Bajko, M Charrondiere, M Benda, V Giloux, C Thiesen, H New Cryogenic Test Station at CERN for Superconducting Magnets and their Components Following the optimization planning of the superconducting magnet test facilities at CERN, a new station for vertical test of R&D magnet has been installed in a building already dedicated to horizontal test of long superconducting magnets built for the LHC. This paper describes the main cryogenic and powering characteristics of the new test station. It gives the details of each cryostat and the related equipment that composes the test station. Although the test station is optimized for low temperature superconducting magnet testing, it offers a wide range of possibility for testing equipment and components of magnets and accelerators over a large range of temperature between 1.8 K and 50 K. The test station will be completed in the next coming years with a cryostat, briefly described here, dedicated for large magnets up to 1 m diameter and 2.5 m long. eng 2013

Imported from Invenio. Brodzinski, K Tavian, L First Measurements of Beam-Induced Heating on the LHC Cryogenic System The Large Hadron Collider (LHC) under operation at CERN is colliding 3.5 TeV hadron beams which are gradually increased in intensity and luminosity. Consequently, beam-induced heating on the beam screens and on the magnet cold masses starts to be observable on the LHC cryogenic system. This paper recalls the cooling principle of the magnet cold masses and beam screens in the LHC standard cells, describes the methods applied for assessing the beam-induced heating, discusses the experimental limitations and compares measurements with expected values. eng 2013
http://cds.cern.ch/record/1507616/files/CERN-ATS-2013-009.pdf; http://cds.cern.ch/record/1507616/files/CERN-ATS-2013-009.pdf?subformat=pdfa;
Imported from Invenio. Chorowski, M Piotriowska, A Tavian, L Updated Risk Analysis of the LHC Cryogenic and Helium Distribution System The Preliminary Risk Analysis (PRA) of the Large Hadron Collider cryogenic system, performed in 1998, was aimed at the identification of all the risks for personnel, equipment or environment caused by the failures that might accidentally occur in any phase of the machine operation, and that could not be eliminated by design. The risk analysis was performed during a design and an early construction phase of the machine, so after the collider commissioning and consolidation experience, especially due to the 080919 incident in the LHC sector 3-4, PRA had to be revised and updated. The paper discusses the criterions of cryogenic failures categorization taking into account their occurrence and severity. eng 2013
http://cds.cern.ch/record/1507615/files/CERN-ATS-2013-008.pdf; http://cds.cern.ch/record/1507615/files/CERN-ATS-2013-008.pdf?subformat=pdfa;
Imported from Invenio. Liu, L Perin, A van Weelderen, R Xiong, L Simulation Study of Cool-Down of the CLIC Wiggler Magnets The cryogenic system for the CLIC wiggler magnets is under design. The cooldown process is one of the main dimensioning factors for the system. In this paper, the heat transfer model used to simulate the cool-down process is presented. Different configurations are then investigated and a detailed analysis of the corresponding temperature evolutions along the magnet strings is calculated. The temperature profiles are evaluated for the flowing helium as well as for the magnets allowing a detailed analysis of the temperature gradients. The impact of some key parameters, like the mass-flow rate, the diameter of the cooling channels and of the thermal coupling between the helium and the magnets is also investigated. eng 2013
http://cds.cern.ch/record/1507614/files/CERN-ATS-2013-007.pdf; http://cds.cern.ch/record/1507614/files/CERN-ATS-2013-007.pdf?subformat=pdfa;
Imported from Invenio. Baglin, V Lebrun, P Tavian, L van Weelderen, R Cryogenic Beam Screens for High-Energy Particle Accelerators Applied superconductivity has become a key enabling technology for high-energy particle accelerators, thus making them large helium cryogenic systems operating at very low temperature. The circulation of high-intensity particle beams in these machines generates energy deposition in the first wall through different processes. For thermodynamic efficiency, it is advisable to intercept these beam-induced heat loads, which may be large in comparison with cryostat heat in-leaks, at higher temperature than that of the superconducting magnets of the accelerator, by means of beam screens located in the magnet apertures. Beam screens may also be used as part of the ultra-high vacuum system of the accelerator, by sheltering the gas molecules cryopumped on the beam pipe from impinging radiation and thus avoiding pressure runaway. Space being extremely tight in the magnet apertures, cooling of the long, slender beam screens also raises substantial problems in cryogenic heat transfer and fluid flow. We present sizing rules and technical solutions for such beam screens, as applied to the existing Large Hadron Collider (LHC) and its upgrades under study. eng 2013
