An improved Helmholtz coil and analysis of its magnetic field homogeneity

We attempt to improve the Helmholtz coil by adding a third coil with the same radius connected in series. In this three-coil array, the distance from the outside coils to the central coil is 0.760 times radius of the coils, and the ratio of the number of turns, central to the outside, is exactly 59 to 111. Numerical results demonstrate that the uniform region of magnetic field in the improved Helmholtz coil is larger than that of the Helmholtz coil and of Maxwell’s tricoil.