billm713@gmail.com said: > If the conductor also has magnetic properties (e.g. if iron were used) then > magnetic saturation could be an issue. Ah... Sorry I wasn't clear. How about Is skin depth an interesting concept if you are using materials commonly used for magnetic shielding, for example mu-metal? The electrical conduction is poor so the normal skin depth reasoning probably won't be useful in practical examples. -- These are my opinions. I hate spam.

On 26/08/16 08:14, Hal Murray wrote: > billm713@gmail.com said: >> If the conductor also has magnetic properties (e.g. if iron were used) then >> magnetic saturation could be an issue. > Ah... Sorry I wasn't clear. How about > > Is skin depth an interesting concept if you are using materials commonly used > for magnetic shielding, for example mu-metal? > > The electrical conduction is poor so the normal skin depth reasoning probably > won't be useful in practical examples. > > For skin depth, the lower conductivity of mu-metal is more than compensated for by its higher permeability. At 50 Hz its skin depth is calculated to be around 0.3 mm assuming that the conductivity and permeability are real (as distinct from complex) and everything is linear. I haven't needed to consider what happens when these assumptions aren't valid so I could only guess how rapidly the skin depth increases when a magnetic material such as mu-metal is pushed past its linear region. The usual skin depth calculation is based upon assumptions about the form of the electromagnetic field and the conductor, which might not apply to the situation in which one is interested. Despite this, it is often used to get an estimate which is useful in a range of applications.

On 8/25/16 8:12 PM, Bill Metzenthen wrote: > On 26/08/16 08:14, Hal Murray wrote: >> billm713@gmail.com said: >>> If the conductor also has magnetic properties (e.g. if iron were >>> used) then >>> magnetic saturation could be an issue. >> Ah... Sorry I wasn't clear. How about >> >> Is skin depth an interesting concept if you are using materials >> commonly used >> for magnetic shielding, for example mu-metal? >> >> The electrical conduction is poor so the normal skin depth reasoning >> probably >> won't be useful in practical examples. >> >> > For skin depth, the lower conductivity of mu-metal is more than > compensated for by its higher permeability. At 50 Hz its skin depth is > calculated to be around 0.3 mm assuming that the conductivity and > permeability are real (as distinct from complex) and everything is > linear. I haven't needed to consider what happens when these > assumptions aren't valid so I could only guess how rapidly the skin > depth increases when a magnetic material such as mu-metal is pushed past > its linear region. > > The usual skin depth calculation is based upon assumptions about the > form of the electromagnetic field and the conductor, which might not > apply to the situation in which one is interested. Despite this, it is > often used to get an estimate which is useful in a range of applications. > it's all about sqrt( rho/mu)... good conductivity and high mu are what you want. soft iron works well... heck, steel works well for a lot of applications. Mu metal (which as others have noted has all sorts of handling and fabrication issues) is for the more exotic cases.. But, could you not run a differential pair of fibers, and both would be affected, but with opposite signs....