The effect of overcompensation on magnetic field gradients in a separate shell magnetic shield

In this paper the concept of overcompensation is introduced. The effect of overcompensation on reducing the gradient of the vertical component of magnetic field inside the separate shell magnetic shield is studied for the operation of a first order SQUID gradiometer. The results show that slight increase in the active compensation current used is capable of eliminating the gradient of B_y component at the area of interest. Finally, A practical implementation is introduced to achieve overcompensation inside the shield.