Attilio Milanese

Design of the EuCARD High Field Model Dipole Magnet FRESCA2

This paper reports on the design of FRESCA2, a dipole magnet model wound with Nb3Sn Rutherford cable. This magnet is one of the deliverables of the High Field Magnets work package of the European FP7-EuCARD project. The nominal magnetic flux density of 13 Tesla in a 100 mm bore will make it suitable for upgrading the FRESCA cable test facility at CERN. The magnetic layout is based on a block coil, with four layers per pole. The mechanical structure is designed to provide adequate pre-stress, through the use of bladders, keys and an aluminum alloy shrinking cylinder.

Performance of a

Future upgrades of the Large Hadron Collider (LHC) will require large aperture and high gradient quadrupoles. Nb3Sn is the most viable option for this application but is also known for its strain sensitivity. In high field magnets, with magnetic fields above 12 T, the Lorentz forces will generate mechanical stresses that may exceed 200 MPa in the windings. The existing measurements of critical current versus strain of Nb3Sn strands or cables are not easily applicable to magnets. In order to investigate the impact of high mechanical stress on the quench performance, a series of tests was carried out within a LBNL/CERN collaboration using the magnet TQS03 (a LHC Accelerator Research Program (LARP) 1-meter long, 90-mm aperture Nb3Sn quadrupole). The magnet was tested four times at CERN under various pre-stress conditions. The average mechanical compressive azimuthal pre-stress on the coil at 4.2 K ranged from 120 MPa to 200 MPa. This paper reports on the magnet performance during the four tests focusing on the relation between pre-stress conditions and the training plateau.

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

The Short Model Coil (SMC) assembly has been designed, as test bench for short racetrack coils wound with cable. The mechanical structure comprises an iron yoke surrounded by a 20 mm thick aluminum alloy shell, and includes four loading pads that transmit the required pre-compression from the outer shell into the two coils. The outer shell is pre-tensioned with mechanical keys that are inserted with the help of pressurized bladders and two 30 mm diameter aluminum alloy rods provide the axial loading to the coil ends. The outer shell, the axial rods, and the coils are instrumented with strain gauges, which allow precise monitoring of the loading conditions during the assembly and at cryogenic temperature during the magnet test. Two SMC assemblies have been completed and cold tested in the frame of a European collaboration between CEA (FR), CERN and STFC (UK) and with the technical support from LBNL (US). This paper describes the main features of the SMC assembly, the experience from the dummy assemblies, the fabrication of the coils, and discusses the test results of the cold tests showing a peak field of 12.5 T at 1.9 K after training.

Quadrupole Under High Stress

The key objective of the superconducting high field magnet work package of the European Project EuCARD, and specifically of the high field model task, is to design and fabricate the Nb3Sn dipole magnet FRESCA2. With an aperture of 100 mm and a target bore field of 13 T, the magnet is aimed at upgrading the FRESCA cable test facility at CERN. The design features four 1.5-m-long double-layer coils wound with a 21-mm-wide cable. The windings are contained in a support structure based on a 65-mm-thick aluminum shell pretensioned with bladders. In order to qualify the assembly and loading procedure and to validate the finite element stress computations, the structure will be assembled around aluminum blocks, which replace the superconducting coils, and instrumented with strain gauges. In this paper, we report on the status of the assembly and we update on the progress on design and fabrication of tooling and coils.

The Short Model Coil (SMC) Dipole: An R&D Program Towards

The key objective of the superconducting high field magnet work package of the European Project EuCARD, and specifically of the high field model task, is to design and fabricate the Nb3Sn dipole magnet FRESCA2. With an aperture of 100 mm and a target bore field of 13 T, the magnet is aimed at upgrading the FRESCA cable test facility at CERN. The design features four 1.5-m-long double-layer coils wound with a 21-mm-wide cable. The windings are contained in a support structure based on a 65-mm-thick aluminum shell pretensioned with bladders. In order to qualify the assembly and loading procedure and to validate the finite element stress computations, the structure will be assembled around aluminum blocks, which replace the superconducting coils, and instrumented with strain gauges. In this paper, we report on the status of the assembly and we update on the progress on design and fabrication of tooling and coils.

