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As a part of the future circular collider conceptual design study for hadron-hadron physics (FCC-hh), conceptual designs of detector magnets are being developed to facilitate the measurement of particle products resulting from the 100-TeV collisions. This paper discusses the design evolution leading from a 65-GJ twin solenoid with forward dipoles design to the present baseline design that features three superconducting solenoids. The central magnet produces 4 T over a free bore of 10 m and a length of 20 m. The forward solenoids provide additional bending power to facilitate tracking of high-pseudo-rapidity particles. The combined stored energy of this system is 13.8 GJ. This design is discussed in terms of powering and quench protection, conductor composition, mechanical properties of the cold masses and vacuum vessels, stray fields, and heat loads. In addition, alternative designs are discussed, including an ultrathin superconducting solenoid concept with comparatively low stored magnet energy. Like the ATLAS central solenoid, this solenoid provides a magnetic field to the tracker, and particles have to tunnel through the solenoid before reaching the calorimeters. An iron yoke returns the flux, thus providing bending power for muon tagging and giving complete magnetic shielding.

As part the Iseult/Inumac project, a French-German initiative focused on very high magnetic-field molecular imaging, the Whole Body 11.7 T MRI Magnet currently under development is the world's largest to-date. It is an actively shielded magnet system, manufactured from NbTi superconductor, with a homogeneous field level of 11.75 T within a 90 cm warm bore. It will operate at a current of 1483 A, in nonpersistent mode, in a bath of superfluid LHe at 1.8 K. 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, the total weight of the magnet is 132 tons. The magnet is serviced by a separate cryogenic and electrical facility forming an integral part of the installation. It is currently being manufactured at Alstom Belfort under the supervision of CEA Saclay. Several reduced scale prototypes, each addressing a specific set of design and manufacturing risks, have been tested. Full-scale serial production of the 170 double pancakes that form the main coil has been finished by Alstom. The project plan includes finishing the cold mass and cryostat assembly in May 2014. Full tests and commissioning of the magnet at 1.8 K will be performed at the Neurospin center upon completion of assembly. The paper reviews the manufacturing status of the 11.7 T magnet and its dedicated equipment.

An ATLAS Barrel Toroid conductor was tested in the Saclay High Current Test Facility. The conductor is a Nb-Ti Rutherford cable imbedded in a high purity aluminum stabilizer. The conductor's width was reduced from 57 mm to 30 mm in order to be able to use an existing sample holder. We tried to measure the critical current in background fields of up to 3 T. The field was produced by a 0.8 m long superconducting dipole magnet. The test station was equipped with a superconducting transformer transferring maximum primary and secondary currents of respectively 174 A and 80 kA. The secondary current was measured with flux coils and with a superconducting Direct Control Current Transducer (DCCT), a modified version of the “Macc+” 600 A commercial DCCT from Hitec, which was operated at currents of up to 57 kA. This paper reports on the performance of the test station, on the results of the quench current measurements performed on the stabilized ATLAS conductor and on the difficulties to measure the critical current of an aluminum stabilizer conductor.

Large quantities of NbTi-based superconductors have been produced for the 11.75 Tesla whole body magnetic resonance imaging project called the Iseult/INUMAC managed by CEA Saclay. The magnet is designed to operate at 1.8 K. Production consisted of nearly 65 t (170 km) of a large 9.2 mm × 4.9 mm Rutherford cable-in-channel for the main coil and 22 t (58 km) of a 9.1 mm × 4.2 mm wire-in-channel for the shield. These have been successfully manufactured, inspected, and delivered. The key technical requirements were dimensional precision, superconducting properties, RRR, and tensile strength. An extensive quality assurance program was instituted to guarantee the final conductor performance. Measured degradation in superconducting characteristics due to cabling and solder integration were negligible (

