Thermo-magnetic instabilities in Nb3Sn Superconducting Accelerator Magnets

International Nuclear Information System (INIS)

Bordini, Bernardo; Pisa U.

2006-01-01

The advance of High Energy Physics research using circulating accelerators strongly depends on increasing the magnetic bending field which accelerator magnets provide. To achieve high fields, the most powerful present-day accelerator magnets employ NbTi superconducting technology; however, with the start up of Large Hadron Collider (LHC) in 2007, NbTi magnets will have reached the maximum field allowed by the intrinsic properties of this superconductor. A further increase of the field strength necessarily requires a change in superconductor material; the best candidate is Nb 3 Sn. Several laboratories in the US and Europe are currently working on developing Nb 3 Sn accelerator magnets, and although these magnets have great potential, it is suspected that their performance may be fundamentally limited by conductor thermo-magnetic instabilities: an idea first proposed by the Fermilab High Field Magnet group early in 2003. This thesis presents a study of thermo-magnetic instability in high field Nb 3 Sn accelerator magnets. In this chapter the following topics are described: the role of superconducting magnets in High Energy Physics; the main characteristics of superconductors for accelerator magnets; typical measurements of current capability in superconducting strands; the properties of Nb 3 Sn; a description of the manufacturing process of Nb 3 Sn strands; superconducting cables; a typical layout of superconducting accelerator magnets; the current state of the art of Nb 3 Sn accelerator magnets; the High Field Magnet program at Fermilab; and the scope of the thesis

Magnetization measurements on multifilamentary Nb3Sn and NbTi conductors

International Nuclear Information System (INIS)

Ghosh, A.K.; Robins, K.E.; Sampson, W.B.

1984-01-01

The effective filament size has been determined for a number of high current Nb 3 Sn multifilamentary composites. In most cases it is much larger than the nominal filament size. For the smallest filaments (approx. 1 micron) the effective size can be as much as a factor of forty times the nominal size. Samples made by the internal tin, bronze route, and jelly roll methods have been examined with filaments in the range one to ten microns. Rate dependent magnetization and flux jumping have been observed in some cases. NbTi composites ranging in filament size from nine to two hundred microns and with copper to super-conductor ratios between 1.6:1 and 7:1 have been examined in the same apparatus. Low field flux jumping was only observed in conductors with very large filaments and relatively little stabilizing copper. 9 references, 6 figures, 3 tables

Properties of idealized designs of NB3SN composites

International Nuclear Information System (INIS)

Smathers, D.B.; Larbalestier, D.C.; Lee, P.J.; Marken, K.R.; McDonald, W.K.; O'Larey, P.M.

1985-01-01

A series of seven idealized bronze-Nb 3 Sn composites were manufactured by the MJR process with varying matrix to filament ratios and pure Nb and Nb 0.8 wt.% Ti cores. The central core of each composite was sealed by a diffusion barrier which results in each filament having an identical source of tin. Initial evaluations of the composites from critical current and transmission electron microscopy measurements are presented and their properties compared to standard MJR composites. The Nb 3 Sn current density does not appear to be a strong function of bronze to Nb ratio over the range 2.4 to 3.2:1. The standard MJR composites have higher critical current densities than the idealized composites. It is proposed that the major reason for the increased current density of the normal MJR conductors is the intrinsically higher quality of the filaments close to the central tin core. It is postulated that the high Sn content of the bronze surrounding these filaments leads to an intrinsically higher Nb 3 Sn filament current density

Low-temperature deuteron irradiation of differently reacted Nb3Sn superconductors

International Nuclear Information System (INIS)

Maier, P.; Seibt, E.

1978-01-01

Irradiation measurements with 50 MeV deuterons at 18 K and subsequent annealing measurements were performed on Nb 3 Sn single and multifilamentary superconductors at the Helium-Bath Irradiation Facility of the Karlsruhe Cyclotron. The critical current densities jsub(c) of Nb 3 Sn bronze-reacted wire samples at various reaction temperatures (Tsub(R)=650,700,750,800 and 850 0 C) with equal layer thickness were measured for integral deuteron fluxes up to PHIsub(t)=0.7x10 18 cm -2 . After a decrease in jsub(c) of 85% at maximum dose a relatively small annealing effect (4 to 10%) was observed at ambient temperatures. The maximum value of the normalized critical current density, jsub(c)/jsub(c0), at PHIsub(t)approximately=10 17 cm -2 increases with increasing reaction temperature. The difference in volume pinning forces before and after irradiation increases less than linear (approximately√PHIsub(t)) with the irradiation dose. An almost linear dependence between the inverse grain diameter (dsub(K) -1 )) and volume pinning force is obtained both before and after irradiation. (Auth.)

Superconducting properties and uniaxial strain characteristics of Nb3Sn fiber-reinforced superconductors with tantalum reinforcement fibers

International Nuclear Information System (INIS)

Arai, Kazuaki; Umeda, Masaichi; Agatsuma, Koh; Tateishi, Hiroshi

1998-01-01

We have been developing fiber-reinforced superconductors (FRS) for high-field and large-scale magnets. Tungsten fibers have been selected as the reinforcement fiber for FRS so far because tungsten has the highest elastic modulus of approximately 400 GPa which can minimize the strain from electromagnetic force. The preparation process of FRS consists of sputtering deposition and heat treatment because it may be difficult to apply drawing methods to materials of high-elastic modulus such as tungsten. Tantalum has high elastic modulus of 178 GPa and its thermal expansion coefficient that is closer to that of Nb 3 Sn than tungsten's, which means prestrain in Nb 3 Sn in FRS is reduced by adopting tantalum fibers. Tantalum has been used as barriers between bronze and copper in conventional Nb 3 Sn superconductors which are usually prepared with drawing process despite of the tantalum's high elastic modulus. That implies drawing process may be applied to prepare FRS with tantalum reinforcement fibers. In this paper, FRS using tantalum fibers prepared with sputtering process are described with making comparison with FRS of tungsten to clarify the basic properties of FRS using tantalum fibers. Depth profiles in Nb 3 Sn layer in FRS were measured to examine reaction between superconducting layers and reinforcement fibers. Superconducting properties including strain and stress characteristics were shown. Those data will contribute to design of FRS using tantalum reinforcement fibers with adopts the drawing processes. (author)

The investigation of the effect of niobium artificial doping with titanium on Nb3Sn superconductors properties

International Nuclear Information System (INIS)

Nikulin, A.; Shikov, A.; Beliakov, N.; Semin, M.

1997-01-01

The effect on titanium doping of Nb filaments, and thus on the properties of bronze processed multifilamentary Nb 3 Sn wires and wires with internal tin sources with copper volume fraction up to 65 %, has been analysed. Either titanium rods or rods of the Nb-50Ti alloy, inserted in the axial area of each filament, were used as a source of titanium. The influence of doping on the quantity, composition, structure and superconducting properties of intermetallic compound Nb 3 Sn after heat treatments at 570-750 degrees C with duration up to 350 h was investigated by means of electrical measurements, optical metallography and methods of microanalysis and X-ray analysis. It was shown that the non-copper critical current density of the doped wires attained 600 and 270 A/mm 2 in 12.5 and 16 T respectively for bronze processed wires and 800 and 300 A/mm 2 for wires with internal tin source. Upper critical field calculated in accordance with Kramer's extrapolation was equal to 29-32 T

Thermal fluctuations in the classical superconductor Nb3Sn from high-resolution specific-heat measurements

International Nuclear Information System (INIS)

Lortz, Rolf; Wang Yuxing; Junod, Alain; Toyota, Naoki

2007-01-01

The range of thermal fluctuations in 'classical' bulk superconductors is extremely small and especially in low-fields hardly experimentally accessible. With a new type of calorimeter we were able to detect a tiny lambda anomaly in the specific-heat of the superconductor Nb 3 Sn within a narrow temperature range around the H c2 line. We show that the evolution of the anomaly as a function of magnetic field follows scaling laws expected in the presence of critical thermal fluctuations

Metallographic investigation of fracture behavior in ITER-style Nb$_{3}$Sn superconducting strands

CERN Document Server

Jewell, M C; Larbalestier, D C; Nijhuis, A

2009-01-01

In this work we specify the extent to which fracture in two ITER-style Nb$_{3}$Sn composite strands occurs in a collective or individual manner, under mechanical tension and bending from the TARSIS apparatus at the University of Twente. A bronze-route strand from European Advanced Superconductors (EAS), which has very uniform, well-spaced filaments, has a widely distributed (200 μm) fracture field and exhibits a composite of individual and collective cracks. An internal tin strand from Oxford Instruments – Superconducting Technology (OST) demonstrates much more localized, collective fracture behavior. The filaments in this strand are about four times larger (in area) than the filaments in the EAS strand, and also agglomerate significantly during heat treatment upon conversion of the Nb to Nb$_{3}$Sn. These results demonstrate that the architecture of the strand can play a significant role in determining the mechanical toughness of the composite, and that strand design should incorporate mechanical consider...

Development of (Nb,Ta3Sn multifilamentary superconductor wire for high current applications

Directory of Open Access Journals (Sweden)

Durval Rodrigues Jr.

2000-10-01

Full Text Available The optimization of the energy generated by a MagnetoHydroDynamic (MHD channel using a superconducting magnet demands the optimization of the magnetic field of the system and of the critical points on the magnet winding. This work must include the development of a high performance superconductor wire suitable for this system. Aiming to the construction of improved performance MHD channel, it was developed a low cost superconductor wire, with the required characteristics. The wire was made using a technology compatible with the assembling steps and heat treatment conditions of the MHD superconducting magnets fabrication. It was used the internal Sn method in Nb-7.5wt%Ta tube to fabricate a 271-filament wire with a diameter of 0.81 mm and a Cu/nonCu ratio of 2.3. The wire was heat treated at 200 °C to diffuse the Sn into the Cu shell, producing bronze, followed by the final reaction at temperatures ranging from 670 °C to 730 °C during 25 to 150 h, to produce (Nb,Ta3Sn. The superconducting wire characterization was made measuring the critical current Ic versus the applied magnetic field in the range of 5 to 20 T, the critical temperature Tc and the residual resistivity ratio (RRR. The wire transported critical currents above those available in commercial superconducting wires. These values of Ic are higher than the expected values for the optimization of the MHD channel.

AC loss time constant measurements on Nb3Al and NbTi multifilamentary superconductors

International Nuclear Information System (INIS)

Painter, T.A.

1988-03-01

The AC loss time constant is a previously univestigated property of Nb 3 Al, a superconductor which, with recent technological developments, shows some advantages over the more commonly used superconductors, NbTi and Nb 3 Sn. Four Nb 3 Al samples with varying twist pitches and one NbTi sample are inductively measured for their AC loss time constants. The measured time constants are compared to the theoretical time constant limits imposed by the limits of the transverse resistivity found by Carr [5] and to the theoretical time constants found using the Bean Model as well as to each other. The measured time constants of the Nb 3 Al samples fall approximately halfway between the theoretical time constant limits, and the measured time constants of the NbTi sample is close to the theoretical lower time constant limit. The Bean Model adequately accounts for the variance of the permeability of the Nb 3 Al superconductor in a background magnetic field. Finally, the measured time constant values of the Nb 3 Al samples vary approximately according to the square of their twist pitch. (author)

Development of Nb3Sn strands for ITER in Japan

International Nuclear Information System (INIS)

Isono, T.; Nunoya, Y.; Matsui, K.; Nabara, Y.; Koizumi, N.; Takahashi, Y.; Okuno, K.

2007-01-01

Nb 3 Sn strands for ITER Toroidal Field (TF) coils and Central Solenoids (CS) are required to have both high current density (Jc) and low hysteresis loss. The required Jc at 12 T, 4.2 K and no external strain is lager than 700 A/mm 2 for bronze processed strand and lager than 800 A/mm 2 for internal tin processed one at 12 T, 4.2 K and no external strain. Upper limit of hysteresis loss is 1,000 mJ/cm 3 at 4.2 K and a cycle of ±3 T. Outer diameter is 0.82 mm and 0.83 mm for TF coils and CS, respectively. Area ratio of copper to non copper is one and outer surface is Cr plated. Japan will procure 25% of Nb 3 Sn for ITER TF coils and 100% for ITER CS. There are four Nb 3 Sn strand suppliers in Japan; three of them use bronze process and the other uses internal tin process. For bronze processed strand, increase Jc was achieved by using bronze with high tin content of 15 to 16%. To keep productivity while using the harder bronze with high tin content, Nb is used for barrier in place of Ta. The material is expected to have better adhesion to other materials such as bronze and copper. For internal tin process, size of modules, each of which has a tin rod and a lot of Nb filaments embedded in a copper cylinder, is reduced, while total amount of tin increase in order to satisfy both required high Jc and low hysteresis loss. Each supplier fabricated a strand of more than 0.1 ton for TF coils and succeeded to develop a strand satisfying the ITER requirements of Jc and hysteresis loss. (authors)

Phase analysis of superconducting Nb-Sn materials by Moessbauer spectroscopy

International Nuclear Information System (INIS)

Sitek, J.; Tomasich, M.; Cirak, J.; Prejsa, M.; Kruzliak, J.

1978-01-01

Moessbauer spectroscopy is used for the optimalization of superconducting Nb-Sn samples preparation in the form of foils. Pure phases of Nb 3 Sn, Nb 6 Sn 5 , and NbSn 2 are determined. Two series of samples are studied at 750 and 900 0 C tinning temperature respectively, and at 750, 860, 900, and 960 0 C heating temperatures. In the samples the phases Nb 3 Sn, Nb 6 Sn 5 , NbSn 2 , and the solid solution Nb-Sn phase are observed. The results from the phase analysis lead to the assumption that the percentage amount of the phases is preferentially dependent on the tinning temperature. (author)

Workshop on effects of chromium coating on Nb3Sn superconductor strand: Proceedings

International Nuclear Information System (INIS)

1994-01-01

This report discusses the following topics: Chromium coating on superconductor strand -- an overview; technology of chromium plating; comparison of wires plated by different platers; search for chromium in copper; strand manufactures' presentations; chromium plating at the Lawrence Livermore National Laboratory; a first look at a chromium plating process development project tailored for T.P.X. and I.T.E.R. strand; and influence of chromium diffusion and related phenomena on the reference ratios of bare and chromium plated Nb 3 Sn strand

Mechanical properties of high-current multifilamentary Nb3Sn conductors

International Nuclear Information System (INIS)

Scanlan, R.M.; Hoard, R.W.; Cornish, D.N.; Zbasnik, J.P.

1980-01-01

Nb 3 Sn is a strain-sensitive superconductor which exhibits large changes in properties for strains of less than 1 percent. The critical current density at 12 T undergoes a reversible degradation of a factor of two for compressive strains of about 1 percent and undergoes an irreversible degradation for tensile strains on the Nb 3 Sn greater than 0.2 percent. Consequently, the successful application of Nb 3 Sn in large high-field magnets requires a complete understanding of the mechanical properties of the conductor. One conductor which is being used for many applications consists of filaments of Nb 3 Sn in a bronze matrix, and much progress has been made in understanding the mechanical behavior of this composite. The Nb 3 Sn filaments are placed in compression due to the differential thermal contraction between Nb 3 Sn and bronze which occurs when the composite is cooled from the Nb 3 Sn formation temperature (typically 700 0 C) to the 4.2 0 K operating temperature. The general behavior of the critical current when this conductor is subjected to a tensile stress is an increase to a maximum when the compressive strain on the Nb 3 Sn is relieved, followed by a decrease as the Nb 3 Sn filemants are placed in tension. The degree of precompression is controlled largely by the ratio of bronze to Nb 3 Sn in the conductor

Thermal fluctuations in the classical superconductor Nb{sub 3}Sn from high-resolution specific-heat measurements

Energy Technology Data Exchange (ETDEWEB)

Lortz, Rolf [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland)], E-mail: Rolf.Lortz@physics.unige.ch; Wang Yuxing; Junod, Alain [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland); Toyota, Naoki [Physics Department, Graduate School of Science, Tohoku University, 980-8571 Sendai (Japan)

2007-09-01

The range of thermal fluctuations in 'classical' bulk superconductors is extremely small and especially in low-fields hardly experimentally accessible. With a new type of calorimeter we were able to detect a tiny lambda anomaly in the specific-heat of the superconductor Nb{sub 3}Sn within a narrow temperature range around the H{sub c2} line. We show that the evolution of the anomaly as a function of magnetic field follows scaling laws expected in the presence of critical thermal fluctuations.

R and D of Nb(3)Sn accelerator magnets at Fermilab

International Nuclear Information System (INIS)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E; Bordini, B.; Bossert, R.; Carcagno, R.; Chichili, D.R.; DiMarco, J.; Elementi, L.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Kephart, R.; Lamm, M.; Limon, P.J.; Novitski, I.; Orris, D.; Pischalnikov, Yu.; Schlabach, P.; Stanek, R.

2004-01-01

Fermilab is developing and investigating different high-field magnet designs for present and future accelerators. The magnet RandD program was focused on the 10-12 T accelerator magnets based on Nb 3 Sn superconductor and explored both basic magnet technologies for brittle superconductors--wind-and-react and react-and-wind. Magnet design studies in support of LHC upgrades and VLHC are being performed. A series of 1-m long single-bore models of cos-theta Nb 3 Sn dipoles based on wind-and-react technique was fabricated and tested. Three 1-m long flat racetracks and the common coil dipole model, based on a single-layer coil and wide reacted Nb 3 Sn cable, have also been fabricated and tested. Extensive theoretical studies of magnetic instabilities in Nb 3 Sn strands, cable and magnet were performed which led to successful 10 T dipole model. This paper presents the details of the Fermilab's high field accelerator magnet program, reports its status and major results, and formulates the program next steps

R and D of Nb(3)Sn accelerator magnets at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E; Bordini, B.; Bossert, R.; Carcagno, R.; Chichili, D.R.; DiMarco, J.; Elementi, L.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Kephart, R.; Lamm, M.; Limon, P.J.; Novitski, I.; Orris, D.; Pischalnikov, Yu.; Schlabach, P.; Stanek, R.; /Fermilab

2004-11-01

Fermilab is developing and investigating different high-field magnet designs for present and future accelerators. The magnet R&D program was focused on the 10-12 T accelerator magnets based on Nb{sub 3}Sn superconductor and explored both basic magnet technologies for brittle superconductors--wind-and-react and react-and-wind. Magnet design studies in support of LHC upgrades and VLHC are being performed. A series of 1-m long single-bore models of cos-theta Nb{sub 3}Sn dipoles based on wind-and-react technique was fabricated and tested. Three 1-m long flat racetracks and the common coil dipole model, based on a single-layer coil and wide reacted Nb{sub 3}Sn cable, have also been fabricated and tested. Extensive theoretical studies of magnetic instabilities in Nb{sub 3}Sn strands, cable and magnet were performed which led to successful 10 T dipole model. This paper presents the details of the Fermilab's high field accelerator magnet program, reports its status and major results, and formulates the program next steps.

