G. de Rijk

European Organization for Nuclear Research

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L. Rossi

Istituto Nazionale di Fisica Nucleare, Laboratori Acceleratori e Superconduttività Applicata

L. Bottura

European Organization for Nuclear Research

M. Bajko

European Organization for Nuclear Research

G. Kirby

European Organization for Nuclear Research

J. van Nugteren

European Organization for Nuclear Research

J. C. Pérez

European Organization for Nuclear Research

R. Bailey

The Ohio State University

E. Todesco

European Organization for Nuclear Research

V. Chabaud

European Organization for Nuclear Research

P. Ferracin

Lawrence Berkeley National Laboratory

Cooperative Institutions

European Organization for Nuclear Research

718

Fermi National Accelerator Laboratory

117

Lawrence Berkeley National Laboratory

Brookhaven National Laboratory

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

Istituto Nazionale di Fisica Nucleare

Centre National de la Recherche Scientifique

SLAC National Accelerator Laboratory

Karlsruhe Institute of Technology

CEA Paris-Saclay

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PERFORMANCE OF LHC MAIN DIPOLES FOR BEAM OPERATION

G. de Rijk M. Bajko L. Bottura Marco Buzio V. Chohan

At present about 90 % of the main dipoles for the LHC have been manufactured and one of the three cold mass assemblers has already completed the production. 85 % of the 1232 dipoles needed for the tunnel have been tested and accepted. In this paper we mainly deal with the performance results: the quench behaviour, the magnetic field quality, the electrical integrity quality and the geometry features will be summarized. PRODUCTION AND QUALITY Production has now reached over 1100 Cold Masses of the 1232 CMs to be installed and is expected to be completed by the end of October 2006 [1]. Cold tests on the remaining ~ 200 CMs are expected to finish by the end of 2006. During CM production the quality at the Cold Mass Assembler factories is assured by an extensive plan, which is an integral part of the technical specification. Early detection of faults during the assembly procedure is provided by a magnetic field measurement at room temperature. A total of 18 cases have been found [2], with 4 faults in the assembly, and 14 non-conform components. Magnetic measurements at room temperature have also been used to locate the position of electrical shorts for 18 cases [3]. Among them, 12 occurred in the inner layer and 4 on the outer one. In all cases the shorts were in the coil heads. After delivery to CERN, tests and measurements in operating (cryogenic) conditions are done to qualify the magnets. These tests are on the geometry, electrical integrity, quench behaviour and magnetic field quality.

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LHC Superconducting Dipole Production Follow-up: Results of Audit on QA Aspects in Industry

IEEE Transactions on Applied Superconductivity (2006)

M. Modena M. Bajko M. Cornelis P. Fessia P. Liénard

The manufacturing of the 1232 Superconducting Main Dipoles for LHC is under way at three European Contractors: Alstom-Jeumont (Consortium), Ansaldo Superconduttori Genova and Babcock Noell Nuclear. The manufacturing is proceeding in a very satisfactory way and in March 2005 the mid production was achieved. To intercept eventually “weak points” of the production process still present and in order to make a check of the Quality Assurance and Control in place for the series production, an Audit action was launched by CERN during summer-fall 2004. Aspects like: completion of Production and Quality Assurance documentation, structure of QC Teams, traceability, calibration and maintenance for tooling, incoming components inspections, were checked during a total of seven visits at the five different production sites. The results of the Audit in terms of analysis of “systematic” and “random” problems encountered as well as corrective actions requested are presented.

Traceability

10.1109/tasc.2006.870496

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Measurement and Numerical Evaluation of AC Losses in a ReBCO Roebel Cable at 4.5 K

IEEE Transactions on Applied Superconductivity (2016)

J. van Nugteren B. van Nugteren Peng Gao L. Bottura M. Dhallé

EuCARD-2 aims to research ReBCO superconducting magnets for future accelerator applications. The properties of ReBCO conductors are very different from low-temperature superconductors. To investigate dynamic field quality, stability, and normal zone propagation, an electrical network model for coated conductor cables was developed. To validate the model, two identical samples were prepared at CERN, after which measurements were taken at the University of Twente and Southampton University. The model predicts that for a Roebel cable, in a changing magnetic field applied in the perpendicular direction, hysteresis loss is much larger than coupling loss. In the case of a changing magnetic field applied parallel to the cable, coupling loss is dominant. In the first case, the experiment is in good agreement with the model. In the second case, the data can only be compared qualitatively because the calibration for the inductive measurement is not available.

