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The CERN Large Magnet Facility (LMF) is currently producing 5.5 m long 11 Tesla dipole and 7.2 m long MQXFB quadrupole coils for the HL-LHC project. Both coil types are fabricated with Nb3Sn conductor with the so-called wind and react technique. These coils require a vacuum pressure impregnation process to form the final insulation and to give the final dimensions. The paper will present the impregnation process applied at CERN focusing in particular on the hardware. The impregnation process and its reproducibility are shown, together with ongoing developments. Furthermore, the LMF impregnation infrastructure and recent applied upgrades are described, aiming for a reliable process workflow based on a modular hardware with an improved interchangeability.

Purpose To investigate the relationship between the microstructure of CAD/CAM blocks and the quality of adhesion as function of the surface treatment and resin cement type. Materials and methods Two nano-ceramic composite resin CAD/CAM blocks, Lava Ultimate (LU) and Cerasmart (CS), and two Leucite-reinforced glass ceramic CAD/CAM IPS blocks, Empress® CAD (EM) and InitialTM LRF (IR), received either Hydrofluoric acid (HF) or sandblasting (SB) surface treatments. The blocks were then luted using two dual-cure resin cements, LinkForce (LF) and Multilink Automix (ML) with their corresponding silanes, resulting in 16 study groups. The luted blocks were then thermal-cycling (TC) for 5000 cycles and subjected to a microtensile bond strength (μTBS) test. Scanning electron microscopy (SEM) micrographs of the treated surfaces were analyzed using ImageJ software and XRD analyses were performed for the two ceramic blocks. The data obtained were submitted to Games-Howell post-hoc nonparametric test to compare combinations of groups or treatments and a linear mixed-effects model for the factors surface treatment, block type, and resin cement, together with their first-degree interactions (α = 0.05). Results The lowest mean μTBS values were obtained with LU-HF, whereas the highest mean μTBS values were obtained with CS regardless of resin cement type and surface treatment method. IR-HF mean μTBS were significantly higher than IR-SB, EM-SB, and EM-HF. Analysis using ImageJ software demonstrated significant differences in the density and pore size after HF surface treatment. Conclusions The specific microstructure of each block material within the same family group impacted the micromechanical retention and the bonded interface strength.

The Nb3Sn FRESCA2 dipole magnet is dedicated to upgrade the CERN cable test facility FRESCA. It is also a technological demonstrator of large-aperture Nb3Sn accelerator magnet. It has an aperture of 100 mm and a target bore magnetic field of 13 T. It is composed of four 1.5-m-long double-pancake “block-type” coils, manufactured following the wind, react and impregnation technique. It is developed by CEA and CERN in the framework of a collaboration agreement, in the continuity of the EuCARD program. Through the fabrication of two full-scale copper prototypes, the different steps of the coil fabrication process (winding, heat treatment, splicing, instrumentation, impregnation, and transport) and the corresponding tooling have been adjusted. The final winding and reaction procedure integrates the possibility to open longitudinal gaps in the winding table and in the central post, in order to accommodate partially the longitudinal contraction of the cable during reaction. This new feature has been experienced through full-scale tests using superconducting cable with a reduced number of turns. This paper reports on the fabrication procedure of these coils. The production phase of the superconducting magnets has started in June 2015.

International audience; The Nb$_{3}$Sn dipole magnet FRESCA2 has been developed and manufactured within the framework of a collaboration between the Centre for Atomic Energy (CEA Saclay) and the European Organization for Nuclear Research (CERN). The aim of the magnet is to upgrade the superconducting cable test station at CERN with a Nb$_{3}$Sn dipole providing a 13-T magnetic field in a 100-mm aperture. The magnet is composed of four coils in a block-type configuration with flared ends, 1.6 m long, housed in a bladder, and key-type mechanical structure. A first assembly of the magnet, FRESCA2a, has been done at CERN at the end of 2016 with the four first Nb$_{3}$Sn coils fabricated at CEA Saclay and CERN. The coils were dimensionally measured, and tailored shims were fabricated and inserted in the coil pack to improve the contact between layers. In addition, tests with pressure sensitive films were carried out to verify the uniformity of the loading. The magnet was cold tested in February 2017 and dismounted to replace one coil. A second assembly, FRESCA2b, was produced and tested in August 2017. In this paper, we provide a detailed description of the various steps of the assembly from the impregnated coils to the delivery of the dipole to the test facility, with a particular emphasis on the procedures followed and the tooling developed.

The key objective of the High Field Magnet work package of the European Project EuCARD is to design and fabricate the Nb3Sn dipole magnet FRESCA2. It has an aperture of 100 mm and a target bore field of 13 T. The design features four 1.5 m long double-layer coils wound with a 21 mm wide cable. The project has now entered its experimental phase in view of the magnet fabrication. We present the experimental test campaign conducted on cable samples in order to understand and to control better the cable behavior and geometry. One full scale double-layer coil using copper cable with the final dimensions and insulation scheme has been wound and heat treated in order to check the fabrication process. This has given useful feedback on the fabrication procedure and on the expected magnet dimensions, as well as on the tooling itself.