Improvement of stability of Nb₃ Sn superconductors by introducing high specific heat substances

Energy Technology Data Exchange (ETDEWEB)

Xu, X. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Li, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zlobin, A. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Peng, X. [Unlisted, US, OH

2018-01-24

High-J_c Nb₃Sn conductors have low stability against perturbations, which accounts for the slow training rates of high-field Nb₃Sn magnets. While it is known that adding substances with high specific heat (C) into Nb3Sn wires can increase their overall specific heat and thus improve their stability, there has not been a practical method that is compatible with the fabrication of long-length conductors. In this work, we put forward a scheme to introduce such substances to distributed-barrier Nb₃Sn wires, which adds minimum difficulty to the wire manufacturing process. Multifilamentary wires using a mixture of Cu and high-C Gd₂O₃ powders have been successfully fabricated along this line. Measurements showed that addition of Gd₂O₃ had no negative effects on residual resitivity ratio or non-Cu J_c, and that flux jumps were remarkably reduced, and minimum quench energy values at 4.2 K, 14 T were increased by a factor of three, indicating that stability was significantly improved. We also discussed the influences of the positioning of high-C substances and their thermal diffusivity on their effectiveness in reducing the superconductor temperature rise against perturbations. Based on these results, we proposed an optimized conductor architecture to maximize the effectiveness of this approach.

DT fusion neutron irradiation of LLL Nb3Sn and LLL superconductor wires at 4.20K

International Nuclear Information System (INIS)

MacLean, S.C.

1977-01-01

The DT fusion neutron irradiation of one LLL superconductor wire and one LLL Nb 3 Sn foil at 4.2 0 K is described. The sample position, beam-on time, and neutron dose record are given. The results from two ''profile'' dosimetry foils measuring the lateral variation in neutron flux are included

Analysis of Nb$_{3}$Sn Rutherford cable production and strand deformations

CERN Document Server

Peggiani, Sonia; Beghi, Marco

The development of cutting-edge 11-12 T superconducting magnets made from Nb$_{3}$Sn technology is one of the major milestones for the upgrade of the Large Hadron Collider at CERN. The upgrade, called High Luminosity LHC Project, was planned in order to reach higher luminosity and discover new particles. Replacing the NbTi superconductor with the Nb$_{3}$Sn makes it possible to reach a practical operating magnetic field limit of up to 16 T. The superconducting coils are formed by Nb$_{3}$Sn Rutherford cables with a trapezoidal cross section and composed of 40 strands. Since the superconducting phase of Nb$_{3}$Sn is very brittle and it is reached after a thermal cycle, the Nb$_{3}$Sn Rutherford cable needs to be wound in a coil before the thermal treatment. The cabling process is a delicate step in the production of high performing cables that need different systems to control their quality. This work aims to provide practical tools to analyze the Nb$_{3}$Sn Rutherford cable production and the strands defo...

Studies on Nb3Sn field coils for superconducting machine

International Nuclear Information System (INIS)

Fujino, H.; Nose, S.

1981-01-01

This paper describes experimental studies on several coils wound with multifilamentary (MF) Nb 3 Sn cables with reinforcing strip for superconducting rotating machine application. To use a Nb 3 Sn superconductor to field winding of a rotating machine, several coil performances of pre-reacted, bronze processed and stranded MF Nb 3 Sn cables were investigated, mainly in relation to stress effect. Bending strain up to 0.64% in strand and winding stress of 5 kg/mm 2 have resulted in nondegradation in coil performance. A pair of impregnated race-track coils designed for a 30 MVA synchronous condenser was energized successfully up to 80% of critical current without quench. 8 refs

TbNb6Sn6: the first ternary compound from the rare earth–niobium–tin system

Directory of Open Access Journals (Sweden)

Viktor Hlukhyy

2010-12-01

Full Text Available The title compound, terbium hexaniobium hexastannide, TbNb6Sn6, is the first ternary compound from the rare earth–niobium–tin system. It has the HfFe6Ge6 structure type, which can be analysed as an intergrowth of the Zr4Al3 and CaCu5 structures. All the atoms lie on special positions; their coordination geometries and site symmetries are: Tb (dodecahedron 6/mmm; Nb (distorted icosahedron 2mm; Sn (Frank–Caspar polyhedron, CN = 14–15 6mm and overline{6}m2; Sn (distorted icosahedron overline{6}m2. The structure contains a graphite-type Sn network, Kagome nets of Nb atoms, and Tb atoms alternating with Sn2 dumbbells in the channels.

Finite Element Analysis of Transverse Compressive Loads on Superconducting Nb3Sn Wires Containing Voids

Science.gov (United States)

D'Hauthuille, Luc; Zhai, Yuhu; Princeton Plasma Physics Lab Collaboration; University of Geneva Collaboration

2015-11-01

High field superconductors play an important role in many large-scale physics experiments, particularly particle colliders and fusion devices such as the LHC and ITER. The two most common superconductors used are NbTi and Nb3Sn. Nb3Sn wires are favored because of their significantly higher Jc, allowing them to produce much higher magnetic fields. The main disadvantage is that the superconducting performance of Nb3Sn is highly strain-sensitive and it is very brittle. The strain-sensitivity is strongly influenced by two factors: plasticity and cracked filaments. Cracks are induced by large stress concentrators due to the presence of voids. We will attempt to understand the correlation between Nb3Sn's irreversible strain limit and the void-induced stress concentrations around the voids. We will develop accurate 2D and 3D finite element models containing detailed filaments and possible distributions of voids in a bronze-route Nb3Sn wire. We will apply a compressive transverse load for the various cases to simulate the stress response of a Nb3Sn wire from the Lorentz force. Doing this will further improve our understanding of the effect voids have on the wire's mechanical properties, and thus, the connection between the shape & distribution of voids and performance degradation.

Synthesis and molecular structures of niobocene derivatives containing Nb-Sn-Nb metallochain

International Nuclear Information System (INIS)

Skripkin, Yu.V.; Volkov, O.G.; Pasynskij, A.A.

1985-01-01

The [Cp 2 Nb(CO)] 2 SnCl 2 (1) complex is synthesized in the form of crystals with 63% yield by the Cp 2 Nb(CO)H reaction wih SnCl 4 in THF in the presence of Et 3 N. The complex 1 is also prepared by interaction of Cp 2 Nb(CO)H with Cp 2 Nb(CO)SnCl 3 with 16% yield. The crystalline more sluble analog [(CH 3 C 5 H 4 ) 2 Nb(CO)] 2 ShCl 2 (2) is extracted, which contains the chain of Nb-Sn-Nb with short Nb-Sn(2.840)2)A bonds and 140.69(5) deg angle between them. The (Cp 2 NbH) 2 Sn(Cl)Et (3) complex is prepared wih 12% yield, possessing the structure analogous to type 2. In 3 each fragment CpNb is connected with the terminal hydride (Nb-H, 1.66(1) and 1.69(1)A) atom forms shortened bond with tin atom Nb-Sn 2.868(1) and 2.856(1) A, NbSnNb angle is 129.44(5)

Method of fabricating composite superconductors

International Nuclear Information System (INIS)

Koike, Y.; Shiraki, H.; Suzuki, E.; Yoshida, M.

1977-01-01

A method of making stabilized superconductors of a composition such as Nb 3 Sn is disclosed. The method includes forming a stock product comprising a tin base alloy as a core with a copper jacket and having a niobium tube clad thereon. The stock product is then embedded in a good thermally and electrically conducting matrix which is then coreduced until the desired size is obtained. This cold worked product is then submitted to a heat treatment to form superconductors of Nb 3 Sn

Method for the manufacture of a superconductive Nb3Sn layer on a niobium surface for high frequency applications

International Nuclear Information System (INIS)

Martens, H.

1978-01-01

A manufacturing method for depositing an Nb 3 Sn layer on a niobium surface for high frequency applications comprising developing a tin vapor atmosphere which also contains a highly volatile tin compound in the gaseous state, and holding the portions of the surface which are to be provided with the Nb 3 Sn layer at a temperature of between 900 0 and 1500 0 C for a predetermined period of time to form the Nb 3 Sn layer permitting niobium surfaces of any shape to be provided with Nb 3 Sn layers of high uniformity and quality

Cu-Nb3Sn superconducting wires prepared by ''Copper Liquid Phase Sintering method'' using the Nb-H

International Nuclear Information System (INIS)

Resende, A.T. de.

1985-01-01

Cu-30% Nb in weighting were prepared by the method of Copper sintering liquid phase the method was improved by substitution of Nb power by Nb-H powder, obtaining a high density material with good mechanical properties, which was reduced to fine. Wire, Without heat treatment. The Cu-Nb 3 Sn wires were obtained by external diffusion process depositing tin in the Cu-30%Nb wires, and by internal diffusion process using the Sn-8.5% Cu in weighting, which was reduced to rods of 3.5 mm. These Cu-30%Nb rods were enclosed in copper tubes and deformed mechanically by rotary swaging and drawing. During the drawing step some wires were fractured, that were analysed and correlated with the microstructure of the Sn-8.5 Wt% Cu alloy. External and internal diffusion samples; after a fast thermal treatment for Sn diffusion, were submited to the temperature of 700 0 C to provide the reaction between Sn and Nb, leading to the Nb 3 Sn phase. Samples with several reaction times, and its influence on T c and J c critical parameters and normal resistivity were prepared and analysed. (author) [pt

Conceptual design of a 15T-class pulsed conductor with fiber-reinforced Nb3Sn superconductor

International Nuclear Information System (INIS)

Tateishi, Hiroshi; Arai, Kazuaki; Agatsuma, Koh

1997-01-01

We have been developing a new type of Nb 3 Sn superconductor with high elastic modulus fibers for the application of high field pulsed superconducting magnets. We call this type of conductor FRS(Fiber-Reinforced Superconductor). This paper tries to show that FRS has great potential for the construction of a 15T-class pulsed magnet, with the size of which equals to that of the central solenoid of ITER(International Thermonuclear Experimental Reactor), because each monofilamentary FRS can support the part of hoop stress under operation of the magnet. Conceptual design of a basic strand with monofilamentary FRS, construction of the first- and second- level subcable, cooling condition of CICC(Cable in conduit conductor), stability and ac losses of the conductor are discussed. (author)

Anisotropy of critical current density in the superconducting Nb/sub 3/Sn tape wires

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A [Technical Univ., Wroclaw (Poland). Inst. of Fundamental Electrotechnics and Electrotechnology

1985-04-01

In this letter the results are presented of an investigation of Isub(c parallel) and Isub(c perpendicular) in Nb/sub 3/Sn layers obtained in the process diffusion of tin atoms from liquid bronze solution Cu-80% Sn to the Nb-1.5% Zr substrate. Measurements of critical current density in Nb/sub 3/Sn layers were carried out in a perpendicular magnetic field of the induction value 4.25 T for different sample surface orientations in relation to the magnetic field strength vector defined by the value of angle. The critical current density was measured at a temperature of 4.2 K. Phase identification and investigation of the microstructure of superconducting Nb-Sn layers were performed on the Moessbauer spectrometer and scanning electron microscope, respectively. Classification measurements of grains in Nb-Sn layers were carried out with TV automatic image analyser. The texture and lattice parameter in Nb/sub 3/Sn layers were investigated by means of an X-ray diffractometer. The surface zone of Nb/sub 3/Sn layer was removed with the use of an argon ion gun. Results are presented and discussed.

R&D of Nb$_{3}$Sn accelerator magnets at Fermilab

CERN Document Server

Zlobin, A V; Andreev, N; Barzi, E; Bordini, B; Bossert, R; Carcagno, R; Chichili, D R; Di Marco, J; Elementi, L; Fehér, S; Kashikhin, V S; Kashikhin, V V; Kephart, R; Lamm, M J; Limon, P J; Novitski, I; Orris, D; Pischalnikov, Y; Schlabach, P; Stanek, R; Strait, J; Sylvester, C D; Tartaglia, M; Tompkins, J C; Turrioni, D; Velev, G; Yamada, R; Yarba, V A; 10.1109/TASC.2005.849507

2005-01-01

Fermilab is developing and investigating different high-field magnets (HFM) for present and future accelerators. The HFM R&D program focused on the 10-12 T magnets based on Nb/sub 3/Sn superconductor and explored both basic magnet technologies for brittle superconductors-wind-and-react and react-and-wind. Magnet design studies in support of LHC upgrades and VLHC were conducted. A series of 1-m long cos-theta dipole models based on the wind-and-react technique was fabricated and tested. Three 1-m long flat racetracks and the common coil dipole model, based on a single-layer coil and react-and-wind technique, were also fabricated and tested. Extensive theoretical and experimental studies of electro-magnetic instabilities in Nb/sub 3/Sn strands, cables and magnets were performed and led to a successful 10 T dipole model. This paper presents the details of Fermilab's HFM program, reports its status and major results, and formulates the next steps for the program.

Intercalation compounds of NbSe2 und SnSe2. Model systems for low-dimensional superconductors

International Nuclear Information System (INIS)

Herzinger, Michael

2013-01-01

experienced a renascence of research activities. Especially, since it represents a well-suited candidate for probing the multi-band model in a quasi-two-dimensional superconductor, due to the negligible vortex pinning in NbSe 2 single crystals. In order to enhance the anisotropic character we intercalated high quality 2H-NbSe 2 single crystals with the organometallic donor molecule cobaltocene, leading to an expansion of the lattice parameter in c direction from 12.53 Aa to 23.81 Aa. While the intercalation of organic compounds (which usually act as electron donors) reduces the superconducting transition temperature Tc from 7.1 K in 2H-NbSe 2 to temperatures below Tc 2 {CoCp 2 } 0.26 with Tc = 7.35 K. Furthermore, the strong increase of the upper critical magnetic field B c2 = 18.5 T in comparison to the native parent compound (B c2 (NbSe 2 ) = 14,5 T) indicates a more pronounced anisotropic behavior. Resistivity, susceptibility and specific heat studies parallel and perpendicular to the NbSe 2 -layers of 2H-NbSe 2 {CoCp 2 } 0.26 reveal both, a field-dependent reentrant superconductivity and a reversibility of the magnetization M(B) over a wide range above 3.5 T, also observed in the native parent NbSe2. Both intercalated materials NbSe 2 {CoCp 2 } x and SnSe2{CoCp 2 } x are good candidates for further theoretical investigation of the low dimensional superconductivity. The experimental results of the layered materials presented in this thesis will contribute to a better understanding of the low dimensional superconducting behavior.

The European Nb3Sn advanced strand development programme

International Nuclear Information System (INIS)

Vostner, A.; Salpietro, E.

2005-01-01

Strands relevant for fusion with high critical current densities and moderate hysteresis losses were developed and already produced on industrial scale. Based on these achievements EFDA-CSU Garching has launched a Nb 3 Sn strand development and procurement action inside Europe in order to assess the current status of the Nb 3 Sn strand production capability. All six addressed companies have replied positively to the strand R and D programme which includes the three major Nb 3 Sn production techniques namely the bronze, internal-tin and powder-in-tube (PIT) route. According to the strand requirements for the ITER TF conductor a critical current density of 800 A/mm 2 (at 12 T, 4.2 K and 10 μV/m) and overall strand hysteresis losses below 500 kJ/m 3 have been specified as the minimum guaranteed strand performance. The second major objective of this programme is to motivate the strand manufacturers to develop and design high performance Nb 3 Sn strands optimised for the ITER conductor. For this purpose, a target critical current density of 1100 A/mm 2 has been added to the specification. This paper describes the strategy behind the strand development programme, the actual status of the strand production as well as first preliminary results obtained from the strand suppliers

Voltage spikes in Nb3Sn and NbTi strands

International Nuclear Information System (INIS)

Bordini, B.; Ambrosio, G.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Lamm, M.J.; Orris, D.; Tartaglia, M.; Tompkins, J.C.; Turrioni, D.; Yamada, R.; Zlobin, A.V.; Fermilab

2005-01-01

As part of the High Field Magnet program at Fermilab several NbTi and Nb 3 Sn strands were tested with particular emphasis on the study of voltage spikes and their relationship to superconductor instabilities. The voltage spikes were detected under various experimental conditions using voltage-current (V-I) and voltage-field (V-H) methods. Two types of spikes, designated ''magnetization'' and ''transport current'' spikes, have been identified. Their origin is most likely related to magnetization flux jump and transport current redistribution, respectively. Many of the signals observed appear to be a combination of these two types of spikes; the combination of these two instability mechanisms should play a dominant role in determining the minimum quench current

Fatigue and strain effects in NbTi, Nb3Sn, and V2(Hf, Zr) multifilamentary superconductors

International Nuclear Information System (INIS)

Kuroda, T.; Wada, H.; Tachikawa, K.

1988-01-01

The effects of cyclic strain on critical current were studied in NbTi, bronze processed Nb 3 Sn, and composite diffusion processed V 2 (Hf,Zr) multifilamentary wires. No appreciable changes in critical current were found in NbTi wires until just prior to fatigue-induced fracture. Critical current degradation was also not observed in Nb 3 Sn or V 2 (Hf,Zr) as long as the wires were strained below the reversible limit strain. For strains beyond this limit strain the critical current was first degraded by an increasing number of cycles and then remained constant after a certain cycle number was passed

Volume pinning force and upper critical field of irradiated Nb3Sn

International Nuclear Information System (INIS)

Maier, P.; Seibt, E.

