Helmholtz coil with a ferrous core

[miloko]

Dear all,
I know that I can create a uniform field using the design of a Helmholtz coil with an air-core. However, if I use a ferrous core like iron, will I still be able to create a uniform field under the same conditions? Also, how is the equation for the magnetic field, B, changed when I add a ferrous core to the center of a Helmholtz coil?

Thanks in advance,
Mike

 

[marcusl]

Are you trying to generate a uniform field inside the object?

 

[miloko]

No. I am trying to create a uniform field between a pair of electromagnets just like the field inbetween any pair of helmholtz coils. Thanks.

 

[marcusl]

This type of magnet used to be universally used for NMR, and can still be purchased, e.g.
http://www.walkerldjscientific.com/Products/Product_Lines/Electromagnetics/electromagnetics.html"

The iron yoke concentrates all of the return flux lines, dramatically increasing the field strength in the useful region, and the two poles concentrate the flux even further. To design a high quality magnet takes more knowledge of electromagnetism and materials than can be provided in a post. Homogeneity depends critically on the size and shape of the pole pieces, and how close to saturation magnetization the iron is, for instance. Suggest you get a copy of a text like Reitz and Milford, Foundations of Electromagnetism, and do some background study. Then take a look online at sites like
http://www.geocities.com/CapeCanaveral/2404/Elect67.htm"

Of course if you aren't too concerned about homogeneity, field strength, electrical efficiency, etc., you can just fool around and see what results.