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Superconducting link bus design for the accelerator project for upgrade of LHC

Description: The Accelerator Project for Upgrade of LHC (APUL) is a U.S. project participating in and contributing to CERN's Large Hadron Collider (LHC) upgrade program. Fermi National Accelerator Laboratory in collaboration with Brookhaven National Laboratory was developing sub-systems for the upgrade of the LHC final focus magnet systems. Part of the upgrade called for various lengths of superconducting power transmission lines known as SC Links which were up to 100 m long. The SC Link electrically connects the current leads in the Distribution Feed Boxes to the interaction region magnets. The SC Link is an extension of the magnet bus housed within a cryostat. The present concept for the bus consists of 22 power cables, 4 x 13 kA, 2 x 7 kA, 8 x 2.5 kA and 8 x 0.6 kA bundled into one bus. Different cable and strand possibilities were considered for the bus design including Rutherford cable. The Rutherford cable bus design potentially would have required splices at each sharp elbow in the SC Link. The advantage of the round bus design is that splices are only required at each end of the bus during installation at CERN. The round bus is very flexible and is suitable for pulling through the cryostat. Development of the round bus prototype and of 2 splice designs is described in this paper. Magnetic analysis and mechanical test results of the 13 kA cable and splices are presented.
Date: June 1, 2011
Creator: Nobrega, F.; Brandt, J.; Cheban, S.; Feher, S.; Kaducak, M.; Kashikhin, V. et al.
Partner: UNT Libraries Government Documents Department

Critical Current of Superconducting Rutherford Cable in High Magnetic Fields with Transverse Pressure

Description: For high energy physics applications superconducting cables are subjected to large stresses and high magnetic fields during service. It is essential to know how these cables perform in these operating conditions. A loading fixture capable of applying loads of up to 700 kN has been developed by NHMFL for LBNL. This fixture permits uniform loading of straight cables over a 122 mm length in a split-pair solenoid in fields up to 12 T at 4.2 K. The first results from this system for Rutherford cables of internal-tin and modified jelly roll strand of Nb{sub 3}Sn produced by IGC and TWC showed that little permanent degradation occurs up to 210 MPa. However, the cable made from internal-tin strand showed a 40% reduction in K{sub c} at 11T and 210 MPa while a dable made from modified jelly roll material showed only a 15% reduction in I{sub c} at 11T and 185 MPa.
Date: September 1, 1998
Creator: Dietderich, D.R.; Scanlan, R.M.; Walsh, R.P. & Miller, J.R.
Partner: UNT Libraries Government Documents Department

Analysis of Voltage Signals from Superconducting Accelerator Magnets

Description: We present two techniques used in the analysis of voltage tap data collected during recent tests of superconducting magnets developed by the Superconducting Magnet Program at Lawrence Berkeley National Laboratory. The first technique was used on a quadrupole to provide information about quench origins that could not be obtained using the time-of-flight method. The second technique illustrates the use of data from transient flux imbalances occurring during magnet ramping to diagnose changes in the current-temperature margin of a superconducting cable. In both cases, the results of this analysis contributed to make improvements on subsequent magnets.
Date: October 30, 2009
Creator: Lizarazo, J.; Caspi, S.; Ferracin, P.; Joseph, J.; Lietzke, A. F.; Sabbi, G. L. et al.
Partner: UNT Libraries Government Documents Department

Report on Furukawa Coax #1

Description: This report contains the results of measurements performed on sample coax No.1 from the Furukawa Cable Co. of Japan. Time domain reflectometer (TOR) and RLC measurements were made at room temperature and superconducting. Network analyzer measurements of S11 and S21 were made for the superconducting coax.
Date: November 26, 1984
Creator: Peterson, D.
Partner: UNT Libraries Government Documents Department

Report on Furukawa Coax #2

Description: This report contains the results of measurements performed on sample coax No.2 from the Furukawa Cable Co. of Japan. Time domain reflectometer (TOR) and RLC measurements were made at room temperature and superconducting. Network analyzer measurements of S11 and S21 were made for the superconducting coax.
Date: December 6, 1984
Creator: Peterson, D.
Partner: UNT Libraries Government Documents Department

Use of High Resolution DAQ System to Aid Diagnosis of HD2b, a High Performance Nb3Sn Dipole

Description: A novel voltage monitoring system to record voltage transients in superconducting magnets is being developed at LBNL. This system has 160 monitoring channels capable of measuring differential voltages of up to 1.5kV with 100kHz bandwidth and 500kS/s digitizing rate. This paper presents analysis results from data taken with a 16 channel prototype system. From that analysis we were able to diagnose a change in the current-temperature margin of the superconducting cable by analyzing Flux-Jump data collected after a magnet energy extraction failure during testing of a high field Nb{sub 3}Sn dipole.
Date: August 17, 2008
Creator: Lizarazo, J.; Doering, D.; Doolittle, L.; Galvin, J.; Caspi, S.; Dietderich, D. R. et al.
Partner: UNT Libraries Government Documents Department