1981-01-01

Irradiation by neutrons and ions in A15 superconductors (Nb 3 Sn, V 3 Ga) exerts a stronger influence on the pinning behavior than in nonordered alloys (NbTi). In this work it is shown for deuteron irradiated Nb 3 /Sn wires prepared by the bronze process that the dose curve of the volume pinning force P/sub V/ can be conveniently described by a sum of two terms, due to the grain boundary pinning and to the radiation pinning, respectively. After deduction of the contribution by the radiation-induced pinning centers, good agreement is obtained between the measured P/sub V/ values and those calculated using the upper critical field B/sub c/2 and the transition temperature T/sub c/ on the basis of the irradiation fluence. The use of a theoretical relationship between B/sub c/2 and T/sub c/ is supported by measured values. Application to multifilamentary superconductors with high current carrying capabilities simplifies the calculation of P/sub V/, since the radiation induced volume pinning force can be neglected

Comparative Study of Heat Transfer from Nb-Ti and Nb$_3$Sn coils to He II

CERN Document Server

La China, M

2008-01-01

In superconducting magnets, the energy deposited or generated in the coil must be evacuated to prevent temperature rise and consequent transition of the superconductor to the resistive state. The main barrier to heat extraction is represented by the electric insulation wrapped around superconducting cables. In the LHC, insulation improvement is a key point in the development of interaction region magnets and injector chain fast-pulsed magnets for luminosity upgrade; the high heat load of these magnets, in fact, is not compatible with the use of current insulation schemes. We review the standard insulation schemes for Nb-Ti and Nb$_{3}$Sn technology from the thermal point of view. We implement, in an analytical model, the strongly nonlinear thermal resistances of the different coil components including the permeability to superfluid helium of Nb-Ti insulations, measured during the LHC main dipole development. We use such a model to compare Nb-Ti and Nb$_{3}$Sn technologies by taking into account their specific...

Voltage spikes in Nb3Sn and NbTi strands

Energy Technology Data Exchange (ETDEWEB)

Bordini, B.; Ambrosio, G.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Lamm, M.J.; Orris, D.; Tartaglia, M.; Tompkins, J.C.; Turrioni, D.; Yamada, R.; Zlobin,; /Fermilab

2005-09-01

As part of the High Field Magnet program at Fermilab several NbTi and Nb{sub 3}Sn strands were tested with particular emphasis on the study of voltage spikes and their relationship to superconductor instabilities. The voltage spikes were detected under various experimental conditions using voltage-current (V-I) and voltage-field (V-H) methods. Two types of spikes, designated ''magnetization'' and ''transport current'' spikes, have been identified. Their origin is most likely related to magnetization flux jump and transport current redistribution, respectively. Many of the signals observed appear to be a combination of these two types of spikes; the combination of these two instability mechanisms should play a dominant role in determining the minimum quench current.

Performance of multifilamentary Nb3Sn under mechanical load

International Nuclear Information System (INIS)

Easton, D.S.; Schwall, R.E.

1976-01-01

The critical current of a commercial multifilamentary Nb 3 Sn conductor has been measured under the application of uniaxial tension at 4.2 K and following bending at room temperature. Significant reductions in J/subc/ are observed under uniaxial loading. Results are presented for a monolithic conductor manufactured by the bronze diffusion technique and for cable conductors formed by the tin-dip technique

$Nb_{3}Sn macrostructure, microstructure, and property comparisons for bronze and internal Sn process strands

CERN Document Server

Lee, P J; Larbalestier, D C

2000-01-01

The variation in irreversibility field, B*(T), with temperature has been measured for Nb/sub 3/Sn superconducting strands manufactured for ITER using vibrating sample and SQUID magnetometers. The high performance strands were developed for both high transport critical current density, J/sub c/, and low hysteresis loss. Despite a wide variety of designs and components, the strands could be split into two distinctive groups, based on the extrapolated irreversibility fields, which lie about 10% lower than the upper critical field. "Bronze-process" strands exhibited consistently higher B*(T) (28 T to 31 T) compared with "internal Sn" process (24 T to 26 T) conductors. The intrinsic critical current density of the superconductor, J/sub c (sc)/, and the specific pinning force of the grain boundaries, Q/sub gb/, were evaluated using the measured J/sub c/, and image analysis of the macro- and micro-structures. A bronze-processed Nb(-Ta)/sub 3 /Sn was found to have a higher J/sub c(sc)/ but lower Q/sub gb/ than Nb/sub...

Nb3Sn accelerator magnet technology R&D at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Chlachidze, G.; DiMarco, J.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; /Fermilab

2007-06-01

Accelerator magnets based on Nb{sub 3}Sn superconductor are being developed at Fermilab. Six nearly identical 1-m long dipole models and several mirror configurations were built and tested demonstrating magnet performance parameters and their reproducibility. The technology scale up program has started by building and testing long dipole coils. The results of this work are reported in the paper.

Method of stabilizing Nb3Sn superconducting foils

International Nuclear Information System (INIS)

Kruzliak, J.; Lences, P.; Allarova, H.

1982-01-01

The stabilization of niobium-tin Nb 3 Sn superconducting foils with copper is carried out by deposition or by diffusion in pure copper or in a tin bath containing different copper levels, with the surface etched or unetched. The foils are covered with a copper film at a temperature of 300 to 5O0 degC using a tin solder, spread on a copper, silver or nickel layer deposited on the foil surface from solutions for electroless plating. The bond between the surface of the superconducting foil and the electroless plated metal layer is annealed in a controlled atmosphere or in a vacuum at a temperature of 200 to 500 degC for over 20 to 60 minutes. The copper stabilization layer can also be produced electrolytically. (J.B.)

Advances in Nb/sub 3/Sn strand for fusion and particle accelerator applications

CERN Document Server

Parrell, J A; Seung, Hong; Youzhu, Zhang; 10.1109/TASC.2005.849531

2005-01-01

Nb/sub 3/Sn conductor made by the internal tin route is the material of choice for the highest field superconducting magnets. These include systems ranging from solenoids used in 900MHz NMR and 20 T laboratory magnets, to large-scale applications such as ITER and possible LHC upgrades. We present our latest results on internal tin strands having critical current density (J/sub c/) values of 3000 A /mm/sup 2/ (4.2 K, 12 T), as it relates to such magnet systems. One obstacle to wider use of internal tin strand is the relatively small billet size, typically limited to 50 kg or less. As part of the R&D for the U.S. High Energy Physics National Conductor Program, we have developed a method of scaling up the distributed barrier internal tin process to billet sizes several times larger. In the past year we have successfully produced a high J/sub c/ distributed barrier strand made entirely by hot extrusion. Results are also presented on a new method of supplying Ti dopant for the Nb/sub 3/Sn that does not rely on...

Production of superconducting Nb3Sn wire using Nb or Nb(Ti) and Sn(Ga) solid solution powders

International Nuclear Information System (INIS)

Thieme, C.L.H.; Foner, S.

1991-01-01

This paper reports on superconducting Nb 3 Sn wire produced by the powder metallurgy method using Nb or Nb-2.9 at% Ti powder in combination with Sn-x at% Ga powders (x = 3, 4.2, 6.2 and 9.0). Ga additions to the Sn caused considerable solid solution hardening which improved its workability. It made the Nb-Sn(Ga) powder combinations convenient for swaging and extensive wire drawing. Anneals at 950 degrees C produced wires with an overall J c of 10 4 A/cm 2 at 21.9 T for wires with both Ti in the Nb and 6.2 at% Ga in the Sn. Comparison of this wire with the best Nb(Ti)-Cu-internal Sn(Ti) shows a higher J c per A15 areas, especially in fields of 22T and above

Performance of multifilamentary Nb3Sn under mechanical load

International Nuclear Information System (INIS)

Easton, D.S.; Schwall, R.E.

1976-11-01

The critical current density of commercial multifilamentary Nb 3 Sn conductor has been measured during the application of uniaxial tension at 4.2 0 K and after bending at room temperature. Significant reductions in the critical current density J/sub c/ occurred under uniaxial loading. Results are presented for a monolithic conductor manufactured by the bronze diffusion technique and for cable conductors formed by the tin-dip technique

Impact of the Residual Resistivity Ratio on the Stability of Nb$_{3}$Sn Magnets

CERN Document Server

Bordini, B; Oberli, L; Rossi, L; Takala, E

2012-01-01

The CERN Large Hadron Collider (LHC) is envisioned to be upgraded in 2020 to increase the luminosity of the machine. The major upgrade will consist in replacing the NbTi quadrupole magnets of the interaction regions with larger aperture magnets. The Nb$_{3}$Sn technology is the preferred option for this upgrade. The critical current density Jc of Nb$_{3}$Sn strands have reached sufficiently high values (in excess of 3000 A/mm2 at 12 T and 4.2 K) allowing larger aperture/stronger field magnets. Nevertheless, such large Jc values may cause magneto-thermal instabilities that can drastically reduce the conductor performance by quenching the superconductor prematurely. In Nb$_{3}$Sn magnets, a relevant parameter for preventing premature quenches induced by magneto-thermal instabilities is the Residual Resistivity Ratio (RRR) of the conductor stabilizing copper. An experimental and theoretical study was carried out to investigate how much the value of the RRR affects the magnet stability and to identify the proper ...

Comparative study of heat transfer from Nb-Ti and Nb_{3}Sn coils to He II

Directory of Open Access Journals (Sweden)

Marco La China

2008-08-01

Full Text Available In superconducting magnets, the energy deposited or generated in the coil must be evacuated to prevent temperature rise and consequent transition of the superconductor to the resistive state. The main barrier to heat extraction is represented by the electric insulation wrapped around superconducting cables. In the LHC, insulation improvement is a key point in the development of interaction region magnets and injector chain fast-pulsed magnets for luminosity upgrade; the high heat load of these magnets, in fact, is not compatible with the use of current insulation schemes. We review the standard insulation schemes for Nb-Ti and Nb_{3}Sn technology from the thermal point of view. We implement, in an analytical model, the strongly nonlinear thermal resistances of the different coil components including the permeability to superfluid helium of Nb-Ti insulations, measured during the LHC main dipole development. We use such a model to compare Nb-Ti and Nb_{3}Sn technologies by taking into account their specific operating margin in different working conditions. Finally, we propose an insulation scheme to enhance the heat transfer capability of Nb-Ti coils.

Synthesis of nano intermetallic Nb{sub 3}Sn by mechanical alloying and annealing at low temperature

Energy Technology Data Exchange (ETDEWEB)

López, M., E-mail: marlope@udec.cl [Department of Materials Engineering, Universidad de Concepción, Edmundo Larenas 270, Concepción (Chile); Jiménez, J.A. [Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalúrgicas, C.S.I.C., Av. Gregorio del Amo 8, 28040 Madrid (Spain); Ramam, K.; Mangalaraja, R.V. [Department of Materials Engineering, Universidad de Concepción, Edmundo Larenas 270, Concepción (Chile)

2014-11-05

Highlights: • Intermetallic Nb{sub 3}Sn nano grains were synthesized by powder metallurgy route. • Structure analysis was studied using a multiphase Rietveld refinement fit. • The presence of Nb{sub 3}Sn 86% and NbO 8% was identified. • More tin content in the equilibrium Nb–Sn diagram was obtained. • Magnetic properties show Nb{sub 3}Sn powders are soft super paramagnetic materials. - Abstract: In this study, intermetallic Nb{sub 3}Sn of nanometer-sized grains was synthesized by powder metallurgy route. Elemental powders of Nb and Sn in the stoichiometric proportions were mechanically alloyed for 3 h in a high-energy mill under a protective atmosphere of argon. X-ray diffraction patterns of milled powders confirmed the formation of a Nb(Sn) solid solution evidenced by the presence of Nb peaks only, which are shifted to higher angles. Rietveld refinements used to analyze this XRD pattern indicated a better fit when a tetragonal structure with the space group I4/mmm is used instead the Nb cubic lattice with space group Im−3m. Size-strain analysis from line-broadening of peak profiles by using “double-Voigt” approaches showed that the broadening is due to both a small crystallite size (around 6 nm) and microstrains. Subsequent heat treatment of the Nb(Sn) powder mixture was required for the formation of the Nb{sub 3}Sn ordered phase. X-ray diffraction patterns obtained after a thermal treatment at 700 °C for 1 h were fitted using a multiphase Rietveld refinement. Although the resulting powders are composed mainly by Nb{sub 3}Sn (up to 87 weight%), certain amount of other intermetallic phases like Nb{sub 6}Sn{sub 5}, NbSn{sub 2} and Nb and Sn oxides were also determined. In agreement with the Rietveld refinement analysis, microprobe analysis also revealed that changes in chemical composition at different sites of powder particles are preserved even after annealing at 700 °C. Magnetic properties measured at 300 K on resulted Nb{sub 3}Sn powders

Comparing Thermal Stability of NbTi and Nb$_3$Sn Wires

CERN Document Server

Breschi, M; Bottura, L; Devred, A; Trillaud, F

2009-01-01

The investigation of quenching in low temperature superconducting wires is of great relevance for a proper design of superconductive cables and magnets. This paper reports the experimental results of a vast measurement campaign of quench induced by laser pulses on NbTi and Nb$_{3}$Sn wires in pool boiling Helium I. A comparison of the quench behavior of two typical NbTi and Nb$_{3}$Sn wires is shown from different standpoints. Different qualitative behaviors of the voltage traces recorded during quenches and recoveries on NbTi and Nb$_{3}$Sn wires are reported and analyzed. It is shown that the Nb$_{3}$Sn wire exhibits a quench or no-quench behavior, whereas quenches and recoveries are exhibited by the NbTi wire. The two wires are also compared considering the behaviors of the two main parameters describing quench, i.e. quench energies and quench velocities, with respect to operation current and pulse duration and magnetic field. It is shown that the Nb$_{3}$Sn wire exhibits a ‘kink’ of the quench energy ...

Positron annihilation study of YBa2Cu3Oy superconductors doped with SnO2

International Nuclear Information System (INIS)

Chen, A.; Zhi, Y.; Li Biaorong; Wang Shaojie

1992-01-01

The positron annihilation lifetime spectra of YBa 2 Cu 3 O y superconductors doped with SnO 2 were measured. The results indicate that the tin element substitutes for Cu(1) sites. A brief discussion is given based on the experimental results. (orig.)

Nb3Sn accelerator magnet technology R and D at Fermilab

International Nuclear Information System (INIS)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Chlachidze, G.; DiMarco, J.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Fermilab

2007-01-01

Accelerator magnets based on Nb 3 Sn superconductor are being developed at Fermilab. Six nearly identical 1-m long dipole models and several mirror configurations were built and tested demonstrating magnet performance parameters and their reproducibility. The technology scale up program has started by building and testing long dipole coils. The results of this work are reported in the paper

Influence of Ta and Ti Doping on the High Field Performance of (Nb, Ta, Ti)3Sn Multifilamentary Wires based on Osprey Bronze with High Tin Content

International Nuclear Information System (INIS)

Abaecherli, V; Uglietti, D; Lezza, P; Seeber, B; Fluekiger, R; Cantoni, M; Buffat, P-A

2006-01-01

Ta and Ti are the most widely used additions for technical Nb 3 Sn multifilamentary superconductors. These elements are known to influence grain growth, grain morphology and chemical composition in the A15 layer, hence the current carrying properties of the wires over a wide magnetic field range. So far only few studies tried to compare systematically Ta and Ti doped and undoped Nb 3 Sn wires in the frame of the same work, down to a nanometric scale. We present an investigation on several multifilamentary (Nb, Ta, Ti) 3 Sn bronze route wires, fabricated at a laboratory scale, with various amounts of additives. The wires consist of fine filaments embedded in a Cu-Sn or Cu-Sn-Ti Osprey bronze with > 15 wt.% Sn and an external Cu stabilization. Microstructural observations are compared with the results of J c and n values measured up to 21 T at 4.2 and 2.2 K, and for longitudinal strains up to 0.5%. Non-Cu J c values up to 300 Amm -2 and n values up to 50 at 17 T and 4.2 K show clearly that wires with Ti addition to the bronze have a better performance with respect to wires with Ti additions to the filaments

Fabrication of Nb_3Al superconductor by the optimized mechanical alloying method with low temperature

International Nuclear Information System (INIS)

Zhang, Y.; Lin, W.J.; Xu, L.Y.; Yang, D.W.; Chen, Y.L.; Li, P.Y.; Pan, X.F.; Yan, G.; Zhao, Y.

2016-01-01

Highlights: • Due to a much better strain tolerance than Nb_3Sn, Nb_3Al has been considered as an excellent candidate for making high field magnets. At present, the Nb_3Al superconducting wires were prepared mainly by the Jelly-roll method combined with a rapid heating and quenching (RHQ) heat treatment at around 2000 °C. In this study, Nb_3Al superconductor with T_c of 15.6 K is directly prepared with a mechanical alloying method followed by a low temperature annealing at 800 to 900 °C. Our results hint the possibility that Nb_3Al superconducting wire with high performance can be prepared below the melting point of Cu (1080 °C) by a conventional powder in tube (PIT) method, thus effectively avoiding high temperature heat treatment and RHQ device. - Abstract: Mechanical alloying was used to synthesize Nb_3Al superconductor successfully, and the process was optimization under various preparation conditions. In the current study, Nb_3Al superconductor with T_c of 15.6 K was directly prepared from high quality Nb (Al) solid solution by mechanical alloying method and heat treatment at a low temperature of 800 to 900 °C. The results showed that Nb_3Al superconducting wire with high performance could be prepared after heat treatment below the melting point of Cu (1080°C) and using Nb (Al) solid solution and conventional powder in tube (PIT) method, thus effectively avoiding ultra-high temperature heat treatment and special rapid heating and quenching(RHQ) device.

