engNakamoto, TTanaka, KYamamoto, ATsuchiya, KBurkhardt, E EHigashi, NKimura, NOgitsu, TOhuchi, NSasaki, KShintomi, TTerashima, AKirby, G AOstojic, RTaylor, T MQuench and Mechanical Behaviour of an LHC Low-$\beta$ Quadrupole ModelAccelerators and Storage RingsLHC-Project-Report-273CERN-LHC-Project-Report-273KEK-98-174A one meter model of the high gradient 70 mm aperture superconducting low-b quadrupole has been developed at KEK. The design field gradient is 240 T/m at a current of 7677 A with a superconducting load line ratio of 92% and peak field of 9.64 T in the coil. A first series of training tests of the magnet was carried out at 1.9 K including a full thermal cycle to room temperature. The highest quench current was 8007 A corresponding to a field gradient of 250 T/m. The magnet was subsequently reassembled to improve its longitudinal mechanical structure. In this paper, quench characteristics and mechanical behavior of the first model magnet are presented.1999-02-10http://cds.cern.ch/record/382853http://cds.cern.ch/record/382853oai:cds.cern.ch:382853 engFikis, HFoitl, MKirchmayr, HLe Naour, SOberli, L RPuzniak, RSzewczyk, AWisniewski, AWolf, RMagnetization Measurements on LHC Superconducting StrandsAccelerators and Storage RingsLHC-Project-Report-245CERN-LHC-Project-Report-245When using superconducting magnets in particle accelerators like the LHC, persistent currents in the superconductor often determine the field quality at injection, where the magnetic field is low. This paper describes magnetization measurements made on LHC cable strands at the Technical University of Vienna and the Institute of Physics of the Polish Academy of Sciences in collaboration with CERN. Measurements were performed at T=2K and T=4.2K on more than 50 strands of 7 different manufacturers with NbTi filament diameter between 5 and 7 micrometer. Two different measurement set-ups were used: vibrating sample magnetometer, with a sample length of about 8mm, and an integrating coil magnetometer, with sample length of about 1m. The two methods were compared by measuring the same sample. Low field evidence of proximity effect is discussed. Statistics like ratio of the width of the magnetization loop at 4.2K and 2K, and the initial slope dM/dB after cooldown are presented. Decrease of the magnetization with time, of the order of 2% per hour, was observed in some samples.1998-10-07http://cds.cern.ch/record/368846http://cds.cern.ch/record/368846oai:cds.cern.ch:368846 engBillan, JBóna, MBottura, LLeroy, DPagano, OPerin, RPerini, DRossi, LSavary, FSiemko, ASievers, PSpigo, GVlogaert, JWalckiers, LWyss, CTest Results on the Long Models and Full Scale Prototype of the Second Generation LHC Arc DipolesAccelerators and Storage RingsLHC-Project-Report-244CERN-LHC-Project-Report-244With the first test of the first full scale prototype in June-July 1998, the R&D on the long superconducting dipoles based on the LHC design of 1993-95 has come to an end. This second generation of long magnets has a 56 mm coil aperture, is wound with 15 mm wide cable arranged in a 5 coil blocks layout. The series includes four 10 m long model dipoles, whose coil have been wound and collared in Industry and the cold mass assembled and cryostated at CERN, and one 15 long dipole prototype, manufactured totally in Industry in the frame of a CERN-INFN collaboration for the LHC. After a brief description of particular features of the design and of the manufacture, test results are reported and compared with the expectation. One magnet reached the record field for long model dipoles of 9.8 T but results have not been well reproducible from magnet to magnet. Guidelines of the modifications that will appear in the next generation of long magnets, based on a six block coil design, are indicated in the conclusions.1998-10-07http://cds.cern.ch/record/368845http://cds.cern.ch/record/368845oai:cds.cern.ch:368845 engMaroussov, VSiemko, AA method to evaluate the temperature profile in a superconducting magnet during a quenchAccelerators and Storage RingsLHC-Project-Report-242CERN-LHC-Project-Report-242A simple method to derive the temperature profile in a superconducting magnet during a quench from measured voltage signals is described. The method was applied to several Large Hadron Collider single aperture dipole models. These measurements show the strong correlation between parameters of the magnet protection system and powering on the one hand and the resulting temperature gradient in the magnet coil on the other. The method allows the localisation of critical points