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).

 

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.

 

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.

In collaboration with IRFU teams, CMS teams are currently making preparations for the first LHC data acquisition campaign.

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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