Specific heat of Nb{sub 3}Sn: The case for a single gap

Energy Technology Data Exchange (ETDEWEB)

Jo, Y. J., E-mail: jophy@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Zhou, Jian; Sung, Zu Hawn; Lee, Peter J.; Larbalestier, D. C. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States)

2014-10-01

The important influence of multiple gaps in the superconductivity of MgB{sub 2} and Fe-based compounds, especially because of the possibility that manipulation of a second gap can significantly raise the upper critical field H{sub c2}, has refocused attention on Nb{sub 3}Sn because anomalies in both specific heat and point-contact tunneling studies have led to the proposal that Nb{sub 3}Sn is also a two-gap superconductor. Here, we search for evidence of the second gap in a careful study of the influence of the homogenization temperature on the sample uniformity. We show that it is very difficult to fabricate samples that are both homogeneous and stoichiometric. We find so-called “second-gap” anomalies disappear only after high temperature and long-term annealing. Such a well-annealed sample shows only a strong, electron-phonon-coupled, single-gap behavior. In contrast, samples reacted and annealed at lower temperatures, as in the earlier two-gap studies, show small chemical composition variations of the A15 phase. We propose that the second gap sightings are actually due to variation of T{sub c} within very difficult-to-fully homogenize samples. A curiosity of the A15 Nb{sub 3}Sn phase is that almost any mixture of Nb and Sn tries to form a stoichiometric A15 composition, but the residue of course contains off-stoichiometric A15, Nb, and other phases when the Nb:Sn ratio departs from the true 3:1 stoichiometry.

The superconductor

International Nuclear Information System (INIS)

Lad, J.K.

1979-01-01

Techniques for fabrication of a few important superconductors like Nb, Ti and Nb 3 Sn are described. Copper or bronze or both can be used as a matrix in the superconductor. Current densities obtained for different ratios of copper to superconductor are studied. The specifications of multi-filament Nb 3 Sn superconductors are given. The relative merits of the two superconductors are discussed. The temperature range obtained is approximately 3 0 K and a magnetic field of 9T(tesla) can be achieved. (A.K.)

Studying superconducting Nb3Sn wire

CERN Multimedia

AUTHOR|(CDS)2099575

2015-01-01

Studying superconducting Nb3Sn wire. From the current experience from LHC and HL-LHC we know that the performance requirements for Nb3Sn conductor for future circular collider are challenging and should exceed that of present state-of-the-art materials.

Studying superconducting Nb$_{3}$Sn wire

CERN Multimedia

AUTHOR|(CDS)2099575

2015-01-01

Studying superconducting Nb$_{3}$Sn wire. From the current experience from LHC and HL-LHC we know that the performance requirements for Nb$_{3}$Sn conductor for future circular collider are challenging and should exceed that of present state-of-the-art materials.

Analysis of voltage spikes in superconducting Nb3Sn magnets

International Nuclear Information System (INIS)

Rahimzadeh-Kalaleh, S.; Ambrosio, G.; Chlachidze, G.; Donnelly, C.

2008-01-01

Fermi National Accelerator Laboratory has been developing a new generation of superconducting accelerator magnets based on Niobium Tin (Nb 3 Sn). The performance of these magnets is influenced by thermo-magnetic instabilities, known as flux jumps, which can lead to premature trips of the quench detection system due to large voltage transients or quenches at low current. In an effort to better characterize and understand these instabilities, a system for capturing fast voltage transients was developed and used in recent tests of R and D model magnets. A new automated voltage spike analysis program was developed for the analysis of large amount of voltage-spike data. We report results from the analysis of large statistics data samples for short model magnets that were constructed using MJR and RRP strands having different sub-element size and structure. We then assess the implications for quench protection of Nb 3 Sn magnets

Low-temperature field evaporation of Nb3Sn compound

International Nuclear Information System (INIS)

Ksenofontov, V.A.; Kul'ko, V.B.; Kutsenko, P.A.

1986-01-01

Investigation results on field evaporation of superconducting Nb 3 Sn compound wth A15 lattice are presented. Compound evaporation is shown to proceed in two stages. Evaporation field and ionic composition of evaporating material are determined. It is found out that in strong electric fields compound surface represents niobium skeleton, wich does not form regular image. Comparison of ion-microscopic and calculated images formed by low-temperature field evaporation indicates to possibility of sample surface reconstruction after preferable tin evaporation

Comparing the thermal stability of NbTi and Nb3Sn wires

International Nuclear Information System (INIS)

Breschi, M; Trevisani, L; Bottura, L; Devred, A; Trillaud, F

2009-01-01

The investigation of quenching in low temperature superconducting wires is of great relevance for a proper design of superconductive cables and magnets. This paper reports the experimental results of a vast measurement campaign of quench induced by laser pulses on NbTi and Nb 3 Sn wires in pool boiling helium I. A comparison of the quench behavior of two typical NbTi and Nb 3 Sn wires is shown from different standpoints. Different qualitative behaviors of the voltage traces recorded during quenches and recoveries on NbTi and Nb 3 Sn wires are reported and analyzed. It is shown that the Nb 3 Sn wire exhibits a quench or no-quench behavior, whereas quenches and recoveries are exhibited by the NbTi wire. The two wires are also compared by considering the behaviors of the two main parameters describing quench, i.e. quench energies and quench velocities, with respect to operating current, pulse duration, and magnetic field. It is shown that the Nb 3 Sn wire exhibits a 'kink' of the quench energy versus current curve that makes the quench energy of Nb 3 Sn lower than that of NbTi at some intermediate current levels. Both the qualitative differences of the voltage traces and the different behaviors of quench energies and velocities are interpreted through a coupled electromagnetic-thermal model, with special emphasis on the detailed description of heat exchange with liquid helium.

Development of manufacturing capability for the fabrication of the Nb3Sn superconductor for the High Field Test Facility. Final report

International Nuclear Information System (INIS)

Spencer, C.R.

Construction of High Field Test Facility (HFTF) at Lawrence Livermore Laboratory (LLNL) requires an extended surface Nb 3 Sn superconductor cable of carrying currents in excess of 7500 amperes in a 12 Tesla magnetic field. This conductor consists of a 5.4 mm x 11.0 mm superconducting core onto whose broad surfaces are soldered embossed oxygen free copper strips. Two different core designs have been developed and the feasibility of each design evaluated. Equipment necessary to produce the conductor were developed and techniques of production were explored

Study of superconducting Nb{sub 3}Sn coils; Etude de bobinages supraconducteurs en Nb{sub 3}Sn

Energy Technology Data Exchange (ETDEWEB)

Vivet, B

1963-07-01

Composite superconducting Nb{sub 3}Sn wires with a diameter of 0.5 mm and a length of about 100 m were made, and Hc-Ic diagrams were plotted up to fields of 80 kgauss for short lengths. Two solenoids producing fields of about 20 kgauss were studied. Nb{sub 3}Sn solenoids, as opposed to those of Nb-Zr or Nb-Ti, appear to have a predictable behavior. Solenoids with less insulation produced stronger fields than heavily insulated solenoids. (author) [French] Une etude des fils composites supraconducteurs de Nb{sub 3}Sn a ete entreprise au C.E.N. Saclay, en collaboration avec la Societe S.O.D.E.R.X. Des fils de 0,5 mm de diametre et d'une centaine de metres de longueur ont ete produits de facon experimentale. Des diagrammes Hc-Ic ont pu etre traces, jusqu'en des champs de 80 kG, sur des echantillons de petite longueur. Deux solenoides ont ete etudies produisant les champs de l'ordre de 20 kg. Il semble que, contrairement aux alliages Nb-Zr ou Nb-Ti, les solenoides en Nb{sub 3}Sn aient un comportement previsible d'apres les tests sur des echantillons courts. On montrera d'autre part qu'un bobinage a faible isolement peut produire un champ notablement plus eleve qu'un bobinage isole. Une production plus extensive permettra, dans les semaines a venir, la fabrication de solenoides de plus grosse dimension et produisant des champs plus eleves. (auteur)

Metallic superconductors. 3. Na3Sn and V3Ga wires (Part one)

International Nuclear Information System (INIS)

Tachikawa, Kyoji

2010-01-01

Nowadays Nb 3 Sn wires are being widely used as one of the key materials in advanced science and technology, with various applications such as NMR, fusion and cryogen-free superconducting magnets. In this article, at first microstructures and fundamental aspects as well as the effect of additional elements in Nb 3 Sn are outlined. Intrinsic superconducting performances, e.g. T c and B c2 , are quite sensitive to the stoichiometry of the Sn concentration. A small amount of Ti and Ta doping is much effective for the increase of B c2 in Nb 3 Sn. The effect of Cu on the enhancement of Nb 3 Sn synthesis has yielded a significant breakthrough for the industrial production of the wires. At present the bronze process and internal Sn process are the twin major fabrication techniques of Nb 3 Sn wires. The recent status of both processes is reviewed in this article. Pronounced progress has been achieved in the performance of Nb 3 Sn wires fabricated through both techniques. Although just half a century has passed since the first fabrication of Nb 3 Sn wire, further progress in Nb 3 Sn technology may be expected like the proverb saying 'Fresh water still comes out from an old spring'. (author)

Improvements in the critical current densities of Nb3Sn by solid solution additions of Sn in Nb

International Nuclear Information System (INIS)

Luhman, T.; Suenaga, M.

1975-01-01

The effectiveness of solid solution additions of Sn to Nb in improving the superconducting properties of diffusion processed Nb 3 Sn conductors was examined. It was found that an increase in the superconducting critical current density, Jc, as function of layer thickness (d) may be obtained for thick Nb 3 Sn layers by solid solution additions of Sn in Nb. A large increase in J/sub c/ (d) is also achieved by increasing the Sn content in the bronze matrix material. In addition to uses of this material in magnet fabrications a potential application of these improved J/sub c/(d) values may lie in the use of Nb 3 Sn in power transmission lines. Here, a high superconducting critical current density is necessary throughout the material to carry the increased current during fault conditions. The magnetic field dependence of J/sub c/ is a function of alloy content but the alloying changes studied here do not increase the high field critical current capability of Nb 3 Sn. (auth)

Fabrication of Nb{sub 3}Al superconductor by the optimized mechanical alloying method with low temperature

Energy Technology Data Exchange (ETDEWEB)

Zhang, Y., E-mail: yongzhang@swjtu.cn [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, and Superconductivity and New Energy R& D Center, Southwest Jiaotong University, Chengdu 610031 (China); Lin, W.J.; Xu, L.Y.; Yang, D.W.; Chen, Y.L. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, and Superconductivity and New Energy R& D Center, Southwest Jiaotong University, Chengdu 610031 (China); Li, P.Y.; Pan, X.F.; Yan, G. [Western Superconducting Technoligies Co., Ltd., Xi' an 710018 (China); Zhao, Y., E-mail: yzhao@home.swjtu.edu.cn [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, and Superconductivity and New Energy R& D Center, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052 NSW (Australia)

2016-11-15

Highlights: • Due to a much better strain tolerance than Nb{sub 3}Sn, Nb{sub 3}Al has been considered as an excellent candidate for making high field magnets. At present, the Nb{sub 3}Al superconducting wires were prepared mainly by the Jelly-roll method combined with a rapid heating and quenching (RHQ) heat treatment at around 2000 °C. In this study, Nb{sub 3}Al superconductor with T{sub c} of 15.6 K is directly prepared with a mechanical alloying method followed by a low temperature annealing at 800 to 900 °C. Our results hint the possibility that Nb{sub 3}Al superconducting wire with high performance can be prepared below the melting point of Cu (1080 °C) by a conventional powder in tube (PIT) method, thus effectively avoiding high temperature heat treatment and RHQ device. - Abstract: Mechanical alloying was used to synthesize Nb{sub 3}Al superconductor successfully, and the process was optimization under various preparation conditions. In the current study, Nb{sub 3}Al superconductor with T{sub c} of 15.6 K was directly prepared from high quality Nb (Al) solid solution by mechanical alloying method and heat treatment at a low temperature of 800 to 900 °C. The results showed that Nb{sub 3}Al superconducting wire with high performance could be prepared after heat treatment below the melting point of Cu (1080°C) and using Nb (Al) solid solution and conventional powder in tube (PIT) method, thus effectively avoiding ultra-high temperature heat treatment and special rapid heating and quenching(RHQ) device.

Nb3Sn for Radio Frequency Cavities

International Nuclear Information System (INIS)

Godeke, A.

2006-01-01

In this article, the suitability of Nb3Sn to improve the performance of superconducting Radio-Frequency (RF) cavities is discussed. The use of Nb3Sn in RF cavities is recognized as an enabling technology to retain a very high cavity quality factor (Q0) at 4.2 K and to significantly improve the cavity accelerating efficiency per unit length (Eacc). This potential arises through the fundamental properties of Nb3Sn. The properties that are extensively characterized in the literature are, however, mainly related to improvements in current carrying capacity (Jc) in the vortex state. Much less is available for the Meissner state, which is of key importance to cavities. Relevant data, available for the Meissner state is summarized, and it is shown how this already validates the use of Nb3Sn. In addition, missing knowledge is highlighted and suggestions are given for further Meissner state specific research

Quench Performance and Field Quality of FNAL Twin-Aperture 11 T Nb$_{3}$Sn Dipole Model for LHC Upgrades

CERN Document Server

Stoynev, S; Apollinari, G; Auchmann, B; Barzi, E; Izquierdo Bermudez, S; Bossert, R; Chlachidze, G; DiMarco, J; Karppinen, M; Nobrega, F; Novitski, I; Rossi, F; Savary, F; Smekens, D; Strauss, T; Turrioni, D; Velev, G; Zlobin, A V

2017-01-01

A 2 m long single-aperture dipole demonstrator and two 1 m long single-aperture models based on Nb$_{3}$Sn superconductor have been built and tested at FNAL. The two 1 m long collared coils were then assembled in a twin-aperture Nb$_{3}$Sn dipole demonstrator compatible with the LHC main dipole and tested in two thermal cycles. This paper summarizes the quench performance of the FNAL twin-aperture Nb$_{3}$Sn 11 T dipole in the temperature range of 1.9-4.5 K. The results of magnetic measurements for one of the two apertures are also presented. Test results are compared to the performance of coils in a single-aperture configuration. A summary of quench propagation studies in both apertures is given.

Advances in Nb3Sn Performance

International Nuclear Information System (INIS)

Godeke, Arno

2008-01-01

Nb 3 Sn wires with non-Cu critical current densities (J c ) that surpass 3 kAmm -2 at 12 T and 4.2 K are commercially available in piece lengths longer than 10 km. Accelerator-type magnets that utilize these conductors have achieved record magnetic fields. This article summarizes key developments in the last decade that have led to these significant improvements in the performance of Nb 3 Sn wires.

Study of superconducting Nb3Sn coils

International Nuclear Information System (INIS)

Vivet, B.

1963-01-01

Composite superconducting Nb 3 Sn wires with a diameter of 0.5 mm and a length of about 100 m were made, and Hc-Ic diagrams were plotted up to fields of 80 kgauss for short lengths. Two solenoids producing fields of about 20 kgauss were studied. Nb 3 Sn solenoids, as opposed to those of Nb-Zr or Nb-Ti, appear to have a predictable behavior. Solenoids with less insulation produced stronger fields than heavily insulated solenoids. (author) [fr

Effect of impurities in niobium on the growth of superconducting Nb/sub 3//Sn. [Al, Cu, Ge, Si, Sn, Zr impurities

Energy Technology Data Exchange (ETDEWEB)

Sekizawa, T

1974-01-01

In order to examine the possibility of reducing the heat treatment temperature in the manufacturing process of the superconducting intermetallic compounds wire or ribbon by the metallurgical bond method, tin cored specimens of niobium including a small amount of impurity (Al, Cu, Ge, Si, Sn and Zr) have been prepared, and the critical currents measured as a function of the heat treatment temperature and time. Experimental results are summarized as follows. (1) The effect of the impurity added into niobium is to stabilize the dislocation network cell structure in niobium, caused by the cold working, up to the forming temperature of Nb/sub 3/Sn. The stabilized dislocation network structure is considered to serve as diffusion pipes of the tin atom. As this diffusion (microscopic) is predominant over bulk diffusion (macroscopic), the cored specimen made of niobium including impurities has lower forming temperature of Nb/sub 3/Sn compared with the specimen made of pure niobium. (2) The critical current vs. heat treatment temperature characteristics show that the critical current peaks at 900/sup 0/C in the case of niobium including Si, while at 950/sup 0/C in the case of pure niobium. 6 references.

New Insights into the Limitations on the Efficiency and Achievable Gradients in Nb3Sn SRF Cavities

Science.gov (United States)

Hall, Daniel Leslie

The A15 superconductor Nb3Sn has shown great promise to replace niobium as the material of choice for the construction of superconducting radio-frequency (SRF) accelerator cavities. It promises, at least on paper, greater efficiency and higher accelerating gradients, with the potential to enable the construction of smaller yet more powerful accelerators than can be constructed using niobium. Although the state-of-the-art performance of cavities coated with Nb3Sn has shown great potential, the achievable limits in cavity quality factor Q0 and accelerating gradient Eacc are still below that expected given theoretical limits. In this work we present and discuss results of experiments carried out to understand the current limitations on Q0 and Eacc, and propose methods to improve these further. We will conclude with an outlook to the future, and the prospects that Nb3Sn could enable.

Technology development of fabrication NbTi and Nb3 Sn superconducting wires

International Nuclear Information System (INIS)

Rodrigues Junior, D.; Bormio, C.; Baldan, C.A.; Ramos, M.J.; Pinatti, D.G.

1988-01-01

The technology development of NbTi and Nb 3 Sn superconducting wires are studied, mentioning the use of fluxes capture theory in the sizing of wires fabrication. The fabrication process, the thermal treatment and the experimental datas of critical temperature and current of Nb 3 Sn wires are described. (C.G.C.) [pt

The optimization of NbTi-Nb/sub 3/Sn high field superconducting magnet used for physics experiments

International Nuclear Information System (INIS)

Han, B.; Han, S.; Feng, Z.X.

