Design and Fabrication of a Single-Aperture 11 T ${\rm Nb}_{3}{\rm Sn}$ Dipole Model for LHC Upgrades

Abstract

The planned upgrade of the LHC collimation system includes additional collimators to be installed in the dispersion suppressor areas of points 2, 3 and 7. To provide the necessary longitudinal space for the collimators, a replacement of 8.33 T Nb-Ti LHC main dipoles with 11 T dipoles based on Nb 3 Sn superconductor compatible with the LHC lattice and main systems is being considered. To demonstrate this possibility FNAL and CERN have started a joint program to develop a 2 m long single-aperture dipole magnet with the nominal field of 11 T at ~11.85 kA current and 60 mm bore. This paper describes the demonstrator magnet magnetic and mechanical designs and analysis, coil fabrication procedure. The Nb 3 Sn strand and cable parameters and test results are also reported.

Quench Performance of a 1 m Long Single-Aperture 11 T <formula formulatype="inline"><tex Notation="TeX">$ \hbox{Nb}_{3}\hbox{Sn}$</tex></formula> Dipole Model for LHC Upgrades

“…The coil cross-section was optimized to provide a dipole field above 11 T in a 60 mm aperture at the 11.85 kA current with 20% margin, and geometrical field errors below 10 -4 . The calculated design parameters of the 2 m long single-and twinaperture dipole magnets are reported in [6]. For a 1 m long model in the single-aperture configuration, the calculated nominal parameters are slightly higher (for example, the central field is 11.07 T at I nom =11.85 kA) due to field enhancement in the magnet center from the coil ends.…”

Design of 11 T Twin-Aperture ${\rm Nb}_{3}{\rm Sn}$ Dipole Demonstrator Magnet for LHC Upgrades

“…The two-layer Nb 3 Sn coils illustrated in Fig.1 and the electrical insulation scheme are identical to the single aperture demonstrator [4,5]. The coil cross-section was optimized using ROXIE [6] for the twin-aperture configuration to provide 11.21 T dipole field in the 60-mm bore at 11.85 kA with 20% operation margin, and geometrical field errors in the 10 -4 level (dark blue area in Fig.…”

“…The coils in the single-aperture demonstrator model have integrated (potted) poles made of Ti alloy [5]. In this analysis the coil outer-layer poles are made of stainless steel while the inner-layer poles are Ti to achieve better stress distribution between inner and outer layers after coolingdown.…”

“…This paper describes the two electromagnetic and mechanical designs of the 11 T twin-aperture Nb 3 Sn dipole demonstrator magnet, one based on the coil with integrated poles and the collared coil design concept used in the singleaperture demonstrator [5], and the other one based on removable coil poles and the new collared coil design. The results of the electromagnetic field optimization and the preliminary structural analysis are discussed in addition to the quench protection scheme.…”

Quench Performance and Field Quality of FNAL Twin-Aperture 11 T Nb3Sn Dipole Model for LHC Upgrades

“…The MBHDP01 quench performance in the first thermal cycle was reported and compared to single-aperture models in [3]. After training at 1.9 K, the bore field in the twin-aperture model reached 11.6 T. This is 97% of its design field of 12 T [4] and is within 1% of the field level reached in the single-aperture models showing that no additional degradation was introduced during coil reassembly in a twin-aperture configuration. In June-July 2016 MBHDP01 was retested with the main goals to check its training memory, measure field quality and further investigate quench propagation between the two apertures.…”