Future high-energy accelerators will need very high magnetic fields in the range of 20 T. The Enhanced European Coordination for Accelerator Research and Development (EuCARD-2) Work Package 10 is a collaborative push to take high-temperature superconductor (HTS) materials into an accelerator-quality demonstrator magnet. The demonstrator will produce 5 T stand alone and between 17 and 20 T when inserted into the 100-mm aperture of a Fresca-2 high-field outsert magnet. The HTS magnet will demonstrate the field strength and the field quality that can be achieved. An effective quench detection and protection system will have to be developed to operate with the HTS superconducting materials. This paper presents a ReBCO magnet design using a multistrand Roebel cable that develops a stand-alone field of 5 T in a 40-mm clear aperture and discusses the challenges associated with a good field quality using this type of material. A selection of magnet designs is presented as the result of the first phase of development.

To investigate whether human intestinal epithelial cell survival involves distinct control mechanisms depending on the state of differentiation, we analyzed the in vitro effects of insulin, pharmacological inhibitors of Fak, MEK/Erk, and PI3-K/Akt, and integrin (β1, β4)-blocking antibodies on the survival of the well-established human Caco-2 enterocyte-like and HIEC-6 cryptlike cell models. In addition, relative expression levels of six Bcl-2 homologs (Bcl-2, Bcl-XL, Mcl-1, Bax, Bak, and Bad) and activation levels of Fak, Erk-2, and Akt were analyzed. Herein, we report that 1) the enterocytic differentiation process results in the establishment of distinct profiles of Bcl-2 homolog expression levels, as well as p125Fak, p42Erk-2, and p57Aktactivated levels; 2) the inhibition of Fak, of the MEK/Erk pathway, or of PI3-K, have distinct impacts on enterocytic cell survival in undifferentiated (subconfluent Caco-2, confluent HIEC-6) and differentiated (30 days postconfluent Caco-2) cells; 3) exposure to insulin and the inhibition of Fak, MEK, and PI3-K resulted in differentiation state-distinct modulations in the expression of each Bcl-2 homolog analyzed; and 4) Fak, β1 and β4 integrins, as well as the MEK/Erk and PI3-K/Akt pathways, are distinctively involved in cell survival depending on the state of cell differentiation. Taken together, these data indicate that human intestinal epithelial cell survival is regulated according to differentiation state-specific control mechanisms.

The small and large intestines differ in their expression profiles of Bcl-2 homologs. Intestinal segment-specific Bcl-2 homolog expression profiles are acquired as early as by mid-gestation (18-20 weeks) in man. In the present study, we examined the question whether such distinctions underlie segment-specific control mechanisms of intestinal cell survival. Using mid-gestation human jejunum and colon organotypic cultures, we analyzed the impact of growth factors (namely insulin; 10 microg/ml) and pharmacological compounds that inhibit signal transduction molecules/pathways (namely tyrosine kinases, Fak, P13-K/Akt, and MEK/Erk) on cell survival and Bcl-2 homolog expression (anti-apoptotic: Bcl-2, Bcl-X(L), Mcl-1; pro-apoptotic: Bax, Bak, Bad). The relative activation levels of p125Fak, p42Erk-2, and p57Akt were analyzed as well. Herein, we report that (1) the inhibition of signal transduction molecules/pathways revealed striking differences in their impact on cell survival in the jejunum and colon (e.g., the inhibition of p125Fak induced apoptosis with a significantly greater extent in the jejunum [approximately 43%] than in the colon [approximately 24%]); (2) sharp distinctions between the two segments were noted in the modulatory effects of the various treatments on Bcl-2 homolog steady-state levels (e.g., inhibition of tyrosine kinase activities in the jejunum down-regulated all anti-apoptotics analyzed while increasing Bax, whereas the same treatment in the colon down-regulated Bcl-X(L) only and increased all pro-apoptotics); and (3) in addition to their differential impact on cell survival and Bcl-2 homolog expression, the MEK/Erk and P13-K/Akt pathways were found to be distinctively regulated in the jejunum and colon mucosae (e.g., insulin in the jejunum increased p42Erk-2 activation without affecting that of p57Akt, whereas the same treatment in the colon decreased p42Erk-2 activation while increasing that of p57Akt). Altogether, these data show that intestinal cell survival is characterized by segment-specific susceptibilities to apoptosis, which are in turn linked with segmental distinctions in the involvement of signaling pathways and the regulation of Bcl-2 homolog steady-state levels. Therefore, these indicate that cell survival is subject to segment-specific control mechanisms along the proximal-distal axis of the intestine.

International audience; The FRESCA2 Dipole Magnet is developed within the framework of a collaboration between CEA Saclay and CERN, in the continuity of the European project EuCARD. The goal is to manufacture a dipole magnet providing a 13 T magnetic field in a 100 mm aperture for a superconducting cable test station at CERN. The magnet is composed of four double-layer $Nb_3Sn$ coils, arranged in a block-type configuration, with flared ends. Four $Nb_3Sn$ coils have been fabricated at CEA Saclay and CERN. This paper reports on the coil fabrication, describing the process, the issues encountered, and the solutions implemented. A series of geometrical and electrical characterizations were also performed on the coils in order to validate their quality. The coils are finally validated and ready to be assembled at CERN to form the magnet. The magnet assembly process is also described: the coils are assembled to form a coil pack, the coil pack is inserted in a shell-based support structure and pre-loaded at room temperature. The margins, expected in the different operation cases, are finally presented.