http://cds.cern.ch/record/1507613/files/CERN-ATS-2013-006.pdf; http://cds.cern.ch/record/1507613/files/CERN-ATS-2013-006.pdf?subformat=pdfa;
Imported from Invenio. Fluder, C Blanco, E Bremer, J Bremer, K Ivens, B Casas-Cubillos, J Claudet, S Gomes, P Ivens, B Perin, A Pezzetti, M Tovar-Gonzalez, A Vauthier, N Main Consolidations and Improvements of the Control System and Instrumentation for the LHC Cryogenics Operation of the LHC during 2010 and 2011 with 3.5 TeV beam energy and luminosity up to 3.65x1033 cm-2 s-1, led to radiation-induced failures of micro-electronic devices used in the cryogenic control system. Mitigating actions addressed equipment relocation and corrective patches on electronics and software. Driven by the technical requirements and by feedback from the cryogenic operation team, numerous consolidations and improvements were implemented on-the-fly, enhancing availability and operability of the LHC cryogenics. Furthermore, additional diagnostic tools, test benches, technical procedures and trainings have been provided to strengthen first line support services. eng 2013
http://cds.cern.ch/record/1507612/files/CERN-ATS-2013-005.pdf; http://cds.cern.ch/record/1507612/files/CERN-ATS-2013-005.pdf?subformat=pdfa;
Imported from Invenio. Claudet, S Brodzinkski, K Ferlin, G Lebrun, P Tavian, L Wagner, U Energy Efficiency of large Cryogenic Systems: the LHC Case and Beyond Research infrastructures for high-energy and nuclear physics, nuclear fusion and production of high magnetic fields are increasingly based on applied superconductivity and associated cryogenics in their quest for scientific breakthroughs at affordable capital and operation costs, a condition for their acceptance and sustained funding by society. The thermodynamic penalty for operating at low temperature makes energy efficiency a key requirement for their large cryogenic systems, from conceptual design to procurement, construction and operation. Meeting this requirement takes a combined approach on several fronts in parallel: management of heat loads and sizing of cooling duties, distribution of cooling power matching the needs of the superconducting devices, efficient production of refrigeration, optimal control resting on precise instrumentation and diagnostics, as well as a targeted industrial procurement policy. The case of the Large Hadron Collider (LHC) at CERN is presented. Potential improvements for future projects are discussed together with qualitative and quantitative impacts. eng 2013
http://cds.cern.ch/record/1507611/files/CERN-ATS-2013-004.pdf; http://cds.cern.ch/record/1507611/files/CERN-ATS-2013-004.pdf?subformat=pdfa;
Imported from Invenio. Balle, C Casas, J Fortescue-Beck, E Vauthier, N Accuracy of the Approximation Function Deduced from the Fixed 3-Points Calibration Delivered with the Cernox™ Sensor The cernox™ sensor is delivered with a 3-point resistance versus temperature cal-ibration that permits the construction of an individual interpolation table by using the data in the CERN thermometer database. For instance at the 4.2 K point, the individual calibration and the manufacturer data are within +/-0.1 K for 99.39% of a sample population of about 5700 sensors. Preliminary results also indicate that accuracies of 0.1 K and 1 K can be obtained below respectively 5 K and 77 K. eng 2013
http://cds.cern.ch/record/1507610/files/CERN-ATS-2013-003.pdf; http://cds.cern.ch/record/1507610/files/CERN-ATS-2013-003.pdf?subformat=pdfa;
Imported from Invenio. Barth, K Benda, V Claudet, S Pezzetti, M Pirotte, O Vullierme, B Upgrade of the Liquid Helium Storage for the Large Hadron Collider The cryogenic system of the Large Hadron Collider (LHC) under operation at CERN has a total helium inventory of 140 t. Up to 50 t can be stored in gas storage tanks. The remaining inventory is stored in a liquid helium storage system consisting of six 15-t liquid helium tanks sited in 4 locations. The first phase with the commissioning of the two first liquid helium tanks including their infrastructure was already presented. In a second phase, four new tanks were commissioned at the end of 2010. The paper describes the modifications relating to these four tanks and presents the measurement of their thermal performance. eng 2013
http://cds.cern.ch/record/1507606/files/CERN-ATS-2013-002.pdf; http://cds.cern.ch/record/1507606/files/CERN-ATS-2013-002.pdf?subformat=pdfa;
Imported from Invenio.