Kirby, G A Auchmann, B Bajko, M Charrondiere, M Bourcey, N Datskov, V I Fessia, P Feuvrier, J Galbraith, P Garcia Tabares, A Garcia-Perez, J Granieri, P Hagen, P Lorin, C Perez, J C Russenschuck, S Sahner, T Segreti, M Todesco, E Willering, G lHC high-luminosity insertion Nb-TI low-B quadrupole models 2013 2013 The design and construction of a 120 mm wide-aperture, Nb-Ti superconducting quadrupole magnet for the LHC insertion region is part of a study towards a luminosity upgrade of the LHC at CERN, envisaged for 2020-22. The main challenges for this accelerator quality magnet are to operate reliably with the high heat and radiation loads that are predicted in the insertion magnet regions. Calculations give approximately 500 Watts over the 30-m-long string of insertion magnets, while today LHC is operating for a nominal heat load of 12 Watts. To extract this heat, the model magnets incorporate new features: Open cable insulation, open ground insulation, open magnet structure, and a quench heater that has open channels to help extract the steady state heat load. This paper presents results from tests at room temperature and 1.8 K for the initial model magnet. We report magnet training, transfer function and field quality measurements, quench heater performance, and heat extraction studies using imbedded heaters to simulate the deposited beam heating profile. Oberli, l IEEE Trans. Appl. Supercond. 10.1109/TASC.2012.2236602 4800704 23 2013 2013 This paper reports on the development of the Nb$_{3}$Sn Rutherford cable for the EuCARD high field dipole magnet FRESCA2 designed to achieve a central field of 13 T at 4.2 K in a 100 mm bore. The FRESCA2 cable is rectangular and made of 40 strands of 1.0 mm diameter. The cable shall be able to carry a current of 15.7 kA at 4.2 K in a field of 15 T. In the first stage of cable development, focus was put on the cable parameters (cable width, cable mid-thickness and pitch length) to provide a cable made with Nb$_{3}$Sn PIT strands achieving both a minimal critical current reduction of the strand during cabling and a good mechanical stability of the cable for coil winding. In the second stage of cable development, the cable was produced with Nb$_{3}$Sn RRP strands. The cables, which were produced following an iterative process, were characterized and the results of the critical current measurements of extracted strands are discussed together with the cabling parameters and the type of strand. Bordini, B Richter, D Alknes, P Ballarino, A Bottura, L Oberli, L IEEE Trans. Appl. Supercond. 10.1109/TASC.2013.2240754 7100806 23 2013 2013 High critical current density Nb$_{3}$Sn wires (Jc > 2500 A/mm2 at 4.2 K and 12 T) are the conductors considered for next generation accelerator magnets. At present, the large magnetization of these strands is a concern within the scientific community because of the impact it might have on the magnet field quality. In order to characterize the magnetic behavior of these wires, an extensive campaign of magnetization measurements was launched at CERN. Powder In Tube (PIT) strands by Bruker-EAS and Restacked Rod Process (RRP®) strands by Oxford Superconducting Technology (OST) were measured between 0 T and 10.5 T at different temperatures (ranging from 1.9 K to 14.5 K). The samples, based on strands with different sub-elements dimensions (35 to 80 μm), were measured with a Vibrating Sample Magnetometer (VSM). The experimental data were analyzed to: 1) calculate the effective filament size and the optimal parameters for the pinning force scaling law; 2) define the field-temperature region where there are flux jumps. It was found that the flux-jump can limit the maximum magnetization of the Nb$_{3}$Sn wires and that the maximum magnetization at higher temperatures can be larger than the one at lower temperatures. In this paper the experimental results and the analysis are reported and discussed. Sitko, M Ballarino, A Fleiter, J IEEE Trans. Appl. Supercond. 10.1109/TASC.2012.2228292 8000204 23 2013 2013 The behavior of HTS tapes under torsion is of key importance for the definition of the allowable twist during cabling activity. In this paper, we report on the elaboration of selfconsistent analytical expressions of Ic dependence on twist pitch for YBCO and BSCCO (2223) conductors. The computed expressions are validated with the results of a series of tests performed at 77 K and in self-field with a purpose-built setup. The Ic was observed to be reduced to 95% of the unstrained value for twist pitches of 114 mm for BSCCO tapes, and 80–90 mm for YBCO tapes. The reduction of performance was identified to be caused mainly by irreversible degradation of Ic at the tapes edges. At lower temperatures, a slightly lower sensitivity to twist is expected. Ballarino, A Di Michiel, M Jin, X Takeuchi, T Kikuchi, A Tsuchiya, K Nakagawa, K Nakamoto, T Scheuerlein, C IEEE Trans. Appl. Supercond. 10.1109/TASC.2012.2233257 6000604 23 2013 2013 Nb3Al superconductors are studied for use in high field magnets. Fine grained Nb3Al with nearly stoichiometric Al content is obtained by a Rapid Heating Quenching and Transformation (RHQT) process. We describe a non destructive in situ study of the transformation process step of a RHQ Nb3Al precursor wire with ramp rates of either 120 °C/h or 800 °C/h. High energy synchrotron x-ray diffraction measurements show the transformation from a Nb(Al)SS supersaturated solid solution into Nb3Al. When heating with a ramp rate of 120 °C/h a strong reduction of the Nb(Al)SS (110) diffraction peak component is observed when the temperature exceeds 660 °C. Additional diffraction peaks are detectable in the approximate temperature interval 610 °C - 750 °C and significant Nb3Al growth is observed above 730 °C. Karppinen, M Andreev, N Apollinari, G Auchmann, B Barzi, E Bossert, R Kashikhin, V Nobrega, A Novitski, I Rossi, L Smekens, D Zlobin, A 2013 2013 The LHC collimation upgrade foresees two additional collimators installed in the dispersion suppressor regions of points 2, 3 and 7. To obtain the necessary