In the initial framework of HL-LHC project, a 90 mm Nb-Ti single aperture quadrupole short model with a gradient of 120 T/m at 1.9 K, has been designed, manufactured and firstly tested at 4.2 K as part of a collaboration between CERN and CEA. This magnet called MQYYM has been recently tested for the first time at 1.9 K and used as a reference magnet for the commissioning of the new CEA Paris-Saclay cryogenic test facility STAARQ (standing for test station for quadrupole accelerator magnets). This test station has been developed to test superconducting magnets up to 5 m-long at 1.9 K in a 1 bara helium bath with a lambda plate. Magnets can be powered up to 13 kA thanks to hybrid HTS current leads. It relies on digital and analog MSS (Magnet Safety System) for quench detection as well as on several types of instrumentation, from voltage taps and temperature sensors to strain gauges. This paper describes and analyzes the test results of MQYYM at 4.6 K and 1.9 K as part of the facility commissioning, with a special focus on mechanical measurements and protection results. In particular, it will conclude on the protection heater validation, necessary for the upcoming MQYY tests.

The MAgnetized Disc and Mirror Axion eXperiment (MADMAX) project aims at detecting axion dark matter in the mass range of 100 μeV. To do so, a dipole detector magnet producing 100 T 2 m 2 is needed. In the framework of an innovation partnership with the Max Planck Institute, CEA Paris-Saclay designed this large-scale magnet producing 9 T in a 1.35-m bore. The magnet is made of a cable in-conduit conductor, operating at 1.8 K. One of the main challenges of this novel design is to guarantee the magnet's safety toward quench management. In order to validate the magnet and conductor designs, a mock-up coil with a quench behavior scalable to MADMAX was designed, manufactured, and cold-tested. This article gives an overview of the main guidelines followed to design the prototype fully representative of the MADMAX quench behavior. The experimental facility, instrumentation, and protocol are presented. The main experimental results are given and extensively analyzed with empirical, analytical, and numerical approaches. This article presents the first experimental observation of the existence of the thermohydraulic quench back phenomenon in stagnant superfluid helium.

Neurospin is a neuroscience research center located in France at the Atomic Energy Commission (CEA Saclay). The facility is hosting an innovative whole-body 11.7 T MRI system that has delivered its first images in October 2021. The core part of the Iseult MRI is an actively shielded NbTi magnet cooled with a pressurized superfluid helium bath at 0.125 MPa and 1.8 K, providing a homogeneous magnetic field of 11.7 T within a 90 cm warm bore. After nearly twenty years of work and efforts, the magnet successfully reached its nominal field for the first time in July 2019. The field homogeneity has been adjusted and the control system tested against internal and external faults that could affect the future MRI operation. MRI peripheral equipment has been integrated and interactions between the gradient coils and the magnet and their impact on cryogenics and on the magnet safety system have also been studied. The MR scanner is now kept permanently at nominal field and the final calibration is on-going to prepare the first acquisition on a human volunteer. The paper will present the Iseult MRI commissioning status and the first images obtained, as well as a first feedback on the cryogenic plant operation after three years and a half at 1.8 K.

The Iseult whole-body MRI delivered its first images in October 2021. The masterpiece of this MRI is an actively shielded NbTi magnet providing a homogeneous magnetic field of 11.7 T within a 90 cm warm bore. A dedicated cryoplant was constructed to cool the magnet at 1.8 K using a superfluid helium bath and it is in nominal operation since March 2019. This paper will present the cryoplant design, as well as the connection of the cryogenic ancillary equipment with the magnet. Estimated thermal losses will be compared with experimental data collected since the beginning of the cooling phase. Then, we will describe the system maintenance and the periodic controls of the various pressurized components performed keeping the continuous nominal operation of the MRI. Finally, we will present the first lessons learned on this unique cryogenic system operation and possible options to improve its reliability.

For the HL-LHC project, a 90 mm NbTi cos(2θ) double aperture quadrupole magnet with an operating gradient of 120 T/m at 1.9 K has been designed as an option to replace the 70 mm aperture LHC quadrupole MQY. CEA in collaboration with CERN designed and manufactured a single aperture short model magnet with a magnetic length of 1.215 m at 1.9 K called MQYYM. The MQYYM cold test occurred at CEA at 4.2 K in a vertical cryogenic station. During the power test, the operating gradient at 1.9 K has been reached after two training quenches. All along the test, magnetic and mechanical measurements were done using respectively a rotating probe and strain gauges. This paper describes the performance of the MQYYM at 4.2 K and gives an analysis of the data acquired during the test, including training behavior, quench detection, protection and field quality measurements.

