Ten years of intense collaborative work between the DACM and DIS teams at IRFU culminated during the summer of 2024 in the successful testing of the MQYYM mock-up superconducting magnet in the new quadrupole accelerator magnet test station, STAARQ. These amazing results have validated 3 key areas of research and development that are closely interconnected between the two departments:
This test was made possible thanks to the involvement of DIS/LDISC for the control system and DIS/LEIGE for the electrical engineering and power electronics.
The Iseult project has unveiled the first human brain images obtained using a 11.7 teslas MRI, after almost 25 years of work. This world first was made possible thanks to the commitment of over 200 CEA employees, who believed in this extremely ambitious project from the very beginning
In the early 2000s, a Franco-German project was launched to develop ultra-high resolution imaging. One of the objectives was to build an imager whose key component was a superconducting magnet reaching 11.7 Tesla with a 900 mm aperture, but there was at this time no MRI manufacturer ready to embark on this crazy adventure alone. Based on its strong expertise in superconducting magnets acquired over the past 40 years, in particular for high energy physics and particle physics (Cern) as well as for fusion (Tore Supra, ITER), CEA decided to take up the challenge. After only a few years of design work, CEA proposed in 2006 an initial design using several innovative technological solutions. After exhaustive tests to validate all of them with several prototypes, the final fabrication started in in 2010. It took 7 years for the CEA and Alstom (now General Electric) teams to finalize the construction of this outstanding magnet, a colossus weighing 132 tons, 5 me in length and 5 meters in diameter. The magnet winding is made of 182 km of superconducting wires cooled to -271.35°C by 7,500 liters of superfluid helium.
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The commissioning of the 11.7 T Iseult MRI in 2021 crowned almost 20 years of AOC research and development. In an article published in the journal Magnetic Resonance Materials in Physics, Biology and Medicine, Nicolas Boulant and Lionel Quettier, Iseult project leaders for the CEA's Joliot and Irfu Institutes, review the details of this commissioning.
Low-temperature superconducting materials are widely used in high-field magnets, but their behaviour is closely related to the strains they undergo. Consequently, studies on the impact of stress on mechanical structures are essential. The SUPRAMITEX project is participating in this research effort by using the AMITEX-FFTP parallel code developed as part of the SIMU/MATIX project to carry out non-linear mechanical simulations on heterogeneous microstructures. This work has shown the interest of the AMITEX code to simulate the mechanical behaviour of these components, at different scales, for elastic and elasto-plastic behaviours at simulation scales that were previously unattainable.
The recent update of the European Strategy for Particle Physics recommended a feasibility study for the future generation of collider. In this context, the Laboratory Directors Group, of which IRFU is a member, has been mandated by the CERN Council to oversee the development of an accelerator R&D roadmap. One of the objectives of this roadmap is the development of technologies for the manufacture of high-field superconducting magnets, essential for future colliders: this is the HFM (High Field Magnets) project.
The MADMAX project, which was launched in November 2016, is led by the Max Planck Institut für Physik in collaboration with several European institutes. The goal of the project is the discovery of axions with a mass of about 100 µeV, potential candidates for dark matter. To detect these axions, it is necessary to develop a specific detector consisting of an electromagnetic signal amplifier and a magnet proportional to the size of the amplifier and delivering a strong magnetic field. In order to validate the innovations in the fabrication of the magnet conductor, its cooling concept and the quench detection, a demonstrator has been designed, fabricated, integrated and tested between March 2020 and August 2021. It is named MACQU for MADMAX Coil for Quench Understanding. The entire design, from the conductor to the support structure, including the MACQU magnet, its thermal shield and the busbars, was carried out at the CEA. The demonstrator, manufactured by the industrial Bilfinger Noell GmbH, arrived in March 2021 and was successfully tested between May 18 and August 27, 2021. The analysis of the data now completed provides the desired answers and opens up unexpected new avenues of work. The feasibility of the cable concept, its cooling as well as the quench detection for the MADMAX magnet was demonstrated during these tests.
The LEAS (Laboratoire d'Etude des Aimants Supraconducteurs) at CEA Paris-Saclay has entirely manufactured a coil based on the superconductor Nb3Sn (niobium-tin), of the SMC (Short Model Coil) type. This coil is a short model intended to be assembled in a magnet structure, then to be tested at cryogenic temperature. Nb3Sn is being considered for future accelerator magnets generating magnetic fields up to 16 T (teslas), which would double the performance of the best magnets currently in use. However, this requires a great deal of technological development. This type of short coil has been developed by Cern, in collaboration with the CEA, to allow the testing of new technologies and new manufacturing processes under conditions representative of future high-field magnets. The fabrication of the SMC-CEA coil took place at LEAS from May to October 2021, then the coil was delivered to Cern to be assembled in a structure, and finally tested in a liquid and superfluid helium bath, under high current, in a dedicated station. The tests delivered encouraging results, demonstrating that LEAS is one of the few European laboratories that now has all the capabilities to manufacture Nb3Sn superconducting coils. This proof of feasibility validates the first step of the development program of high field magnets for future accelerators.
