Design of a Superconducting 28 GHz Ion Source Magnet for FRIB Using a Shell-Based Support Structure

Abstract

The Superconducting Magnet Program at the Lawrence Berkeley National Laboratory (LBNL) is completing the design of a 28 GHz NbTi ion source magnet for the Facility for Rare Isotope Beams (FRIB). The design parameters are based on the parameters of the ECR ion source VENUS in operation at LBNL since 2002 featuring a sextupole-in-solenoids configuration. Whereas most of the magnet components (such as conductor, magnetic design, protection scheme) remain very similar to the VENUS magnet components, the support structure of the FRIB ion source uses a different concept. A shell-based support structure using bladders and keys is implemented in the design allowing fine tuning of the sextupole preload and reversibility of the magnet assembly process. As part of the design work, conductor insulation scheme, coil fabrication processes and assembly procedures are also explored to optimize performance. We present the main features of the design emphasizing the integrated design approach used at LBNL to achieve this result.

Development and status of the FRIB 28 GHz SC ECRIS

“…The magnet is based on the LBNL VENUS ECR [5] but with modified mechanical design to allow for swapping sextupole coils. LBNL's Bladder and Key Technology was used to preload the magnets in the structure [6]. The technology allows adjustments and reversibility in magnet preloading -also making it possible to replace magnet components in the structure.…”

Mechanical Study of a Superconducting 28-GHz Ion Source Magnet for FRIB

“…The FRIB ECR magnet structure ( Fig. 1), described in detail in [4] and [8], is comprised of the solenoid-mandrel subassembly and the sextupole coil pack subassembly.…”