Design of Active Coils System Can Build a Uniform Magnetic Field and Tune The Gradients Up to The Third Order

An extremely uniform magnetic field is often required in high precision measurements such as the search neutron Electric Dipole Moment (nEDM) in order to reduce the false signals. One way to achieve that is to use magnetic shielding material such as mu-metal sheets. Another way is to use gradient coils to build an equivalent and opposite gradient of the background to cancel higher orders gradients. I will present an active system of coils that can build a uniform magnetic field and gradient up to the third order of solid harmonic gradients.