P. Bredy

SOLEIL synchrotron, Gif, Île-de-France, France

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Publications (62)36.64 Total impact

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    ABSTRACT: Within the framework of the Broader Approach Agreement, the Linear IFMIF Prototype Accelerator (LIPAc) has been launched with the objective to validate the low energy part (9 MeV) of the two IFMIF linacs (40 MeV, 125 mA of D+ beam in continuous wave). Starting in mid-2007, the project is managed by two Home Teams (JA-HT and EU-HT) and coordinated by the Project Team at the Broader Approach site in Rokkasho with the aim to complete the validation activity with the installation and commissioning of the whole LIPAc by June 2017. This paper describes the activities underway with a view to the arrival of the first components in Rokkasho at the beginning of 2013, following prior testing in Europe. After a presentation of the status of the accelerator components, the integration activities are described, such as the 3D mockup integration and the Interface Management System (IMS) tools developed for use at the Integrated Project Team level. In preparation of the delivery of the first components at the Rokkasho Broader Approach site, implementation and installation activities of the various components are described, in particular assembly procedures associated with each subsystem.
    Fusion Engineering and Design 10/2014; 88(9-10):2497-2501. · 0.84 Impact Factor
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 06/2014; 24(3):1-5. · 1.20 Impact Factor
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 06/2014; 24(3):1-6. · 1.20 Impact Factor
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    ABSTRACT: France is participating as one of the European vol-untary contributors to the joint Europe-Japan so-called Broader Approach (BA) activities in support of ITER and DEMO activities, consisting of three projects: the engi-neering design and validation of a 14-MeV-neutron ir-radiation facility (IFMIF-EVEDA), the building of the International Fusion Energy Research Centre (IFERC), and the ITER Satellite Tokamak Programme (STP–JT-60SA). This paper gives an overview of the French con-tributions to the BA projects and reports on the present status of these projects since 2007. Note: The figures in this paper are in color only in the electronic version.
    Fusion Science and Technology 03/2013; 64(November 2013):719. · 0.52 Impact Factor
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 06/2012; 22(3):4400804-4400804. · 1.20 Impact Factor
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    ABSTRACT: An experimental model has been studied to predict the pressure rise in the Iseult coil during a quench. The model is built of 10 copper equivalent pancake slices and 7 helium channels per pancake. The heat produced by a quench of the Iseult magnet is simulated by electrical heaters put inside each copper plate. Cryogenic pressure and temperature sensors have been fitted in the helium channels and in the bath. The model is cooled by pressurized superfluid helium at 1.8 K. Bath pressure measurements are given for various heating powers and various numbers of heated plates. A scaling law is put forward to extrapolate the model results to the Iseult pressure rise during a quench. Then the hydraulic circuit is numerically simulated to verify the efficiency of the quench valves to limit the pressure to 0.4 MPa.
    IEEE Transactions on Applied Superconductivity 01/2012; 22(3):4700604-4700604. · 1.20 Impact Factor
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    ABSTRACT: The Linear IFMIF Prototype Accelerator (LIPAc) will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. The SRF Linac design is based on superconducting Half Wave Resonators (HWR) cavities operating at 4.4 K. Due to space charge associated to the high intensity beam, a short, but strong, superconducting focusing magnet package is necessary between cavities. The selected configuration has been a superconducting NbTi solenoid acting as a magnetic lens and a concentric outer solenoid in antiparallel configuration to reduce the harmful stray field on the cavities. The selected arrangement for the steerers is a pair of parallel racetrack coils for each vertical and horizontal axis. This paper describes the manufacturing techniques of the different coils, and the tests realized in warm and cold conditions. Special attention is put to the training test of the main solenoid, since the nominal working point in the load line is very high (86.2%).
    IPAC2011; 09/2011
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    ABSTRACT: In the framework of the International Fusion Materials Irradiation Facility (IFMIF), which consists of two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV [1], a Linear IFMIF Prototype Accelerator (LIPAc) is presently under design for the first phase of the project. A superconducting option has been chosen for the 5 MeV RF Linac, based on a cryomodule composed of 8 low-beta Half Wave Resonators, 8 Solenoid Packages and 8 RF couplers. This paper will mainly focus on recent tests in laboratory of the main components of this cryomodule: HWR, RF coupler mock up, and solenoid prototypes. A section is dedicated to the HWR activities: realization and preliminary vertical tests of the two HWR prototypes. One prototype was equipped with the innovating cold tuning system, located in the central region of the cavity. Another section gives results on RF coupler’mock-up and solenoids prototypes. Finally, the LIPAc cryomodule current design is also presented.
    SRF11; 07/2011
