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Development of high-performance Nb3Sn quadrupoles is one of the major goals of the LHC Accelerator Research Program (LARP). As part of this program, long racetrack magnets are being made in order to check that the change in coil length that takes place during reaction is correctly accounted for in the quadrupole design and to check for length effects in implementing the ‘shell’ method of coil support. To check the racetrack magnet manufacturing plan, a short racetrack magnet is being made. This magnet will be the first to use restack-rod process Nb3Sn, making it a ‘long sample’ test vehicle for this new material. The paper reports the reaction and characterization of the Nb3Sn, and construction features and test results from the short racetrack magnet. The paper also reports on the status of the construction of the first long racetrack magnet. [ABSTRACT FROM AUTHOR]

In support of the development of a large-aperture Nb3Sn superconducting quadrupole for the Large Hadron Collider luminosity upgrade, two models (TQS and TQC) with a 90-mm aperture are being constructed at LBNL and FNAL within the framework of the US LHC Accelerator Research Program (LARP). These models use two identical Nb3Sn coils but have different coil support structures. This paper describes the fabrication, assembly, cool-down and test of TQS01—a model based on key and bladder technology with supporting iron yoke and an aluminum shell. Comparison of the test measurements with design expectations is also reported. [ABSTRACT FROM AUTHOR]

The US LHC Accelerator Research Program (LARP) is developing Nb3Sn accelerator magnets for a possible LHC luminosity upgrade. As part of the LARP supporting R&D, a subscale racetrack quadrupole magnet (SQ) has been developed in order to provide a cost effective tool for technology development studies. The first magnet (SQ01), reported earlier, was tested as a proof-of-principle model that applied for the first time LBNL shell-based loading structure to Nb3Sn racetrack coils in a quadrupole configuration. The new loading structure, pre-loaded with water-pressurized bladders and keys, provided predictable and controllable pre-stress to four subscale racetrack coils, both in the end region and across the straight section. A second magnet (SQ02) has been recently completed, with the goal of assessing the conductor performance and the influence of the coil axial support on training. SQ02 implements four new coils wound around aluminum bronze islands and instrumented with voltage taps and spot heaters, in order to monitor quench locations and propagation velocities. This paper reports the SQ02 test results, including magnet quench performance with respect to short sample expectations, training history, and quench locations. [ABSTRACT FROM AUTHOR]

In 2004, the US DOE established the LHC Accelerator Research Program (LARP) with the goal of developing a technology base for future upgrades of the LHC. The focus of the magnet program, which is a collaboration of three US laboratories, BNL, FNAL and LBNL, is an development of high gradient quadrupoles using Nb3Sn superconductor. Other program components address issues regarding magnet design, radiation-hard materials, long magnet scale-up, quench protection, fabrication techniques and conductor and cable R&D. This paper presents an overall view of the program with emphasis on the current quadrupole project and outlines the long-term goals of the program. [ABSTRACT FROM AUTHOR]

Magnet programs at BNL, LBNL and FNAL have observed instabilities in high Jc Nb3 Sn strands and magnets made from these strands. This paper correlates the strand stability determined from a short sample-strand test to the observed magnet performance. It has been observed that strands that carry high currents at high fields (greater than 10 T) cannot sustain these same currents at low fields (1-3 T) when the sample current is fixed and the magnetic field is ramped. This suggests that the present generation of strand is susceptible to flux jumps (FJ). To prevent flux jumps from limiting stand performance, one must accommodate the energy released during a flux jump. To better understand FJ this work has focused on wire with a given sub-element diameter and shows that one can significantly improve stability by increasing the copper conductivity (higher residual resistivity ratio, RRR, of the Cu). This increased stability significantly improves the conductor performance and permits it to carry more current. [ABSTRACT FROM AUTHOR]

A full-scale mechanical model of the LHC Nb3Sn quadrupole magnet structure has been designed, built and tested. The structure will support a 90 mm bore, lm long magnet prototype as part of the US LHC Accelerator Research Program (LARP). The structure utilizes Bladder and Key Technology to control and transfer pre-stress from an outer aluminum shell to an inner coil. Axial aluminum rods take care of pre-stress at the ends--ensuring that the coil is fully constrained along all three axes. The outer aluminum shell and an inner "dummy coil" (aluminum tube) were extensively instrumented with strain gauges. The gauges were used to monitor and map the effectiveness of the stress relation between the loading structure and a "dummy" coil through varying mechanical load conditions--from bladder and key pit-stress at room temper- attire through cool-down. Test results of the stress distribution in the structure and the in dummy coil is reported and compared with expected results calculated with the structural analysis program ANSYS. [ABSTRACT FROM AUTHOR]

Building accelerator quality magnets using Nb3Sn for next generation facilities is the challenge of the next decade. The Superconducting Magnet Group at LBNL has developed an innovative support structure for high field magnets. The structure is based on an aluminum shell over iron yokes using hydraulic bladders and locking keys for applying the pre-stress. At cool down the pre-stress is almost doubled due to the differences of thermal contraction. This new structure allows precise control of the pre-stress with minimal spring back and conductor over-stress. At present the support structure has been used with prototype magnets up to one meter in length. In this paper, the design of a 4-meter long, 11 Tesla, wind-and-react racetrack dipole will be presented as a possible step toward the fabrication of long Nb3Sn accelerator magnets. [ABSTRACT FROM AUTHOR]

The article focuses on the IEEE Council on Superconductivity Awards in Applied Superconductivity Presented at 2004 Applied Superconductivity Conference. The IEEE Awards in Applied Superconductivity, sponsored by the IEEE Council on Superconductivity, were presented during the Applied Superconductivity Conference 2004, which was held in Jacksonville FL on October 3-8, 2004. These Awards, approved by the Institute of Electrical and Electronic Engineers (WEE), were established to recognize researchers, engineers and managers, who, during their professional careers, have made outstanding contributions to the field of applied superconductivity.

From the standpoint of overall conductor cost, it is desirable to minimize the amount of Cu that is co-processed with the superconductor during strand fabrication. We are investigating several approaches for fabricating multistrand cables in which the Cu is added at the final, i.e., cabling, stage of manufacture. These include mixed strand Rutherford-type cables with pure Cu strands cabled together with superconductor strands that have a low volume fraction of Cu, Cu added as a core to a Rutherford-type cable, and Cu strip added to the surface of the cable. Results on fabrication of several alternate types of Nb3Sn cables are presented. The more promising types of mixed strand and cored cables are being evaluated in short sample and small magnet tests. These results will be presented and the performance will be compared with conventional Rutherford cables where the Cu is an integral component of the superconductor strand. [ABSTRACT FROM AUTHOR]