in the magnet design, in particular, the efficiency of the magnet protection system can be evaluated.1998-10-01http://cds.cern.ch/record/368720http://cds.cern.ch/record/368720oai:cds.cern.ch:368720 engAng, ZBejar, IBottura, LRichter, DSheehan, MWalckiers, LWolf, RMeasurement of AC Loss and Magnetic Field during Ramps in the LHC Model DipolesAccelerators and Storage RingsLHC-Project-Report-241CERN-LHC-Project-Report-241We describe the systems for AC loss and magnetic field measurements developed for the LHC superconducting magnets. AC loss measurements are performed using an electric method, while field measurements are performed using either fixed pick-ups or rotating coils. We present results obtained on 1-m long model dipoles, and compare the results of the different methods in terms of average inter-strand resistance and low order field harmonics.1998-09-30http://cds.cern.ch/record/368717http://cds.cern.ch/record/368717oai:cds.cern.ch:368717 doi:10.1109/77.783400engAdam, J DLeroy, DOberli, L RRichter, DStrand Coating for the Superconducting Cables of the LHC Main MagnetsAccelerators and Storage RingsLHC-Project-Report-251CERN-LHC-Project-Report-251The electrical resistance of contacts between strands in the Rutherford type superconducting cables has a major effect on the eddy current loss in cables, and on the dynamic magnetic field error in the LHC main magnets. In order to guarantee the value and constancy of the contact resistance, various metallic coatings were studied from the electrical and mechanical points of view in the past. We report on the molten bath Sn95wt.Ag5wt. coating, oxidized thermally in air after the cabling is completed, that we adopted for the cables of the LHC main magnets. The value of the con-tact resistance is determined by the strand coating and cabling procedures, oxidation heat treatment, and the magnet coil cu-ring and handling. Chemical analysis helps to understand the evolution of the contacts. We also mention results on two electrolytic coatings resulting in higher contact resistance.1998-10-07http://cds.cern.ch/record/36859610.1109/77.783400http://cds.cern.ch/record/368596oai:cds.cern.ch:368596 doi:0.1109/77.783499engBauer, POberli, L RWolf, RWilson, M NMinimum Quench Energies of LHC StrandsAccelerators and Storage RingsLHC-Project-Report-247CERN-LHC-Project-Report-247Within the framework of the LHC Project a program has been initiated at CERN to establish the influence of various strand parameters (coating, Cu/Sc ratio, RRR, billet design, cooling) on the Minimum Quench Energy (MQE) of LHC prototype strands operating in superfluid helium at 1.9K in peak-fields of 9T. The experimental technique is based on a graphite-paste tip heater described in [1]. The analysis of the measurements was facilitated by a theoretical model based on the numerical solution of the one-dimensional heat balance equation.1998-10-07http://cds.cern.ch/record/3685930.1109/77.783499http://cds.cern.ch/record/368593oai:cds.cern.ch:368593 engVerweij, A PGenest, JKnezovic, ALeroy, DMarzolf, J POberli, L R1.9 K Test Facility for the Reception of the Superconducting Cables for the LHCAccelerators and Storage RingsLHC-Project-Report-246CERN-LHC-Project-Report-246A new test facility (called FRESCA) is under construction at CERN to measure the electrical properties of the LHC superconducting cables. Its main features compared to existing test facilities are: a) independently cooled background magnet, b) test currents up to 32 kA, c) temperature between 1.8 and 4.5 K, d) long measurement length of 60 cm, e) field perpendicular or parallel to the cable face, f) measurement of the current distribution between the strands. The facility consists of an outer cryostat containing a superconducting NbTi dipole magnet with a bore of 56 mm and a maximum operating field of 9.5 T. The current through the magnet is supplied by an external 16 kA power supply and fed into the cryostat using self-cooled leads. The lower bath of the cryostat, separated by means of a so called lambda-plate from the upper bath, can be cooled down to 1.9 K using a subcooled superfluid refrigeration system. Within the outer cryostat, an inner cryostat is installed, containing the superconducting cable samples. This approach makes it possible to change samples while keeping the background magnet cold, and thus decreasing the helium consumption and cool-down time of the samples. The cable samples are connected through self-cooled leads to an external 32 kA power supply. The lower bath of the inner cryostat, containing the sample