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Helmholtz Zentrum Berlin HZB operates two large scale facilities the research reactor BER 2 and the syn chrotron source for soft X rays BESSY 2. This year HZB s neu tron instrument suite around BER 2 has been strengthened by a unique high magnetic field facility for neutron scattering. Its main components are the High Field Magnet HFM , which is the most powerful dc magnet for neutron scattering worldwide, and the Extreme Environment Di ffractometer EXED , which is a dedicated neutron instrument for time of flight technique. The hybrid magnet system is projected according to the special geo metric constraints of analyzing samples by neutron scattering in a high field magnet. Following our past experience, only steady state fields are adequate to achieve the goals of the project. In particular, inelastic scattering studies would virtually be excluded when using pulsed magnets. The new series connected hybrid magnet with a horizontal field orientation was designed and constructed in collaboration with the National High Magnetic Field Laboratory NHMFL , Tallahassee, FL, USA. With a set consisting of a su perconducting cable in conduit coil and different resistive coils of conical shape, maximum fields between 26 31 T are possible with cooling power between 4 and 8 MW for the resistive part. A series of commissioning activities of the magnet components and the technical infrastructure systems 20 kA power supply, water cooling, and 4 K Helium refrigerator was completed at HZB. The maximum field achieved with a 4 MW resistive coil was 26 T

The final assembly of the Series-Connected Hybrid magnet system for the Helmholtz-Zentrum Berlin for Materials and Energy (HZB) has occurred with the integration of the superconducting cold mass, cryostat, resistive Florida-Bitter coils, and the cryogenic, chilled water, power, and control subsystems. The hybrid magnet consists of a 13-T superconducting $\hbox{Nb}_{3}\hbox{Sn/CICC}$ coil and a set of 12-T resistive, water cooled coils at 4.4 MW. Much of the cryostat and cold mass functional requirements were dictated by the electromagnetic interactions between the superconducting and resistive coils. This includes the radial decentering and axial aligning forces from normal operations and a 1.1 MN fault load. The system assembly was an international achievement with the cold mass being completed at the NHMFL in the USA, cryostat to cold mass interfaces made at Criotec Impianti in Italy, and final assembly at the HZB in Germany.

BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Recent activities that were conducted on the Helmholtz Zentrum Berlin Series-Connected Hybrid outsert coil included the reaction heat treatment and vacuum-pressure impregnation. A thermocouple was wound into the windings for diagnostic purposes during processing of the coil. To maintain a reasonable temperature differential across the coil, the ramp rate was limited to approximately 2.7°C/hr. Epoxy impregnation was conducted with an epoxy developed in-house. The epoxy is transferred in vacuum but cured with one atmosphere gage pressure applied. Subsequently, the winding hardware was removed including the stainless steel mandrel through a machining operation. After assembly of voltage breaks and voltage taps, Paschen tests to 4 kV were conducted successfully that qualified the ground insulation. In addition, surge tests to qualified the internal insulation with 3 kV applied across the leads were conducted. Impedance measurements were conducted to confirm the internal insulation integrity.

A new series connected 25 T hybrid magnet system is being developed by the Helmholtz Zentrum Berlin (HZB) for neutron scattering experiments. In collaboration with CRPP, high temperature superconducting (HTS) current leads have been developed for the powering of the outer superconducting coil. These HTS current leads, with a nominal current rating of 20 kA, have been designed and are being manufactured by CRPP, based on the design of the 18 kA EDIPO leads. Each of the two current leads consists of an HTS module cooled only by heat conduction from the cold end and a copper part actively cooled by helium gas of 44 K inlet temperature. To reach a temperature of 53.7 K at the warm end of the HTS a helium mass flow rate of 1.37 g/s per lead is required at a current of 20 kA. The estimated heat leak at the 4.5 K level caused only by heat conduction is as low as 1.4 W. The evolution of the temperatures in the case of a loss of flow has been calculated. In addition to the design, the main fabrication steps are described. (C) 2012 Published by Elsevier B. V. Selection and/or peer-review under responsibility of the Guest Editors.

