Development and Test of a Single-Aperture 11 T $ \hbox{Nb}_{3}\hbox{Sn}$ Demonstrator Dipole for LHC Upgrades

Abstract

The upgrade of the LHC collimation system foresees installation of additional collimators around the LHC ring. The longitudinal space for the collimators could be provided by replacing some 8.33 T NbTi LHC main dipoles with shorter 11 T Nb 3 Sn dipoles compatible with the LHC lattice and main systems. To demonstrate this possibility, FNAL and CERN have started a joint program with the goal of building a 5.5 m long twin-aperture dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2 m long single-aperture demonstrator dipole with a nominal field of 11 T at the LHC nominal current of 11.85 kA and ∼20% margin. This paper describes the design, construction, and test results of the first single-aperture Nb 3 Sn demonstrator dipole model.

Towards future circular colliders

“…Parallel efforts are underway to establish complementary programmes in the United States, Japan, and other countries, in order to explore different SC-wire production lines and different coil layouts (e.g. cosθ coil [45], block coil [46], and canted cosθ coil [47] exceeded a field of 16 T at the coil [48]. While the FCC-hh design relies on Nb 3 Sn technology, the SPPC's 20 T accelerator dipole magnets must include a significant portion of high-temperature superconductor, for which both Bi-2212 or YBCO are being considered [13].…”

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 design concepts of 11 T Nb 3 Sn dipole in single-aperture and twin-aperture configurations are described in [3,4]. 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 .…”

“…Therefore, the heater studies in MBHSP02 were performed at P AV =50-55 W/cm 2 . Simulations [12] and MBHSP01 heater studies [9] demonstrated that quench quite rapidly propagates in the radial direction from outer layer (OL) to inner layer (IL) coil blocks. Quench delay time was measured separatelly for OL and IL blocks both at 4.5 K and 1.9 K. To observe the quench propagation from the coil outer to the inner layer, the extraction dump was delayed by 1000 ms. Quench delay time was determined as the time between the heater ignition (t=0) and the voltage detection time in the coil (see Fig.…”

“…Replacing some 8.33 T 15 m long NbTi LHC main dipoles (MB) with shorter 11 T Nb 3 Sn dipoles compatible with the accelerator lattice and the LHC main systems could provide the required longitudinal space for the collimators. These twinaperture dipoles operating at 1.9 K and powered in series with the main dipoles should deliver the same integrated strength of 119 Tm at the operational current of 11.85 kA.…”

“…Two such dipoles with a collimator in between will replace one 15 m long MB dipole. The program started at the end of 2010 with the design and construction of a 2 m long single-aperture Nb 3 Sn demonstrator magnet (MBHSP01) [2] which was tested at FNAL in June 2012 and reached 10.4 T at the LHC operating temperature of 1.9 K [3]. To improve the magnet quench performance and field quality, as well as to demonstrate performance reproducibility, the fabrication of a series of 1 m long collared coils was started at FNAL last year.…”