Efficient water-cooled Bitter-type electromagnet for Zeeman slowing in cold-atom experiments

We describe the design, construction, and characterization of a Bitter-type electromagnet that produces a spatially-dependent magnetic field used for Zeeman slowing in cold-atom experiments. The coil consists of stacked copper arcs separated by PTFE spacers of varying thicknesses, generating a near-optimal field profile using a single power supply. With an electrical resistance of $26.5(3)$~m$\Omega$ and self-inductance of $19.1(1)$~$\mu$H, our design achieves a fast electrical switching time of $\tau \approx 100$~$\mu$s in a compact, 30-cm-long package. Water circulating helically through holes in the copper and channels in the spacers ensures efficient thermal management, limiting the temperature rise to $\sim 5^\circ$~C over $36$~s of continuous operation at $200$~A.