Bernhard Auchmann

Development and Test of a Single-Aperture 11 T

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 Nb3Sn 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 Nb3Sn demonstrator dipole model.

\hbox{Nb}_{3}\hbox{Sn}

The High-Luminosity Large Hadron Collider upgrade (LHC) project aims to increase the peak luminosity of the LHC to 5 ×1034 cm - 2s - 1, and a total integrated luminosity of 3000 fb - 1 from 2020 to 2030 by upgrading the low-beta insertion system for the ATLAS and CMS experiments. The aperture of the insertion magnets including the focusing/defocusing quadrupoles and separation dipoles will be doubled to achieve a smaller β*. This paper presents the latest design updates of the separation dipole D1 magnet, including the study of the different cable types to vary the main field; the modifications of the iron shape for the new design options to minimize the iron saturation effect on field quality; and the optimization of the coil ends to reduce the peak field and higher order harmonic field integrals in the ends.

Demonstrator Dipole for LHC Upgrades

A key challenge for a future circular collider (FCC) with centre-of-mass energy of 100 TeV and a circumference in the range of 100 km is the development of high-field superconducting accelerator magnets, capable of providing a 16 T dipolar field of accelerator quality in a 50 mm aperture. This paper summarizes the strategy and actions being undertaken in the framework of the FCC 16 T Magnet Technology Program and the Work Package 5 of the EuroCirCol.

Design Optimization of the New D1 Dipole for HL-LHC Upgrade

FNAL and CERN are performing an R&D program with the goal of developing a 5.5 m long twin-aperture 11 T Nb3Sn dipole suitable for installation in the Large Hadron Collider (LHC). An important part of the program is the development and test of a series of short single-aperture and twin-aperture models with a nominal field of 11 T at the LHC nominal current of 11.85 kA and 20% margin. This paper describes design and fabrication features, and test results of a 1 m long single-aperture Nb3Sn dipole model tested at FNAL.

The 16 T Dipole Development Program for FCC

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 Nb3Sn 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 Nb3Sn strand and cable parameters and test results are also reported.

Quench Performance of a 1 m Long Single-Aperture 11 T

The upgrade of the Large Hadron Collider (LHC) collimation system foresees additional collimators in the LHC dispersion suppressor areas. The longitudinal space for the collimators could be provided by replacing some NbTi LHC main dipoles with shorter 11 T Nb3Sn dipoles. To demonstrate this possibility, Fermilab and CERN have started a joint program to develop a Nb3Sn dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2-m-long, 60-mm-bore, single-aperture demonstrator dipole with the nominal field of 11 T at the LHC operational current of 11.85 kA. This paper presents the results of magnetic measurements of the single-aperture Nb3Sn demonstrator dipole including geometrical harmonics, coil magnetization, and iron saturation effects. The experimental data are compared with the magnetic calculations.

\hbox{Nb}_{3}\hbox{Sn}

The electrical integrity of superconducting magnets that go through a resistive transition (quench) is an important consideration in magnet design. Numerical quench simulation leads to a coupled thermodynamic and electromagnetic problem, due to the mutual dependence of material parameters. While many tools treat the electromagnetic field problem and the thermodynamic one independently, more recent developments adopt a strongly coupled approach in a 3-D finite-element environment. We introduce a computationally efficient weak electromagnetic-thermodynamic coupling within an integrated design environment for superconducting magnets.

Dipole Model for LHC Upgrades

The design and construction of a wide-aperture, superconducting quadrupole magnet for the LHC insertion region is part of a study towards a luminosity upgrade of the LHC at CERN. The engineering design of components and tooling, the procurement, and the construction work presented in this paper includes innovative features such as more porous cable insulation, a new collar structure allowing horizontal assembly with a hydraulic collaring press, tuning shims for the adjustment of field quality, a fishbone like structure for the ground-plane insulation, and an improved quench-heater design. Rapid prototyping of coil-end spacers and trial-coil winding led to improved shapes, thus avoiding the need to impregnate the ends with epoxy resin, which would block the circulation of helium. The magnet construction follows established procedures for the curing and assembly of the coils, in order to match the workflow established in CERNs “large magnet facility.” This requirement led to the design and procurement of a hydraulic press allowing for both a vertical and a horizontal position of the coil-collar pack, as well as a collapsible assembly mandrel, which guarantees the packs four-fold symmetry during collaring. The assembly process has been validated with the construction of two short models, instrumented with strain gauges and capacitive pressure transducers. This also determines the final parameters for coil curing and shim sizes.

Design and Fabrication of a Single-Aperture 11 T

Purpose – The purpose of this paper is to present a geometric approach to the problem of dimensional reduction. To derive (3 + 1) D formulations of 4D field problems in the relativistic theory of electromagnetism, as well as 2D formulations of 3D field problems with continuous symmetries.Design/methodology/approach – The framework of differential‐form calculus on manifolds is used. The formalism can thus be applied in arbitrary dimension, and with Minkowskian or Euclidean metrics alike.Findings – The splitting of operators leads to dimensionally reduced versions of Maxwells equations and constitutive laws. In the metric‐incompatible case, the decomposition of the Hodge operator yields additional terms that can be treated like a magnetization and polarization of empty space. With this concept, the authors are able to solve Schiffs paradox without use of coordinates.Practical implications – The present formalism can be used to generate concise formulations of complex field problems. The differential‐form ...

{\rm Nb}_{3}{\rm Sn}

The paper describes a flexible, extensible, and user-friendly framework to model electrothermal transients occurring in superconducting magnets. Simulations are a fundamental tool for assessing the performance of a magnet and its protection system against the effects of a sudden transition from the superconducting to the normal state (also known as a quench). The application has a scalable and modular architecture based on the object-oriented programming paradigm, which opens an easy way for future extensions. Models are composed of thousands of lumped-element blocks automatically created in MATLAB&Simulink. Additionally, it is possible to run sets of simulations with varying parameters and model structure. Due to its flexibility the framework has been used to simulate various protection and magnet configurations. The experimental results were in a very good agreement with simulations.