Mechanical Design and Construction of Superconducting e-Lens Solenoid Magnet System for RHIC Head-on Beam-Beam Compensation

Each 2.6-m long superconducting e-Lens magnet assembly consists of a main solenoid coil and corrector coils mounted concentric to the axis of the solenoid. Fringe field and “antifringe field” solenoid coils are also mounted coaxially at each end of the main solenoid. Due to the high magnetic field of 6 T large interactive forces are generated in the assembly between and within the various magnetic elements. The central field uniformity requirement of ±0.50% and the strict field straightness requirement of ±50 microns over 2.1 m of length provide additional challenges. The coil construction details to meet the design requirements are presented and discussed. The e-Lens coil assemblies are installed in a pressure vessel cooled to 4.5 K in a liquid helium bath. The design of the magnet adequately cools the superconducting coils and the power leads using the available cryogens supplied in the RHIC tunnel. The mechanical design of the magnet structure including thermal considerations is also presented.