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Magnetic insulation

  1. Dec 8, 2006 #1
    hey everyone im new on the site and ive had a burning quistion in the back of my mind for ever

    will M.U. metal work as a magnetic insulator?
    if so, could you make the magnetic waves travel in a beam like light.
    PLEASE answer think about this, i really need everyones help.

  2. jcsd
  3. Dec 8, 2006 #2


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    Staff: Mentor

    Mu metal attracts free-space magnetic field and concentrates it inside the mu metal itself. If the mu metal is formed into something like a hollow pipe, it will still concentrate the field lines inside the metal, and basically nothing will be inside the pipe. So I don't think you can use mu metal for an "insulating" function, although you certainly can use it as a magnetic circuit (or any ferrous metal can be used for a "magnetic conductor" like you use in transformers, etc.).

    Transverse magnetic field waves are part of light, of course, as part of the whole transverse electromagnetic wave (TEM wave) effect.
  4. Dec 8, 2006 #3


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    Staff Emeritus
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    We may be interpreting "insulating" differently, but the pipe you described insulates the insides from external fields, doesn't it?

    Mumetal is routinely used for magnetic shielding.
  5. Dec 8, 2006 #4


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    Staff: Mentor

    Very true, but I interpreted the OP question to be something like he'd like to have a B-field conductor that is insulated from other fields. I guess you could use something like a coaxial arrangement, where the outer mu metal hollow pipe has an air gap to an inner mu metal rod. The outer cylinder does as you say and insulates the inner rod from the outside fields, and the inner mu metal rod serves as the conductor for the desired field.

    But it also sounded like frozendreams wanted the resulting protected B field to be in free space...?
  6. Jan 8, 2007 #5
    mu-metal is used as a shield against weak magnetic fields, such as the earth's field, in scientific instruments where a weak field is a problem. mu-metal is used in oscilloscopes using cathode-ray tubes.
    If the mu-metal is arranged as an enclosure, then incident magnetic lines will follow the mu-metal and not penetrate the inside volume.
    mu-metal is easily saturated and not useful for high fields.

    silicon-steel is used at a magnetic shield at higher magnetic field levels, however silicon steel is transparent to weak fields.

    A composite of mu-metal and silicon-steel layers provides a shield against all magnetic fields up to the saturation level of the silicon-steel.
  7. Jan 8, 2007 #6
    I just reread your post and I think we are trying to do the same thing. See my post, "Are magnetic bubbles possible?".

    If a magnetic field can be collimated and sent like a beam of light, then a magnetic bubble can also be created.

    If it is impossible to collimate a magnetic field, then a magnetic bubble is also impossible I think.
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