The first test campaign of the NOUGAT high field magnet was successfully carried out at the CNRS LNCMI Grenoble. This laboratory wishes to build a 30-tesla magnet by assembling a resistive magnet from LNCMI and a superconducting magnet designed by IRFU based on high temperature superconducting materials. To date, the field reached 20.8 T, including 12.8 T generated by the superconducting magnet alone. This is a decisive step towards NOUGAT's 30 T operating point and the validation of MI (Metal-as-Insulation) winding technology, where traditional insulation is replaced by metal co-insulation, developed in the DACM's Superconducting Magnet (LEAS) Laboratory.
The DACM is involved in several high-field magnet projects including medical (MRI) and large test stations (such as the hybrid magnet LNCMI at 43T). To obtain high field values, it is necessary to use new generation high temperature superconductors (HTS) instead of NbTi or Nb3Sn. The department's HTS R&D is studying ways of producing such magnets and solving the problems inherent in these conductors at these high field values (thesis by G. Dilasser[1], thesis by M. ALHarake[2], internal R&D for non-insulated windings...).
1] Experimental and numerical study of shielding currents in REBCO high temperature superconducting magnets, thesis defended in 2017, G. Dilasser
2] Contribution to the study of a high field magnet 30-40 T, thesis in progress, Dr. ALHArake
After the validation of the last superconducting toroidal field coils, the CEA's contribution to the construction of the Japanese JT-60SA Tokamak, dedicated to the study of nuclear fusion, is nearing completion. Ten of them (out of twenty) were manufactured under the responsibility of the CEA by GE Power in Belfort. These coils of nearly 16 tons each will fly to Naka in mid-February to join their sisters and integrate the structure of the Japanese Tokamak. These essential components for the Japanese fusion device are part of the International Thermonuclear Experimental Reactor (ITER) extended approach project, an international project for a civil nuclear fusion research reactor currently being built at Cadarache (Bouches-du-Rhône).
Designed to equip the FRESCA2 testing station at CERN (Facility for the Reception of Superconducting Cables), the niobium-tin dipole magnet of the same name has reached a record 13.3 T magnetic field for a 100 mm aperture. It was designed and developed as part of a collaboration between IRFU and CERN. The objective is a magnetic-field homogeneity 1% over a length of 540 mm.
The CHyMENE project (Cible d'Hydrogène Mince pour l'Etude des Noyaux Exotiques -Thin hydrogen target for the study of exotic nuclei) has the ambitious goal of producing a thin target of pure hydrogen, without using a container, suitable for experiments using the low-energy heavy ion beam planned for SPIRAL2.
A team from IRFU (SPhN and SACM) and from l'Inac/SBT have recently applied cryogenic techniques to successfully produce a ribbon of solid hydrogen 100 μm thick. The target will soon be tested in the beam. This will be a world first.
Below: Interview with Alain GILLIBERT, who is working on the CHyMENE project with Alexandre OBERTELLI and Emmanuel POLLACO
Start image: a solid hydrogen ribbon of extruded H2 (width 10 mm, thickness 100 μm), viewed through the porthole of the vacuum chamber (Photo V. Lapoux).
Work on a new clean room, begun in July 2007 at the Saclay accelerator platform, has just been completed. The new clean room will be officially opened on 24 November 2009 and will replace the chemical facilities and clean room of IRFU's Accelerators, Cryogenics and Magnetism Division (SACM) located at L'Orme, which could no longer undergo all the improvements required to keep pace with current development work. A hall in building 124 (previously the Saturne laboratory) has therefore been renovated to accommodate the future facilities and equipment compatible with future accelerator research requirements and collaborative projects with industrial partners interested in the control of superconducting cavity systems.
For more than 20 years, solid niobium has had the monopoly on high-gradient applications of superconducting radio frequency (SRF) cavities for particle accelerators. But it will soon have reached its limits. It was only recently that A. Gurevich, a theoretician from Florida State University, put forward a theory explaining the reasons behind niobium's success and a way of breaking its monopoly. Until now, this theoretical model had never been experimentally demonstrated. This has now changed for a collaborative project between IRFU (Saclay) and INAC (Grenoble) has just made this vital step towards new acceleration technology.
On November 14, 2008, the Compact Muon Solenoid (CMS) successfully generated a nominal magnetic field of 4 tesla. This success rewards IRFU efforts for the design and construction of what constitutes the largest superconducting solenoid magnet in the world. Over a period of approximately one month, CMS teams conducted a continuous data acquisition campaign with the detector operating under nominal conditions. Approximately 300 million cosmic events were recorded. This also provided an excellent opportunity to showcase the specific expertise of IRFU teams, particularly in areas such as detection systems, electronics, trace data reconstruction techniques and laser control systems.
The high energy part of the SPIRAL2 linear accelerator (new GANIL1 accelerator scheduled for implementation in 2012) uses two types of superconducting cavities. IRFU's Accelerator, Cryogenics and Magnetism Department is responsible for the design and development of 12 cryomodules2 of the first type, to be installed at the injector output.
On December 8, 2008, the qualification prototype cryomodule was successfully tested at full power. The superconducting cavity attained an accelerating gradient of 10.3 MV/m (million volts per meter), far greater than the specified value of 6.5 MV/m.
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Dernière mise à jour : Nov 19th, 2024
