The association of two inner resistive coils (Polyhelix and Bitter) producing 34.5 T with an outer NbTi superconducting coil producing 8.5 T to obtain a 43 T hybrid magnet is a technical challenge. Accidental failure modes leading to complex electromagnetic behaviors and large transient dynamical forces should be anticipated. These considerations lead to a reinforced design and a thermo-hydraulic strategy to limit the overpressure. The cryostat has been designed with innovative thermomechanical supports sustaining the coil at 1.8 K-1200 hPa and the eddy current shield at 30 K, both being possibly overloaded by high dynamic forces in the worst accidental failure case. (C) 2014 The Authors. Published by Elsevier B.V.

A CEA-CNRS French collaboration is currently developing a new hybrid magnet to produce in a first step a continuous magnetic field of 43 T in a 34-mm warm bore aperture. This magnet combines a resistive insert, composed of Bitter and polyhelix coils, and a large bore superconducting “outsert.” The superconducting coil is based on the novel development of a Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled down to 1.8 K by a bath of superfluid helium at atmospheric pressure. It aims at producing a nominal magnetic field of 8.5 T in a 1.1-m cold bore diameter. The specifications of the RCOCC will be presented together with the design and parameters of the cryogenic system. The solution to reduce the coupling between resistive and superconducting coils will be recalled as well as the constraints for designing the mechanical structure. The design study phase is coming to an end. The status of the conductor production and the next steps of the project are presented.

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).

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 R 3 B-Glad superconducting Magnet is a large acceptance dipole, dedicated to the analysis of Reactions with Relativistic Radioactive ions Beams. It takes part in the FAIR Project at GSI. As the superconducting NbTi Rutherford cable was under production, detailed studies of the mechanical structure (with both simulation and experiment on a half-scale mock-up) led to revise the magnet design and to abandon the grading of the coils in three stages. Due to the large magnetic forces (up to 400 tons/m), the maximum shear stress level of 20 MPa was impossible to meet in the coils. The main reasons consist in the orthotropic thermo-mechanical behavior of the coils together with the large differential thermal shrinkage between the Cu stabilized coils and their Al alloy casings. Indeed after several studies of different mechanical designs, we decided to simplify the magnet in order to cope with these difficulties. One innovative point is that the coils are not blocked at room temperature, but only at 4.5 K. This paper presents the magnetic calculations of this active shielded magnet, and shows how the new design features meet the specifications. Currently, the 22 tons magnet cold mass, i.e. the 6 coils and their integration in the casings, is ordered and under construction. Meanwhile, the design of the magnet cryostat has evolved into a shape of elliptical cylinder with a lateral satellite. The total weight is expected to be around 50 tons.

The R3B-GLAD (GSI Large Acceptance superconducting Dipole) magnet provides the magnetic field needed for the R3B (Reaction studies with Radioactive Relativistic Beams) experiment which will be implemented on the future FAIR Facility (Facility for Antiproton and Ion Research). There are six trapezoidal racetrack coils for the R3B-GLAD magnet. Two main coils and four lateral coils are connected in series in a butterfly-like shape. The total weight of the six coils is 5.2 t. The cold mass assembly consists of coils, coil-casings, structural linking components and other non-structural components. The cold mass assembly weighs 22 t with envelope dimensions of 3.1 m (L) × 4.6 m (W) × 2.8 m (H). It is supported by the three cold to warm cryogenic supports. The magnet configuration was finalized in June 2008. The final cold mass design was accomplished end of July 2008. The manufacturing of the cold mass assembly has been launched since January 2009. The cold mass will be ready for test in the test station at CEA Saclay by the end of 2010. This paper gives an overview on the final design of the R3BGLAD cold mass assembly and manufacturing status.

The R3B-GLAD magnet is a large acceptance superconducting dipole magnet. It provides the magnetic field needed for the R3B (Reaction studies with Radioactive Relativistic Beams) experiment which will be implemented on the future FAIR Facility (Facility for Antiproton and Ion Research). The cold mass structure of the magnet is designed to hold the six superconducting coils in position and to resist high level magnetic forces. The cold mass assembly consists of coils, coil casings and linking components. It is supported by the three cold to warm supports. It weighs about 20 tons with envelope dimensions of 3 rm(rL) x 5 rm(rW) x 3 rm(rH).Engineering design of the cold mass structure has been carried out through extensive finite element analyses. This paper gives an overview on the mechanical behavior of the cold mass assembly during energizing phase and cool-down phase.

The ATLAS barrel toroid magnet is a large air-core toroid that provides the magnetic field needed for the ATLAS muon spectrometer. The barrel toroid structure, named warm structure, holds the eight superconducting coils evenly positioned around the beam axis with an outer diameter of 20 m. The warm structure supports not only the coils but also muon detectors, services and access for the ATLAS experiment. The warm structure withstands about 1400 tons of weight and strong magnetic forces. Physics performance of the muon detectors, and the fact that many design aspects of the toroid and of other related sub-system of the ATLAS experiment are intertwined, impose stringent requirements on the warm structure design. Extensive finite element analyses have been carried out to achieve the final design. Manufacturing feasibilities and facilities have been taken into account. This paper gives an overview on the design and manufacturing of the ATLAS Barrel Toroid Warm Structure

The ATLAS barrel toroid magnet provides the magnetic field needed for the ATLAS muon spectrometer. The barrel toroid structure holds the eight superconducting coils evenly positioned around the beam axis with an outer diameter of 20m. It supports not only the coils but also the barrel muon chambers, the services and the access for the ATLAS experiment. The structure withstands about 1400tons of weight and strong magnetic forces. The physics performance of the muon spectrometer, and the fact that many design aspects of the toroid and of other related sub-systems of the ATLAS detector are deeply intertwined, impose stringent requirements on the design of the barrel toroid structure. The evolution of the design is presented in the paper.