Ac loss calorimeter for three-phase cable

Description: A calorimeter for measuring ac losses in meter-long lengths of HTS superconducting power transmission line cables is described. The calorimeter, which is based on a temperature difference technique, has a precision of 1 mW and measures single, two-phase (coupling), and three-phase losses. The measurements show significant coupling losses between phases.
Date: October 1, 1996
Creator: Daney, D.E.; Boenig, H.J.; Maley, M.P.; McMurry, D.E. & DeBlanc, B.G.
Partner: UNT Libraries Government Documents Department

Development and fabrication of a Bi-2223 racetrack coil for generator applications

Description: The development and fabrication of a layer-wound, epoxy-impregnated Bi-2223 high-temperature superconducting (HTS) racetrack coil which generates 40,000 ampere-turns of magnetomotive force (MMF) at 25 K is described. The coil was wound using Ag-sheathed Bi-2223 tape conductor laminated with copper foils for strength enhancement and insulated using a paper-wrap method. After epoxy impregnation, the coil was tested over a range of 16--25 K in a vacuum dewar using a closed-cycle helium refrigeration system. Descriptions of the tape lamination and insulation processing, the coil winding and impregnation, and the experimental test setup are given.
Date: December 31, 1996
Creator: Herd, K.G.; Salasoo, L.; Laskaris, E.T.; Ranze, R.A.; King, C.G.; Haldar, P. et al.
Partner: UNT Libraries Government Documents Department

Stability measurements on cored cables in normal and superfluid helium

Description: The relative stability of LHC type cables has been measured by the direct heating of one of the individual strands with a short duration current pulse. The minimum energy required to initiate a quench has been determined for a number of cables which have a central core to increase the effective inter-strand cross-over resistance. Experiments were performed in both normal helium at 4.4 K and superfluid at 1.9 K. Conductors in general are less stable at the lower temperature when measured at the same fraction of critical current. Results show that the cored-cables, even when partially filled with solder or with a porous-metal filler exhibit a relatively low stability at currents close to the critical current. It is speculated that the high inter-strand electrical and thermal resistance inherent in these cables may effect the stability at high currents.
Date: July 1, 1998
Creator: Ghosh, A.K.; Sampson, W.B.; Kim, S.W.; Leroy, D.; Oberli, L.R. & Wilson, M.N.
Partner: UNT Libraries Government Documents Department

AC Losses of Prototype HTS Transmission Cables

Description: Since 1995 Southwire Company and Oak Ridge National Laboratory (ORNL) have jointly designed, built, and tested nine, l-m long, high temperature superconducting (HTS) transmission cable prototypes. This paper summarizes the AC loss measurements of five of the cables not reported elsewhere, and compares the losses with each other and with theory developed by Dresner. Losses were measured with both a calorimetric and an electrical technique. Because of the broad resistive transition of the HTS tapes, the cables can be operated stably beyond their critical currents. The AC losses were measured in this region as well as below critical currents. Dresner's theory takes into account the broad resistive transition of the HTS tapes and calculates the AC losses both below and above the critical current. The two sets of AC 10SS data agree with each other and with the theory quite welL In particular, at low currents of incomplete penetration, the loss data agree with the theoretical prediction of hysteresis loss based on only the outer two Iayers carrying the total current.
Date: September 13, 1998
Creator: Demko, J.A.; Dresner, L.; Hughey, R.L.; Lue, J.W.; Olsen, S.K.; Sinha, U. et al.
Partner: UNT Libraries Government Documents Department

Analysis of a HTSC current lead under nonlinear heat transfer conditions

Description: The main objective of this paper is to consider the influence of the temperature dependence of the convective heat transfer coefficient on the optimal thermal design of the high temperature superconducting a HTSCI part of a cryogenic current lead. In the previous study the analysis of a HTSC lead was performed with the assumption that the heat transfer coefficient between the coolant (boil-off liquid helium) and the lead is finite but constant along the lead. In a present effort the heat transfer coefficient is allowed to vary along die lead causing an additional nonlinearity in the model. Numerically obtained current lead temperature profiles and corresponding helium vapor temperature profiles were used to calculate entropy generation within the lead as a function of the relevant design parameters. It has been demonstrated that additional nonlinearities do not cause a significant change of optimal design parameters.
Date: April 1, 1995
Creator: Sekulic, D.P.; Uzelac, Z. & Edeskuty, F.J.
Partner: UNT Libraries Government Documents Department