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: A neuroscience research center with very high field MRI equipment was opened in November 2006 by the CEA life science division. One of the imaging systems requires a 11.75 T magnet with a 900 mm warm bore, the so-call Iseult/Inumac magnet. Regarding the large aperture and field strength, this magnet is a challenge as compared to the largest MRI systems ever built, and will be developed within an ambitious R&D program. With the objective of demonstrating the possibility of achieving field homogeneity better than 1 ppm using double pancake windings, a 24 double pancakes model coil, working at 1.5 T has been designed. This model magnet was manufactured by Alstom MSA and tested at CEA. It has been measured with a very high precision, in order to fully characterize the field homogeneity, and then to investigate and discriminate the parameters that influence the field map. This magnet has reached the bare magnet field homogeneity specification expected for Iseult and thus successfully demonstrated the feasibility of building a homogenous magnet with the double pancake winding technique.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: A neuroscience research center with very high field MRI equipments was opened in November 2006 by the CEA life sciences division. Three MRI systems operating at 3, 7 and 17 T have been already installed. One of the imaging systems will require a 11.75 T magnet with a 900 mm warm bore. The large aperture and high field strength of this magnet provide a substantial engineering challenge compared to the largest MRI systems ever built. This magnet is being developed within an ambitious R&D program, Iseult, whose focus is high field MRI. Traditional MRI magnet design principles are not readily applicable and thus concepts taken from high energy physics or fusion experiments, namely the Tore Supra tokamak magnet system, will be used. The coil will be made of a niobium-titanium conductor cooled by a He II bath at 1.8 K, permanently connected to a cryoplant. Due to its design the magnet will be operated in a non-persistent mode. As the field stability needed for MRI imaging requires a field drift of less than 0.05 ppm/h, it is hardly feasible to directly transpose these requirements in the power supply specification. Two existing solutions developed for other applications have been selected: one using a semi-persistent mode, and the other using a short-circuited superconducting coil in the inner bore. In order to make a decision on experimental basis, an ambitious R&D field stability program has been set-up based on magnet prototypes, high field test facility (Seht, a 44 H and 8 T magnet with a warm bore to 600 mm). We will present development and experimental results of the two stabilization solutions. In conclusion, the stability solution selected for the Iseult magnet is given.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: 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.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: In the framework of the International Fusion Materials Irradiation Facility (IFMIF), which consists of two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV, an accelerator prototype (EVEDA) is presently under design for the first phase of the project [1]. A superconducting option has been chosen for the 9 MeV RF Linac, based on a cryomodule composed of 8 low-beta Half-Wave Resonators (HWR), 8 Solenoid Packages and 8 RF couplers. This paper will focus on the HWR sub-system: the RF, thermo mechanical design, and the realization of the first prototype of HWR will be presented. The resonator tuning frequency is controlled by an innovating tuning system, located in the central region of the cavity. The different options for tuning will be discussed and the final thermo mechanical design will be detailed. A dedicated testbench for the tuning system under development is presented.
    IPAC2010; 05/2010
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    IPAC2010; 05/2010
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    ABSTRACT: The IFMIF-EVEDA accelerator will handle a 9 MeV, 125 mA continuous wave (CW) deuteron beam which aims to validate the technology that will be used in the future IFMIF accelerator. The Linac design is based on superconducting Half Wave Resonators (HWR) operating at 4.4 K. Due to space charge associated to the high intensity beam, a strong superconducting focusing magnet package is necessary between cavities, with nested steerers and a Beam Position Monitor (BPM). First of all, this paper describes the preliminary study to choose between two quadrupoles or one solenoid as focusing device, both using NbTi wire. The solenoid shows more advantages, mainly associated to available space and reliability. Then, electromagnetic and mechanical design of the solenoid and the steerers are reported. Special care is taken in order to fulfil the fringe field limit at the cavity flange. An active shield configuration using an anti-solenoid has been adopted, avoiding remnant magnetization associated to passive shielding materials.
    01/2010;
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    ABSTRACT: The driver of the International Fusion Material Irradiation Facility (IFMIF) consists of two 125 mA, 40 MeV CW deuteron accelerators. A superconducting option for the 5 to 40 MeV linac based on Half-Wave Resonators (HWR) has been chosen. The first cryomodule houses 8 HWR's supplied by high power RF couplers; each of them should be able to operate at 200 kW in CW. This paper will give an overview of the RF design of the 175 MHz CW power coupler. The detailed mechanical studies and the fabrication will be performed by an industrial company. Global approach of the contract and the organization of the intermediate validation tests will be discussed. In a second part, the choices made and the progress of the couplers RF power test stand will be described.
    01/2010;
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    ABSTRACT: The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead-lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosities up to 1034 cm−2 s−1 (1027 cm−2 s−1). At the core of the CMS detector sits a high-magnetic-field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4π solid angle. Forward sampling calorimeters extend the pseudorapidity coverage to high values (|η| ≤ 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t.
    Journal of Instrumentation 08/2008; 3(08):S08004. · 1.66 Impact Factor