A neuroscience research center with a very high field magnetic resonance imaging (MRI) equipment was opened in November 2006 in the Neurospin site at CEA Saclay. One of the imaging systems requires a whole body 11.75 T MRI magnet with a 900 mm warm bore. Operating at a homogeneous field level of 11.75 T, the cryostat has external dimensions of 4.8 m in diameter and 5.0 m in length. With the large aperture and high field strength, this magnet represents a real challenge when compared to the largest MRI systems ever built. The coil is made from a copper-stabilized niobium-titanium conductor cooled by a superfluid helium bath at 1.8 K and permanently connected to a cryo-plant. The main coil is constructed from a stack of 170 double pancakes and the magnet is actively shielded by two large coils connected in series to fulfill the stray field specifications. The two shielding coils, each of about 4 m in diameter, are presently being manufactured by Alstom Power Systems STTG Magnets, Belfort. This paper describes the design of these coils and presents the latest progress of their fabrication. Details are given of the winding technique, impregnation method, and the first results of electrical and geometrical tests.

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.

The Iseult system is a highly homogeneous 11.7 T superconducting magnet. This high field 900 mm warm bore coil will provide the main field of the Iseult/Inumac MRI system, dedicated to the Neurospin center of the CEA life science division. The cold mass structure of the magnet is designed to support and accurately locate the central and shielding coils. The main winding is made of a 3.8 m length stacking of 2 m outer diameter double-pancakes. Under self load, the axial compression of the main coil reaches 8100 t. The two shielding coils are 4 m outer diameter short length solenoids. The cold mass assembly consists of the main coil suspension and preload system, surrounded by the shielding coils casing. It weighs 105 t with envelop dimensions of 4 m diameter × 4 m length. The engineering design of the cryostat has been carried out. This paper gives a description of the system, and an overview of the mechanical behavior of the cold mass assembly.

In the framework of the French-German consortium Iseult/INUMAC, focused on very-high-magnetic-field molecular imaging, the development of an 11.7 T whole body MRI magnet has been launched in 2006. This magnet is mainly composed of one wet and cryostable main coil and two fully impregnated coils that shield the magnetic field in order to meet the security requirements on the fringe field. To protect the magnet in case of quench, the stored magnetic energy (338.5 MJ) is dissipated in an external resistor and inside the two shielding coils windings. It is thus an important issue to master the normal zone propagation kinetics in those coils. This paper presents the 3d finite-element computations carried out to treat that problem and the more significant obtained results.

A Whole Body 11.7 T MRI Magnet is presently being developed at the CEA Saclay for 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. The magnet will be installed at the Neurospin center, Saclay, in 2012. This actively shielded magnet system, with a stored energy of 338 MJ and an inductance of 308 H, has external dimensions of 5 m in diameter and 5.2 m in length. The magnet will operate at a homogeneous field level of 11.75 T within a 90 cm warm bore and at a current of 1483 A. The technological choice for the cryostable winding is a double pancake structure, using NbTi conductors cooled with a pressurized bath of Helium II at 1.8 K. In April 2009, the project passed an important milestone with the publication of the Technical Design Report, which defines the engineering parameters, design of the magnet, and establishes its engineering feasibility. In the paper, the status of the 11.7 T magnet is reviewed and the future developments are presented.

The ATLAS Experiment at the LHC (CERN) has a toroidal magnet system composed of one barrel toroid and two end cap toroids powered in series at 20.5 kA with a total stored energy of 1.6 GJ. So far the three magnets have been tested independently. In preparation of the overall magnet system test, here we review the quench behavior under normal and faulty conditions including the information gained from the test of the three single magnets. In particular the consequences of variations in effective quench detection and quench heater activation times are studied. The effects on energy re-distribution, peak temperatures and internal voltage in the three toroids and between the 8 coils within a single toroid are investigated. Based on simulation studies partly verified by experiments, conclusions regarding the quench performance of the entire system are drawn.

The air-core Barrel Toroid of the ATLAS Detector at the CERN Large Hadron Collider, is the largest superconducting magnet ever built. This muon-spectrometer magnet consists of 8 discrete coils, arranged symmetrically around the beam axis. The average field is 0.5 T, and the stored energy 1.1 GJ. The windings are 25 m long, 5 m wide and 0.4 m thick. Each coil cold mass consists of 2 double pancakes of aluminum-stabilized NbTi conductor securely fixed in an aluminum alloy casing. Before assembly, each coil is tested individually in the presence of a magnetic mirror to simulate the magnetic forces exerted on the tie rods. This mirror is composed of several iron plates made of magnetically non-linear material. Each coil is enclosed in a separate, stainless-steel cryostat with relative magnetic permeability slightly larger than 1. In this paper the magnetic field distribution and Lorenz forces between the magnetic mirror and the coil in centered and shifted positions are presented. The magnetic influence of the cryostat on the field distribution is also discussed.

