Design and fabricating of a two-in-one compact magnet array.

Usually two Halbach[1] magnet arrays are required in order to make a force balance for a whole rotary magnetic refrigerator system. Except for a large volume of magnet array, a coupling gear is needed for the two magnet arrays. It is found that a new magnet array may avoid the above disadvantages. The magnet arrays are divided into inner two-hole Halbach-like magnet array and outer Halbach magnet array. The outer magnet array may rotate around the inner magnet array. The inner Halbach-like magnet array contains two rectangular holes parallel to cylindrical axis. The magnetic fields in the holes of inner magnet array are uniform and equal with opposite directions. The field in two holes alternately varies with the rotation of outer magnet array. It is shown that the field may be fairly uniform by calculation. The real two-in-one magnet array is made successfully and the measuring data of magnetic field support the calculation results.