Radial Ring in Ring Magnet

[TomXY]

Hi,

I did some Simulation with EMSworks, and I'm not sure if the results are correct. They make just no sense for me. The actually setup are 2 Ring-Magnets (N42) magnetization radial, for both rings into the same direction.

The Dim. of the End setup are:
- Inner Ring: Outer-Radius=18mm, Wall=7mm,
- Outer Ring: Outer Radius=63mm, Wall=10mm
- Height of both Magnets=50mm

So the Air-Gap between the Rings=3.5mm

Actually I expected a homogenous Flux in the Gap, of about 0.6T.
The strange thing is, that the Simulation shows something completely different. You see how small the Flux becomes to the 25mm Mid-Plane.
Because of this, I did also some Simulation for H=10mm, which shows a normal behaviour and a Flux of about 0.6T, then I did a Simulation for H=25mm, ther the Flux is smaller, at about 0.4T. I did also a Simulation with two Rings, H=10mm, bout with a Distance in H-Direction of 5mm, so at the End H=25mm.

Plase note: the Colors are not the same for all Simulations. Mesh size was 1mm for the Gap. Total Mseh: 0.5Mio inkl. Air.
I did also some Simulation with flat magnets, same result. So why the flux becomes smaller for larger magnet plates? Or is it a simulation mistake?

Woulkd be great if someone could help me.

Tom

 

[MagBen]

the higher the magnet donot necessarily get you a higher field here (some flux will be cancelled out with radial magnetized, flux goes circumferentially right outside the ring), the wall thickness does. Try to simulate a thicker wall, it probably gets you a higher field.

by the way, your design with smaller ring inside the bigger ring is unlikely working.