The ATLAS Barrel Toroid, the largest toroid ever built with 1.1 GJ stored energy, has been successfully tested after installation in the underground cavern in fall 2006. The eight coils of the Barrel Toroid were tested individually before and showed fully acceptable performances. We observed only one training quench during an individual coil test (at 30 A below the maximum test current) and no training during the test of the fully assembled toroid. At currents up to the nominal value of 20.5 kA, the toroid has been quenched inducing normal zones by means of heaters or by stopping the helium flow in the current leads. The quench safety system worked perfectly. Given the safe peak temperatures measured in the cold mass following various quenches, it is concluded that the Barrel Toroid can be operated safely. In this paper, the hot spot of the toroid is presented in detail: the measurement data are compared to various theoretical models.

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 as compared to the largest MRI systems ever built, and is then developed within an ambitious R&D program, Iseult, focus on high field MRI. The conservative MRI magnet design principles are not readily applicable and 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.

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.

Each of the eight huge coils of the Barrel Toroid of the ATLAS detector consists of two double pancakes which are embedded in an aluminum alloy coil casing. The 57 mm times 12 mm sized conductor is a Rutherford cable with NbTi-Cu strands co-extruded with a high purity aluminum stabilizer. The race track coils have overall dimensions of 25 m times 5 m and the length of the conductor in the windings is 6.7 km. The coils are conduction cooled with forced flow helium. The nominal operating current is 20.5 kA and the nominal ramp rate is 4 A/s. During the test program of the individual coils the ramp losses are measured to confirm that they do not exceed the design cooling capacity of the ATLAS cryogenic system. The losses are determined from the amount of evaporated helium in the return flow. The ramp losses in the conductor consist of the hysteresis and coupling current losses in the Rutherford cable and eddy current loss in the pure aluminum stabilizer. Ohmic losses are generated in the coil casing which acts as a low resistive secondary of a transformer formed by the coil and the casing. In this paper the results of the loss measurements on the different coils, with different RRR (residual resistance ratio), are presented. Measurements are performed at various ramp rates. The results are in good agreement with the calculated losses, which are dominated by the loss in the coil casing

Each superconducting coil of the ATLAS Barrel Toroid has to pass the commissioning tests on surface before the installation in the underground cavern for the ATLAS Experiment at CERN. Particular acceptance criteria have been developed to characterize the individual coils during the on-surface testing. Based on these criteria and the limited time of the test, a compressed test program was proposed and realized. In only a few cases some additional tests were required to justify the coil performance and acceptance. In this paper the analysis of the test results is presented and discussed with respect to the acceptance criteria. Some differences in the parameters found between the identical coils are analyzed in relation to coil production features

The last two years have seen the completion of the integration and the cryostating of 8 superconducting coil windings for the ATLAS Barrel Toroid air-core magnet (BT). The Barrel Toroid is a 20 m in diameter, 25 m long and 5 m wide superconducting magnet for ATLAS, one of the two experiments dedicated to the search of the Higgs boson, which will be installed on the LHC ring at CERN in 2006. The paper presents the last steps of this integration progress which ends with the cold acceptance tests. A special emphasis is put on the integration of the cold mass into the vacuum vessel. The integration of the windings in their coil casings has been completed in October 2003 and the last coil cryostating was performed in June 2005. The BT coils are now being installed in the ATLAS cavern at CERN

The ATLAS Barrel Toroid consists of 8 racetrack coils symmetrically placed around the LHC beam axis. The coil dimensions are 25-m of length, 5-m of width and 1-m of thickness. Each cold mass is held in its cryostat by different types of supports. The paper describes the design, the tests and the behavior of each element during on surface test of individual coils