Construction and testing of arc dipoles and quadrupoles for the relativistic heavy ion collider (RHIC) at BNL

Description: The production run of superconducting magnets for the Relativistic Heavy Ion Collider (RHIC) project at Brookhaven National Laboratory (BNL) is well underway. Of the 288 arc dipoles needed for the collider, more than 120 have been delivered. More than 150 arc quadrupoles have been delivered. All of these magnets have been accepted for RHIC. This paper reports the construction and performance of these magnets. Novel features of design and test, introduced to enhance technical performance and control costs, are also discussed. Other papers submitted to this Conference summarize work on the sextupoles and tuning quads, arc correctors, and combined corrector-quadrupole-sextupole assemblies (CQS).
Date: May 1, 1995
Creator: Wanderer, P.; Muratore, J. & Anerella, M.
Partner: UNT Libraries Government Documents Department

Application of Electrical and Calorimetric Methods to the A.C. Loss Characterization of Cable Conductors

Description: Due to the higher currents (and therefore higher losses) compared to individual wires and tapes, the ac loss characterization of HTS cable conductors carrying transport current can be performed using calorimetric as well as electrical methods. We discuss the main features of two calorimetric methods, one based on temperature profile determination, and one, more recently developed, based on nitrogen boil-off rate, and of the electrical method, substantially derived from that already established for tapes, based on voltage measurement by a Lock-In amplifier. Advantages and limits of each approach are analyzed and compared. Tests have been carried out with the three methods on samples 1 to 1.5 m long cut from a Bi-2223 cable conductor prototype fabricated by Pirelli in a longer length. Results obtained from measurements covering a wide range of currents are compared and thoroughly discussed.
Date: September 13, 1998
Creator: Coletta, C.; Gherardi, L.; Gomory, F.; Cereda, E.; Ottoboni, V.; Daney, D.E. et al.
Partner: UNT Libraries Government Documents Department

Electrical resistance of superconducting cable splices

Description: The electrical resistance of superconducting cable splices is known to be in the 10{sup -9} {Omega} range which to be measured conventionally would require the use of a micro voltmeter with a power supply capable of generating kilo Amperes plus a liquid helium cryostat with large power leads. Here we present a system for carrying on such measurements that requires besides the microvoltmeter a power supply capable of generating only up to 35 {Alpha} and a 152 mm diameter neck helium dewar using less than 25 liters per day after initial cool down. In this paper we describe the apparatus and present the data taken with it in its first use which for data acquisition used just a chart recorder. The method is based in making the splice in a loop of cable, inducing a current in it and measuring its decay time constant. Generating high currents in superconductors by induction is not a new technique but the use of the decay constant of currents generated this way for the determination of minute electrical resistance seems novel to the author. Unexpected details in the results will be discussed.
Date: July 1, 1997
Creator: Kuchnir, M.
Partner: UNT Libraries Government Documents Department

Constant of thermal heat conduction and stabilization of the bus bar conductor for superconducting accelerators

Description: Using the one-dimensional, time-independent conduction state, a constant of thermal heating conduction is given that brings about the known stabilization theorem and a closed expression for the bus bar to be cryogenically stable in superconducting accelerators.
Date: July 1, 1993
Creator: Lopez, G.
Partner: UNT Libraries Government Documents Department

Detection of the normal zone with cowound sensors in cable-in conduit conductors

Description: Tokamaks in the future will use superconducting cable-in-conduit- conductors (CICC) in all poloidal field (PF) and toroidal field (TF) magnets. Conventional quench detection, the measurement of small resistive normal zone voltages ({lt}1 V) in the magnets will be complicated by the presence of large inductive voltages ({gt}4 kV). In the quench detection design for TPX, we have considered several different locations for internal co-wound voltage sensors in the cable cross-section as the primary mechanism to cancel this inductive noise. The Noise Rejection Experiment (NRE) at LLNL has been designed to evaluate which internal locations will produce the best inductive- noise cancellation, and provide us with experimental data for comparison with previously developed theory. The details of the experiments and resulting data are presented and analyzed.
Date: July 30, 1996
Creator: Martovetsky, N.N. & Chaplin, M.R.
Partner: UNT Libraries Government Documents Department

Superconducting current transformer for testing Nb3Sn cable splicing technique

Description: To provide a quick feedback on different approaches to superconducting cable splicing design and assembly techniques, a superconducting current transformer that can deliver more than 20 kA for testing splice samples has been designed and fabricated. The existing infrastructure of the Short Sample Test Facility at Fermilab, including its cryostat, power supply, and data acquisition system, was used for housing and operating the transformer. This report presents the design features of the transformer and the main results of cable splice tests.
Date: September 10, 2002
Creator: al., Nicolai Andreev et
Partner: UNT Libraries Government Documents Department