Design and demonstration of low current density dc septum magnet

Conventional direct-drive direct current (dc) septum magnets suffer from a high current density in the drive coil, which can cause magnet failures such as coil shorting due to the strong heat cycles, and result in large power consumption. Requirements for a thin septum and narrow gap in the magnet design naturally limit the space for coils, causing a high current density to be inevitably applied to the small cross-section coils. In this paper, we presented a new design for a dc septum magnet that largely decreased the current density and power consumption, while keeping an injection amplitude using a thin dogleg-shaped septum. According to our design comparison, the current density and power consumption were reduced from 145 A/mm2 and 24.5 kW for the conventional direct-drive configuration to 4.5 A/mm2 and 1.0 kW, respectively. The primary idea presented in paper leads to a power reduction of a factor of 25. We also detailed the fabrication process and magnet performance of the dc septum magnet developed for the next generation light source.