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

We describe concepts of resistive magnets for FCC-ee, a large lepton collider being considered at CERN, Geneva, Switzerland. The main peculiarity is the twin aperture geometry, which is exploited—for both dipoles and quadrupoles—to generate field in the two apertures in a coupled way, resulting in a 50% power saving with respect to separate units. This paper reports the cross-sections of the magnets together with their main parameters. Short prototypes are being built at the moment and they are briefly described as well.

Accelerator Magnets

The large hadron collider (LHC) at CERN has been operating and generating physics experimental data since September 2008, and following its first long shut down, it has entered a second, 4-year-long physics run. It is to date the largest superconducting installation ever built, counting over 9000 magnets along its 27-km long circumference. A significant operational experience has been accumulated, including the occurrence and consequences of electrical faults at the level of the superconducting magnets, as well as their protection and instrumentation circuits. The purpose of this paper is to provide a first overview of the most common electrical faults and their frequency of occurrence in the first years of operation, and to perform a statistical analysis that can provide reference values for future productions of similar dimensions and nature.

Development of the EuCARD Nb3Sn Dipole Magnet FRESCA2

Satellites and spacecrafts are exposed to space radiation environment during their mission. This environment consists of cosmic rays, solar particles and trapped particles. Cosmic rays are coming from the outside of our solar system. Solar particles are produced by the Sun. These particles can be trapped around the Earths magnetic field lines when they approach the Earths atmosphere. These particles can affect performance and robustness of electronic components or materials used in space and such effects can be classified as Total Ionising Dose (TID), Single Event Effect (SEE) and Displacement Damage (DD). To ensure the performance of innovative components or materials that will be used in space, they must be tested before they are launched to space. Currently, only TID tests can be realized in Turkey but others cannot be performed yet. METU is building a beamline to perform some types of SEE tests. METU-DBL (Defocusing Beam Line) project supported by the Ministry of Development started in August 2015 is funded with 7 million TL. This project is conducted in collaboration with CERN for knowledge and technology transfer to Turkey. After this 10 meter long beamline is built, SEE tests can be performed with 15–30 MeV protons. As a part of this project, solar cells and Li-Ion battery of the IMECE satellite will be tested by METU-DBL.

Development of the EuCARD

METU-Defocusing Beam Line (METU-DBL) Project has been started in August 2015 and aims to construct a beam line at Turkish Atomic Energy Authority (TAEA) Sarayköy Nuclear Education and Research Center (SANAEM) Proton Accelerator Facility (PAF) to perform Single Event Effect (SEE) tests for the first time in Turkey. The METU-DBL is an 8m-long beam line which has quadrupole magnets to enlarge the beam size and collimators to reduce the flux. When complete, the METU-DBL will provide a beam that is suitable according to the ESA ESCC No. 25100 Single Event Effects Test Method and Guidelines standard. The final METU-DBL beam size at the target area will be 15.40 cm x 21.55 cm and the flux setting will be selectable between 10 p/cm/s and 10 p/cm/s. The METU-DBL will serve space, particle, nuclear and medical physics communities starting from 2018 by performing irradiation tests. A preliminary test setup is being constructed towards first tests in May 2017. The beam size will be 6 cm x 8 cm and the flux will be 3.4x10 p/cm/s for preliminary test setup. The METUDBL project construction status for the preliminary test setup is presented in this proceedings.

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

The key objective of the superconducting high field magnet work package of the European Project EuCARD, and specifically of the high field model task, is to design and fabricate the Nb3Sn dipole magnet FRESCA2. With an aperture of 100 mm and a target bore field of 13 T, the magnet is aimed at upgrading the FRESCA cable test facility at CERN. The design features four 1.5-m-long double-layer coils wound with a 21-mm-wide cable. The windings are contained in a support structure based on a 65-mm-thick aluminum shell pretensioned with bladders. In order to qualify the assembly and loading procedure and to validate the finite element stress computations, the structure will be assembled around aluminum blocks, which replace the superconducting coils, and instrumented with strain gauges. In this paper, we report on the status of the assembly and we update on the progress on design and fabrication of tooling and coils.