The Grenoble Hybrid magnet is a modular platform using resistive and superconducting technologies to produce various continuous high magnetic field and flux configurations for the scientific community. They range from 43 T in 34 mm diameter with 24 MW electrical power to 9 T in 800 mm diameter when the superconducting coil is used alone. Thanks to the ongoing upgrade of the electrical power installation of LNCMI-Grenoble up to 30 MW and possibly to 36 MW, the possibility to increase the total field up to 45-46 T in the near future is foresee and deeply studied. The key design parameters will be briefly recalled including the specifically developed Nb-Ti/Cu conductor, the large bore outsert superconducting coil, the magnet cryostat with its structure including the eddy-current shield, the cryogenic line for the interconnection with the cryogenic satellite and the fully dedicated 150 l/h He liquefaction plant. All components of the hybrid magnet platform have been built, tested and delivered to LNCMI-Grenoble, where integration and assembly are ongoing. The status of the project will be given with focus to the recent commissioning tests of the cryogenic satellite producing the pressurized superfluid He at 1.8 K as well as to the successful powering tests of the specially developed current leads at ultimate current and under fully degraded cooling conditions simulating the worst-case accidental scenario.

The Grenoble Hybrid magnet is a modular platform using resistive and superconducting technologies to produce various DC high magnetic field and flux configurations for the scientific community. They range from 43 T in 34 mm diameter with 24 MW electrical power to 9 T in 800 mm diameter when the superconducting coil is used alone. Thanks to the ongoing upgrade of the electrical power installation at LNCMI-Grenoble to 30 MW, and possibly to 36 MW, the opportunity to increase the total field well above 45 T in the near future is anticipated and studied in detail. The key design parameters will be recalled comprising the specifically developed Nb-Ti/Cu conductor, the large-bore outsert superconducting coil, the magnet cryostat with its structure including the eddy-current shield, the cryogenic line for the interconnection with the cryogenic satellite and the dedicated 150 l/h He liquefaction plant. All components of the superconducting part of the hybrid magnet platform have been built, tested and delivered to LNCMI-Grenoble, where integration and final assembly are continuing. The status of the project will be presented with the main problems encountered and solved. It includes the recent commissioning tests of the cryogenic satellite producing the pressurized superfluid He at 1.8 K as well as the successful powering tests of the specially developed current leads at ultimate current and under fully degraded cooling conditions simulating the worst-case accidental scenario.

Based on a close collaboration between CEA and CNRS, a new hybrid magnet is being built at LNCMI-Grenoble. By combining a resistive insert, which is made of Bitter and polyhelix coils, with a large bore superconducting outsert, an overall continuous magnetic field of at least 43 T will be produced in a 34-mm warm bore aperture. The superconducting coil relies on the novel development of a Nb-Ti/Cu Rutherford cable-on-conduit conductor cooled down to 1.8 K by a bath of superfluid helium at atmospheric pressure and will produce a nominal magnetic field of 8.5 T in a 1.1-m cold bore diameter. After thorough reviews of the hybrid magnet design, which have anticipated possible upgrades of the maximum magnetic field produced, the project has entered in its production phase. The status and the next steps of the project will be reviewed highlighting the remaining technical challenges.

A new innovative whole-body 11.7-T MRI magnet is currently being manufactured at Alstom Belfort as part the Iseult/Inumac project, a French-German initiative focused on very high magnetic field molecular imaging. It will be installed at the end of year 2016 in a neuroscience research center with other very high field MRI equipment, operating in France at CEA Saclay since November 2006. The main coil constructed from a stack of 170 double pancakes of 2-m diameter, with a finished height of 4 m and 50 t in weight, has been completed within required tolerances. The two shielding coils, vacuum impregnated solenoids of 4 m in diameter and 10 t in weight, have been also completed within tolerances. A crack has been discovered inside the 2-m diameter mandrel of the cryogenic correction coils. A new mandrel has been manufactured, with delivery in July 2015. The main coil and the shielding coils have been integrated inside the helium vessel, and the assembly of thermal shield and vacuum vessel is due to start, with completion expected by the middle of 2016. The magnet will be serviced by a separate cryogenic and electrical facility; the installation of this external equipment will be completed by the end of 2015 when the first phase of the commissioning will start. Full tests and commissioning of the magnet at 1.8 K are expected at NeuroSpin at the beginning of 2017.

