Measurement principle and main application of Helmholtz coil measurement system

        According to the shape of the coil, Helmholtz coils can be divided into circular Helmholtz coils and square Helmholtz coils; according to the direction of the magnetic field, Helmholtz coils can be divided into one-dimensional Helmholtz coils, two-dimensional Helmholtz coils Helmholtz coils and three-dimensional Helmholtz coils; according to the nature of the coil current, Helmholtz coils can be divided into DC Helmholtz coils and AC Helmholtz coils.

        The Helmholtz coil has a large volume in the uniform area, an open space for use, and is easy to operate. It can generate a very weak magnetic field up to a magnetic field of several hundreds of Gauss; it can realize one-dimensional, two-dimensional, and three-dimensional combined magnetic fields, and can provide and coil current. Proportional AC magnetic field or DC magnetic field; its internal space can be equipped with a suitable non-magnetic support table, which is convenient for users to place the measured instruments or experimental equipment, and is very suitable for various research institutes, universities and enterprises to do material magnetic or detection experiments , used in materials, electronics, biology, medical, aerospace, chemistry, applied physics and other disciplines.

Main uses of Helmholtz coils:

     1. Generate a standard magnetic field (magnetic field generator);

     2. Cancellation and compensation of the earth's magnetic field;

     3. Geomagnetic environment simulation;

     4. Determination of magnetic shielding effect;

     5. Electromagnetic interference simulation experiment;

     6. Calibration of Hall probes and various magnetometers;

     7. Mobile phone magnetic compass algorithm calibration;

     8. Research on biological magnetic field and research on the magnetic properties of matter.

        The use and function of the Helmholtz coil magnetic field need to measure the magnetic field in industry, national defense, and scientific research. There are many methods for measuring the magnetic field, such as the impulse galvanometer method, the Hall effect method, the nuclear magnetic resonance method, the balance method, the electrical Magnetic induction, etc.

        Due to the open nature of the Helmholtz coil, other instruments can be easily inserted or removed, and direct visual observation is also possible. Therefore, it is a commonly used device for experiments. Using the Helmholtz coil can measure the change of the magnetic flux generated by the rotation of the permanent magnet, and thus obtain the magnetic performance parameters of the permanent magnet, including the magnetization direction, the remanence Br and the coercive force Hc.

　    A pair of coils whose axial distance is equal to the coil radius constitutes a Helmholtz coil. When the coils are connected in series and supplied with a stable direct current, a relatively uniform axial magnetic field can be generated in the central area of the coil. Mholtz coils can also measure parameters of permanent magnets placed inside them.