Engineering overview of the ITER hybrid central solenoid

The hybrid central solenoid was proposed as a possible alternative to the segmented central solenoid since it avoids the most serious issue of the segmented solenoid design: the placement of superconducting joints in a 13 T field. The hybrid is so named because it adopts features from both the reference and segmented designs in a configuration which results in the fields at the superconducting joints being similar to those in the reference design. This paper overviews the engineering details of the reference, segmented, and hybrid designs and discusses the tradeoffs involved in the various designs. Although the hybrid was not adopted for the EDA design due to unresolved issues, it evolved into the present reference design which includes some of the design details of the hybrid.