engLebrun, PRiddone, GTavian, LWagner, UDemands in refrigeration capacity for the Large Hadron ColliderAccelerators and Storage RingsLHC-Project-Report-18CERN-LHC-Project-Report-181996-07-12http://cds.cern.ch/record/315773http://cds.cern.ch/record/315773oai:cds.cern.ch:315773 engBallarino, AIjspeert, AlbertWagner, UPotential of High-Temperature Super Conductor Current Leads for LHC CryogenicsAccelerators and Storage RingsLHC-Project-Report-19CERN-LHC-Project-Report-191996http://cds.cern.ch/record/326938http://cds.cern.ch/record/326938oai:cds.cern.ch:326938 engBenda, VDauvergne, J PHaug, FKnoops, SLebrun, PMomal, FSergo, STavian, LVullierme, BUpgrade of the CERN Cryogenic Station for Superfluid Helium Testing of Prototype LHC Superconducting MagnetsAccelerators and Storage RingsLHC-Project-Report-20CERN-LHC-Project-Report-201997http://cds.cern.ch/record/326937http://cds.cern.ch/record/326937oai:cds.cern.ch:326937revised version number 1 submitted on 2004-02-17 08:58:02 doi:10.1016/B978-008042688-4/50103-4engFerlin, GJenninger, BLebrun, PPeón-Hernández, GRiddone, GSzeless, BalázsComparison of floating and thermalized multilayer insulation systems at low boundary temperatureAccelerators and Storage RingsLHC-Project-Report-21CERN-LHC-Project-Report-21The Large Hadron Collider (LHC) is 26.7 km circumference particle collider using high-field superconducting magnets operating in superfluid helium. An efficient and robust thermal insulation system is therefore required to minimize the residual heat in leak to the large surface area at 1.9 K constituted by the stainless steel wall of the helium enclosure. The baseline solution uses "floating" multilayer reflective insulation. Moreover, an alternative consists of a combination of multilayer reflective films and a soft screen, partially thermalized to the 5 K level and supported away from the cold wall by net-type insulating spacers. This chapter establishes the improvement potential of the alternative over the baseline solution, and compares their insulation performance on the basis of measured characteristics of thermal contacts and spacers.1996-07-17http://cds.cern.ch/record/31003210.1016/B978-008042688-4/50103-4http://cds.cern.ch/record/310032oai:cds.cern.ch:310032 engHaug, FDauvergne, J PPassardi, GiorgioCragg, DCuré, CPailler, PMayri, CYamamoto, ARefrigeration System for the ATLAS ExperimentDetectors and Experimental TechniquesLHC-Project-Report-28CERN-LHC-Project-Report-28The proposed ATLAS detector for the 27 km circumference LHC collider is of unprecedented size and complexity. The magnet configuration is based on an inner superconducting solenoid and large superconducting air-core toroids (barrel and two end-caps) each made of eight coils symmetrically arranged outside the calorimetry. The total cold mass approaches 600 tons and the stored energy is 1.7 GJ. The cryogenic infrastructure will include a 6 kW @ 4.5 K refrigerator, a precooling unit and distribution systems and permits flexible operation during cool-down, normal running and quench recovery. A dedicated LN2 refrigeration system is proposed for the three liquid argon calorimeters (84 m3 of LAr). Magnets and calorimeters will be individually tested prior to their definitive installation in a large scale cryogenic test area on the surface. The experiment is scheduled to be operational in 2005.1996-07-15http://cds.cern.ch/record/313308http://cds.cern.ch/record/313308oai:cds.cern.ch:313308 engKirby, G AOstler, J MPerini, DSiegel, NSiemko, ATommasini, DWalckiers, LPower Test Results of the First LHC Second Generation Superconducting Single Aperture 1m Long Dipole ModelsAccelerators and Storage RingsLHC-Project-Report-30CERN-LHC-Project-Report-30Within the LHC magnet research and development programme, a series of single aperture 1m long models of second generation are presently being built and tested at CERN. The main features of these magnets are: five-block, two layer coils wound from 15mm wide graded NbTi cables, enlarged 56mm aperture and all-polyimide insulation. This paper reviews the power test data of magnets tested to date in both supercritical and superfluid helium. The results of the quench training, the initial location and propagation of quenches and their sensitivity to energy extraction are presented and discussed in terms of the design parameters and the aims of this short dipole model test program.1996-07-18http://cds.cern.ch/record/307559http://cds.cern.ch/record/307559oai:cds.cern.ch:307559revised version number 1 submitted on 2004-02-17 10:06:13 engSzeless, BalázsRodríguez-Mateos, FCalvone, FDevelopment of Industrially Produced Composite Quench Heaters for the LHC Superconducting Lattice MagnetsAccelerators and Storage RingsLHC-Project-Report-48CERN-LHC-Project-Report-48The quench heaters are vital elements for the protection of the LHC superconducting lattice magnets in the case of resistive transitions