J. E. Munoz Garcia

Development of the EuCARD Nb3Sn Dipole Magnet FRESCA2

The key objective of the superconducting high field magnet work package of the European Project EuCARD, and specifically of the high field model task, is to design and fabricate the Nb3Sn dipole magnet FRESCA2. With an aperture of 100 mm and a target bore field of 13 T, the magnet is aimed at upgrading the FRESCA cable test facility at CERN. The design features four 1.5-m-long double-layer coils wound with a 21-mm-wide cable. The windings are contained in a support structure based on a 65-mm-thick aluminum shell pretensioned with bladders. In order to qualify the assembly and loading procedure and to validate the finite element stress computations, the structure will be assembled around aluminum blocks, which replace the superconducting coils, and instrumented with strain gauges. In this paper, we report on the status of the assembly and we update on the progress on design and fabrication of tooling and coils.

Mechanical and Magnetic Design of the Superferric Dipoles for the Super-FRS of the FAIR Project

The Superconducting FRagment Separator (SuperFRS) is a part of the Facility for Antiproton and Ion Research, a new international accelerator facility for the research with antiprotons and ions to be built in Darmstadt, Germany. The Super-FRS is a two-stage fragment separator consisting of a PreSeparator and a Main-Separator, which includes 24 superferric H-type dipole magnets with trapezoidal structure and large aperture. The dipole magnets of the separator will have a deflection radius of 12.5 m, a magnetic field of up to 1.6 T, and an effective length of more than 2 m to bend ion beams with a rigidity from 2 T · m up to 20 T · m. Two trapezoidal-shaped Nb-Ti coils will be located inside a cryostat cooled with liquid helium, but the dipole will have a warm iron yoke with a wide air trim slot. This air trim slot and four chamfered removable poles are designed to meet the required field homogeneity. This paper reports on the current status of the mechanical and magnetic design of such a dipole. The structural stability of the coil case based on 3-D finite-element analysis and the magnetic field simulations of the magnet are presented in detail.

Assembly, Loading, and Cool-Down of the FRESCA2 Support Structure

This paper reports on the assembly process and cool-down to cryogenic temperature of the support structure of FRESCA2, which is a dipole magnet for upgrading the actual CERN cable test facility FRESCA. The structure of the FRESCA2 magnet is designed to provide the adequate pre-stress, through the use of keys, bladders, and an Al alloy shrinking cylinder. To qualify the assembly and loading procedures, the structure was assembled with Al blocks (dummy coils) that replaced the brittle Nb3Sn coils, and then cooled-down to 77 K with liquid nitrogen. The evolution of the mechanical behavior was monitored via strain gauges located on different components of the structure (shell, rods, yokes and dummy coils). We focus on the expected stresses within the structure after assembly, loading and cool-down. The expected stresses were determined from the 3-D finite element model of the structure. A comparison of the 3-D model stress predictions with the strain gauge data measurements is made. The coherence between the predicted stresses with the experimental gauge measurements will validate the FEM model of the structure.

Development of the EuCARD

The key objective of the superconducting high field magnet work package of the European Project EuCARD, and specifically of the high field model task, is to design and fabricate the Nb3Sn dipole magnet FRESCA2. With an aperture of 100 mm and a target bore field of 13 T, the magnet is aimed at upgrading the FRESCA cable test facility at CERN. The design features four 1.5-m-long double-layer coils wound with a 21-mm-wide cable. The windings are contained in a support structure based on a 65-mm-thick aluminum shell pretensioned with bladders. In order to qualify the assembly and loading procedure and to validate the finite element stress computations, the structure will be assembled around aluminum blocks, which replace the superconducting coils, and instrumented with strain gauges. In this paper, we report on the status of the assembly and we update on the progress on design and fabrication of tooling and coils.

\hbox{Nb}_{3}\hbox{Sn}

The Nb3Sn FRESCA2 dipole magnet is dedicated to upgrade the CERN cable test facility FRESCA. It is also a technological demonstrator of large-aperture Nb3Sn accelerator magnet. It has an aperture of 100 mm and a target bore magnetic field of 13 T. It is composed of four 1.5-m-long double-pancake “block-type” coils, manufactured following the wind, react and impregnation technique. It is developed by CEA and CERN in the framework of a collaboration agreement, in the continuity of the EuCARD program. Through the fabrication of two full-scale copper prototypes, the different steps of the coil fabrication process (winding, heat treatment, splicing, instrumentation, impregnation, and transport) and the corresponding tooling have been adjusted. The final winding and reaction procedure integrates the possibility to open longitudinal gaps in the winding table and in the central post, in order to accommodate partially the longitudinal contraction of the cable during reaction. This new feature has been experienced through full-scale tests using superconducting cable with a reduced number of turns. This paper reports on the fabrication procedure of these coils. The production phase of the superconducting magnets has started in June 2015.

