In order to reduce the strong magnetic fields of powerful magnets (e.g. NMR), stray field shields with a high saturation flux density are used. Typically, pure iron or silicon iron alloys are used for this purpose.

This is mostly to reduce the area around the magnet to less than 5 Gauss (500µT), which is the recommended limit for people with implants such as pacemakers.

However, the application is not only limited to keeping within the 5 Gauss line, but also depends on the customer’s specifications. In biological research, for example, values in the order of magnitude of the earth’s magnetic field, i.e. approx. 50µT, are often required so that biological experiments can be carried out in a “neutral” environment, or components must be protected that are located in a very strong, static magnetic field.

With the stray field shielding system, the fields of magnets can be effectively reduced. The necessary thickness, size and materialisation of the shielding surface is determined using 3D Finite Element Method simulations.