--- In MEG_builders@yahoogroups.com, "sanderpupae" <s.sinttruye@w...>
wrote:
> Hello my name is Steven (new to this list and MEG'ing)
>
> I have a question about flux transfer through the MEG.
> First of all, I did some flux simulations with Femm. I was
> experimenting with different MEG designs like the MEGII as on
> http://starglider.netfirms.com/ But here is the thing I don't
> understand about flux traveling trough steel: What we do in case of
> the meg is switching the (most of it) magnetic flux through the
> metal in a "closed loop" from magnet north> through metal> to south.
> Well Femm simulation show a strong magnetic field through the steel.
> Well, I created that test setup. BUT when you hold a pieces of steel
> next to the meg-arm with the whole flux going trough, it is not
> attracted to it at all (well, maybe just a little) So the flux of
> the magnet is completely "IN" the steel of the MEG. So how can that
> be efficient for generating power when the magnetic field does
> not 'radiate' outside the steel for us to capture with a coil..?
>
> Hope anyone can give me some insight on this.
> Thanks!

Hi,

You cannot think in terms of magnetic lines when dealing with EMF. It
very easy to demonstrate that an area in space that contains no
magnetic field or lines can contain EMF. The reason is because EMF
not only depends upon the magnetic field polarity but also the
direction the field is traversing. For example, you could have a
magnetic field (down polarity) traversing right and another magnetic
field (up polarity) traversing left and you get EMF but no magnetic
field. That is, the magnetic fields cancel out but they are still
there. Even though the magnetic fields are canceled out they are
still traversing in opposite directions so the EM forces sum up.

You could have a perfect uniform field in a perfect toroid, and FEMM
will tell you that there is ZERO magnetic field outside the toroid,
but in reality there would be strong EMF.

FEMM is good for getting a rough idea on ONLY magnetic fields, not
EMF, and assuming you are not saturating any magnetic materials.

YT