Dipole Magnet FRESCA2

FRESCA2 is a dipole magnet dedicated to upgrade the present CERN cable test station FRESCA to a nominal bore field of 13 Tesla (T) in a 100 mm clear aperture. This paper reports on the assembly process and the three cool-down tests to cryogenic temperature of the support structure of FRESCA2. This structure is based on an aluminum alloy shrinking cylinder pre-loaded through the use of water-pressurized bladders. To verify the assembly and loading processes, this structure was assembled using full block aluminum alloy “dummy coils” standing for the Nb3Sn coils. Then, the whole assembled structure was cooled-down to 77 K with liquid nitrogen in a dedicated facility at CERN. The mechanical behavior was monitored at all stages by strain gauges located on different components of the structure. Three cryogenic tests were made by increasing the loading gradually up to values corresponding to the ultimate field of 15 T. The expected stresses within the structure after assembly, loading and cool-down were determined from the 3-D finite-element model of the support structure. A comparison of the model predictions with the strain gauge data is presented.

“Block-Type” Coils Fabrication Procedure for the Nb 3 Sn Dipole Magnet FRESCA2

The key objective of the High Field Magnet work package of the European Project EuCARD is to design and fabricate the Nb3Sn dipole magnet FRESCA2. It has an aperture of 100 mm and a target bore field of 13 T. The design features four 1.5 m long double-layer coils wound with a 21 mm wide cable. The project has now entered its experimental phase in view of the magnet fabrication. We present the experimental test campaign conducted on cable samples in order to understand and to control better the cable behavior and geometry. One full scale double-layer coil using copper cable with the final dimensions and insulation scheme has been wound and heat treated in order to check the fabrication process. This has given useful feedback on the fabrication procedure and on the expected magnet dimensions, as well as on the tooling itself.

Mechanical Validation of the Support Structure of the

The key objective of the High Field Magnet work package of the European Project EuCARD is to design and fabricate the Nb3Sn dipole magnet FRESCA2. It has an aperture of 100 mm and a target bore field of 13 T. The design features four 1.5 m long double-layer coils wound with a 21 mm wide cable. The project has now entered its experimental phase in view of the magnet fabrication. We present the experimental test campaign conducted on cable samples in order to understand and to control better the cable behavior and geometry. One full scale double-layer coil using copper cable with the final dimensions and insulation scheme has been wound and heat treated in order to check the fabrication process. This has given useful feedback on the fabrication procedure and on the expected magnet dimensions, as well as on the tooling itself.

\hbox{Nb}_{3}\hbox{Sn}

The key objective of the High Field Magnet work package of the European Project EuCARD is to design and fabricate the Nb3Sn dipole magnet FRESCA2. It has an aperture of 100 mm and a target bore field of 13 T. The design features four 1.5 m long double-layer coils wound with a 21 mm wide cable. The project has now entered its experimental phase in view of the magnet fabrication. We present the experimental test campaign conducted on cable samples in order to understand and to control better the cable behavior and geometry. One full scale double-layer coil using copper cable with the final dimensions and insulation scheme has been wound and heat treated in order to check the fabrication process. This has given useful feedback on the fabrication procedure and on the expected magnet dimensions, as well as on the tooling itself.

Magnet FRESCA2

The key objective of the superconducting high field magnet work package of the European Project EuCARD, and specifically of the high field model task, is to design and fabricate the Nb3Sn dipole magnet FRESCA2. With an aperture of 100 mm and a target bore field of 13 T, the magnet is aimed at upgrading the FRESCA cable test facility at CERN. The design features four 1.5-m-long double-layer coils wound with a 21-mm-wide cable. The windings are contained in a support structure based on a 65-mm-thick aluminum shell pretensioned with bladders. In order to qualify the assembly and loading procedure and to validate the finite element stress computations, the structure will be assembled around aluminum blocks, which replace the superconducting coils, and instrumented with strain gauges. In this paper, we report on the status of the assembly and we update on the progress on design and fabrication of tooling and coils.