A neuroscience research center with very high field magnet resonance imaging (MRI) equipment has been opened in November 2006 in the Neurospin site of French Atomic Energy and Alternative Energies Commission (CEA, Saclay, France). One of the imaging systems, the so-called Iseult project, will require a whole body 11.75 T MRI magnet with a 900-mm warm bore. The coil is made of a niobium-titanium conductor cooled by a He II bath at 1.8 K, permanently connected to a cryoplant. The main coil is made of a stack of 170 double pancakes submitted to a peak field up to 12 T. A demonstrator made of six reduced double pancakes using the conductor developed for this project has been designed, manufactured, and tested at CEA/Saclay. The objective was to demonstrate that the Iseult main coil winding pack is able to sustain the high stress level calculated, 170 MPa azimuthally and 110 MPa radially. This demonstrator has been successfully energized up to 6000 A in a background field. A maximum azimuthal stress of 225 MPa has been reached, much higher than the nominal Iseult value. This paper presents the design, the manufacturing, and the cryogenics test results of this demonstrator.

The Whole Body 11.7 T MRI Magnet is an actively shielded magnet system, with a stored energy of 338 MJ and an inductance of 308 H. Operating at a homogeneous field level of 11.75 T within a 90 cm warm bore, the cryostat has external dimensions of 4.8 m in diameter and 5.0 m in length. It is part of the Iseult/Inumac project, a French-German initiative focused on very-high-magnetic-field molecular imaging to improve sensitivity, spatial, temporal, and spectral resolution for preclinical and/or clinical MR systems. After the qualification of two first unit lengths of 820 m, the NbTi conductor with a current of 1483 A is now being produced at Luvata Waterbury. Winding of the main coil, made of 170 double pancakes, is starting at Alstom Belfort. Several pieces of equipment have already been delivered to the Neurospin site, CEA Saclay,; including the main refrigerator produced by Air Liquide. Several prototypes have been tested and confirmed the soundness of the magnet design. This paper describes the 11.7 T magnet and the latest progress in its design and fabrication.

The construction, commissioning, and operation phases of the W7-X cryomagnetic test facility in CEA Saclay lasted ten years. The large diversity of equipments called, specialties involved and problems solved attest the expertise that was required to operate the test facility and test the coils. Nearly one hundred cryogenic tests were performed on the seventy W7-X coils, at a rate always increasing, using two cryostats each holding two coils.This paper presents the test facility and its operation first, the cryogenic difficulties that were confronted with their solutions, the electro-magnetic difficulties encountered along with corrective actions, and finally the instrumentation and data acquisition aspects. (C) 2011 Elsevier Ltd. All rights reserved.

In the framework of the Broader Approach Activities, the EU will deliver to Japan the 18 superconducting coils, which constitute the JT-60SA Toroidal field magnet. These 18 coils, manufactured by France and Italy, will be cold tested before shipping to Japan. For this purpose, the European Joint Undertaking for ITER, the Development of Fusion Energy ("Fusion for Energy", F4E) and the European Voluntary Contributors are collaborating to design and set-up a coil test facility (CTF) and to perform the acceptance test of the 18 JT-60SA Toroidal Field (TF) coils. The test facility is designed to test one coil at a time at nominal current and cryogenic temperature. The test of the first coil of each manufacturer includes a quench triggered by increasing the temperature. The project is presently in the detailed design phase. (C) 2011 Elsevier B.V. All rights reserved.

Quench experiments were performed in the CEA Saclay facility on the Seht superconducting magnet. The Seht facility is part of the Iseult R&D program. Seht is an 8-T coil wound in sixty double pancakes using NbTi conductor. The coil is cooled by steady state superfluid helium at 1.8 K and 1.2 bar. Instrumentation, inside the coil and in the helium bath, includes voltage taps, pressure and temperature sensors, as well as flow meters. The major issues in the Seht experiments will be addressed here: the normal zone propagation in the coil during quench and the pressure and temperature rise in the helium.

As part of the Iseult/Inumac project, the development of a 500 MHz whole body MRI magnet has been launched in 2006. This magnet with a central field of 11.7 T in a warm bore of 900 mm has outstanding specifications with respect to usual MRI systems. The normal operation of this magnet will need the construction of a cryoplant able to cool its superconducting coils with pressurized HeII 1.8 K. A helium liquefier and 4.2 K/1.8 K refrigeration stage will be installed in the vicinity of the magnet. Before that, a magnet test facility (Seht-"station d'essais huit teslas") installed at CEA/Saclay has been built in order to validate technical and control-process aspects during all operating phases: cooling down, nominal operation, quench event. The cryogenic system has been designed according to the principles foreseen for Iseult. The facility integration, commissioning, and operating results will be presented. The design of the final cryogenic installation for Iseult magnet, adapted to the facility experiences, is previously described.