The ATLAS Barrel Toroid, part of the ATLAS Detector built at CERN, is comprised of 8 coils symmetrically placed around the LHC beam axis. The coil dimensions are 25 m length, 5 m width and 0.4 m thickness. Each coil cold mass consists of 2 double pancakes of aluminum stabilized NbTi conductor held in an aluminum alloy casing. Because the magnet is conduction cooled a good bonding between the superconducting winding and the coil casing is a basic requirement. Due to the high load level induced by the Lorentz forces on the double pancakes, a pre-stressing technique has been developed for the assembling of the double pancake windings in the coil casing. This prestressing technique uses inflatable bladders made of extruded aluminum tubes filled with glass microballs and epoxy resin then cured under pressure. The paper describes the design of the system as well as the problems occurred during the assembling of the 8 superconducting ATLAS coils and the ATLAS B0 prototype coil, and the behavior of the Barrel Toroid coils with respect to this prestress during the cold tests

The ATLAS B0 model coil has been extensively tested, reproducing the operational conditions of the final ATLAS barrel toroid coils (ten Kate, 1999). Two test campaigns have taken place on B0, at the CERN facility where the individual BT coils are about to be tested. The first campaign aimed to test the cool-down, warm-up phases and to commission the coil up to its nominal current of 20.5 kA, reproducing Lorentz forces similar to the ones on the BT coil. The second campaign aimed to evaluate the margins above the nominal conditions. The B0 was tested up to 24 kA and specific tests were performed to assess: the coil temperature margin with respect to the design value, the performance of the double pancake internal joints, static and dynamic heat loads, behavior of the coil under quench conditions. The paper reviews the overall test program with emphasis on second campaign results not covered before.

ATLAS is one of the two experiments dedicated the search of the Higgs boson, which will be installed on the LHC ring at CERN in 2006. The ATLAS barrel toroid air-core magnet (BT) is 20 m in diameter and consists of 8 superconducting coils, each one 25 m long and 5 m wide. After several years of technological development, the major concepts have been proved in 1999/2000 during the construction of the B0 prototype; a technological model for BT. The delivery by several European industrial companies of all the major components for BT is nearly finished. The eight BT coils are now being integrated at CERN. The paper presents a general overview of the component manufacturing and integration progress. A special emphasis is put on the major component delivery (conductor, double pancake windings, aluminum coil casing and cryostat) together with a description of the two phases of the integration process: integration of the windings into their coil casings and integration of the cold mass into the vacuum vessel. The integration of the windings in their coil casings will be completed in October 2003. The closure of the first cryostat is planned for the end of the year. The start of the first cold test and the assembly in the cavern is foreseen for the beginning of 2004.

The 9-m long superconducting model coil B0 was built to verify design parameters and exercise the construction of the Barrel Toroid magnet of ATLAS Detector. The model coil has been successfully tested at CERN. An intensive test program to study quench propagation through the coil windings as well as the temperature distribution has been carried out. The coil is well equipped with pickup coils, voltage taps, superconducting quench detectors and temperature sensors. The current is applied up to 24 kA and about forty quenches have been induced by firing internal heaters. Characteristic numbers at full current of 24 kA are a normal zone propagation of 15 m/s in the conductor leading to a turn-to-turn propagation of 0.1 m/s, the entire coil in normal state within 5.5 s and a safe peak temperature in the windings of 85 K. The paper summarizes the quench performance of the B0 coil. Based on this experience the full-size coils are now under construction and first test results are awaited by early 2004. 7 Refs.

In order to measure high current (several tens of kilo Ampere) at low temperature (down to 4.2 K), we have developed collaboration with Hitec Power Protection (Netherlands ex. Holec). This company sell the Macc+ (a low cost Direct Current Control Transformer) which measures up to 600 A (AC and DC) at 300 K. Several limitations of the standard Macc+ will be pointed out to find the adapted solutions for the different user conditions (temperature, current level and background magnetic field). With some minor modifications to the standard produce, we could place the torus sensor at low temperature and we measured up to RA in liquid helium at low field. Analysis of the behavior of the device in nonstandard conditions and experimental results will be reported. With more modifications, we could measure up to 38 kA at 4.2 K in a 0.5 T-background magnetic field.

