Spatial magnetic field details

Forces and torques

Spheres of uniform ferromagnetic material experience translational forces near magnets, but no torque.

• Asymmetric ferromagnetic objects (for example long cylinders) may experience both translational forces and torques. For such objects the translational force can be orders of magnitude lower than those related to torque.
• Magnetic translational force depends on the force product (B0 grad(B0)) with the maximum force occurring for the maximum force product.
• Torques increase rapidly with (B₀ )² and depend on angle from B₀ and shape of object.
• MR compatibility investigators have reported the maximum static magnetic fringe field gradient in the past as a safety criterion. For each maximum the maximum values, the spatial locations (cylindrical coordinates (Z,R)), and the values of the other (typically non-maximum) parameters are given below for GE magnets.

The peak static spatial gradients table contains coordinates for and values of maximum B₀, maximum grad(B₀), and maximum B₀(grad(B₀)). MR compatibility investigators have reported the maximum static magnetic fringe field gradient in the past as a criterion for MR compatibility though the force product actually determines translational force on ferromagnetic objects. The maximum field values (shown with red borders), the spatial locations (in cylindrical coordinates (z,R)), and the values of the other (typically non-maximum) parameters are given below for GE magnets

Useful units of conversion