Low Permeable Materials

[slava74]

Hi, I am looking for a low permeable materials (MuR<20) & a supplier of thin rods made from such a material. The story is that it's supposed to work in a cryogenic environment, so ferrites seem not to be the best choice (not sure about, rather suspisious).
Please, advise if somebody knows where to look for.

 

[sreid]

Are you looking for low perm materials or "zero" perm materials?

 

[slava74]

Thanks for reply. Permeability is in the range 10<MrU<20 @ 60 Hz.

 

[hacksaw]

there are a variety of powders that meet your spec but may have to be encapsulated to permit use in UHV and cryo temps.

 

[sreid]

Magnetics Inc

http://www.mag-inc.com/powder/powder_cores.asp

has MPP and Kool-Mu cores down to 26 mu relative. Don't know their low temperature propertities.