TECH TOPICS
. . . things we know we should know.
Occasionally we receive inquiries from those just beginning their journey through the maze of magnetic theory.
For instance, we recently had a question that asked if it was possible to shield a magnetic field caused by a large coil using just a .002” sheet of CO-NETIC AA foil.
Now, you and I know that the use of the word “shield” is a misnomer to begin with. Magnetic shield materials have high magnetic permeability, i.e. they absorb magnetic energy.
Really fine materials have low coercive force properties, i.e., they can be exposed to a high level magnetic field, and then removed, without retaining any magnetic characteristics. These materials are referred to as “magnetically soft”.
Of course the thicker the shielding material, the higher its magnetic permeability (ability to absorb).
So, trying to absorb a 6 to 8 Gauss field with a thin layer of foil would be problematic, to say the least. The inherent characteristics of the material also determines its shielding capability; such as MuMetal, CONETIC AA or NETIC alloys.
We try to provide the tools necessary to measure both magnetic field strength, and calculate the amount of field attenuation necessary to reduce the interference.
Gaussmeters are available to rent from our web site: (http://www.magnetic-shield.com/products/gaussmeter.html) or for sale (http://www.magnetic-shield.com/products/gausssell.html)
Calculators are available free of charge from our offices; drop us an e-mail to shields@magnetic-shield.com, call 1-888-766- 7800 (U.S.) or fax us at 1-630-766-2813.
If you need to calculate a potential shield requirement, you can access a calculator (providing you know the Gauss vale of the magnetic field) at http://www.magnetic-shield.com/faq/calculate.html.