A high DC current (100 kA-design) test facility for superconducting material is under realisation. Aluminum stabilised conductor (as for LHC detectors) can be tested Including the stabiliser in a 4.75 T dipole field of 0.8 m length which can be rotated in both cable perpendicular directions. A superconductor transformer creates the high current with a primary current from -200 A to +200 A. The output power useable is 25 kJ so that junctions between cables or conductors can be measured at high current. Samples, with a cross sections up to 12 mm/spl times/30 mm, were 0.8 m long and were equipped with soldered cables of 0.4 m length at both ends. To test different samples without warming the dipole magnet, samples are placed in a separate dewar. The conception design is described and the first results without external dipole magnetic field are reported.

The B0 coil is a technological model for the ATLAS Barrel Toroid coils. The major concepts and the construction procedures are the same as those specified for the BT coils. So the manufacturing feasibility has been extensively proved and the technological developments have been carried out for the industrial production of the conductor, the welding technique of the coil casing, the prestress of the coil with bladders, the cold to warm supports, the construction and assembly of the cryostat. The paper illustrates all these phases.

The production of the conductor for the superconducting toroids of the ATLAS experiment at LHC (CERN) is under way. The conductor is obtained by coextruding a big Rutherford cable with very pure aluminium. All toroids, one Barrel Toroid (BT) and two End Cap Toroids (ECT), require a conductor with a critical current of about 60 kA at 5 T, 4.2 K and a RRR in excess of 800 (at zero field), together with a very good bonding between cable and aluminum: 20 MPa for the BT and 15 MPa for the ECT. So far four long lengths, approximately 7 km out of the 90 km of the total need, have been successfully produced, thus demonstrating the feasibility of the process. The paper describes the results of the R&D phases and the results obtained in this first production. The critical current degradation due to cabling and coextrusion was found quite moderate (7-8% in total), despite the low copper content of the strands (Cu:NbTi=1.09-1.18). The bonding was also very good with values well in excess of the specification. A special control system based on continuous ultrasonic inspection was used in the coextrusion line to monitor the bonding quality in real time during production.

A permanent magnet motor with a superconducting armature has the high current densities of superconductors and the simplicity of a cooled rotating permanent magnet inductor to benefit from the better magnetic properties of rare earth magnets when the temperature decreases. A small-scale model has been developed to prove the experimental feasibility and to study its behavior. The layout of this eight-pole, 750-rpm, 15-kW machine is conventional with a horizontal axis and a rotating inductor. The three-phase winding was made with (6+1) cable of 0.25-mm-diameter strands comprising 597102 NbTi filaments. This model required a fiber glass composite helium cryostat. The helium enthalpy recovery from the helium vessel cools the NdFeB magnets. The cantilevered rotating part inside the armature facilitates the cooling. The machine has been assembled. The main cryogenic and first electrical tests are reported. The experimental demonstration of a superconducting permanent magnet motor has been proved with satisfactory operation. >

To produce a continuous magnetic field of at least 8.5 T in a 1.1 m cold bore diameter, the superconducting outsert of the Grenoble Hybrid magnet is based on the novel development of a Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled to 1.8 K by a bath of superfluid helium pressurized at atmospheric pressure. The main results of the conductor studies and development are presented after a brief introduction to the specificity of hybrid magnets, namely the electromagnetic couplings between resistive and superconducting coils. Results obtained with short samples of conductor are reviewed including the measurements of the elastic limit, AC losses, stability and critical current. The final specification of the RCOCC is presented highlighting the proposed method for the industrialization of the insertion process of the Rutherford cable on the hollow Cu-Ag stabilizer as well as its validation phase on short samples.