1989-01-01

The approach to the optimum cost design of multigraded NbTi-Nb/sub 3/Sn high field superconducting magnet is proposed. Investigation shows that by reasonably choosing the contribution of NbTi and Nb/sub 3/Sn coils to the central field required and properly increasing the parameters β of both NbTi and Nb/sub 2/Sn coils, the optimum cost design of the NbTi-Nb/sub 3/Sn solenoid magnet can be obtained. This is the base on which the minimum cost design of multi-graded NbTi-Nb/sub 3/Sn high field superconducting magnet is reached. As an example, a calculation of a 14T three graded NbT-Nb/sub 3/Sn superconducting magnet with a bore of 31mm in diameter is given

Design and Fabrication of a Single-Aperture 11T Nb3Sn Dipole Model for LHC Upgrades

International Nuclear Information System (INIS)

Andreev, N.; Apollinari, G.; Barzi, E.; Bossert, R.; Nobrega, F.; Novitski, I.; Turrioni, D.; Yamada, R.; Zlobin, A.V.; Auchmann, B.; Karppinen, M.

2011-01-01

The planned upgrade of the LHC collimation system includes additional collimators to be installed in the dispersion suppressor areas of points 2, 3 and 7. To provide the necessary longitudinal space for the collimators, a replacement of 8.33 T Nb-Ti LHC main dipoles with 11 T dipoles based on Nb 3 Sn superconductor compatible with the LHC lattice and main systems is being considered. To demonstrate this possibility FNAL and CERN have started a joint program to develop a 2 m long single-aperture dipole magnet with the nominal field of 11 T at ∼11.85 kA current and 60 mm bore. This paper describes the demonstrator magnet magnetic and mechanical designs and analysis, coil fabrication procedure. The Nb 3 Sn strand and cable parameters and test results are also reported.

An intermetallic powder-in-tube approach to increased flux-pinning in Nb3Sn by internal oxidation of Zr

Science.gov (United States)

Motowidlo, L. R.; Lee, P. J.; Tarantini, C.; Balachandran, S.; Ghosh, A. K.; Larbalestier, D. C.

2018-01-01

We report on the development of multifilamentary Nb3Sn superconductors by a versatile powder-in-tube technique (PIT) that demonstrates a simple pathway to a strand with a higher density of flux-pinning sites that has the potential to increase critical current density beyond present levels. The approach uses internal oxidation of Zr-alloyed Nb tubes to produce Zr oxide particles within the Nb3Sn layer that act as a dispersion of artificial pinning centres (APCs). In this design, SnO2 powder is mixed with Cu5Sn4 powder within the PIT core that supplies the Sn for the A15 reaction with Nb1Zr filament tubes. Initial results show an average grain size of ˜38 nm in the A15 layer, compared to the 90-130 nm of typical APC-free high-J c strands made by conventional PIT or Internal Sn processing. There is a shift in the peak of the pinning force curve from H/H irr of ˜0.2 to ˜0.3 and the pinning force curves can be deconvoluted into grain boundary and point-pinning components, the point-pinning contribution dominating for the APC Nb-1wt%Zr strands.

Tunneling spectroscopy on superconducting Nb3Sn with artioficial barriers

International Nuclear Information System (INIS)

Schneider, U.

1984-03-01

Tunneling diodes on Nb 3 Sn were prepared by magnetron sputtering. The superconducting transition temperatures of the Nb 3 Sn films were in the range of 5 to 18 K. An energetically low-lying structure in the tunneling density of states has been localized by detailed studies of the second derivative of the current-voltage characteristics of the diodes. This structure was found near 5.5 meV for stoichiometric Nb 3 Sn (Tsub(c) approx.= 18 K) and at 6.7 meV for understoichiometric Nb 3 Sn (Tsub(c) approx.= 5 K). The minimum in the conductance at zero energy found in the normal state could be identified to be mainly due to inelastic phonon processes of barrier phonons and Nb 3 Sn phonons. Deformations were found in the tunneling density of states of stoichiometric Nb 3 Sn diodes which lead to contradiction when explained by proximity effects. (orig./GSCH)

Making superconductors

International Nuclear Information System (INIS)

McDonald, W.K.

1981-01-01

A method is described of producing composite rod or wire of increased strength and fineness wherein the composite is formed by reducing a lamina of two metals which have been rolled to form a cylindrical billet in which one of the metals is in expanded form. The composite produced can be encased in copper and fabricated to produce a superconductor. Alloys contemplated for producing superconductors are Nb 3 Sn, Nb 3 Ga, Nb 3 Ge, Nb 3 Si, Nb-Ti, V 3 Ga, V 3 Si, V 3 Sn, V 3 Al, and V 3 Ge laminated on bronze, Al, Cu, Ta, or combinations thereof. (author)

A New Understanding of the Heat Treatment of Nb-Sn Superconducting Wires

Science.gov (United States)

Sanabria, Charlie

Enhancing the beam energy of particle accelerators like the Large Hadron Collider (LHC), at CERN, can increase our probability of finding new fundamental particles of matter beyond those predicted by the standard model. Such discoveries could improve our understanding of the birth of universe, the universe itself, and/or many other mysteries of matter--that have been unresolved for decades--such as dark matter and dark energy. This is obviously a very exciting field of research, and therefore a worldwide collaboration (of universities, laboratories, and the industry) is attempting to increase the beam energy in the LHC. One of the most challenging requirements for an energy increase is the production of a magnetic field homogeneous enough and strong enough to bend the high energy particle beam to keep it inside the accelerating ring. In the current LHC design, these beam bending magnets are made of Nb Ti superconductors, reaching peak fields of 8 T. However, in order to move to higher fields, future magnets will have to use different and more advanced superconducting materials. Among the most viable superconductor wire technologies for future particle accelerator magnets is Nb3Sn, a technology that has been used in high field magnets for many decades. However, Nb3Sn magnet fabrication has an important challenge: the fact the wire fabrication and the coil assembly itself must be done using ductile metallic components (Nb, Sn, and Cu) before the superconducting compound (Nb3 Sn) is activated inside the wires through a heat treatment. The studies presented in this thesis work have found that the heat treatment schedule used on the most advanced Nb3Sn wire technology (the Restacked Rod Process wires, RRPRTM) can still undergo significant improvements. These improvements have already led to an increase of the figure of merit of these wires (critical current density) by 28%.

Comparison Between Nb3Al and Nb3Sn Strands and Cables for High Field Accelerator Magnets

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Kikuchi, A.; Barzi, E.; Chlachidze, G.; Rusy, A.; Takeuchi, T.; Tartaglia, M.; Turrioni, D.; Velev, V.; Wake, M.; Zlobin, A.V.; /Fermilab

2010-01-01

The Nb{sub 3}Al small racetrack magnet, SR07, has been successfully built and tested to its short sample limit beyond 10 Tesla without any training. Thus the practical application of Nb{sub 3}Al strands for high field accelerator magnets is established. The characteristics of the representative F4 strand and cable, are compared with the typical Nb{sub 3}Sn strand and cable. It is represented by the OST high current RRP Nb{sub 3}Sn strand with 108/127 configuration. The effects of Rutherford cabling to both type strands are explained and the inherent problem of the Nb{sub 3}Sn strand is discussed. Also the test results of two representative small racetrack magnets are compared from the stand point of Ic values, and training. The maximum current density of the Nb{sub 3}Al strands is still smaller than that of the Nb{sub 3}Sn strands, but if we take into account of the stress-strain characteristics, Nb{sub 3}Al strands become somewhat favorable in some applications.

Nb3Sn dipole magnet reacted after winding

International Nuclear Information System (INIS)

Taylor, C.; Scanlan, R.; Peters, C.; Wolgast, R.; Gilbert, W.; Hassenzahl, W.; Meuser, R.; Rechen, J.

1984-09-01

A 5 cm bore dia., 1-m-long dipole model magnet was constructed by winding un-reacted cable, followed by reaction and epoxy-impregnation. Experience and test results are described on the 1.7 mm dia. internal-tin wire, the eleven-strand flattened cable, fiberglass insulation, and construction of the magnet. Each half of the magnet has two double-pancake-type windings that were reacted in a single operation. The two double-pancakes were then separately vacuum impregnated after soldering the flexible Nb-Ti leads to the Nb 3 Sn conductors. No iron flux return yoke was used. In initial tests a central field of 8.0 T was reached at 4.4 K. However, evidence from training behavior, and 1.8 K tests indicate that premature quenching, rather than critical current of the cable, limited the field intensity. The magnet was reassembled and more rigidly clamped; additional test results are reported

Design Studies and Optimization of High-Field Nb$_3$Sn Dipole Magnets for a Future Very High Energy PP Collider

Energy Technology Data Exchange (ETDEWEB)

Kashikhin, V. V. [Fermilab; Novitski, I. [Fermilab; Zlobin, A. V. [Fermilab

2017-05-01

High filed accelerator magnets with operating fields of 15-16 T based on the $Nb_3Sn$ superconductor are being considered for the LHC energy upgrade or a future Very High Energy pp Collider. Magnet design studies are being conducted in the U.S., Europe and Asia to explore the limits of the $Nb_3Sn$ accelerator magnet technology while optimizing the magnet design and performance parame-ters, and reducing magnet cost. The first results of these studies performed at Fermilab in the framework of the US-MDP are reported in this paper.

Stress effects on multifilamentary Nb3Sn wire

International Nuclear Information System (INIS)

Bartlett, R.J.; Taylor, R.D.; Thompson, J.D.

1979-01-01

Critical current I/sub c/ measurements were obtained on highly stabilized mf Nb 3 Sn wires as a function of heat treatment, stress, temperature, and applied magnetic field. The ratio of the area of the copper to bronze core-niobium tube is about 8, and the filaments are concentrated in the inner 30% of the wire cross section. Values of I/sub c/ and T/sub c/ were determined for samples subjected to a wide range of heat treatments. Diffusion reaction times and temperatures in the ranges 16 to 128 hr and 700 to 750 0 C provided a number of mf Nb 3 Sn wires having similar I/sub c/ characteristics. To some extent the residual compressive loading on the Nb 3 Sn wires varied with the particular heat treatment. This loading arises primarily from the differential contraction of the remaining bronze and the Nb 3 Sn layer when cooled from the reaction temperature to the operating temperature. It was found that, by controlled bending or stretching of the wires, whereby some of the strain in the Nb 3 Sn is relieved, the I/sub c/ at 14 K is increased by as much as 30% and the critical temperature is increased by up to 1 K

Influence of oxygen content on some properties of Nb3Sn tape used for superconducting transmission lines

International Nuclear Information System (INIS)

Jergel, M.; Melisek, T.; Allarova, H.; Synak, D.; Neuschl, J.; Ivan, J.

1982-01-01

The influence of the presence of oxygen in the Nb-Zr substrate upon some physical and mechanical properties of the Nb-ZrO 2 substrate and/or Nb 3 Sn tape superconductor prepared from such a substrate has been studied The results have shown that the Nb 3 Sn grains are much finer in the case of Nb-ZrO 2 , than those obtained on Nb-Zr substrate. As a result, both the electrical and mechanical properties have been substantially improved. The critical current at a field of 5 T increased by between 100 and 200%, the alternating current losses decreased by about one order of magnitude, the tensile strength increased by about a factor of three and the microhardness value also increased by about a factor of three for oxygen contents in the range 0.03 to 0.70 wt%. The specific resistance of this substrate increased at the same time from 17 to 22 μΩ cm and the relative elongation decreased from 5 to 3%. (author)

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires.

Science.gov (United States)

Li, Yingxu; Gao, Yuanwen

2017-04-25

We present a model for the variation of the upper critical field H c2 with Sn content in A15-type Nb-Sn wires, within the Ginzburg-Landau-Abrikosov-Gor'kov (GLAG) theory frame. H c2 at the vicinity of the critical temperature T c is related quantitatively to the electrical resistivity ρ, specific heat capacity coefficient γ and T c . H c2 versus tin content is theoretically formulated within the GLAG theory, and generally reproduces the experiment results. As Sn content gradually approaches the stoichiometry, A15-type Nb-Sn undergoes a transition from the dirty limit to clean limit, split by the phase transformation boundary. The H-T phase boundary and pinning force show different behaviors in the cubic and tetragonal phase. We dipict the dependence of the composition gradient on the superconducting properties variation in the A15 layer, as well as the curved tail at vicinity of H c2 in the Kramer plot of the Nb 3 Sn wire. This helps understanding of the inhomogeneous-composition inducing discrepancy between the results by the state-of-art scaling laws and experiments.

Influence of stresses on superconducting properties of Nb3Sn conductors

International Nuclear Information System (INIS)

Suenaga, M.; Luhman, T.S.; Sampson, W.B.; Onishi, T.; Klamut, C.J.

1978-01-01

This investigation of the degradation in the superconducting properties of Nb 3 Sn conductors when subjected to mechanical strain can be divided into the following areas: (I) monofilamentary Nb 3 Sn wires, (II) multifilamentary Nb 3 Sn conductors and wires, (III) effects of additives to Nb 3 Sn, (IV) mechanisms for degradation, and (V) construction of test facilities. Efforts to the present time have been concentrated in the investigation of T/sub c/, J/sub c/, and H/sub c2/ variations in monofilamentary wires. The most important finding in this study is that a Nb 3 Sn composite wire can sustain an effective mechanical strain well beyond ''1%'' if a proper ratio of the matrix to the Nb core has been chosen

Stabilization of a Nb3Sn persistent current switch

International Nuclear Information System (INIS)

Urata, M.; Maeda, H.; Nakayama, S.; Yoneda, E.; Oda, Y.; Kumano, T.; Aoki, N.; Tomisaki, T.; Kabashima, S.

1993-01-01

A 2000 A class Nb 3 Sn persistent current switch has been successfully fabricated in the Toshiba R and D Center. The Nb tube processed conductor with Cu-10 wt.% Ni matrix has been developed for the switch in the Showa Electric Wire and Cable Co. Ltd. The magnetic instability which was observed in the previous 35 Ω Nb 3 Sn persistent current switch was improved in the present switch. The problem of quench current degradation and flux jump on magnetization, emerged in the previous switch, were confirmed to be solved. In the fast ramp, however, the switch degrades from the calculated results assuming the self field ac loss. In the Nb 3 Sn reaction process, Sn in the bronze diffuses into the Nb tube, which decreases the switch resistance. It was observed by a computer aided micro analysis (CMA) that Ni in the CuNi matrix precipitated on the Nb tube, which slightly reduced the switch resistance. (orig.)

Thermodynamics of superconducting Nb3Al, Nb3Ge, Nb3Sn, and V3Ga

Science.gov (United States)

Mitrović, B.; Schachinger, E.; Carbotte, J. P.

1984-06-01

We have calculated the superconducting thermodynamic properties for several high-transition-temperature A15 compounds: Nb-Al, Nb-Ge, Nb-Sn, and V-Ga. In our calculations we have used the tunneling electron-phonon-coupling spectra α2F for all four systems considered, and in the case of Nb-Al and Nb-Ge we have also used α2F=CG, where G is the measured generalized phonon density of states and C is a constant. We find that all Nb-based A15 compounds display similar thermodynamic properties, which do not depend explicitly on the band density of states: 2Δ0κBTc≅4.6, ΔCγTc≅2.5-2.6,-Tc[dHc(T)dT]TcHc(0)≅2.1, γ[TcHc(0)]2≅0.134, and positive D(t)'s with the maximum value around 0.02. For Nb3Sn we find good agreement between the calculated properties and the old specific-heat experimental results (γ≅52 mJ/mol K2). The same applies to V3Ga, where the theoretical results have been compared with the experiments of Junod et al. However, we do not find good agreement between calculated ΔCγTc, - Tc[dHc(T)dT]TcHc(0), γ[TcHc(0)]2, and experimental values for Nb3Al and Nb3Ge, presumably due to broadened transitions. It is argued that the tunneling experiments underestimate the value of the gap which should be associated with the inverted α2F.

Conceptual Design Study of Nb(3)Sn Low-beta Quadrupoles for 2nd Generation LHC IRs

Science.gov (United States)

Zlobin, A. V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bauer, P.

2002-10-01

Conceptual designs of 90-mm aperture high gradient quadrupoles based on the Nb3Sn superconductor, are being developed at Fermilab for possible 2nd generation IRs with the similar optics as in the current low-beta insertions. Magnet designs and results of magnetic, mechanical, thermal and quench protection analysis for these magnets are presented and discussed.

Conceptual design study of Nb3Sn low-beta quadrupoles for 2nd generation LHC IRs

International Nuclear Information System (INIS)

Alexander V Zlobin et al.

2002-01-01

Conceptual designs of 90-mm aperture high-gradient quadrupoles based on the Nb 3 Sn superconductor, are being developed at Fermilab for possible 2nd generation IRs with the similar optics as in the current low-beta insertions. Magnet designs and results of magnetic, mechanical, thermal and quench protection analysis for these magnets are presented and discussed

Recovery and Purification of Tin from Tailings from the Penouta Sn–Ta–Nb Deposit

Directory of Open Access Journals (Sweden)

Félix Antonio López

2018-01-01

Full Text Available A concentrate obtained from mining tailings containing mainly cassiterite and columbotantalite was reduced for the production of tin metal. The compounds CaCO3, Na2CO3, K2CO3, and borax were used as fluxes in the pyrometallurgical reduction smelting process, and graphite was employed as the reducing agent. The greatest recovery of Sn (>95% was obtained when using CaCO3 as the flux; the purity of Sn was 96%. A slag equivalent to 25% of the mass of the initial concentrate was produced during the recovery of the Sn. This contained 45% Nb2O5 and Ta2O5, adding extra value to the mine tailings. The tin metal ingot was purified by electrorefining involving a tin and H2SO4 electrolyte solution and a 101.9 A/m2 current applied for 148 h. Under these conditions, 90 wt % of the Sn in the ingot was recovered at a purity of 99.97%.

Comparison of direct inter-filament resistance measurement on Nb3Sn strands between University of Twente and ENEA

NARCIS (Netherlands)

Zhou, Chao; Dhalle, Marc M.J.; Nijhuis, Arend; Breschi, M.; Spina, T.; Della Corte, A.; Corato, V.