The National High Magnetic Field Laboratory (NHMFL) in Tallahassee, Florida has designed and is now constructing two Series Connected Hybrid (SCH) magnets, each connecting a superconducting outsert coil and a resistive Florida Bitter insert coil electrically in series. The SCH to be installed at the NHMFL will produce 36 T and provide 1 ppm maximum field inhomogeneity over a 1 cm diameter spherical volume. The SCH to be installed at the Helmholtz Center Berlin (HZB) in combination with a neutron source will produce 25 T to 30 T depending on the resistive insert. The two magnets have a common design for their cable-in-conduit conductor (CICC) and superconducting outsert coils. The CICC outsert coil winding packs have an inner diameter of 0.6 m and contribute 13.1 T to the central field using three grades of CICC conductors. Each conductor grade carries 20 kA and employs the same type of Nb3Sn superconducting wire, but each grade contains different quantities of superconducting wires, different cabling patterns and different aspect ratios. The cryostats and resistive insert coils for the two magnets are different. This paper discusses the progress in CIC conductor and coil fabrication over the last year including specification, qualification and production activities for wire, cable, conductor and coil processing.

The National High Magnetic Field Laboratory (NHMFL) has been funded to design and construct two series-connected hybrids (SCH), one each for the NHMFL in Tallahassee, FL and the Helmholtz Centre Berlin for Materials and Energy (HZB), Germany. The original designs for both hybrids contained three concentric coils comprising a Nb3Sn superconducting cable-in-conduit (CIC) main-field outsert coil, a resistive main-field insert coil and a NbTi superconducting CIC shield coil. The fringe field requirements for both facilities were met by designing the NbTi shield coil to match the 9.6 times 106 A-m2 dipole moment of the main field coils at an average radius of 1.16 m. Subsequent, alternate magnetic shielding concepts for both hybrids have been investigated with the objective of reducing the anticipated $700 k NbTi shield coil cost. The HZB fringe field requirements were targeted to a local area of concern at the adjacent Spin Echo facility, centered 15.65 m from the hybrid magnet center. An alternate, lower-cost shield concept comprised a set of four smaller shield coils positioned orthogonally around the HZB spin echo facility with a resultant total 85% to 90% reduction in required dipole moment compared to the original NbTi shield coil. The fringe field requirements at the NHMFL were not changed, but a lower-cost iron shielding option (not described here) located around the NHMFL hybrid was found to be a viable alternative. As a result, the NbTi CIC coil can be eliminated from the common superconducting magnet design for both the HZB and the NHMFL SCH's in favor of viable lower cost shielding options.

The National High Magnetic Field Laboratory is developing resistive-superconducting hybrid magnets both for internal use and for installation at other facilities. The Tallahassee magnet will have a vertical bore and provide 36 T in a 40-mm bore with 1-ppm homogeneity over a 10-mm diameter spherical volume. The Berlin version will provide a horizontal field of 25 T in a converging-diverging bore configuration suitable for neutron-scattering experiments. A design study is underway for a third magnet for Oak Ridge that will be similar to the Berlin version but provide >30 T. The three magnets will use very similar ~ 13 T Nb3Sn CICC coils for the superconducting outserts. The resistive insert magnets will be different configurations operating at different power levels. In designing the magnet systems we have developed a new numerical model to predict the critical current of Nb3Sn CICC's, tested several conductors in-house and abroad, designed cryostats and refrigeration systems, and developed new resistive magnet technology. An overview of the innovations and present status is presented.

A new series connected 25 T hybrid magnet system is being set up by the Helmholtz Zentrum Berlin (HZB) for neutron scattering experiments. CRPP has designed and manufactured a pair of 20 kA current leads for the powering of the outer superconducting coils of the hybrid magnet system. In connection with the test of joints for JT60SA, the current leads were tested at ENEA at low voltage up to a current of 18 kA. The mass flow rates required to cool the current leads at different currents measured in the test are in line with the design calculations. For the sum of the resistances of the warm and cold end copper contacts of the HTS module values of 13 (Lead A) and 11 nΩ (Lead B) were measured. In addition, the helium flow through the heat exchanger part was stopped at 10 and 12 kA to study the behaviour of the current leads in case of a loss of flow. The time elapsed between stopping of the helium mass flow and the initiation of a quench was found to be 117 s (Lead A) and 125 s (Lead B) compared to a calculated value of 86 s. The lower value obtained by the calculation can be attributed to the lower initial temperatures in the experiment. © Published under licence by IOP Publishing Ltd.

