What is Magnetic Shield?
Magnetic shield is the barrier used to block electromagnetic field in space. MuMetal is the best alloy which is used in magnetic shielding. It is made up of 4.5%molybdenum, 80% nickel and 15.5% iron to give it permeable properties. The material is highly susceptible to a magnetic field and easily accepts the flow of the magnetic field.
The benefit of this property can be used to direct magnetic field away from areas we need to be free of magnetic field. In this case a hollow structure ofMuMetal is built and placed surrounding the area we need to be free of magnetic field. This area is not affected by any external fields.
What are the Advantages of Magnetic Shielding
Magnetic shielding is used in a lot of applications from small components in a speaker to large rooms which are shielded magnetically called MuRooms. The shield is better when it has fewer joints and angles. When large areas need to be magnetically shielded the design has to be maximised to increase its efficiency.
A MuMetal of cylindrical shape can be easily produced and performs well. If you view Mumetal through a microscopic scale youwill see it as a crystalline substance with a magnetic field. The magnetic field is due to the superior permeability of MuMetal. In order to increase its magnetic domains a heat treatment is implemented in a furnace of hydrogen in the final stages of the shield preparation. This helps the shield to have the best performance.
How Sensitive Electronics are protected by Magnetic Shielding
Magnetic fields of low frequency can have a marked influence on electronic devices, generating unnecessary flow of current in sensitive areas that can cause errors, noise and disrupt circuits which are carefully balanced. In consumer systems like computers and cell phones the low frequency magnetic fields can result in poor communication and loss of data but in other systems the influence can be devastating.
Magnetic fields cannot be extinguished or destroyed but can be redirected and for this we use the magnetic shielding material. In real life different type of enclosures is required that are magnetically permeable especially for opening for wires and seams between joints. Magnetic shielding is another layer that is used to enclose sensitive circuits. Engineers in the field have to find materials which are magnetically permeable and suitable mechanically for any application.
What are the best Materials for Magnetic Shielding?
Any ferromagnetic material which contains nickel, cobalt and iron is good for magnetic shielding. Steel is ferromagnetic and is also used in magnetic shielding for redirecting. Steel is easily available and inexpensive and is commonly used in magnetic shields. The thickness of the magnetic shield depends on a few factors.
The thickness of the shield should be able to protect the flux. If it is thin it will get saturated with the flux. In cases when saturation becomes an issue multiple layers of material are used in the magnetic shield. Magnetic shielding material has low saturation point and high permeability. Permeability is the ability of the material to absorb flux.
So, the higher the permeability of the material the better will be shield for protection.
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