A neuroscience research center with very high field MRI equipments has been opened in November 2006 by the CEA life science division. One of the imaging systems will require a 11.75 T magnet with a 900 mm warm bore. Regarding the large aperture and field strength, this magnet is a real challenge when compared to the largest MRI systems ever built, it is being developed within an ambitious R&D program, Iseult, focused on high field MRI. The conservative MRI magnet design principles are not readily applicable, other concepts taken from high energy physics or fusion experiments, namely the Tore Supra tokamak magnet system, will be used. The coil will thus be made of a niobium-titanium conductor cooled by a He II bath at 1.8 K, permanently connected to a cryoplant. Due to the high level of stored energy, about 340 MJ, and a relatively high nominal current, about 1500 A, the magnet will be operated in a non-persistent mode with a conveniently stabilized power supply. In order to take advantage of superfluid helium properties and regarding the high electromagnetic stresses on the conductors, the winding will be made of wetted double pancakes meeting the Stekly criterion for cryostability. The magnet will be actively shielded to fulfill the specifications regarding the stray field. In order to develop the magnet design on an experimental basis, an ambitious R&D program has been set-up based on magnet prototypes, high field test facility (Seht) and stability experiments. The main results from these experiments and their impact on the Iseult magnet design will be discussed.

A new innovative Whole Body 11.7 T MRI magnet is currently being manufactured at Alstom Belfort as part of the Iseult/Inumac project, a French-German initiative focused on very high magnetic-field molecular imaging. It will be installed in 2015 in a neuroscience research center with other very high field MRI equipment, operating in France at CEA Saclay since November 2006. This actively shielded magnet system, manufactured from NbTi superconductor, will generate a homogeneous field level of 11.75 T within a 90 cm warm bore, and will operate at a current of 1483 A, in driven mode, in a bath of superfluid LHe at 1.8K. The stored energy is 338 MJ and the inductance 308 H. The cryostat has external dimensions of 5 m in diameter and 5.2 m in length, for a total weight of the magnet of 132 tons. Before the start of the magnet manufacturing, developments made on prototypes have confirmed a specific set of design and manufacturing options including the conductor choice and the proposed cryogenic and electrical schemes. The main coil is wound as double pancakes laterally wetted by HeII. The magnet is serviced by a separate cryogenic and electrical facility forming an integral part of the installation. The developments and the magnet manufacturing have been supervised by an independent Magnet Advisory Committee. Full-scale serial production of the 170 double pancakes which form the main coil package has been finished by Alstom. The main coil is being assembled and the cryostating of the magnet should be finished by the middle of 2015. Full tests and commissioning of the magnet at 1.8K at Neurospin are expected in 2015.

Neurospin, a neuroscience research centre with very high field MRI equipments, just opened in November 2006 at Saclay by the CEA life science division. One of the imaging systems will require an 11.7 T magnet with a 900 mm warm bore. This magnet is currently under development at CEA Saclay, in collaboration with Siemens Medical Solutions and Alstom Magnets and Superconductors, within the framework of the French-German consortium Iseult/INUMAC (Imaging of Neuro disease Using high field. MAgnetic resonance and Contrastophores). The main aim of the consortium is to promote magnetic resonance and molecular imaging within high magnetic fields. The proposed magnet design is based on conservative options, but definitely unusual construction methods, for an MRI magnet (pancake winding, liquefier, stabilized power supply). These key design points therefore need to be assessed with several prototypes, integrated within a 5 years projected development plan, ending in 2011. The paper will present the objectives of the project as well as the main characteristics of the magnet and its development plan.

The upgrade of JT-60U to JT-60 Super Advanced (JT-60SA), a fully superconducting tokamak, will be performed in the framework of the Broader Approach (BA) agreement between Europe (EU) and Japan. In particular, the Toroidal Field (TF) system, which includes 18 coils, is foreseen to be procured by France, Italy and Germany. This work covers activities from design and manufacturing to shipping to Japan. The present paper is mainly devoted to the analyses that lead to the conductor design and to the technical specifications of the joints for the JT-60SA TF coils. The conductor geometry is described, which is derived from Cable-In-Conduit concept and adapted to the actual JT-60SA tokamak operating conditions, principally the ITER-like scenario. The reported simulations and calculations are particularly dealing with the stability analysis and the power deposition during normal and off-normal conditions (AC losses, nuclear heating). The final conductor solution was selected through a trade-off between scientific approach and industrial technical orientation. Besides, the TF system connections layout is shown, derived from the industrially assessed twin-box concept, together with the associated thermo-hydraulic calculations ensuring a proper temperature margin.