of the conductor. The basic concept of magnet protection and technical solutions are briefly presented. The quench heater consists of partially copper clad stainless steel strips sandwiched in between electric insulating carrier foils with electrical and mechanical properties such as to withstand high voltages, low temperatures, pressures and ionizing radiation. Testing of some commercial available electric insulation foils, polyimide (PI), polyetheretherketon (PEEK) and polyarylate (PA) and combinations of adhesive systems which are suitable for industrial processing are described. Possible industrial methods for series production for some 80 km of these composite quench heaters are indicated.1996-09-23http://cds.cern.ch/record/615758http://cds.cern.ch/record/615758oai:cds.cern.ch:615758 engCruikshank, PKos, NRiddone, GTavian, LInvestigation of Thermal and Vacuum Transients on the LHC Prototype Magnet StringAccelerators and Storage RingsLHC-Project-Report-50CERN-LHC-Project-Report-50The prototype magnet string, described in a companion paper, is a full-scale working model of a 50-m length of the future Large Hadron Collider (LHC), CERN's new accelerator project, which will use high-field superconducting magnets operating below 2 K in superfluid helium. As such, it provides an excellent test bed for practising standard operating modes of LHC insulation vacuum and cryogenics, as well as for experimentally assessing accidental behaviour and failure modes, and thus verifying design calculations. We present experimental investigation of insulation vacuum pumpdown, magnet forced-flow cooldown and warmup, and evolution of residual vacuum pressures and temperatures in natural warmup, as well as catastrophic loss of insulation vacuum. In all these transient modes, experimental results are compared with simulated behaviour, using a non-linear, one-dimensional thermal model of the magnet string.1996-05-20http://cds.cern.ch/record/309215http://cds.cern.ch/record/309215oai:cds.cern.ch:309215 engBallarino, AIjspeert, AlbertTeng, MWagner, UHarrison, SSmith, KCowey, LDesign of 12.5 kA current leads for the Large Hadron Collider using high temperature superconductor materialAccelerators and Storage RingsLHC-Project-Report-62CERN-LHC-Project-Report-62The Large Hadron Collider will be equipped with about 8000 superconducting magnets. Some 2600 current leads will feed the currents ranging from 25 to 12500 A. CERN aims to reduce the consumption of liquid helium, using high temperature superconductors in these leads. A development of leads for 12.5 kA is being conducted in collaboration with Oxford Instruments. The design options for these leads are described. A test rig and prototype lead have been made according to one of the options. Electrical contact tests are in progress on BSCCO-2212 and YBCO-123 samples. In the first run, the prototype carried 13000 A.1996-10-23http://cds.cern.ch/record/314613http://cds.cern.ch/record/314613oai:cds.cern.ch:314613 engBallarino, AIjspeert, AlbertDesign and Tests on the 30 to 600 A HTS Current Leads for the Large Hadron ColliderAccelerators and Storage RingsLHC-Project-Report-78CERN-LHC-Project-Report-78Some 800 correction magnets of the Large Hadron Collider will be individually powered. Each of them needs a pair of current leads. To reduce the heat leak through these leads, the current has been chosen as low as reasonably possible, 30 to 600 A. For the same reason CERN started in-house a development of current leads using commercial bulk BSCCO-2212 material.This paper discusses the design and the test results of this lead. We tested several prototypes, measured the heat leak through the lead, studied and tested what happens if the lead is brought to critical temperature causing it to quench.1996-10-24http://cds.cern.ch/record/313676http://cds.cern.ch/record/313676oai:cds.cern.ch:313676revised version submitted on 2004-08-19 11:32:52 engDauvergne, J PDelikaris, DHaug, FTechnical Analysis and Statistics from Long Term Helium Cryoplant Operation with Experimental Superconducting Magnets at CERNAccelerators and Storage RingsCERN-LHC-96-013-ECRCERN regularly uses a large number of liquid helium cryoplants for cooling the superconducting magnets of large particle detectors. They are installed in the experimental areas of the electron-positron collider LEP and the proton (and heavy ion) accelerator SPS for the observation of high-energy interactions of elementary particles. The typical cold mass of a detector magnet ranges from 1 to 40 tons, and typical cryoplant cooling capacities are between 400 and 800 W/4.5 K entropy equivalent. Operation must be very flexible to meet the varying experimental requirements. We intend to present technical data of the system and statistics from over 180'000 running hours during the four years from 1992 to 1995. Operation includes phases of cool-down, steady-state cooling, recovery