2. Magnet design : Halbach Magnet 

MRI HALHBACH 0.23 TESLA MAGNET
(alias name : Field effect magnet or magic ring magnet)

These magnets are made with permanent magnetic field material.
Example of design:
- the inner ring is made of Neodymium Iron Boron composite
total mass = 3076 Kg or 6781 lb.
- the outer ring is made of Ferrite materials
total mass = 2777 Kg or 6112 lb.

Field generation
0.233 tesla (2330 gauss) in the magnet isocenter

1-3D view of the MRI magic ring magnet

2- 3D view of a single bar of magnetic materials
(the arrow show the direction of the permanent field cuboid element)

3- Orientation of the bars in order to produce a constant field in the X direction.
( the angle of orientation is twice the angle of position) 

4- Magnetic Field Map of the Bx component

5- Contour Magnetic Field Map of the Bx component