These Mumetal cylindrical chambers divert the lines of magnetic flux
around the layers, reducing the magnetic field inside them. Open- and capped-end versions are available, the capped-ends available in two diameters. The open-end version is best used with the external field transverse to the axis of the shield, in a recommended East-West orientation. The capped-end versions have additional shielding at either end of the sample chamber and so are less reliant on
orientation. Either will typically attenuate the Earth’s field of ≈50,000nT to a level of a few nT, enabling the user to measure remanent magnetism in small components or errors in magnetic sensors.
Even small inhomogeneities or stresses in the shield can lead to low
level magnetism accumulating inside the cylinder. This can be removed
with the Bartington Instruments Degaussing Wand, which ensures that
the field inside the cylinder is as close as possible to zero before critical
measurements are made.