Large Volume Degausser with Gradient Compensation

A solution is presented to the practical problem of adapting known theoretical multicoil magnetic field generators for compensation of slightly inhomogeneous fields. Three concentric orthogonal sets of coils are used as uniform field generators. The two sets used to compensate the strong field components are each an array of four parallel, equal-size square coils, separated by ⅓ of a side length, i.e., uniformly spaced on the surface of a cube. Each of these sets generates a magnetic field uniform to 2×10−4 within the central sphere of diameter equal to 0.2 of the side length of a coil. The outer pair of coils (22 turns each) and the inner pair (13 turns each) are series connected to a single current supply. By shunting small fractions of the current from one-half of two of the three coil sets, and by appropriate location of two pairs of small coils near the main degausser coils (also series connected), field gradients that result in variations of the order of 2×10−3 of the uncompensated field over the central sphere can be compensated. Construction and performance specifications are given.