Superconducting Coils

10.1109/tasc.2016.2525919

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The LEP Magnet System at 100 GeV (or more)

G. de Rijk

The maximum energy for which the LEP magnet system can be used is reviewed. The limiting system MQA can still be upgraded by a few percent. The quench behaviour of the superconducting quadrupoles is reviewed. The LEP magnets are subject to ageing effects due to the synchrotron radiation. Predictions of the radiation damage are evaluated. 1 LIMITS OF FIELD AND GRADIENT The LEP magnet system has been designed with considerable safety margins [1]. The machine, which was intended for 86 GeV, has already been used at energies of 96 GeV. Further increase of the energy to 100 GeV is foreseen in 1999. In Table 1 the situation for the various magnet systems is summarised. For each system the maximum possible field or field gradient is compared with the values needed for running at 100 GeV with the 102°/90°-1.25m/4cm optics [2]. The 4 MQA magnets used for QS8.2 and QS8.6 are 3% above the given maximum. The current limit of these magnets can be lifted by 10% as magnetically the saturation will become a limit at 110% of the present maximum. The cooling situation of these magnets will be re-optimised, during the 1998/1999 shutdown, to allow for this upgrade. For all other magnet systems the maximum fields are well above the energy limit which is imposed by the available total RF voltage. Table 1 Field and gradient limits for LEP magnets Magnet B / G max B / G for 100 GeV E max (GeV) MB 0.135 T 0.1125 T 120 MQ 9.5 T/m 8.34 T/m 113.9 MQA 11.0 T/m (+10%) 11.34 T/m 106.7 MSF 180 T/m 83.39 T/m 215.9 MSD 180 T/m 117.41 T/m 153.3 MQSC 60 T/m 54.8 T/m 109.5 During the cold checkout, preceding each year’s run, the cooling of the magnet system is tested during a socalled heat-run. The system is run up to above the excitation values of the following run for at least 10 hours. The cooling water is kept at the high temperature values of the mid-summer situation. All heating problems are repaired during successive tests until a problem free test is achieved. In 1998 the test was done for excitation values corresponding to the 102°/90°-1.5m/5cm optics at 100 GeV (except for QS8.2 and QS8.6 which were run at 97 GeV). For the 1999 test the system will be tested for the values of the 102°/90°-1.25m/4cm optics at 102 GeV.

Upgrade

Dipole magnet

Saturation (graph theory)

Limiting

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Design of a high-field twin aperture superconducting dipole model

IEEE Transactions on Magnetics (1988)

D. Leroy R. Perin G. de Rijk W. Thomi

An initial design for the Large Hadron Collider to be installed in the tunnel of the CERN LEP machine is based on the so-called two-in-one concept, originally proposed and tested at Brookhaven National Laboratory for fields up to approximately 5 T. The dipole magnets of the two rings have a common magnetic circuit and are located in one cryostat. Two major lines of development are followed for the construction of models of high-field magnets: (1) using Nb/sub 3/Sn superconducting cables at 4.5 K, and (2) using NbTi alloy superconducting cables at 2 K. The models discussed are 1 m long twin aperture dipoles. They employ NbTi alloy superconducting cables at 2 K but, apart from the coils, the mechanical design concepts are equally valid for magnets using using Nb/sub 3/Sn cables. A role of the models is to test the various components and procedures of fabrication in order to obtain the best performances at lowest cost. Possible variants in the design are mentioned.< >

Cryostat

Niobium-tin

Superconducting Super Collider

Dipole magnet

10.1109/20.11495

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Citations (34)

