Please let me describe what I am trying to achieve and I will pose my question in the end.
I am trying to design a small chamber which can have a uniform magnetic field inside. I want to see if a design using permanent block magnets is feasible in terms of cost and construction. The volume inside the chamber is approximately 13cm x 13cm x 13cm.
I am thinking of using an iron or steel yoke as shown in the picture below. I got the idea from this article in supermagnete.de.
The picture below shows a top-view of my current design, where the green is a block magnet and the gray is iron or steel:
To reduce construction costs, I am planning to laser-cut many pieces and stack them as shown below:
This is an experimental prototype design, in which I care more about the field homogeneity rather than the field strength itself.
My question is the following: Would such a construction produce a fairly homogeneous field? I am concerned that the size of the magnet and the geometry of certain areas of the sheet matter, but I am not entirely sure how to design for them.
Given the technical details of the magnets, for example this datasheet, how can I estimate the field strength inside the chamber?
With that in mind, is there any free software that can easily simulate the fields in such a geometry? I could use that to see the effect of different geometries and magnets.
Thanks for all the help in advance!
Best Answer
The magnetic field in the region between the arms would be relatively uniform in direction, but non-uniform in intensity. Below, I've attached an image of the field that I made using very simple simulation software (note: this is extremely simple software meant for didactic use only. its results are not necessarily representative of reality); notice how the magnetic field is more intense (whiter) on the left side, near the permanent magnet, and less intense (greener) as you move to the right.
If I adjust the intensity a bit to better show it, you can also see that the field between the arms is far lower in magnitude than the field nearer the permanent magnet:
This may be good enough for you. Or it may not. Personally, I'd use a Helmholtz coil and just deal with having to wind the thing manually; it's tedious, but at least you only have to do it once.