D.R. Dietderich

Magnet RaD for the US LHC Accelerator Research Program (LARP)

TUA2OR6 Magnet RD fax: 510-486-5310; e-mail: sagourlay@lbl.gov). G. Ambrosio, N. Andreev, E. Barzi, R. Bossert, V. S. Kashikhin, V. V. Kashikhin, F. Nobrega, I. Novitsky, D. Turrioni, R. Yamada, and A.V. Zlobin are with Fermilab National Accelerator Laboratory, Batavia, IL 3 M. Anerella, A. Ghosh , , R. Gupta, M. Harrison, J. Schmazle, and P. Wanderer are with Brookhaven National Laboratory, Upton, NY.

Design and Analysis of TQS01, a 90 mm

The US LHC Accelerator Research Program (LARP) is developing Nb 3Sn accelerator magnet technology for the LHC luminosity upgrade. Two 90 mm Technology Quadrupole models (TQS01, TQC01) are being developed in close collaboration between LBNL and FNAL, using identical coil design, but two different support structures. The TQS01 structure was developed and tested at LBNL. With this approach coils are supported by an outer aluminum shell and assembled using keys and bladders. In contrast, the second model TQC01, utilize stainless steel collars and a thick stainless steel skin. This paper describes the TQS01 model magnet, its 3D ANSYS stress analysis, and anticipated instrumentation and assembly procedure

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As a first step toward the development of a large-aperture Nb3Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade, two-layer technological quadrupole models (TQS01 at LBNL and TQC01 at Fermilab) are being constructed within the framework of the US LHC Accelerator Research Program (LARP). Both models use the same coil design, but have different coil support structures. This paper describes the TQC01 design, fabrication technology and summarizes its main parameters

Model Quadrupole for LHC Luminosity Upgrade Based on a Key and Bladder Assembly

Wires based on the Bi-2212 HTS superconductor are becoming available commercially, with current densities that are attractive for some applications. The authors report here on their success in using these Bi-2212 wires to fabricate multistrand, kiloamp conductors that can be used to construct dipole and quadrupole magnets for particle accelerator applications. Multistrand cables have been made from several types of Bi-2212 wire supplied by two manufacturers. These cables were made with cores of various compositions and dimensions in order to optimize the fabrication process. In addition, cables have been made from aspected strands as well as round strands. Cable critical currents are reported and compared for the various cable parameters investigated in this study.

Development of TQC01, a 90 mm

Future insertion quadrupoles with large apertures and high gradients will be required for the Phase II luminosity upgrade (1035 cm−2s−1) of the Large Hadron Collider (LHC). Although improved designs, based on NbTi, are being considered as an intermediate step for the Phase I upgrade, the Nb3Sn conductor is presently the best option that meets the ultimate performance goals for both operating field and temperature margin. As part of the development of Nb3Sn magnet technology, the LHC Accelerator Research Program (LARP) developed and tested several 1-meter long, 90-mm aperture Nb3Sn quadrupoles. The first two series of magnet used OST MJR 54/61 (TQ01 series) and OST RRP 54/61 (TQ02 series) strands. The third series (TQ03) used OST RRP 108/127 conductor. The larger number of sub-elements and the consequent reduction of the effective filament size, together with an increased fraction of copper and a lower Jc were expected to improve the conductor stability. The new coils were tested in the TQS03 series using a shell structure assembled with keys and bladders. The objective of the first test (TQS03a) was to evaluate the performances of the 108/127 conductor and, in particular, its behaviour at 1.9 K, while the second test (TQS03b) investigated the impact on high azimuthal pre-stress on the magnet performance. This paper reports on TQS03 fabrication, the strain gauge measurements performed during assembly, cool-down, excitation and the quench behaviour of the two magnets.

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We report on our progress in the development of the technology for the application of Bi2Sr2CaCu2O8+x(Bi-2212) in Wind-and-React accelerator magnets. A series of superconducting subscale coils has been manufactured at LBNL and reacted at the wire manufacturer SWCC. Selected coils are impregnated and tested in self-field, even though the coils exhibited leakage during the partial melt heat treatment. Other coils have been disassembled after reaction and submitted to critical current (Ic) tests on individual cable sections. We report on the results of the current carrying capacity of the coils. Voltage-current (VI) transitions were reproducibly measured up to a quench currents around 1400 A, which is 25% of the expected performance. The results indicate that the coils are limited by the inner windings. We further compare possibilities to use Bi-2212 and Nb3Sn tilted solenoid, and YBa2Cu3O7-delta (YBCO) racetrack inserts to increase the magnetic field in HD2, a 36 mm bore Nb3Sn dipole magnet which recently achieved a bore magnetic field of 13.8 T. The application of Bi-2212 and/or YBCO in accelerator type magnets, if successful, will open the road to higher magnetic fields, far surpassing the limitations of Nb3Sn magnet technology.

