G. Bellomo

Development of a Curved Fast Ramped Dipole for FAIR SIS300

At present, one of the main options for beam bending dipoles of the SIS 300 synchrotron, under design for the FAIR facility at GSI, is a single layer magnet 7.8 m long, 100 mm in bore diameter, generating 4.5 T. This coil has two main features: it is curved, with a curvature radius of 66.67 m (the corresponding sagitta is 114 mm), and shall be ramped at 1 T/s. Both these characteristics demand challenging R&D, aimed at the development of the required conductor and winding technology. The paper discusses both these aspects, in the frame of a general ongoing R&D program at INFN, under the name DISCORAP. Its goal is the construction of a short prototype (3.8 m) dipole, fully integrated into its horizontal cryostat, within three years. The R&D program includes: 1) the activities required to develop low loss superconducting wires and cable; 2) the technological developments (at the industrial level) for defining and optimizing the dipole constructing methods; 3) the construction of curved dipole coil winding models; 4) the construction of the complete curved dipole; 5) the test of the curved dipole in a vertical cryostat; 6) the integration of the curved dipole into a horizontal cryostat, for the final test at GSI.

Field Quality and Losses for the 4.5 T Superconducting Pulsed Dipole of SIS300

This paper presents the 2D design of the SIS300 synchrotron dipole of the FAIR facility at GSI. The dipole has a length of 7.8 m, a field of 4.5 T, in a 100 mm bore, and is ramped at 1 T/s. The studies are performed by INFN (Frascati, Genova and Milano-LASA) in a R&D collaboration with GSI. The program started in 2006 (DISCORAP) and has as a final goal the construction and test of a prototype. Particular emphasis is given to the study of the field quality and of the losses during the ramping of the magnet. Some calculation methods and different codes for magnet design are evaluated and compared.

Low-Loss NbTi Rutherford Cable for Application to the SIS-300 Dipole Magnet Prototype

INFN (Istituto Nazionale di Fisica Nucleare, Italy) has started in 2006 the DISCORAP project, which foresees the design, manufacture and test of a dipole prototype for the SIS-300 synchrotron of the FAIR facility at GSI. In order to minimize the losses produced by the fast ramp rate (1 T/s) at which the magnet is operated, we are developing with European industries, a Rutherford cable which incorporates several technologies to reduce the losses, and namely a NbTi filament diameter on the order of 2.5-3.5 mum, Cu 0.5 wt%Mn interfilamentary matrix and stainless steel core. In this paper we present the design principles and the first experimental results; we also analyze the impact of the CuMn paramagnetism on the field distortion at the different operating magnetic fields.

The 16 T Dipole Development Program for FCC

A key challenge for a future circular collider (FCC) with centre-of-mass energy of 100 TeV and a circumference in the range of 100 km is the development of high-field superconducting accelerator magnets, capable of providing a 16 T dipolar field of accelerator quality in a 50 mm aperture. This paper summarizes the strategy and actions being undertaken in the framework of the FCC 16 T Magnet Technology Program and the Work Package 5 of the EuroCirCol.

The Construction of the Model of the Curved Fast Ramped Superconducting Dipole for FAIR SIS300 Synchrotron

The Facility for Anti-proton and Ion Research (FAIR), under development at GSI, includes the synchrotron SIS300, so called because the magnetic rigidity is 300 Tm. In order to reach the required high intensities of proton and heavy ions beams, the bending dipole magnets have to be pulsed from the injection magnetic field of 1.5 T up to 4.5 T maximum field at the rate of 1 T/s. These 7.8 m long magnets have cos θ shaped coils with a 100 mm bore and the particular characteristic to be geometrically curved, with a sagitta of 112.9 mm. These challenging requirements triggered R&D activities, aimed at the development of suitable construction technologies for fast ramped curved coils. The heart of the R&D program is the construction of a 3.9 m long model. The paper discusses the main problems faced during the design and the construction of the cold mass, mainly covering the aspects related to the manufacture.

Low Loss Nb-Ti Superconducting Rutherford Cable Manufacture for the SIS300 INFN Model Dipole

The INFN (Istituto Nazionale di Fisica Nucleare, Italy) has launched in 2006 the DISCORAP (DIpoli SuperCOnduttori RApidamente Pulsati, or fast-pulsed superconducting dipoles) project which foresees the design, manufacture and test of a fast cycled (1 T/s) 4.5 T, cos θ , dipole model for the SIS 300 synchrotron of the FAIR (Facility for Antiproton and Ion Research) facility at GSI (Darmstadt, Germany). This magnet is now close to completion at ASG company (Genova, Italy); it is based on a Rutherford cable, manufactured by Luvata Superconductors, which incorporates several technologies to reduce the AC losses, namely a Nb-Ti filament diameter around 3 μm, Cu 0.5wt%Mn interfilamentary matrix and a Rutherford cable with stainless steel core. The development of the Rutherford foresees two subsequent generations of Rutherford cables, aimed to reach the demanding goals of the SIS-300 specifications in steps. In this paper we present the results of the manufacture of the first generation Rutherford cable, and the assessment of its electromagnetic performances, including critical current density, twist pitch impact on critical current degradation, filament hysteresis and de formation, transverse resistivity, Cu-Mn paramagnetism.