2013-01-01

Experimental results of interfilament resistance measurements obtained with different facilities are compared. Two internal tin Nb3Sn strand types are tested at the University of Twente (UT) and ENEA Frascati. The direct interfilament resistance is measured with a standard four-point voltage-current

Superconductivity optimization and phase formation kinetics study of internal-Sn Nb3Sn superconducting wires

International Nuclear Information System (INIS)

Zhang, Chaowu

2007-07-01

Superconductors Nb 3 Sn wires are one of the most applicable cryogenic superconducting materials and the best choice for high-field magnets exceeding 10 T. One of the most significant utilization is the ITER project which is regarded as the hope of future energy source. The high-Cu composite designs with smaller number of sub-element and non-reactive diffusion barrier, and the RRP (Restacked Rod Process) internal-Sn technology are usually applied for the wire manufacturing. Such designed and processed wires were supplied by MSA/Alstom and WST/NIN in this research. The systematic investigation on internal-Sn superconducting wires includes the optimization of heat treatment (HT) conditions, phase formation and its relation with superconductivity, microstructure analysis, and the phase formation kinetics. Because of the anfractuosity of the configuration design and metallurgical processing, the MF wires are not sufficient for studying a sole factor effect on superconductivity. Therefore, four sets of mono-element (ME) wires with different Sn ratios and different third-element addition were designed and fabricated in order to explore the relationship between phase formation and superconducting performances, particularly the A15 layer growth kinetics. Different characterization technic have been used (magnetization measurements, neutron diffraction and SEM/TEM/EDX analysis). The A15 layer thicknesses of various ME samples were measured and carried out linear and non-linear fits by means of two model equations. The results have clearly demonstrated that the phase formation kinetics of Nb 3 Sn solid-state reaction is in accordance with an n power relation and the n value is increased with the increase of HT temperature and the Sn ratio in the wire composite. (author)

Continuous, flexible, and high-strength superconducting Nb3Ge and Nb3Sn filaments

International Nuclear Information System (INIS)

Ahmad, I.; Heffernan, W.J.

1976-01-01

Fabrication of continuous, flexible, and high-strength (1600 MN/m 2 ) composite filaments of Nb 3 Ge (T/subc/ 18 0 K) and Nb 3 Sn is reported, involving chemical vapor deposition of these compounds on Nb-coated high-strength W--1% ThO 2 filaments

Nb3Sn accelerator magnet development around the world

Energy Technology Data Exchange (ETDEWEB)

Michael J. Lamm

2003-06-23

During the past 30 years superconducting magnet systems have enabled accelerators to achieve energies and luminosities that would have been impractical if not impossible with resistive magnets. By far, NbTi has been the preferred conductor for this application because of its ductility and insensitivity of Jc to mechanical strain. This is despite the fact that Nb{sub 3}Sn has a more favorable Jc vs. B dependence and can operate at much higher temperatures. Unfortunately, NbTi conductor is reaching the limit of it usefulness for high field applications. Despite incremental increases in Jc and operation at superfluid temperatures, magnets are limited to approximately a 10 T field. Improvements in conductor performance combined with future requirements for accelerator magnets to have bore fields greater than 10 T or operate in areas of large beam-induced heat loads now make Nb{sub 3}Sn look attractive. Thus, laboratories in several countries are actively engaged in programs to develop Nb{sub 3}Sn accelerator magnets for future accelerator applications. A summary of this important research activity is presented along with a brief history of Nb{sub 3}Sn accelerator magnet development and a discussion of requirements for future accelerator magnets.

In-Situ Neutron Diffraction Under Tensile Loading of Powder-in-Tube Cu/Nb$_{3}$Sn Composite Wires Effect of Reaction Heat Treatment on Texture, Internal Stress State and Load Transfer

CERN Document Server

Scheuerlein, C; Thilly, L

2007-01-01

The strain induced degradation of Nb$_{3}$Sn superconductors can hamper the performance of high field magnets. We report elastic strain measurements in the different phases of entire non-heat treated and fully reacted Nb$_{3}$Sn composite strands as a function of uniaxial stress during in-situ deformation under neutron beam. After the reaction heat treatment the Cu matrix loses entirely its load carrying capability and the applied stress is transferred to the remaining Nb-Ta alloy and to the brittle (Nb-Ta)3Sn phase, which exhibits a preferential grain orientation parallel to the strand axis.

Superconductivity optimization and phase formation kinetics study of internal-Sn Nb{sub 3}Sn superconducting wires

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chaowu

2007-07-15

Superconductors Nb{sub 3}Sn wires are one of the most applicable cryogenic superconducting materials and the best choice for high-field magnets exceeding 10 T. One of the most significant utilization is the ITER project which is regarded as the hope of future energy source. The high-Cu composite designs with smaller number of sub-element and non-reactive diffusion barrier, and the RRP (Restacked Rod Process) internal-Sn technology are usually applied for the wire manufacturing. Such designed and processed wires were supplied by MSA/Alstom and WST/NIN in this research. The systematic investigation on internal-Sn superconducting wires includes the optimization of heat treatment (HT) conditions, phase formation and its relation with superconductivity, microstructure analysis, and the phase formation kinetics. Because of the anfractuosity of the configuration design and metallurgical processing, the MF wires are not sufficient for studying a sole factor effect on superconductivity. Therefore, four sets of mono-element (ME) wires with different Sn ratios and different third-element addition were designed and fabricated in order to explore the relationship between phase formation and superconducting performances, particularly the A15 layer growth kinetics. Different characterization technic have been used (magnetization measurements, neutron diffraction and SEM/TEM/EDX analysis). The A15 layer thicknesses of various ME samples were measured and carried out linear and non-linear fits by means of two model equations. The results have clearly demonstrated that the phase formation kinetics of Nb{sub 3}Sn solid-state reaction is in accordance with an n power relation and the n value is increased with the increase of HT temperature and the Sn ratio in the wire composite. (author)

Thermodynamics of superconducting Nb3Al, Nb3Ge, Nb3Sn, and V3Ga

International Nuclear Information System (INIS)

Mitrovic, B.; Schachinger, E.; Carbotte, J.P.

1984-01-01

We have calculated the superconducting thermodynamic properties for several high-transition-temperature A15 compounds: Nb-Al, Nb-Ge, Nb-Sn, and V-Ga. In our calculations we have used the tunneling electron-phonon--coupling spectra α 2 F for all four systems considered, and in the case of Nb-Al and Nb-Ge we have also used α 2 F = CG, where G is the measured generalized phonon density of states and C is a constant. We find that all Nb-based A15 compounds display similar thermodynamic properties, which do not depend explicitly on the band density of states: 2Δ 0 /k/sub B/T/sub c/approx. =4.6, ΔC/γT/sub c/approx. =2.5--2.6, -T/sub c/[dH/sub c/(T)/dT]c/ H/sub c/(0)approx. =2.1, γ[T/sub c//H/sub c/(0)] 2 approx. =0.134, and positive D(t)'s with the maximum value around 0.02. For Nb 3 Sn we find good agreement between the calculated properties and the old specific-heat experimental results (γapprox. =52 mJ/mol K 2 ). The same applies to V 3 Ga, where the theoretical results have been compared with the experiments of Junod et al. However, we do not find good agreement between calculated ΔC/γT/sub c/, -T/sub c/[dH/sub c/(T)/dT]c/H/sub c/(0), γ[T/sub c//H/sub c/(0)] 2 , and experimental values for Nb 3 Al and Nb 3 Ge, presumably due to broadened transitions. It is argued that the tunneling experiments underestimate the value of the gap which should be associated with the inverted α 2 F

The influence of strain introduced by differential thermal contraction on the critical current of Nb3Sn supercontractors

International Nuclear Information System (INIS)

Pasztor, G.; Jakob, B.

1992-01-01

The NET Team initiated in 1988 a development program for a high current cable-in-conduit superconductor planned for fusion magnets. The basic strand chosen for the cable was a Nb 3 Sn wire of TWCA made by the MJR method. The electrical testing of the stand and sub-cables was carried out at several European Laboratories including PSI (Paul Scherrer Institute). The inter-laboratory comparison of the results revealed large differences in the measured critical currents of the strands. Obviously, each laboratory performed the measurement of critical current in its own way, and as a result some discrepancies in the measured values were inevitable. No standard technique of measuring critical current has been developed for Nb 3 Sn wires. The main source of difficulty arises from the strain sensitivity of Nb 3 Sn. It has been shown that the sample holder material and geometry as well as the bonding method of the specimen to its holder have important effects on the critical current measurements. It was found recently that the reaction mandrel material significantly influences the current-carrying capacity of Nb 3 Sn wires. The aim of this paper is to improve current understanding of the effect of sample configuration on critical current in Nb 3 Sn multifilamentary wires. The present study confirms the important role of reaction mandrel material on critical current. Based on comparative critical current measurements of straight and coil samples, an attempt is made to find the sample configuration which eliminates the strain induced in the specimen

Formation of Nb3Al in powder processed Nb-Al superconductors

International Nuclear Information System (INIS)

Johnson, P.E.

1987-05-01

In high magnetic fields, the critical current density is strongly dependent on the upper critical field, which is determined primarily by the stoichiometry of the Nb 3 Al. The critical temperature (T/sub c/), like the upper critical field, is considered to be a measure of the ''intrinsic'' quality of the superconductor, indicating the stoichiometry, order, and strain. If the A15 phase is stoichiometric and well ordered, a high T/sub c/ (and high H/sub C 2 /) is expected, regardless of the volume fraction of superconductor. On the other hand, if sigma phase is present with the A15, the resultant composition gradient across the sigma-A15 interface(s) requires that some of the A15 be off-stoichiometric, and therefore that the T/sub c/ (and H/sub C 2 /) be low. Thus the extent of the A15 (Nb 3 Al) reaction and the quality of the A15 formed are interdependent. This work focuses on the factors that control the extent of Nb 3 Al formation in Nb/Al powder wires. The morphology and content of the reacted and unreacted wires are studied in optical, SEM, and TEM micrographs. Critical current density data and its dependence on processing are explained in terms of the unreacted microstructure and its effect on the extent of Nb 3 Al formation. As a method of improving the critical current density, a new variation of the conventional powder process for wire manufacturing is developed and tested

Technology development and commercial production of current-carrying elements on the basis of Nb3Sn superconductor

International Nuclear Information System (INIS)

Nikulin, A.D.; Shikov, A.K.; Davydov, I.I.

1995-01-01

A description of a current carrying element intended for Tokamak-15 magnetic system is presented. The element is produced from multicore wires with superconducting Nb 3 Sn cores and calculated for 8.5 kA critical current in magnetic field of 8 T. Main processing procedures of its manufacturing are shown. Extrusion conditions needed for production of composite bronze-niobium rods and multicore wire 1.5 mm in diameter with 14641 niobium cores are determined. Heat treatment used results in formation of Nb 3 Sn intermetallics and assures maximal current-carrying capacity of 910-920 A in 8 T magnetic field. 15 refs., 9 figs

[Hyp-Au-Sn9(Hyp)3-Au-Sn9(Hyp)3-Au-Hyp]-: the longest intermetalloid chain compound of tin.

Science.gov (United States)

Binder, Mareike; Schrenk, Claudio; Block, Theresa; Pöttgen, Rainer; Schnepf, Andreas

2017-10-12

The reaction of the metalloid tin cluster [Sn 10 (Hyp) 4 ] 2- with (Ph 3 P)Au-SHyp (Hyp = Si(SiMe 3 ) 3 ) gave an intermetalloid cluster [Au 3 Sn 18 (Hyp) 8 ] - 1, which is the longest intermetalloid chain compound of tin to date. 1 shows a structural resemblance to binary AuSn phases, which is expected for intermetalloid clusters.

Heat treatment effect on the strain dependence of the critical current for an internal-tin processed Nb3Sn strand

International Nuclear Information System (INIS)

Oh, Sangjun; Park, Soo-Hyeon; Lee, Chulhee; Choi, Heekyung; Kim, Keeman

2010-01-01

A comparative study on the effects of heat treatment, especially, the duration of the A15 reaction temperature plateau on the strain dependence of the critical current for an internal-tin processed Nb 3 Sn strand has been carried out. The strain dependence of the critical current is measured by a variable temperature Walter spiral probe that we have developed. It was shown that prolonged heat treatment can be a very effective way to improve the strain dependency. For a quantitative analysis, the measured data were analyzed with various proposed scaling laws: the scaling law based on strong-coupling theory, the modified deviatoric strain scaling law, and the interpolative scaling law. We found that there is a slight increase in the critical temperature and a substantial improvement in the maximum pinning force. The origin of improved strain dependency is further discussed.

Strain dependence of the critical current and critical field in multifilamentary Nb3Sn composites

International Nuclear Information System (INIS)

Ekin, J.W.

1979-01-01

High-J/sub c/ multifilamentary Nb 3 Sn superconductors with widely varying amounts of prestrain and critical field values can be characterized fairly accurately by a single normalized critical field-strain relationship. Such a relationship permits first order prediction of critical-current degradation at arbitrary magnetic field magnitudes with knowledge of only two parameters for any conductor, the prestrain and the maximum critical field. Some of the conductor-fabrication factors affecting the parameters are considered

Superconducting Nb{sub 3}Sn intermetallics made by electrochemical reduction of Nb{sub 2}O{sub 5}-SnO{sub 2} oxides

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A; Fray, D J; Yan, X-Y; Chen, G

2003-05-01

The article is focused on low temperature superconducting Nb{sub 3}Sn material manufactured by novel electrodeoxidizing method developed in Cambridge whereby the range of alloys and intermetallics are produced cheaply making potential superconducting wires more cost effective. The process of direct electrochemical reduction of Nb{sub 2}O{sub 5}-SnO{sub 2} mixtures and in situ formation of the Nb{sub 3}Sn is discussed in details.

Development of Nb3Sn AC superconducting wire. Pt. 2

International Nuclear Information System (INIS)

Kasahara, Hobun; Torii, Shinji; Akita, Shirabe; Ueda, Kiyotaka; Kubota, Yoji; Yasohama, Kazuhiko; Kobayashi, Hisayasu; Ogasawara, Takeshi.

1993-01-01

For the realization of superconducting power apparatus, it is important that the development of highly stable superconducting cables. Nb 3 Sn wire has higher critical temperature than NbTi wire. Therefore, it is possible to make highly stable superconducting wires. In this report, we examine a manufacturing process of Ac Nb 3 Sn wire. This manufacturing process has four times higher critical current density than conventional processes. We have made a 400 kVA class AC coil with React and Wind method. The loss density of this coil was 20MW/m 3 at just before the quench. In this case, the temperature of cable increased about 3.8 K. This means that the Nb 3 Sn coil has a very high stability. (author)

Advantage and Challenges of $Nb_3Sn$ Superconducting Undulators

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A. V. [Fermilab; Barzi, E. [Fermilab; Turrinoni, D. [Fermilab; Ivanyushenkov, Yu. [Argonne; Kesgin, I. [Argonne

2018-04-01

Utilization of Nb3Sn superconducting wires offers the possibility to increase undulators’ nominal operation field and temperature margin, but requires overcoming chal-lenges that are described in this paper. The achievable field levels for a Nb3Sn version of superconducting undulators being developed at APS-ANL and the conductor choice are also presented and discussed.

Analysis of Nb3Sn surface layers for superconducting radio frequency cavity applications

Science.gov (United States)

Becker, Chaoyue; Posen, Sam; Groll, Nickolas; Cook, Russell; Schlepütz, Christian M.; Hall, Daniel Leslie; Liepe, Matthias; Pellin, Michael; Zasadzinski, John; Proslier, Thomas

2015-02-01

We present an analysis of Nb3Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb3Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (Tc) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ˜2 μm thick Nb3Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb3Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low Tc regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb3Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

Analysis of Nb3Sn surface layers for superconducting radio frequency cavity applications

International Nuclear Information System (INIS)

Becker, Chaoyue; Posen, Sam; Hall, Daniel Leslie; Groll, Nickolas; Proslier, Thomas; Cook, Russell; Schlepütz, Christian M.; Liepe, Matthias; Pellin, Michael; Zasadzinski, John

2015-01-01

We present an analysis of Nb 3 Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb 3 Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T c ) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb 3 Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb 3 Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T c regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb 3 Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators

Effects of low-temperature fusion neutron irradiation on critical properties of a monofilament niobium-tin superconductor

International Nuclear Information System (INIS)

Guinan, M.W.; Van Konynenburg, R.A.; Mitchell, J.B.

1984-01-01

The objective of this work was to irradiate a Nb 3 Sn superconductor with 14.8 MeV neutrons at 4 K and measure critical current in transverse fields of up to 12 T, irradiating up to a fluence sufficient to decrease the critical current to below its initial value. Critical temperatures were also to be measured. The samples were to be kept near 4 K between the irradiation and the measurement of critical properties. This work is directed toward establishing an engineering design fluence limit for Nb 3 Sn when used in fusion reactor superconducting magnets

Effects of low-temperature fusion neutron irradiation on critical properties of a monofilament niobium-tin superconductor

Energy Technology Data Exchange (ETDEWEB)

Guinan, M.W.; Van Konynenburg, R.A.; Mitchell, J.B.

1984-03-22

The objective of this work was to irradiate a Nb/sub 3/Sn superconductor with 14.8 MeV neutrons at 4 K and measure critical current in transverse fields of up to 12 T, irradiating up to a fluence sufficient to decrease the critical current to below its initial value. Critical temperatures were also to be measured. The samples were to be kept near 4 K between the irradiation and the measurement of critical properties. This work is directed toward establishing an engineering design fluence limit for Nb/sub 3/Sn when used in fusion reactor superconducting magnets.

Evidence for highly localized damage in internal tin and powder-in-tube Nb{sub 3}Sn strands rolled before reaction obtained from coupled magneto-optical imaging and confocal laser scanning microscopy

Energy Technology Data Exchange (ETDEWEB)

Polyanskii, A A; Lee, P J; Jewell, M C; Larbalestier, D C [Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Barzi, E; Turrioni, D; Zlobin, A V [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

2009-09-15

Nb{sub 3}Sn strands for high-current, high-field magnets must be cabled before reaction while the conductor is still composed of ductile components. Even though still in the ductile, deformable state, significant damage can occur in this step, which expresses itself by inhomogeneous A15 formation, Sn leakage or even worse effects during later reaction. In this study, we simulate cabling damage by rolling recent high performance powder-in-tube (PIT) and internal tin (IT) strands in controlled increments, applying standard Nb{sub 3}Sn reaction heat treatments, and then examining the local changes using magneto-optical imaging (MOI), scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These combined characterizations allow any local damage to the filament architecture to be made clear. MOI directly reveals the local variation of superconductivity while CLSM is extremely sensitive in revealing Sn leakage beyond the diffusion barrier into the stabilizing Cu. These techniques reveal a markedly different response to deformation by the PIT and IT strands. The study demonstrates that these tools can provide a local, thorough, and detailed view of how strands degrade and thus complement more complex extracted strand studies.