Model Quadrupole for LHC Upgrade Based on SS Collar

The High Luminosity (HiLumi) Large Hadron Collider (LHC) project has, as the main objective, to increase the LHC peak luminosity by a factor five and the integrated luminosity by a factor ten. This goal will be achieved mainly with a new interaction region layout, which will allow a stronger focusing of the colliding beams. The target will be to reduce the beam size in the interaction points by a factor of two, which requires doubling the aperture of the low-β (or inner triplet) quadrupole magnets. The use of Nb3Sn superconducting material and, as a result, the possibility of operating at magnetic field levels in the windings higher than 11 T will limit the increase in length of these quadrupoles, called MQXF, to acceptable levels. After the initial design phase, where the key parameters were chosen and the magnets conceptual design finalized, the MQXF project, a joint effort between the U.S. LHC Accelerator Research Program and the Conseil Européen pour la Recherche Nucléaire (CERN), has now entered the construction and test phase of the short models. Concurrently, the preparation for the development of the full-length prototypes has been initiated. This paper will provide an overview of the project status, describing and reporting on the performance of the superconducting material, the lessons learnt during the fabrication of superconducting coils and support structure, and the fine tuning of the magnet design in view of the start of the prototyping phase.

Fabrication and test results for Rutherford-type cables made from BSCCO strands

The LHC Accelerator Research Program (LARP) has a primary goal to develop, assemble, and test full size Nb3Sn quadrupole magnet models for a luminosity upgrade of the Large Hadron Collider (LHC). A major milestone in this development is to assemble and test, by the end of 2009, two 4 m-long quadrupole cold masses, which will be the first Nb3Sn accelerator magnet models approaching the length of real accelerator magnets. The design is based on the LARP Technological Quadrupoles (TQ), under development at FNAL and LBNL, with gradient higher than 200 T/m and aperture of 90 mm. The mechanical design will be chosen between two designs presently explored for the TQs: traditional collars and Al-shell based design (preloaded by bladders and keys). The fabrication of the first long quadrupole model is expected to start in the last quarter of 2007. Meanwhile the fabrication of 4 m-long racetrack coils started this year at BNL. These coils will be tested in an Al-shell based supporting structure developed at LBNL. Several challenges have to be addressed for the successful fabrication of long Nb3Sn coils. This paper presents these challenges with comments and solutions adopted or under study for these magnets. The coil design of these magnets, including conductor and insulation features, and quench protection studies are also presented.

Test results of TQS03: A LARP shell-based Nb3Sn quadrupole using 108/127 conductor

Rutherford-type cables made of high critical current Nb/sub 3/Sn strands are being used in several laboratories for developing new generation superconducting magnets for present and future accelerators and upgrades. Testing of cable short samples is an important part of these R&D programs and the instability problem found in some short model magnets at Fermilab made these tests even more significant. Fermilab in collaboration with BNL, CERN and LBNL has developed sample holders and sample preparation infrastructure and procedures for testing Nb/sub 3/Sn cable short samples at BNL and CERN test facilities. This paper describes the sample holders, sample preparation and instrumentation, and test results. Several samples made of MJR or PIT strands 1 mm in diameter have been tested. Some samples were unstable (i.e. quenched at low transport currents) at low fields and reached the critical surface at higher fields.

Progress in Wind-and-React Bi-2212 Accelerator Magnet Technology

Lawrence Berkeley National Laboratory develops high-field Nb3Sn magnets for HEP applications. In the past few years, this experience has been extended to the design and fabrication of undulator magnets. Some undulator applications require devices that can operate in the presence of a heat load from a beam. The use of Nb3Sn permits operation of a device at both a marginally higher temperature (5-8 K) and a higher Jc, compared to NbTi devices, without requiring a larger magnetic gap. A half-undulator device consisting of 6 periods (12 coil packs) of 14.5 mm period was designed, wound, reacted, potted and tested. It reached the short sample current limit of 717 A in 4 quenches. The non-Cu Jc of the strand was over 7,600 A /mm2 and the Cu current density at quench was over 8,000 A/mm2 . Magnetic field models show that if a complete device was fabricated with the same parameters one could obtain beam fields of 1.1 T and 1.6 T for pole gaps of 8 mm and 6 mm, respectively.