after magnet quench or other incidents and warm-up of the superconducting magnets. Emphasis will be laid on the analysis of fault conditions, multiple interaction between perturbations and consequences for the users of liquid helium supply interruption.1996-08-07http://cds.cern.ch/record/321825http://cds.cern.ch/record/321825oai:cds.cern.ch:321825 engBarranco-Luque, MClaudet, SGayet, PSolheim, N OWinkler, GOperation of the cryogenic system for superconducting cavities in LEPAccelerators and Storage RingsCERN-LHC-96-010-ACR1996-07-16http://cds.cern.ch/record/315769http://cds.cern.ch/record/315769oai:cds.cern.ch:315769 engMelaaen, EOwren, GWadahl, AWagner, USimulation program for cryogenic plants at CERNAccelerators and Storage RingsCERN-LHC-96-009-ACR1996-07-11http://cds.cern.ch/record/315767http://cds.cern.ch/record/315767oai:cds.cern.ch:315767 engBremer, JDauvergne, J PDelikaris, DDelruelle, NKesseler, GPassardi, GiorgioRieubland, Jean MichelTischhauser, JohannHaug, FCryogenics for CERN experiments: past, present and futureAccelerators and Storage RingsCERN-LHC-96-006-ECRUse of cryogenics at CERN was originated (in the 1960s) by bubble chambers and the associated s.c. solenoids. Complex cryoplants were installed to provide cooling at LH2 and LHe temperatures. Continuity (in the 1970s) in He cryogenics for experiments was provided by spectrometer magnets for fixed target physics of the SPS accelerator. More recently (in the 1980s), large "particle-transparent" s.c. solenoids for collider experiments (LEP) have been built demanding new cryoplants. The LHC experiments (in the 2000s) will continue the tradition with s.c. dipoles (ALICE and LHCb), solenoids (CMS, ATLAS) and toroids (ATLAS) of unusual size. Cryogenics for experiments using noble liquids follows the same trend since the development (in the 1970s) of the first shower LAr detectors. A LKr calorimeter (about 10 m3) will be operated in 1996 and the ATLAS experiment foresees a set of three huge LAr calorimeters (almost 90 m3 total volume of liquid) to be installed underground.1996-06-17http://cds.cern.ch/record/305518http://cds.cern.ch/record/305518oai:cds.cern.ch:305518 engDecker, LLöhlein, KSchustr, PVins, MBrunovsky, ILebrun, PTavian, LA cryogenic axial-centrifugal compressor for superfluid helium refrigerationAccelerators and Storage RingsLHC-Project-Report-22CERN-LHC-Project-Report-22CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.1996-05-17http://cds.cern.ch/record/308239http://cds.cern.ch/record/308239oai:cds.cern.ch:308239 engBézaguet, Alain-ArthurCasas-Cubillos, JGuinaudeau, HHilbert, BLebrun, PSerio, LSuraci, AVan Weelderen, RCryogenic operation and testing of the extended LHC prototype magnet stringAccelerators and Storage RingsLHC-Project-Report-23CERN-LHC-Project-Report-23After the assembly, commissioning and successful first operation of a full-scale superconducting magnet string, and as a new prototype dipole magnet was added to approach final configuration, the cryogenic system has been slightly modified to allow the verification of the performance of the superfluid helium cooling loop in counter-current two-phase flow. At the same time the control system strategies have been updated and only two quench relief valves have been installed, one at each end of the string. We report on the cryogenic operation of the extended version of the string and the response of the system to transients.1996-05-17http://cds.cern.ch/record/308240http://cds.cern.ch/record/308240oai:cds.cern.ch:308240revised version number 1 submitted on 2004-02-17 09:05:47 engPeón-Hernández, GJenninger, BSzeless, BalázsCharacterisation of net type thermal insulators at 1.8 K low boundary temperatureAccelerators and Storage RingsLHC-Project-Report-76CERN-LHC-Project-Report-76The Large Hadron Collider's superconducting magnets are cooled by superfluid helium at 1.8 K and housed in cryostats that minimise the heat inleak to this temperature level by extracting heat at 70 and 5 K. In the first generation of prototype cryostats, the radiative heat to the 1.8 K temperature level accounted for 70 % of the total heat inleak. An alternative to enhance the cryostat thermal performance incorporates a thermalised radiation screen at 5 K. In order to avoid contact between the 5 K radiation screen and the cold mass, insulators are placed between both surfaces. Sets of commercial fibre glass nets are insulator candidates to minimise the heat inleak caused by a accidental contact between the two temperature levels. A model to estimate their performance is presented. A set-up to thermally characterise them has been designed and is also described in the paper. Finally, results as a function of the number of the spacer nets, the boundary temperatures and the compressive force in the spacer are presented.1996-11-13http://cds.cern.ch/record/316268http://cds.cern.ch/record/316268oai:cds.cern.ch:316268