Demagnetization

The main method of demagnetization is to act on magnetic materials with an alternating magnetic field with a decreasing amplitude . An electromagnet is commonly used as a source of alternating magnetic field. A decrease in the amplitude of the magnetic field acting on the object of demagnetization can be ensured by reducing the amplitude of the current in the electromagnet, or, in simpler cases, by increasing the distance between the electromagnet and the demagnetized object.

Since the magnetic properties of materials disappear when heated above a certain temperature, in production, in special cases, demagnetization is carried out using thermal processing (see the Curie point ).

Electronic Beam Tube ( CRT ) Devices

The process of degaussing on a CRT monitor

In devices with an electron beam tube , such as a TV or monitor , an embedded hardware function is often implemented to eliminate the magnetization of the shadow mask, frame, and other metal parts of the tube. Degaussing is usually provided only on devices with a multicolor phosphor, because, unlike monochrome CRTs (in which magnetization causes a slight geometric distortion), with a few phosphor colors, a slight deviation of the electron flux causes the phosphor corresponding to a different color to flash, and leads to a very noticeable color distortion (blemishes, color shift).

The system of demagnetization of a CRT is based on an electromagnet and is a thick harness (loop) that runs along the mask perimeter (outside the CRT) and is connected to a low-frequency generator and large capacitors. Capacitors accumulate charge, which is discharged through the generator on the harness, causing an alternating magnetic field that changes the residual magnetization of metallic elements. Due to attenuation and variable magnetization, the residual magnetization of the elements becomes less critical (causing color distortions).

Many devices with a CRT perform automatic demagnetization immediately after turning on the power (as long as the cathode warms up).

Elements of electromagnets

Electromagnets are used for electronic locks , relays , reed switches . In these devices, parts that were conceived by the developer as magnetically soft , that is, not having their own magnetic induction in the absence of a current in the coil, can become magnetized and cause the device to become inoperable.

Tools and equipment

When working with technological devices and tools, it is necessary that the material being processed, the workpiece, the part or product does not move after moving devices. This is especially true for manual work. For example, in many cases it is inconvenient to use a magnetized screwdriver, tweezers.

Navigating

Ship degaussing in civilian ships is used to reduce the deviation of a magnetic compass, and in military affairs - to reduce the likelihood of detonation on mines with a magnetic or inductive fuse.