Method of production multifilamentary intermetallic superconductors

International Nuclear Information System (INIS)

Marancik, W.G.; Young, M.S.

1980-01-01

A method of making A-15 type intermetallic superconductors is disclosed which features elimination of numerous annealing steps. Nb or V filaments are embedded in Cu matrices; annular layers of Sn or Ga, respectively, separated from each other by Cu layers, provide the other component of the intermetallic superconductors Nb3Sn and V3Ga

High-temperature superconductors make major progress

CERN Multimedia

CERN Bulletin

2014-01-01

This month's Nature Materials featured an important breakthrough for high-temperature superconductors. A new method has been found for processing Bi-2212 high-temperature superconducting round wire in order to drastically increase its critical current density. The result confirms that this conductor is a serious candidate for future very-high-field magnets.   This image shows the cross-section of two Bi-2212 wires. The bottom wire has less leakage and void porosity due to a heat treatment done at an overpressure of 100 bar - about 100 times the pressure used to produce the top wire (image from [Nature Materials, Vol. 13 (2014), 10.1038/nmat3887]). The workhorse for building superconducting accelerator magnets has been, so far, the Niobium-Titanium (Nb-Ti) alloy superconductor. But with Nb-Ti having reached its full potential, other conductors must be used to operate in higher magnetic fields beyond those reached with the LHC magnets. Today, the intermetallic Niobium-Tin (Nb3Sn) is th...

Quench Modeling in High-field Nb3Sn Accelerator Magnets

Science.gov (United States)

Bermudez, S. Izquierdo; Bajas, H.; Bottura, L.

The development of high-field magnets is on-going in the framework of the LHC luminosity upgrade. The resulting peak field, in the range of 12 T to 13 T, requires the use Nb3Sn as superconductor. Due to the high stored energy density (compact winding for cost reduction) and the low stabilizer fraction (to achieve the desired margins), quench protection becomes a challenging problem. Accurate simulation of quench transientsin these magnets is hence crucial to the design choices, the definition of priority R&D and to prove that the magnets are fit for operation. In this paper we focus on the modelling of quench initiation and propagation, we describe approaches that are suitable for magnet simulation, and we compare numerical results with available experimental data.

Nb$_{3}$Sn quadrupole magnets for the LHC IR

CERN Document Server

Sabbi, G L; Chiesa, L; Coccoli, M; Dietderich, D R; Ferracin, P; Gourlay, S A; Hafalia, R R; Lietzke, A F; McInturff, A D; Scanlan, R M

2003-01-01

The development of insertion quadrupoles with 205 T/m gradient and 90 mm bore represents a promising strategy to achieve the ultimate luminosity goal of 2.5 * 10/sup 34/ cm/sup -2/s/sup -1/ at the Large Hadron Collider (LHC). At present, Nb/sub 3/Sn is the only practical conductor which can meet these requirements. Since Nb/sub 3/Sn is brittle, and considerably more strain sensitive than NbTi, the design concepts and fabrication techniques developed for NbTi magnets need to be modified appropriately. In addition, IR magnets must provide high field quality and operate reliably under severe radiation loads. The results of conceptual design studies addressing these issues are presented. (25 refs).

Nb3Sn Quadrupole Magnets for the LHC IR

International Nuclear Information System (INIS)

Sabbi, G.; Caspi, S.; Chiesa, L.; Coccoli, M.; Dietderich, D.R.; Ferracin, P.; Gourlay, S.A.; Hafalia, R.R.; Lietzke, A.F.; McInturff, A.D.; Scanlan, R.M.

2001-01-01

The development of insertion quadrupoles with 205 T/m gradient and 90 mm bore represents a promising strategy to achieve the ultimate luminosity goal of 2.5 x 10 34 cm -2 s -1 at the Large Hadron Collider (LHC). At present, Nb 3 Sn is the only practical conductor which can meet these requirements. Since Nb 3 Sn is brittle, and considerably more strain sensitive than NbTi, the design concepts and fabrication techniques developed for NbTi magnets need to be modified appropriately. In addition, IR magnets must provide high field quality and operate reliably under severe radiation loads. The results of conceptual design studies addressing these issues are presented.

Proof-of-principle demonstration of Nb3Sn superconducting radiofrequency cavities for high Q0 applications

Science.gov (United States)

Posen, S.; Liepe, M.; Hall, D. L.

2015-02-01

Many future particle accelerators require hundreds of superconducting radiofrequency (SRF) cavities operating with high duty factor. The large dynamic heat load of the cavities causes the cryogenic plant to make up a significant part of the overall cost of the facility. This contribution can be reduced by replacing standard niobium cavities with ones coated with a low-dissipation superconductor such as Nb3Sn. In this paper, we present results for single cell cavities coated with Nb3Sn at Cornell. Five coatings were carried out, showing that at 4.2 K, high Q0 out to medium fields was reproducible, resulting in an average quench field of 14 MV/m and an average 4.2 K Q0 at quench of 8 × 109. In each case, the peak surface magnetic field at quench was well above Hc1, showing that it is not a limiting field in these cavities. The coating with the best performance had a quench field of 17 MV/m, exceeding gradient requirements for state-of-the-art high duty factor SRF accelerators. It is also shown that—taking into account the thermodynamic efficiency of the cryogenic plant—the 4.2 K Q0 values obtained meet the AC power consumption requirements of state-of-the-art high duty factor accelerators, making this a proof-of-principle demonstration for Nb3Sn cavities in future applications.

Evidence from EXAFS for Different Ta/Ti Site Occupancy in High Critical Current Density Nb3Sn Superconductor Wires.

Science.gov (United States)

Heald, Steve M; Tarantini, Chiara; Lee, Peter J; Brown, Michael D; Sung, ZuHawn; Ghosh, Arup K; Larbalestier, David C

2018-03-19

To meet critical current density, J c , targets for the Future Circular Collider (FCC), the planned replacement for the Large Hadron Collider (LHC), the high field performance of Nb 3 Sn must be improved, but champion J c values have remained static for the last 10 years. Making the A15 phase stoichiometric and enhancing the upper critical field H c2 by Ti or Ta dopants are the standard strategies for enhancing high field performance but detailed recent studies show that even the best modern wires have broad composition ranges. To assess whether further improvement might be possible, we employed Extended X-ray Absorption Fine Structure (EXAFS) to determine the lattice site location of dopants in modern high-performance Nb 3 Sn strands with J c values amongst the best so far achieved. Although Ti and Ta primarily occupy the Nb sites in the A15 structure, we also find significant Ta occupancy on the Sn site. These findings indicate that the best performing Ti-doped stand is strongly sub-stoichiometric in Sn and that antisite disorder likely explains its high average H c2 behavior. These new results suggest an important role for dopant and antisite disorder in minimizing superconducting property distributions and maximizing high field J c properties.

Development of Nb3Sn cabled conductor by external diffusion process and the effect of strain on the critical current

International Nuclear Information System (INIS)

Pasztor, G.; Ekin, J.W.

1984-01-01

The planned extension of the High Field Test Facility SULTAN at SIN to provide 12 T operation in a 60 cm bore has led to an increased involvements on the part of SIN in the development of reliable A15 multifilamentary conductors. It is the purpose of this paper to describe the development of stranded Nb 3 Sn conductors using the external diffusion technique. Although not fully optimized, the primary cables have high overall critical current densities. Problems associated with the diffusion of the tin into the copper matrix, such as tin coalescence and development of Kirkendall porosity were successfully solved using small diameter wires and by appropriate diffusion and reaction heat treatment conditions. The elastic strain sensitivity of the critical current of a previously developed cable was comparable to that of bronze processed monolithic Nb 3 Sn, while the irreversible strain limit of 1.2% was significantly higher, On the other hand a longer current transfer length (about 4 times that of bronze processed monolithic conductors) was found

Analysis of Nb{sub 3}Sn surface layers for superconducting radio frequency cavity applications

Energy Technology Data Exchange (ETDEWEB)

Becker, Chaoyue [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Posen, Sam; Hall, Daniel Leslie [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Groll, Nickolas; Proslier, Thomas, E-mail: prolier@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Cook, Russell [Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Schlepütz, Christian M. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liepe, Matthias [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Pellin, Michael [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zasadzinski, John [Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

2015-02-23

We present an analysis of Nb{sub 3}Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb{sub 3}Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T{sub c}) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb{sub 3}Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb{sub 3}Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T{sub c} regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb{sub 3}Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

Nb3Sn accelerator magnet technology scale up based on cos-theta coils

International Nuclear Information System (INIS)

Nobrega, F.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Novitski, I.; Pischalnikov, Yu.; Sylvester, C.; Tartaglia, M.; Turrioni, D.; Yamada, R.; Zlobin, A.V.; Fermilab

2006-01-01

After successful testing of a 1 m long dipole mirror magnet and three dipole models based on two-layer Nb 3 Sn coils, Fermilab has started a Nb 3 Sn technology scale-up program using the dipole mirror design and the developed Nb 3 Sn coil fabrication technology based on the wind-and-react method. The scale-up will be performed in several steps starting from a 2 m long coil made of Powder-in-Tube (PIT) strand. This will be followed by 4 m long Nb 3 Sn coils made of PIT and RRP strands that will be fabricated into dipole mirror magnets and tested. This paper presents a summary of Fermilab's wind-and-react short model program. It includes details on the 2 m and 4 m long, 2 layer Nb 3 Sn dipole mirror magnet design, mechanical structure, and fabrication infrastructure

Nb3Sn accelerator magnet technology scale up based on cos-theta coils

Energy Technology Data Exchange (ETDEWEB)

Nobrega, F.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Novitski, I.; Pischalnikov, Yu.; Sylvester, C.; Tartaglia, M.; Turrioni, D.; Yamada, R.; Zlobin, A.V.; /Fermilab

2006-08-01

After successful testing of a 1 m long dipole mirror magnet and three dipole models based on two-layer Nb{sub 3}Sn coils, Fermilab has started a Nb{sub 3}Sn technology scale-up program using the dipole mirror design and the developed Nb{sub 3}Sn coil fabrication technology based on the wind-and-react method. The scale-up will be performed in several steps starting from a 2 m long coil made of Powder-in-Tube (PIT) strand. This will be followed by 4 m long Nb{sub 3}Sn coils made of PIT and RRP strands that will be fabricated into dipole mirror magnets and tested. This paper presents a summary of Fermilab's wind-and-react short model program. It includes details on the 2 m and 4 m long, 2 layer Nb{sub 3}Sn dipole mirror magnet design, mechanical structure, and fabrication infrastructure.

Fabrication and component testing results for a Nb3Sn dipole magnet

International Nuclear Information System (INIS)

Dell'Orco, D.; Scanlan, R.M.; Taylor, C.E.; Lietzke, A.; Caspi, S.; van Oort, J.M.; McInturff, A.D.

1994-10-01

At present, the maximum field achieved in accelerator R ampersand D dipoles is slightly over 10T, with NbTi conductor at 1.8 K. Although Nb 3 Sn has the potential to achieve much higher fields, none of the previous dipoles constructed from Nb 3 Sn have broken the 10T barrier. We report here on the construction of a dipole with high current density Nb 3 Sn with a predicted short sample limit of 13T. A wind and react technique, followed by epoxy impregnation of the fiberglass insulated coils, was used. The problems identified with the use of Nb 3 SD in earlier dipole magnets were investigated in a series of supplemental tests. This includes measurement of the degradation of J c with transverse strain, cabling degradation, joint resistance measurements, and epoxy strength tests. In addition, coff assembly techniques were developed to ensure that adequate prestress could be applied without damaging the reacted Nb 3 Sn cable. We report here the results of these tests and the construction status of this 50 mm bore dipole

Recent Progress in Application of Internal Oxidation Technique in Nb3Sn Strands

Energy Technology Data Exchange (ETDEWEB)

Xu, Xingchen [Fermilab; Peng, Xuan [Hyper Tech Research Inc.; Sumption, Michael [Ohio State U.; Collings, E. W. [Ohio State U.

2016-10-13

The internal oxidation technique can generate ZrO2 nano particles in Nb3Sn strands, which markedly refine the Nb3Sn grain size and boost the high-field critical current density (Jc). This article summarizes recent efforts on implementing this technique in practical Nb3Sn wires and adding Ti as a dopant. It is demonstrated that this technique can be readily incorporated into the present Nb3Sn conductor manufacturing technology. Powder-in-tube (PIT) strands with fine subelements (~25 µm) based on this technique were successfully fabricated, and proper heat treatments for oxygen transfer were explored. Future work for producing strands ready for applications is proposed.

A Nb3Sn high field dipole

International Nuclear Information System (INIS)

McClusky, R.; Robins, K.E.; Sampson, W.B.

1990-01-01

A dipole magnet approximately 1 meter long with an 8 cm bore has been fabricated from cable made from Nb 3 Sn multifilamentary strands. The coil consists of four layers of conductor wound in pairs to eliminate internal joints. Each set of layers is separately constrained with Kevlar-epoxy bands and the complete assembly clamped in a split laminated iron yoke. The inner coil pairs were wound before heat treating while the outer coils were formed from pre-reacted cable using conventional insulation. A NbTi version of the magnet was fabricated using SSC version of the magnet was fabricated using SSC conductor to test the construction techniques. This magnet reached a maximum central field of 7.6 Tesla, at 4.4K which is very close to the limit estimated from conductor measurements. The Nb 3 Sn magnet, however, only reached a maximum field at 8.1T considerably short of the field expected from measurements on the inner cable. 7 refs., 5 figs

A multiple-field coupled resistive transition model for superconducting Nb3Sn

Science.gov (United States)

Yang, Lin; Ding, He; Zhang, Xin; Qiao, Li

2016-12-01

A study on the superconducting transition width as functions of the applied magnetic field and strain is performed in superconducting Nb3Sn. A quantitative, yet universal phenomenological resistivity model is proposed. The numerical simulation by the proposed model shows predicted resistive transition characteristics under variable magnetic fields and strain, which in good agreement with the experimental observations. Furthermore, a temperature-modulated magnetoresistance transition behavior in filamentary Nb3Sn conductors can also be well described by the given model. The multiple-field coupled resistive transition model is helpful for making objective determinations of the high-dimensional critical surface of Nb3Sn in the multi-parameter space, offering some preliminary information about the basic vortex-pinning mechanisms, and guiding the design of the quench protection system of Nb3Sn superconducting magnets.

A model for phase evolution and volume expansion in tube type Nb3Sn conductors

Science.gov (United States)

Xu, X.; Sumption, M. D.; Collings, E. W.

2013-12-01

In this work, an analytic model for phase formation and volume expansion during heat treatment in tube type Nb3Sn strands is presented. Tube type Nb3Sn conductors consist of Nb or Nb-Ta alloy tube with a simple Cu/Sn binary metal insert to form the basic subelement (filament). A number of these elements, each with an outer Cu jacket, are restacked to form a multifilamentary strand. The present tube type conductors, with 4.2 K, 12 T non-Cu critical current density (Jc) in the 2000-2500 A mm-2 range and effective subelement diameters (deff) in the 12-36 μm range, are of interest for a number of applications. During the reaction of typical tube type strands, the Sn-Cu becomes molten and reacts with the Nb tube first to form NbSn2, then Nb6Sn5. At later times in the reaction sequence, all of the NbSn2 and Nb6Sn5 is converted to Nb3Sn. Some of the Nb3Sn is formed by a Nb-Sn reaction and has a fine grain (FG) structure, while some is converted from Nb6Sn5, which results in a coarse grain (CG) region. The fractions of FG and CG A15 are important in determining the final conductor properties. In this work we develop an analytic model to predict the radial extents of the various phases, and in particular the final FG and CG fractions based on the starting Nb, Cu, and Sn amounts in the subelements. The model is then compared to experimental results and seen to give reasonable agreement. By virtue of this model we outline an approach to minimize the CG regions in tube type and PIT strands and maximize the final FG area fractions. Furthermore, the volume change during the various reaction stages was also studied. It is proposed that the Sn content in the Cu-Sn alloy has a crucial influence on the radial expansion.

The relationship between critical current and microstructure of internal tin wire

International Nuclear Information System (INIS)

Dietderich, D.R.; Hassenzahl, W.V.; Morris, J.W. Jr.

1986-01-01

Prior work on internal tin wire has shown that an increase in critical current results when the Nb 3 Sn reaction temperatures (650-730 0 C) are preceded by low temperature diffusion heat treatments that distribute the tin. These heat treatments produce a more uniform tin distribution through the niobium filament array before substantial Nb 3 Sn formation has occurred. Heat treatments as long as 19 days have been proposed as the optimal heat treatment for the conductor. However, it is possible to substantially reduce the low temperature heat treatment time while retaining the same high critical current. The success of shortened heat treatments may be interpreted on the basis of the Cu-Sn reaction, diffusion kinetics and the Nb 3 Sn growth kinetics

submitter 16 T Nb$_{3}$Sn Racetrack Model Coil Test Result

CERN Document Server

Perez, J C; Bajko, M; Bottura, L; Bordini, B; Chiuchiolo, A; De Rijk, G; Ferracin, P; Feuvrier, J; Grosclaude, P; Juchno, M; Rochepault, E; Rysti, J; Sarasola, X

2016-01-01

In the framework of the European project EuCARD, the High Field Magnet project, led by a CERN-CEA collaboration, implied the development of a large aperture Nb$_{3}$Sn dipole magnet called FRESCA2. The magnet uses four double-pancake block-type coils, each about 1.5 m long. In order to characterize strand and cable properties, as well as to qualify the coil fabrication process, CERN started in 2012 the design and fabrication of the Racetrack Model Coil (RMC) magnet, a short model magnet using the same cable as FRESCA2 magnet with only two flat double-pancake coils about 0.8 m long. In 2013, two superconducting coils have been fabricated, making use of two different types of superconductor. In 2014 and 2015, the coils were tested both in a single and in a double-coil configuration in a support structure based on an external aluminum shell pre-loaded with water-pressurized bladders. In this paper, we describe the design of the RMC magnet and its coils, provide the main parameters of the superconductor, and repo...

