Shielding of the z-component of the magnetic field in a 2-D magnetizer with a deep yoke

Compact two-dimensional magnetizers with deep yokes can achieve very high flux densities (~2 T) at the expense of increasing the z-component of the magnetic field (Hz), in the measurement region. Hz is often reduced by shielding, where the shields are placed at an optimum distance from the sample. The paper will show that a given shield distance is not effective in minimizing Hz over the entire flux density range. Larger spacings (> 18 mm) were effective at high flux densities, while lower ones (9 to 10 mm) were effective at low flux densities. This was validated experimentally where the shield distances of 10 mm and 22.5 mm reduced Hz of the unshielded case by 83 % at 0.5 T and 72 % at 1.5 T, respectively. In addition, the paper will show that the magnetic properties and the interaction of the sample and shields, reduces the effectiveness of shielding in deep saturation.