The impedance spectrum test was employed for detection of short circuits within Wendelstein 7-X (W7-X) superconducting magnetic field coils. This test is based on measuring the complex impedance over several decades of frequency. The results are compared to predictions of appropriate electrical equivalent circuits of coils in different production states or during cold test. When the equivalent circuit is not too complicated the impedance can be represented by an analytic function. A more detailed analysis is performed with a network simulation code. The overall agreement of measured and calculated or simulated spectra is good. Two types of short circuits which appeared are presented and analyzed. The detection limit of the method is discussed. It is concluded that combined high-voltage ac and low-voltage impedance spectrum tests are ideal means to rule out short circuits in the W7-X coils.

High magnetic fields can create exotic states which challenge our basic understanding of matter. This requires a deep and precise knowledge of the spatial ordering of atoms and associated magnetic moments. Particularly interesting would be to disclose magnetic field dependency of various fluctuations and collective modes. Such information can be obtained from neutron scattering experiments. The Helmholtz Zentrum Berlin (HZB) is known for its sample environment that is available for both internal and external users. Presently, a project that combines dedicated scattering instrument (EXED) with a horizontal hybrid solenoid magnet with tapered 300cones is being finalized at HZB. To achieve an optimal performance, a 13 T superconducting Nb3Sn cable-in-conduit coil is combined with resistive insert coils of 12 T to 18 T (see figure), depending on electric power (between 4.4 and 8.0 MW), to give a maximum of 25 to 31 T. The magnet that has been developed in collaboration with the National High Magnetic Field Laboratory of Florida State University, Tallahassee, FL, USA [1] provides a 50 mm diameter room temperature bore. For sample cooling a 3He cryostat with a pulse tube precooling stage is being developed. The magnet will be permanently mounted at the dedicated time-of-flight instrument EXED at the end of a multispectral neutron guide NL4a, about 76 m away from the neutron source. The EXED instrument is optimized for diffraction under restricted geometrical conditions and is being upgraded to include inelastic option. This unique experimental setup is supposed to play a major role in high-field neutron studies and should be ready for use in early 2015. The contribution describes not only the most important design features of the system, the outline of the building for the technical infrastructure and the status of the installation and commissioning but also the scientific possibilities and limitations of the setup.

The series-connected hybrid magnets for the National High Magnetic Field Laboratory and the Helmholtz Zentrum Berlin (HZB) that are under construction utilize three grades of cable-in-conduit conductor (CICC). Each coil contains over 5000 kg of Nb3Sn/Cu CICC in five piece-lengths. Fabrication of the coils has commenced with the winding of the outsert coil for HZB first. Work on both coils will proceed in parallel as the winding for the HZB coil is completed and is prepared for reaction heat treatment. Aspects of the coil fabrication process and quality controls will be discussed with attention given to the coil winding and joint assembly.

The Helmholtz Centre Berlin (HZB) is a user facility for the study of structure and dynamics with neutrons and synchrotron radiation with special emphasis on experiments under extreme conditions. Neutron scattering is uniquely suited to study magnetic properties on a microscopic length scale, because neutrons have comparable wavelengths and, due to their magnetic moment, they interact with the atomic magnetic moments. At HZB a dedicated instrument for neutron scattering at extreme magnetic fields and low temperatures is under construction, the Extreme Environment Diffractometer ExED. It is projected according to the time-of-flight principle for elastic and inelastic neutron scattering and for the special geometric constraints of analysing samples in a high field magnet. The new hybrid magnet will not only allow for novel experiments, it will be at the forefront of development in magnet technology itself. With a set of superconducting and resistive coils a maximum field above 30 T will be possible. To compromise between the needs of the magnet design for highest fields and the concept of the neutron instrument, the magnetic field will be generated by means of a coned, resistive inner solenoid and a superconducting outer solenoid with horizontal field orientation. To allow for experiments down to Millikelvin Temperatures the installation of a 3He or a dilution cryostat with a closed cycle precooling stage is foreseen.

Two identical coils will be wound at the National High Magnetic Field Laboratory for different series-connected hybrid projects. A model coil with half the length of the production superconducting coil has been fabricated to qualify all fabrication steps. After winding each layer, the impedance spectrum test has been employed to detect short circuits. After impregnation the model coil will undergo a high-voltage surge test which will explore the margin of the layer insulation. Results of impedance testing are reported here.