The R3B-Glad magnet is part of a large acceptance spectrometer devoted to the physics of exotic nuclei, under construction at CEA Saclay (France) for the future FAIR facility at GSI (Darmstadt, Germany). The R3B-Glad project is in its final phase where the magnet cold mass is achieved and will be tested at 4.6 K and nominal current in the fall of 2011. We present the results of the R&D tests programs that were implemented to answer some issues raised after the technical design review. First, this superconducting dipole will be cooled down by indirect cooling, and its 22 tons cold mass maintained at 4.6 K by means of a two-phase helium thermosiphon loop. An experimental model set-up has been specifically built to demonstrate the cooling efficiency despite the presence of large quasi-horizontal sections in the circuit. Then the superconducting Rutherford cable joints, required between the 26 coil double pancakes, were designed and tested to minimize their electrical resistance. Finally a reduced scale mock-up of a coil in its casing, with a general design similar to the final magnet, was tested at low temperature to validate the indirect cooling and the mechanical blocking system of the coil in its casing by differential thermal shrinkage. This test was performed at a higher current (8800 A) than the nominal one (3600 A) to reach the same value of temperature margin before quenching, together with similar high level of magnetic forces on the coil (100 to 200 t/m in final magnet).

The Iseult/INUMAC 11.7 T MRI magnet uses NbTi conductors larger than those typically used in conventional MRI magnets. The principal conductors are the main coil one, producing the magnetic field of 11.7 T and the conductor of the shielding coil that limits the fringe field. Both conductors are being produced by Luvata Waterbury Inc. The main coil conductor is a Rutherford cable in a copper channel (160 km) and carries 1500 A at 12 T and 2.8 K (2727 A at 9.5 T and 4.2 K). The shielding coil conductor is a wire in channel (60 km) and carries 2100 A at 5 T and 4.2 K. The conductor shape must be very precise with reproducible dimensions (tolerances below 15 microns) to enable good magnetic field homogeneity. They must also simultaneously exhibit a low electrical resistance (20 μΩ/m at 10 K and 12 T) and a high mechanical strength (σ0.2%>;250 MPa). Conductors of this industrial production are characterized by mechanical, electrical and geometrical measurements.

A CEA-CNRS French collaboration is currently developing a new hybrid magnet; this magnet combines a resistive insert composed of Bitter and polyhelix coils and a new large bore superconductor outsert to create an overall continuous magnetic field of 42+ T in a 34 mm warm aperture. The design of the superconducting coil outsert has been completed after thorough studies and successful experimental validation phases. Based on the novel development of a Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled down to 1.8 K by the mean of a bath of superfluid helium at atmospheric pressure, the superconducting coil aims to produce a continuous magnetic field of 8.5 T in a 1.1 m cold bore diameter. The main results of the final design studies of the superconducting coil are presented including the 2D and 3D mechanical stress analysis, the conductor and coil specifications, the coil protection system as well as the required cryogenics infrastructure. The final design of the resistive insert coils is also described.

The R3B-Glad magnet is part of a large acceptance spectrometer devoted to the physics of exotic nuclei, under construction at CEA Saclay (France) for the present GSI and the future Fair facilities (Darmstadt, Germany). In this paper is presented the fabrication of the cold mass (22 t), divided into three batches (coil manufacture, machining of coil casings, and integration of the coils inside their casings). The work began in January 2009 and ended in December 2010. A real size prototype coil, was developed to validate the winding process, with double pancakes assembled in a stacking tool, and the procedure for impregnating coils, inserted into a mold. After impregnation of the prototype and the first coil, a failing (short circuit between turns) was detected in both coils by electrical testing. The repair of various defects has been a success. Insulation reinforcements were performed on the following coils to avoid any further electrical default. The whole set of coils was wound and impregnated in 2010 (6 coils, about 3 meter long each). The casings are made of aluminum alloy 5083 (with the exception of a few pins, screws and bolts made of stainless steel) and machined from single blocks without welding. All parts were machined in two stages. The first step was a premachining to perform a blank assembly of the whole cold mass (performed in February 2010). The final machining was performed according to the actual dimensions of the manufactured coils, in order to get a perfect fit of the coils within their casings. The integration of the coils inside their casings (including shims setting, adjusting of pushing systems, bonding of drains and thermal sensors) occurred in autumn 2010. The set of coils in their casings was delivered to Saclay in December 2010.

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.