A silicon strip detector telescope for the measurement of production and decay of charmed particles

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment (1984)

R. Bailey E. Belau T. Böhringer M. Bosman V. Chabaud

10.1016/0168-9002(84)90165-7

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Citations (17)

Experimental limit on the decay D0→e∓μ±

Physics Letters B (1987)

H. Pałka R. Bailey H. Becker E. Belau T. Böhringer

10.1016/0370-2693(87)91303-7

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THE SPS AS LEAD-ION ACCELERATOR

X. Altuna E. Brouzet C Niquille A. Faugier J. Wenninger

In 1995 the CERN SPS was used during two months to accelerate fully stripped ions of the Pb 208 isotope from the equivalent proton momentum of 13 GeV/c to 400 GeV/c. The radio frequency swing which is needed in order to keep the synchronism during acceleration is too big to have the SPS cavities deliver enough voltage for all frequencies. In a first stage, the beam is accelerated from 13 GeV/c to 26 GeV/c using the fixed frequency mode. During this stage the beam is grouped in four 2μsec batches, separated by 3μsec holes during which the frequency is changed in order to keep synchronism. At 26 GeV the beams are de-bunched and recaptured in order to fill the 3μsec holes. From there on the lead ions are then accelerated up to 400 GeV/c with the normal frequency program. The de-bunching and recapture at 26 GeV improved the effective spill at extraction by a factor of three. Intensities up to 3.9 10 10 charges could be obtained at 400 GeV/c. The total efficiency of the two RF captures was 64%.

Synchronism

Momentum (technical analysis)

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Training Behavior of the Main Dipoles in the Large Hadron Collider

IEEE Transactions on Applied Superconductivity (2017)

E. Todesco Bernhard Auchmann M. Bajko L. Bottura Oliver Brüning

In 2015, the 1232 Nb-Ti dipole magnets in the Large Hadron Collider (LHC) have been commissioned to 7.8 T operational field, with 172 quenches. More than 80% of these quenches occurred in the magnets of one of the three cold mass assemblers (3000 series), confirming what was already observed in 2008. In this paper, the recent analysis carried out on the quench performance of the Large Hadron Collider dipole magnets is reported, including the individual reception tests and the 2008 and 2015 commissioning campaigns, to better understand the above-mentioned anomaly and give an outlook for future operation and possible increase of the operational field. The lower part of the quench probability spectrum is compatible with Gaussian distributions; therefore, the training curve can be fit through error functions. An essential ingredient in this analysis is the estimate of the error to be associated with the training data due to sampling of rare events, allowing to test different hypothesis. Using this approach, an estimate of the number of quenches required to reach 8.3 T (corresponding to the 7 TeV nominal energy) is given, and we propose to have two LHC sectors trained toward this target before the next warm up of the LHC.

10.1109/tasc.2017.2657504

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Differential geometry method for minimum hard-way bending 3D design of coils with ReBCO tape conductor

Superconductor Science and Technology (2022)

Thomas Nes G. de Rijk A. Kario Herman H.J. ten Kate

Abstract The use of tape conductor poses design challenges for superconducting magnets. Due to its very high aspect ratio, it is hardly possible to bend the conductor over its thin edges (hard-way bending) rather than over its wide side (easy-way bending). Overstraining the conductor causes critical current degradation. In this paper, we propose a new design approach to three-dimensional coil layouts and coil end geometries with tape conductor, which considers the tape’s geometrical limitations. To geometrically describe the conductor surface, we use the thin strip model, also referred to as constant perimeter geometry. To prevent conductor degradation, new optimization criteria valid for three-dimensional geometries are presented, which are prevention of conductor creasing, minimization of overall bending energy, and prevention of over-straining the conductor. We will apply this to two 3D coil designs called helix and canted cosine theta. For the design of the coil ends, we propose a new design method using Bézier splines, which allows for much greater design flexibility than previous methods. Two examples of coil end geometries generated with Bézier splines are presented: the so-called cloverleaf and cosine-theta.

10.1088/1361-6668/ac8e39

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Citations (6)