Design of compact coils and a big stable current driver for Feshbach resonance researches

Atomic Feshbach resonance is one of the important tools in quantum gases experiments. The position of a resonance, B0, typically occurs at a few hundred gauss for alkali atoms. The width of a resonance Δ can be relatively smaller, thus requires a stable magnetic field. A set of compact Helmholtz coils were designed, which are capable of carrying a high current for the strong magnetic field while maintaining the required stability. The negative integral feedback loop was used to regulate a current stability up to 10-5.