A Model Dipole for FAIR SIS300: 3D Design of the Mechanical Structure

Design activities coupled with conductor R&D and model coil construction are under way for developing a curved fast cycled superconducting dipole suitable for operations of the SIS300 synchrotron at FAIR. The main target is the construction within 2009 of a model magnet (cold mass fully integrated in a horizontal cryostat). This magnet is designed for generating 4.5 T magnetic field in a bore of 100 mm, able to be operated at a field rate of 1 T/s. The magnetic length is 3.8 m with a curvature radius of 66.67 m (the sagitta is 27 mm). The mechanical structure is based on 3 mm thick laminated stainless steel collars, assembled through keys, and 1 mm thick iron yoke laminations, assembled through large Al alloy C-shaped clamps. A 2D finite element analysis has been performed to evaluate stresses and deformations coming out during assembly, cool-down and energization. Particular emphasis has been given to the possible fatigue problems ensuing from the large operating field rate over a large lifetime cycle number, 107. Numerical results are presented and discussed.The FAIR facility, under development at GSI, includes the synchrotron SIS300 (300 Tm rigidity). In order to reach the required high intensities of proton and heavy ion beams, the bending dipole magnets have to be pulsed from the injection magnetic field of 1.5 T up to 4.5 T maximum field at the rate of 1 T/s. These 7.8 m long magnets have cos-theta shaped coils with a 100 mm bore with the particular characteristic to be geometrically curved (the sagitta is 114 mm). The 2D mechanical cross section has been designed in detail: it consists of 3 mm thick laminated stainless steel collars, assembled through keys, and 1 mm thick iron yoke laminations, assembled through large stainless steel C-shaped clamps. This paper analyses some aspects that are intrinsically 3-dimensional: the mechanical behavior of the ends, the effect of the longitudinal pre-stress, the design of the external flange and outer shell.

The Curved Fast Ramped Superconducting Dipoles for FAIR SIS300 Synchrotron: From First Model to Future Developments

The synchrotron SIS300 is a fundamental component of the FAIR facility under construction at the GSI laboratory in Darmstadt. The acceleration of high intensity proton and heavy ion beams requires 4.5 T magnets, up to 7.8 m long, to be ramped up at a rate of 1 T/s. These challenging magnets have also the particular characteristic to be geometrically curved with a sagitta of 114 mm. To demonstrate the feasibility of curved fast cycled cos-theta dipoles, R&D activities were performed at the Italian National Institute of Nuclear Physics. Important steps of the R&D have been: 1) the development of a low loss superconducting Rutherford cable; 2) the construction of coil winding models for assessing the constructive feasibility of curved coils; and 3) the construction and tests of a complete model magnet composed of a cold mass enclosed in its horizontal cryostat. During 2012 the cold mass was tested at Italian National Institute of Nuclear Physics-LASA in a vertical cryostat. The paper discusses the main issues of the R&D activity from design to manufacture, results, future developments, and future perspectives.

Electromagnetic Design of the Coil-Ends for the FAIR SIS300 Model Dipole

Design activities, conductor R&D and model coil construction are under way for developing a curved fast cycled superconducting dipole for the SIS300 synchrotron at FAIR. The main target is the construction within year 2009 of a half-length model magnet (cold mass fully integrated in a horizontal cryostat). This magnet is designed for a maximum central field of 4.5 T in a bore of 100 mm, with a ramp rate of 1 T/s. The magnetic length of the prototype is 3.8 m with a curvature radius of 66.67 m (27 mm of sagitta). This paper describes the electromagnetic design of the coil-ends of the magnet. Particular emphasis is given to the study of the losses due to the eddy currents in collar and yoke, and to the other losses during the cycling of the magnet. The study has been performed with finite element codes, and it allowed to optimize the configuration in order to minimize both the peak field on the conductor and the total losses.

NbTi Superferric Corrector Magnets for the LHC Luminosity Upgrade

CERN and INFN, Italy, have signed an agreement for R&D activities relating to high-luminosity LHC superconducting magnets, which include the design, construction, and cryogenic test of a set of five prototypes, one for each type foreseen, from the skew quadrupole to the dodecapole. The reference layout of these magnets is based on a superferric design type, which allows reaching the required integrated field strength with a relatively simple design. Since the number of magnets of all the types required for the series is 36, emphasis has been put on modularity, reliability, ease of construction, and on the use of an available superconducting wire. This paper presents the status of the development work being performed at INFN, LASA Laboratory, and at CERN, focusing on the following issues: the electromagnetic 2- and 3-D design including harmonic component study; the fringe field analysis; the magnet powering and quench protection; mechanical and construction main choices.