holder, is separated by means of a so called lambda-plate from the upper bath and can be cooled down to 1.9 K. The samples can be rotated while remaining at liquid helium temperature, enabling measurements with the background field perpendicular or parallel to the broad face of the cable. Several arrays of Hall probes are installed next to the samples in order to estimate possible current imbalances between the strands of the cables.1998-10-07http://cds.cern.ch/record/368592http://cds.cern.ch/record/368592oai:cds.cern.ch:368592 engBauer, PDonnier, JOberli, L RTip Heater for Minimum Quench Energy Measurements on Superconducting StrandsAccelerators and Storage RingsLHC-Project-Report-248CERN-LHC-Project-Report-248Superconducting strands can be characterized by their Minimum Quench Energy (MQE), i.e. the minimum heat pulse needed to trigger a quench in operation conditions (field, temperature, current), in the limit of a (temporally and spatially) d-shaped disturbance. The sub-mm/µs range of perturbation space has only recently been achieved using the electrical graphite-paste heater technique [1]. The present work has put this technique into practice for the strands of the LHC main magnets, which are designed to operate at 1.9K in peak fields of up to 9T [1]. No way has been found yet to calibrate MQE measurements. To make relative statements on the MQE of different samples possible, the reproducibility of the measurements was emphasized. First heater prototypes did not come up to this stipulation. Finally the tip-heater configuration was found to meet the requirements. It generates a heat pulse in a thin resistive graphite paste deposit on top of a small tip that is pressed against the sample with a clamp. The clamp guarantees a maximum of exposure of the sample to the surrounding cryogen. The most striking aspect of repeated measurements on a reference sample is that in open bath conditions the MQE as a function of transport current in subcooled helium can reach hundred times the corresponding value in adiabatic conditions (i.e. with the sample potted in a low conductivity medium). This extraordinary cooling performance of superfluid helium, predicted by many (e.g. [2]) has rarely been shown in superconductor stability experiments.1998-10-07http://cds.cern.ch/record/372931http://cds.cern.ch/record/372931oai:cds.cern.ch:372931 doi:10.1109/77.783502engKim, S WLeroy, DBehaviour of Copper Matrix in Quench Process Calculated by 2-strand 4-wire ModelAccelerators and Storage RingsLHC-Project-Report-249CERN-LHC-Project-Report-249In a simulation of a superconducting strand, it is usual to treat the strand as superconducting wire and copper wire in a parallel connection. When simulating a multi-stranded cable, strands are treated as a mixture of superconductor and copper, usually. All parameters are calculated from a combination of those for superconductor and copper. This means the role of copper was just changing properties of the strand. However in real current transition process, the copper matrix may play a role of a path of current and heat. In this paper, one strand is considered as two wires; superconductor and copper, and calculations were done for a cable with two strands. The simulation model and some results which show behavior of the copper matrix in quench process are presented in this paper. The difference between 'matrix heating' and 'filament heating' is also discussed. (6 refs).1998-10-05http://cds.cern.ch/record/36859410.1109/77.783502http://cds.cern.ch/record/368594oai:cds.cern.ch:368594 doi:10.1109/77.783501engKim, S WLeroy, DWilson, M NGhosh, ASampson, W BStability Measurements of Rutherford Cables with Various TreatmentsAccelerators and Storage RingsLHC-Project-Report-250CERN-LHC-Project-Report-250To improve the stability of Rutherford type superconducting cables, various methods of treating cables were considered and tested. These treatments include strand coating, partial soldering, "barber-pole" insulation and "porous $9 metal" solder filling. To study the effect of these treatments, several cables were prepared and MQE (minimum quench energy) values were measured. Coating, partial soldering or "barber-pole insulation" improved the relative stability $9 for some cables. The "porous metal" filled cables showed higher MQE. However the results suggest that the porous metal process needs to be improved. The measured data for cables with various treatments are presented. (8 refs).1998-09-07http://cds.cern.ch/record/36859510.1109/77.783501http://cds.cern.ch/record/368595oai:cds.cern.ch:368595