Halbach Array is a special arrangement of permanent magnets that augments the magnetic field on one side of the array while cancelling the field to near zero on the other side.This is achieved by having a spatially rotating pattern of magnetisation.
The rotating pattern of permanent magnets (on the front face; on the left, up, right, down) can be continued indefinitely and have the same effect. The effect of this arrangement is roughly similar to many horseshoe magnets placed adjacent to each other, with similar poles touching.
Halbach Arrays are a very interesting arrangement of magnets. If you place them in a specific pattern you end up with most of the magnetic lines projected in one direction, and hardly any in the other.
This results in a magnet that sticks to a fridge one one side, but not on the other. Very weird! I put one inside a cylinder and it will always roll to one side on a metal object.
Making them is difficult, as they do NOT want to stay put together. You have to use force to keep them pressed together. I used superglue to make a fragile array and then wrapped them in a layer of aluminum tape. This made them sturdy enough to play with, and the tape is thin enough to not reduce the effect.
Post time: 06-01-2016