longitudinal space for the collimators, a solution based on an 11 T dipole as replacement of the 8.33 T LHC main dipoles is being considered. CERN and FNAL have started a joint development program to demonstrate the feasibility of Nb$_{3}$Sn technology for this purpose. The program started with the development and test of a 2-m-long single-aperture demonstrator magnet. The goal of the second phase is the design and construction of a series of 2-m-long twin-aperture demonstrator magnets with a nominal field of 11 T at 11.85 kA current. This paper describes the electromagnetic design and gives a forecast of the field quality including saturation of the iron yoke and persistent-current effects in the Nb$_{3}$Sn coils. The mechanical design concepts based on separate collared coils, assembled in a vertically split iron yoke are also discussed. Otto, Th Scheuerlein, C Catherall, R Glaser, M Militaru, O Flükiger, R Ballarino, A Bottura, L IEEE Trans. Appl. Supercond. 10.1109/TASC.2012.2233263 6000504 23 2013 2013 Superconducting magnets based on Nb$_{3}$Sn technology are being developed for the LHC high luminosity upgrade. In this context irradiation induced changes of the superconducting properties of state-of-the-art Ti and Ta doped Nb$_{3}$Sn wires are presently studied. During irradiation tests with protons of 65 MeV at the cyclotron of Université Catholique de Louvain (UCL), 1.4 GeV at the CERN ISOLDE facility, and 24 GeV at the CERN IRRAD1 facility, the superconductor samples become radioactive and their handling must follow the legal specifications for radioactive materials. We have estimated the activation and the resulting ambient dose equivalent rate up to a fluence of 1017 p/cm2 with the Monte-Carlo Code FLUKA. The estimates were verified with experimental activation spectra. Samples for magnetization measurements with a mass of approximately 20 mg have to be considered as radioactive, but they do not have the potential to harm the operators handling them at radiation levels below 1 uSv/h. Larger samples (longer wires and sample holder materials like Cu and TiAl6V4) show correspondingly higher ambient dose equivalent rates and activation levels and they must be handled by radiation workers in designated areas, taking into account the standard precautions for work with radioactive materials. The use of radiation shielding during handling is recommended. Ferracin, P Devaux, M Durante, M Fazilleau, P Fessia, P Manil, P Milanese, A Munoz Garcia, J Oberli, L Perez, J Rifflet, J de Rijk, G Rondeaux, F Todesco, E IEEE Trans. Appl. Supercond. 10.1109/TASC.2013.2243799 4002005 23 2013 2013 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 Nb$_{3}$Sn 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 pre-tensioned 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. Savary, F Prin, H Perin, A Lackner, F 2013 2013 In 2013, a long shutdown of the Large Hadron Collider (LHC) at CERN will allow comprehensive maintenance plus consolidation of the machine components, in particular of the 13 kA circuits that feed the main superconducting magnets around the 27-km ring. This shutdown will prepare the accelerator for operation at nominal energy, 14 TeV, with adequate margin on the critical performance parameters. An essential part of the consolidation program consists of adding to the 13 kA splices of the magnet interconnects a copper shunt of high RRR (> 300) that will carry the current in the event of a busbar quench. An important R&D program was conducted in 2010 to design a sound solution for the shunt and for an improved insulation system. The development of the insulation system has required iterations aiming at adequate solution. The functional requirements for the insulation are a breakdown voltage of at least 3.1 kV in superfluid helium and sufficient mechanical strength to withstand stresses of the order of 50 MPa. The insulation system shall provide mechanical restraint for the shunted splices so that their transversal deflection is limited to 0.25 mm. This paper describes the final design of the insulation and the optimization process. The results from dielectric tests and numerical optimization of the insulation cover will be also presented. Finally the performance of the new insulation will be compared to the previous version. Bajas, H Ambrosio, G Anerella, M Bajko, M Bossert, R Caspi, S Chiuchiolo, A Chlachidze, G Dietderich, D Dunkel, O Felice, H Ferracin, P Feuvrier, J Fiscarelli, L Ghosh, A Giloux, C Godeke, A Hafalia, A Marchevsky, M Russenschuck, S Sabbi, G Salmi, T Schmalzle, J Todesco, E Wanderer, P Wang, X Yu, M 2013 2013 The HQ magnet is a 120 mm aperture, 1-meter-long Nb$_{3}$Sn quadrupole developed by the LARP collaboration in support of the High-Luminosity LHC project. Several tests were performed at LBNL in 2010-2011 achieving a maximum gradient of 170 T/m at 4.4 K. As a next step in the program, the latest model (HQ01e) was sent to CERN for testing at 1.9 K. As part of this test campaign, the magnet training has been done up to a maximum current of 16.2 kA corresponding to 85 % of the short sample limit. The ramp rate dependence of the quench current is also identified. The efficiency of the quench heaters is then studied at 4.2 K and at 1.9 K. The analyses of the magnet resistance evolution during fast current discharge showed evidence of quench whereas high energy quenches have been successfully achieved and sustained with no dump resistor. Allain, H Ambrosio, G Borgnolutti, F Cerutti, F Dietderich, D Esposito, L Felice, H Ferracin, P Sabbi, G Wanderer, P Van Weelderen, R Todesco, E 2013 2013 In this paper we outline the present status of the design studies for the high luminosity LHC, focusing on the choice of the aperture of the inner triplet quadrupoles. After reviewing some critical aspects of the design as energy deposition, shielding, heat load and protection, we present the main tentative parameters for building a 150 mm aperture Nb$_{3}$Sn quadrupole, based on the experience gathered by the LARP program in the past several years.