Development of a 15 T Nb₃Sn Accelerator Dipole Demonstrator at Fermilab

Abstract

A 100 TeV scale Hadron Collider (HC) with a nominal operation field of at least 15 T is being considered for the post-LHC era, which requires using the Nb3Sn technology. Practical demonstration of this field level in an accelerator-quality magnet and substantial reduction of the magnet costs are important requirements for realization of such a machine. Fermilab has started the development of a 15 T Nb3Sn dipole demonstrator for a 100 TeV scale HC. The magnet design is based on optimized 60-mm aperture 4-layer shell-type coils, graded between the inner and outer layers to maximize the performance and reduce the cost. The experience gained during the Nb3Sn magnet R&D is applied to various aspects of the magnet design. This paper describes the magnetic and structural designs and parameters of the 15 T Nb3Sn dipole demonstrator and the steps towards its fabrication.

Development and First Test of the 15 T Nb3Sn Dipole Demonstrator MDPCT1

“…The details of the MDPCT1 design and the magnet design parameters are presented in [2]. The magnet consists of a 60mm aperture 4-layer shell-type coil, graded between the inner and outer layers, a cold iron yoke, a thick stainless steel shell, and a coil axial support structure.…”

“…During and after magnet cool-down, the coil stress is controlled by the size of the vertical gap between the yoke blocks. The transverse mechanical rigidity of the structure is provided by the rigidity of the iron laminations, aluminum clamps and stainless steel skin [2], [8].…”

“…The magnet design concept uses optimized 4-layer shell-type coils and a cold iron yoke [1]. An innovative mechanical structure based on strong aluminum I-clamps and thick stainlesssteel skin [2] or aluminum shell [3] was developed to preload brittle Nb3Sn coils and support large Lorentz forces. The structure with the stainless-steel skin was selected as a baseline due to its relative simplicity and lower cost.…”

Superconducting accelerator magnet technology in the 21st century: A new paradigm on the horizon?

“…The high field Nb 3 Sn dipole development activity is broken down into two components. One is establishment of a baseline design to demonstrate feasibility based on the well-known cos-theta geometry using 4-layers to achieve a design field of approximately 15 T [54], Fig. 22.…”

Mechanical Structure for the PSI Canted-Cosine-Theta (CCT) Magnet Program

“…This activity is aimed at bolstering the credibility of CCT as an option for a large-scale accelerator such as the FCC. The Nb 3 Sn Rutherford cables for the program are based, in the case of CD1, on the CCT R&D cable (strand diameter of 0.85 mm, RRP 108/127 [13], 21 strands) of the US Magnet Development Program (MDP) at LBNL, and, in the case of CD2, on the inner-layer cable of the MDP's 15 T dipole demonstrator, currently being built at FNAL [14] (strand diameter of 1 mm, RRP 150/169 [13], 28 strand).…”