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Re: Magnetic Shielding Materials

  1. Jul 21, 2006 #1
    Hi all,

    I was looking into magnetic shielding materials. I have the impression that nickle, copper, steel standalone are good shileding materials. However, some people claim that an alloy of these elements (eg. netics) are better shielding materials. Is this simply an empirical measurement or is there a scientific reason behind it?

    Thanks,
    Michael
     
  2. jcsd
  3. Jul 21, 2006 #2

    Gokul43201

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    You must not be speaking of magnetic shielding.

    Copper is pretty useless as a magnetic shield (it's hardly better than air) with a relative permeability fairly close to 1. While nickel and steel could be used for magnetic shields, they are not anywhere near the best materials. They have permeabilities close to a couple hundred. On the other hand, Mumetal and MetGlas have permeabilities that are in the tens (or hundreds) of thousands.

    As for a reason - the reason is in the permeabilities of the materials. A greater permeability implies a higher flux density inside the material, which results in a reduced flux density outside the material, and in its vicinity. This is essentially what magnetic shielding is.

    Note: Shielding capability involves geometric factors in addition to material properties - the above comparison is with a fixed geometry.
     
    Last edited: Jul 21, 2006
  4. Jul 26, 2006 #3

    Mk

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    What shield compounds are used for satellites?
     
  5. Jul 28, 2006 #4

    Gokul43201

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    Depends on the specific area where it's used in addition to all kinds of other bureaucratic constraints. Most commonly, I believe Co-netic alloys are used on small parts like specific PCBs and some kind of mu-metal alloy (like Hy-mu) is used in larger parts, like detector assemblies.
     
  6. Jul 30, 2006 #5

    Astronuc

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    Magnetic shielding
    http://farside.ph.utexas.edu/teaching/jk1/lectures/node52.html

    I recently read an article describing the use of soft iron for shielding micro-electronics. However, I believe mu-metal would be more appropriate, because one tries to maximize permittivity per unit mass.
     
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