Magnetic Field Measurements of an HTS Retrofit Synchrotron Dipole

A copper coil dipole magnet from the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL) has been retrofitted by HTS-110 Ltd with coils made from Bi-2223 wire and a self-contained cryogenic cooling system, while keeping the magnet's original iron yoke. This modified bending dipole, which is the first such known retrofit HTS-based accelerator magnet, provides the benefits of a compact coil design to accommodate space-limited experimental issues and a significant reduction in power costs as compared to the original copper magnet. In order to validate this modified design for use in the synchrotron, a detailed magnetic field map has been measured using a multiple-Hall probe assembly and transporter system. The results are discussed in this paper, along with the performance of the closed circuit cryogenics system in keeping the coils below 45 K.