Re: Shielding Magnetic Fields of Permanent Magnets

[miloko]

Hi all,

In one of the books I'm reading, it says that shields are only used in the presence of alternating fields. However, in some websites, I see people using magnetic shields for permanent magnets which has a magnetostatic field. I ran some simulations, and the filed of a permanent magnet seems to be shielded by a layer of nickel. So, who's telling the truth?

Thanks,
Michael

 

[Gokul43201]

In one of the books I'm reading, it says that shields are only used in the presence of alternating fields.

This person is wrong (emphasis added by me to point out error).

Static shields (like Mumetal) are commonly used in many applications. See the similar thread under the Materials Engineering subforum.

 

[astrokreng]

Hello Michael,

Thank you for bringing up this interesting topic. I can understand your confusion regarding the use of shields for permanent magnets. Let me clarify this for you.

Firstly, it is important to understand the difference between alternating fields and magnetostatic fields. Alternating fields are constantly changing, while magnetostatic fields are constant and do not change over time.

Shields are commonly used to protect against alternating fields because they can induce electrical currents in materials, which can be harmful or interfere with electronic devices. In this case, a shield made of a conductive material such as copper or aluminum can redirect these currents, protecting the surrounding area.

On the other hand, permanent magnets produce magnetostatic fields, which do not induce electrical currents. However, these fields can still be shielded by materials such as nickel, as you have observed in your simulations. This is because nickel is a ferromagnetic material, meaning it can redirect or absorb magnetic fields.

So, to answer your question, both sources are correct. Shields are primarily used for protecting against alternating fields, but they can also be effective in shielding magnetostatic fields, depending on the material used.

I hope this explanation helps clear up any confusion. Keep up the good work with your research and simulations!