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Name: Phillip W.
Status: educator
Age: 50s
Location: N/A
Country: N/A
Date: 8/4/2004


Question:
Does there exist a solid material that will not allow magnetic lines of force to pass through it, or one that does a substantial job of disallowing them to pass through?

I have diligently searched your archives and have now reviewed the web sites that you suggested, but still have not found the answer to my question.

Many of the previously asked questions in your archives seem to either ask about, or were answered as though they asked about magnetic shielding. The answers and the current commercial trends typically tend to redirect the magnetic lines of force through a high-permeability material in an effort to shield the object of interest from the magnetic lines that would otherwise permeate the space being protected.

I do not want to redirect those magnetic lines by either attraction or repulsion, or by use of a high-mu material. I do, however, need to find a material that has such a high magnetic reluctance that it simply will not tolerate the conductance of any magnetic lines of force through it (or nearly so). (Superconductors are definitely out of the question in this application.)

Your help and consideration are greatly appreciated, and I know your time is limited, so I hope this clears up what I am trying to ask. Any suggestions of materials or information resources will definitely be investigated.


Replies:
Superconductors are literally the only physical possibility I have ever heard of, for providing zero magnetic permeability. Type I superconductors in particular are required, which in turn needs liquid helium refrigerant.

The problem is that empty space itself has some admittance to magnetic lines, and most materials can only add more of their own, or not, to that of the space they occupy. Superconductors are a surprising development in a sense, because they oppose the otherwise universal admittance by reacting with infinite conductivity. To ponder this, it would help to study Maxwell's 4 equations.

In some weak-field applications people try to fake it by actively using sensors, amplifiers, and electromagnet coils. But that is not successfully applicable to everything.



Jim Swenson



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