, the two iron cores are respectively subjected to the superposition of H0 H ~ and H0-H H ~, I .e. alternating and constant magnetic fields, thus generating even harmonic voltage in the detection coil. After selecting the frequency amplification and synchronous detection links, the second harmonic voltage is taken, and its reading is proportional to the measured constant magnetic field strength H0. The fluxgate magnetometer is very sensitive, with a resolution of 100 Pitt. It is mainly used to measure weak magnetic fields. It is widely used in geological, marine and space technology. The optical pump magnetometer developed in the 60 s and 70 s of the 20th century and the superconducting quantum magnetometer made of superconducting quantum interference devices (squid) have higher sensitivity and resolution of 10-7 and 10-9 A/m respectively.
⑤ Hall effect magnetometer: a semiconductor rectangular sheet is placed in a magnetic field (magnetic flux density is B) perpendicular to the plane of the sheet. if a direct current I is passed between the opposite two ends of the sheet, electromotive force e (Hall effect) will be generated between the corresponding points on the other two ends. When I is a constant, E is proportional to B, and the coefficient of proportionality is related to the width B, length l and thickness d of the sheet and the material used. This property of the material is also known as magnetic sensitivity. A magnetometer made using the Hall effect can measure magnetic flux density values in the range of 1 micro to 10 t. The error is 0.1 ~ 5%. The Hall plate can be made thin and small, which can be measured in a narrow gap and can also be used to measure non-uniform magnetic fields. Magnetic sensitive devices, in addition to the Hall chip, there are bismuth spiral, magnetic diodes and so on.
⑥ Nuclear magnetic resonance magnetometer: under the action of magnetic flux density B, the magnetic moment of the nucleus will precess around the direction of the magnetic field, and its precession frequency ƒ 0 = γB(γ is the gyromagnetic ratio, which is a constant for a certain substance). if a small magnetic field is applied in the direction perpendicular to B, when its frequency is equal to ƒ 0, alternating resonance absorption phenomenon will occur, namely nuclear magnetic resonance. The magnetic flux density or magnetic field strength can be accurately calculated from the resonance frequency. This magnetometer has a measurement range of 0.1 mtex to 10 tex. The accuracy is very high, the error is less than 10-4~10-5, commonly used to provide a standard magnetic field and as a calibration standard.
⑦ Magnetic potential meter: used to measure the magnetic potential difference between two points a and B in space. if it is a uniform magnetic field, the magnetic field strength can be calculated. A magnetic level meter can also be used to measure the strength of a magnetic field inside a material. Since the tangential components of the magnetic field strength at the interface of the magnetic material are equal, the magnetic field strength measured by the magnetic potential meter along the surface space of the material is the tangential component of the magnetic field strength inside the material. The structure of the magnetic level meter is to uniformly wind a thin insulated wire on a non-magnetic soft tape or hard sheet. The former is called a soft magnetic level meter; the latter is called a hard magnetic level meter. The measuring instrument shall be an impact galvanometer or a fluxmeter. For a constant magnetic field, the magnetic flux linked by the magnetic level meter must be changed during the measurement. If a uniform magnetic field is measured, the magnetic field strength is calculated by the magnetic potential difference. Magnetic potential meter can be calibrated in the standard uniform magnetic field, according to the magnetic field strength value scale.
changing magnetic field measurement
The measurement of an alternating magnetic field as a function of time. It is usually measured by converting the magnetic quantity of the magnetic field into electromotive force using the electromagnetic induction effect. Taking the alternating magnetic field with periodic monotonic rise and fall as an example, when measuring the magnetic flux density, only the detection coil needs to be connected to the average voltmeter, and the maximum magnetic flux density Bm can be calculated from the reading of the voltmeter, and ƒ is the frequency, S is the effective cross section of the iron core, and N2 is the number of turns of the measuring coil. The magnetic flux density can be directly measured by the Hall plate. If I is kept as DC, the waveform of the output electromotive force E is the same as the waveform of the magnetic flux density. The magnetic flux density value can be calculated from E. When measuring the magnetic field strength, if the average voltmeter is used as the measuring instrument of the magnetic level meter, the maximum value of the magnetic field strength can be calculated according to the voltmeter reading, and it can also be calibrated in a uniform standard magnetic field.
Other magnetic field measurements
The 1. uses the ampere force calculation formula F = BIL to measure the magnetic induction intensity B
2. measurement of magnetic induction intensity B using induced electromotive force
3. uses the relationship between the electric quantity of the circuit and the magnetic induction intensity when the induced electromotive force is generated to measure the magnetic induction intensity B
Helmholtz coil: two identical coils are parallel to each other and pass current (I) in the same direction. theoretical calculation shows that when the coil spacing a is equal to the coil radius r, the combined magnetic field of the two coils is both in Canada in a large range near the axis (the center of the two coils is connected). this magnetic field is widely used.
Hunan Yongyi Technology Co., Ltd.The main magnetic field measuring devices are:
GaussiometerSeries (FE-102 Handheld Gaussmeter,FE-105 Gaussmeter,FE-103 table gaussmeter, FE-1052 dual channel gaussmeter)
magnetic flux meterSeries (FE-201 Flux Meter, FE-210B High Precision Flux Meter, FE-201 Scale Detector)
Permanent magnet measurement (FE-2100MD rare earth permanent magnet magnetic flux density experimental device, FE-2100MQ rare earth permanent magnet material quality test device,Automatic measuring device for FE-2100H permanent magnetic materials, FE-2100AM permanent magnet magnetic declination measuring instrument)
Table magnetic distribution measurement series (FE-2100RA multi-pole magnetic ring distribution measurement device (manual version),FE-2100RB meter magnetic distribution measuring device (automatic version), FE-2100RC space magnetic field distribution measuring instrument, FE-2100RD space magnetic field distribution measuring instrument
Soft magnetic AC/DC measuring equipment (DC Measuring Device for FE-2100SD Soft Magnetic Materials, FE-2100HC soft magnetic material coercivity measuring device, FE-35A iron core measuring instrument, FE-2100SC solenoid valve magnetic flux measuring instrument, FE-2100SA soft magnetic material AC measuring device)
Soft magnetic silicon steel equipment (Automatic measuring device for FE-2100M silicon steel material, FE-30SST silicon steel sheet iron loss meter)
Magnetic Field Products (FE-MAG1200/2500 Seriesmagnetizing machine, FE-3580AF biological AC magnetic field experimental device, multi-degree-of-freedom magnetic navigation gradient magnetic field control system, parking lot geomagnetic sensor automatic detection control system, China UnionPay high-precision static magnetic field generating equipment)
Small accessories for magnetic field measurement (Hall probe,Helmholtz coil, electrode head and tile fixture, FE-SST-500 single-chip silicon steel magnetometer, 25cm standard Epstein square ring)
Related News
Hunan Forever Elegance Technology Co.,Ltd.
Address: 10th Floor, New Cooperation International Trade City, Economic and Technological Development Zone, Loudi City, Hunan Province (Intersection of Xiangyang Street East and Yingchun Road)
Douyin
Customer Message
Copyright © Hunan Forever Elegance Technology Co.,Ltd.
This site supports IPv4 IPv6.
Business License