A multiple-field coupled resistive transition model for superconducting Nb3Sn

Directory of Open Access Journals (Sweden)

Lin Yang

2016-12-01

Full Text Available A study on the superconducting transition width as functions of the applied magnetic field and strain is performed in superconducting Nb3Sn. A quantitative, yet universal phenomenological resistivity model is proposed. The numerical simulation by the proposed model shows predicted resistive transition characteristics under variable magnetic fields and strain, which in good agreement with the experimental observations. Furthermore, a temperature-modulated magnetoresistance transition behavior in filamentary Nb3Sn conductors can also be well described by the given model. The multiple-field coupled resistive transition model is helpful for making objective determinations of the high-dimensional critical surface of Nb3Sn in the multi-parameter space, offering some preliminary information about the basic vortex-pinning mechanisms, and guiding the design of the quench protection system of Nb3Sn superconducting magnets.

Improved multifilamentary Nb3Sn conductors produced by the titanium-bronze process

International Nuclear Information System (INIS)

Tachikawa, K.; Itoh, K.; Kamata, K.; Moriai, H.; Tada, N.

1985-01-01

The effects of a titanium addition to the bronze matrix of superconducting Nb 3 Sn wires have been investigated. The titanium addition to the matrix remarkably increases the Nb 3 Sn growth rate and the high-field, critical current density of the wire. An overall critical-current density of 3.8 . 10 4 A/cm 2 at 15 T has been obtained for the multifilamentary Nb/Cu-7.5 at.% Sn-0.4 at.% Ti wire with 4.7 μm-diameter 31 x 331 cores. The anisotropy in the critical current with respect to the field direction becomes larger with increasing aspect ratio of the rectangular-shaped multifilamentary wires. A 9.5 mm wide and 1.8mm thick Nb/Cu-7.5Sn-0.4Ti conductor with 5 μm-diameter 349 x 361=125 989 cores has been successfully fabricated on an industrial scale. This conductor carries a superconducting current of over 1300 A at 16.5 T. The newly developed Ti-bronze Nb 3 Sn conductor makes it feasible to generate a field of proportional 15 T in a large diameter bore. (orig.)

Advances in development of Nb3Sn superconducting radio-frequency cavities

Science.gov (United States)

Posen, Sam; Liepe, Matthias

2014-11-01

A 1.3 GHz Nb3Sn superconducting radio-frequency cavity prepared with a modified annealing step reached Bp k>50 mT , well above Bc 1=25 ±7 mT , without the strong Q -slope observed in previous Nb3Sn cavities. At 4.2 K, it has a Q0 of approximately 1 ×1 010 at >10 MV /m , far outperforming Nb at useable gradients. At 2 K, quench occurred at ˜55 mT , apparently due to a defect, so additional treatment may increase the maximum gradient. Material parameters of the coating were extracted from Q vs T data, including a Tc of 18.0 ±0.1 K , close to the maximum literature value. High power pulses were used to reach fields far higher than in CW measurements, and near Tc, quench fields close to the superheating field were observed. Based on a review of previous experience with Nb3Sn cavities, a speculative mechanism involving weak link grain boundaries is presented to explain how the modified annealing step could be the cause of the absence of strong Q -slope. Finally, an analysis of the progress to date provides hints that the path forward for Nb3Sn cavities should focus on minimizing defects.

Assembly and Test of HD2, a 36 mm bore high field Nb3Sn Dipole Magnet

International Nuclear Information System (INIS)

Ferracin, P.; Bingham, B.; Caspi, S.; Cheng, D.W.; Dietderich, D.R.; Felice, H.; Godeke, A.; Hafalia, A.R.; Hannaford, C.R.; Joseph, J.; Lietzke, A.F.; Lizarazo, J.; Sabbi, G.; Trillaud, F.; Wang, X.

2008-01-01

We report on the fabrication, assembly, and test of the Nb 3 Sn dipole magnet HD2. The magnet, aimed at demonstrating the application of Nb 3 Sn superconductor in high field accelerator-type dipoles, features a 36 mm clear bore surrounded by block-type coils with tilted ends. The coil design is optimized to minimize geometric harmonics in the aperture and the magnetic peak field on the conductor in the coil ends. The target bore field of 15 T at 4.3 K is consistent with critical current measurements of extracted strands. The coils are horizontally pre-stressed during assembly using an external aluminum shell pre-tensioned with water-pressurized bladders. Axial pre-loading of the coil ends is accomplished through two end plates and four aluminum tension rods. The strain in coil, shell, and rods is monitored with strain gauges during assembly, cool-down and magnet excitation, and compared with 3D finite element computations. Magnet's training performance, quench locations, and ramp-rate dependence are then analyzed and discussed.

Method for preparation of superconductors

Energy Technology Data Exchange (ETDEWEB)

Barber, A.C.; McDougall, I.L.

1975-07-10

The invention deals with a method to prepare a superconductor consisting of a superconducting compound of at least two elements. It especially deals with superconductors which surround a superconducting intermetallic compounds of at least two elements, examples of which are Nb/sub 2/Sn and Nb/sub 3/Al.

Method for preparing high transition temperature Nb.sub.3 Ge superconductors

Science.gov (United States)

Newkirk, Lawrence R.; Valencia, Flavio A.

1977-01-01

Bulk coatings of Nb.sub.3 Ge superconductors having transition temperatures in excess of 20 K are readily formed by a chemical vapor deposition technique involving the coreduction of NbCl.sub.5 and GeCl.sub.4 in the presence of hydrogen. The NbCl.sub.5 vapor may advantageously be formed quantitatively in the temperature range of about 250.degree. to 260.degree. C by the chlorination of Nb metal provided the partial pressure of the product NbCl.sub.5 vapor is maintained at or below about 0.1 atm.

LARP Long Nb3Sn Quadrupole Design

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Ferracin, P.; Ghosh, A.; Hafalia, R.; Hannaford, R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

2008-01-01

A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb 3 Sn conductor. The goal of these magnets is to be a proof of principle that Nb 3 Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure

LARP Long Nb3Sn Quadrupole Design

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; Fermilab; Brookhaven; LBL, Berkeley; Texas A-M

2007-01-01

A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb3Sn conductor. The goal of these magnets is to be a proof of principle that Nb3Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure

LARP Long Nb3Sn Quadrupole Design

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; Ghosh, A.; Hafalia, A.R.; Hannaford, C.R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

2007-01-01

A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb 3 Sn conductor. The goal of these magnets is to be a proof of principle that Nb 3 Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure

A Method to Increase Current Density in a Mono Element Internal Tin Processed Superconductor Utilizing Zr Oxide to Refine Grain Size; Final Report Phase 2

International Nuclear Information System (INIS)

Zeitlin, Bruce A.; Gregory, Eric

2008-01-01

The effect of Oxygen on (Nb1Zr)3Sn multifilament conductors manufactured by the Mono Element Internal Tin (MEIT) process was explored to improve the current density by refining the grain size. This followed work first done by General Electric on the Nb3Sn tape process. Techniques to fabricate the more difficult Nb1Zr composites are described and allowed fabrication of long lengths of .254 mm diameter wire from an 88.9 mm diameter billet. Oxygen was incorporated through the use of SnO2 mixed with tin powder and incorporated into the core. These were compared to samples with Ti+Sn and Cu+Sn cores. Heat treatments covered the range of 700 C to 1000 C. Current density vs. H, grain size, and reaction percentages are provided for the materials tested. The Oxygen gave superior results in the temperature range of 815-1000 C. It also stabilized the filament geometry of the array in comparison to the other additions at the higher temperatures. At 815 C a peak in layer Jc yielded values of 2537 A/mm2 at 12 T and 1353 A/mm2 at 15T, 8-22% and 30-73% greater respectively than 700 C values. Results with Oxygen at high temperature show the possibility of high speed continuous reaction of the composite versus the current batch or react in place methods. In general the Ti additions gave superior results at the lower reaction temperature. Future work is suggested to determine if the 815 C reaction temperature can lead to higher current density in high tin (Nb1Zr+Ox)3Sn conductors. A second technique incorporated oxygen directly into the Nb1Zr rods through heat treatment with Nb2O5 at 1100 C for 100 hours in vacuum prior to extrusion. The majority of the filaments reduced properly in the composite but some local variations in hardness led to breakage at smaller diameters.

Advances in development of Nb_{3}Sn superconducting radio-frequency cavities

Directory of Open Access Journals (Sweden)

Sam Posen

2014-11-01

Full Text Available A 1.3 GHz Nb_{3}Sn superconducting radio-frequency cavity prepared with a modified annealing step reached B_{pk}>50  mT, well above B_{c1}=25±7  mT, without the strong Q-slope observed in previous Nb_{3}Sn cavities. At 4.2 K, it has a Q_{0} of approximately 1×10^{10} at >10  MV/m, far outperforming Nb at useable gradients. At 2 K, quench occurred at ∼55  mT, apparently due to a defect, so additional treatment may increase the maximum gradient. Material parameters of the coating were extracted from Q vs T data, including a T_{c} of 18.0±0.1  K, close to the maximum literature value. High power pulses were used to reach fields far higher than in CW measurements, and near T_{c}, quench fields close to the superheating field were observed. Based on a review of previous experience with Nb_{3}Sn cavities, a speculative mechanism involving weak link grain boundaries is presented to explain how the modified annealing step could be the cause of the absence of strong Q-slope. Finally, an analysis of the progress to date provides hints that the path forward for Nb_{3}Sn cavities should focus on minimizing defects.

High-field specific heats of A15 V3Si and Nb3Sn

Science.gov (United States)

Stewart, G. R.; Brandt, B. L.

1984-04-01

In order to further understand the anomalous behavior of the specific heat of Nb3Sn in an 18-T magnetic field discovered by Stewart, Cort, and Webb [Phys. Rev. B 24, 3841 (1981)], we have performed specific-heat measurements on a different sample of Nb3Sn at lower fields both in the normal and mixed states, as well as measurement to 19 T on both transforming and nontransforming V3Si. The high-field data for V3Si indicate that this material behaves quite normally, and that γtransJunod and Muller [Solid State Commun. 36, 721 (1980)]. Nb3Sn, however, remains anomalous, with both the same "kink" in the normal-state field data as observed by Stewart, Cort, and Webb (although at a slightly higher temperature) and unusual mixed-state behavior. The mixed-state specific heat of the V3Si samples is as expected, based on earlier work on the mixed-state specific heat of V and Nb.

Effect of Nb on the Growth Behavior of Co3Sn2 Phase in Undercooled Co-Sn Melts

Science.gov (United States)

Kang, Jilong; Xu, Wanqiang; Wei, Xiuxun; Ferry, Michael; Li, Jinfu

2016-12-01

The growth behavior of the primary β-Co3Sn2 phase in (Co67Sn33)100- x Nb x ( x = 0, 0.5, 0.8, 1.0) hypereutectic alloys at different melt undercoolings was investigated systematically. The growth pattern of the β-Co3Sn2 phase at low undercooling changes with the Nb content from fractal seaweed ( x = 0, 0.5) into dendrite ( x = 0.8) and then returns to fractal seaweed ( x = 1.0) as a response to the changes in interface energy anisotropy and interface kinetic anisotropy. As undercooling increases, the dendritic growth of the β-Co3Sn2 phase in (Co67Sn33)99.2Nb0.8 alloy gives way to fractal seaweed growth at an undercooling of 32 K (-241 °C). At larger undercooling, the fractal seaweed growth is further replaced by compact seaweed growth, which occurred in the other three alloys investigated. The growth velocity of the β-Co3Sn2 phase slightly increases at low and intermediate undercooling but clearly decreases at larger undercooling due to the Nb addition. The growth velocity sharply increases as the growth pattern of the Co3Sn2 phase transits from fractal seaweed into compact seaweed.

Development of cost-effective Nb3Sn conductors for the next generation hadron colliders

International Nuclear Information System (INIS)

Scanlan, R.M.; Dietderich, D.R.; Zeitlin, B.A.

2001-01-01

Significant progress has been made in demonstrating that reliable, efficient high field dipole magnets can be made with Nb 3 Sn superconductors. A key factor in determining whether these magnets will be a cost-effective solution for the next generation hadron collider is the conductor cost. Consequently, DOE initiated a conductor development program to demonstrate that Nb 3 Sn can be improved to reach a cost/performance value of $1.50/kA-m at 12T, 4.2K. The first phase of this program was initiated in Jan 2000, with the goal of improving the key properties of interest for accelerator dipole magnets--high critical current density and low magnetization. New world record critical current densities have been reported recently, and it appears that significant potential exists for further improvement. Although new techniques for compensating for magnetization effects have reduced the requirements somewhat, techniques for lowering the effective filament size while maintaining these high Jc values are a program priority. The next phase of this program is focused on reducing the conductor cost through substitution of lower cost raw materials and through process improvements. The cost drivers for materials and fabrication have been identified, and projects are being initiated to demonstrate cost reductions

Electromechanical properties of superconductors for DOE fusion applications

International Nuclear Information System (INIS)

Ekin, J.W.; Bray, S.L.; Lutgen, C.L.; Bahn, W.L.

1994-01-01

The electrical performance of many superconducting materials is strongly dependent on mechanical load. This report presents electromechanical data on a broad range of high-magnetic-field superconductors. The conductors that were studied fall into three general categories: Candidate conductors, experimental conductors, and reference conductors. Research on candidate conductors for fusion applications provides screening data for superconductor selection as well as engineering data for magnet design and performance analysis. The effect of axial tensile strain on critical-current density was measured for several Nb 3 Sn candidate conductors including the US-DPC (United States Demonstration Poloidal Coil) cable strand and an ITER (International Thermonuclear Experimental Reactor) candidate conductor. Also, data are presented on promising experimental superconductors that have strong potential for fusion applications. Axial strain measurements were made on a V 3 Ga tape conductor that has good performance at magnetic fields up to 20 T. Axial strain data are also presented for three experimental Nb 3 Sn conductors that contain dispersion hardened copper reinforcement for increased tensile strength. Finally, electromechanical characteristics were measured for three different Nb 3 Sn reference conductors from the first and second VAMAS (Versailles Project on Advanced Materials and Standards) international Nb 3 Sn critical-current round robins. Published papers containing key results, including the first measurement of the transverse stress effect in Nb 3 Sn, the effect of stress concentration at cable-strand crossovers, and electromechanical characteristics of Nb 3 Al, are included throughout the report

The crystal structure of (Nb$_{0.75}$Cu$_{0.25}$)Sn$_{2}$ in the Cu-Nb-Sn system

CERN Document Server

Martin, Stefan; Nolze, Gert; Leineweber, Andreas; Leaux, Floriane; Scheuerlein, Christian

2017-01-01

During the processing of superconducting Nb$_{3}$Sn wire, several intermediate intermetallic phases including a previously encountered Cu-Nb-Sn phase show up. The yet unknown crystal structure of this phase is now identified by a combination of different experimental techniques and database search to be of the hexagonal NiMg2 type with a proposed composition of about (Nb0.75Cu0.25)Sn2. The structure determination started from an evaluation of the lattice parameters from EBSD Kikuchi patterns from quenched material suggesting hexagonal or orthorhombic symmetry. A database search then led to the hexagonal NiMg2 type structure, the presence of which was confirmed by a Rietveld analysis on the basis of high energy synchrotron X-ray powder diffraction data. Assuming a partial substitution of Nb in orthorhombic NbSn2 by Cu, the change of the valence electron concentration provokes a structural transformation from the CuMg2 type for NbSn2 to the NiMg2 type for (Nb0.75Cu0.25)Sn2. In the previous literature the (Nb0.7...

Design and fabrication of Sn-Nb-Cu-Ta-C composites for multifilamentary superconducting Nb/sub 3/Sn wires by using the modified tube technique

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A; Kosek, Z M

1987-10-01

The factors determining the design and fabrication of Nb/sub 3/Sn multifilamentary wires by the tube technique are discussed. New improved methods of obtaining multifilamentary Nb/sub 3/Sn wires on the basis of both external diffusion and internal diffusion processes, by using the tube technique in a simpler and less expensive way, are presented.

Development and manufacture of a Nb3Sn superconductor for the high-field test facility

International Nuclear Information System (INIS)

Scanlan, R.M.; Cornish, D.N.; Spencer, C.R.; Gregory, E.; Adam, E.

1981-01-01

The High-Field Test Facility (HFTF) project has two primary goals. The first is to establish manufacturing capability for a Nb 3 Sn conductor suitable for use in a mirror fusion coil. The second is to provide a test facility for evaluating other fusion conductor designs at high fields. This paper describes some of the problems encountered and the solutions devised in working toward the first goal. Construction of the test facility coils will be described in a subsequent paper

High field superconductor development and understanding

Energy Technology Data Exchange (ETDEWEB)

Larbalestier, David C. [Florida State Univ., Tallahassee, FL (United States); Lee, Peter J. [Florida State Univ., Tallahassee, FL (United States); Tarantini, Chiara [Florida State Univ., Tallahassee, FL (United States)

2014-09-28

All present circular accelerators use superconducting magnets to bend and to focus the particle beams. The most powerful of these machines is the large hadron collider (LHC) at CERN. The main ring dipole magnets of the LHC are made from Nb-Ti but, as the machine is upgraded to higher luminosity, more powerful magnets made of Nb₃Sn will be required. Our work addresses how to make the Nb₃Sn conductors more effective and more suitable for use in the LHC. The most important property of the superconducting conductor used for an accelerator magnet is that it must have very high critical current density, the property that allows the generation of high magnetic fields in small spaces. Nb₃Sn is the original high field superconductor, the material which was discovered in 1960 to allow a high current density in the field of about 9 T. For the high luminosity upgrade of the LHC, much higher current densities in fields of about 12 Tesla will be required. The critical value of the current density is of order 2600 A/mm² in a field of 12 Tesla. But there are very important secondary factors that complicate the attainment of this critical current density. The first is that the effective filament diameter must be no larger than about 40 µm. The second factor is that 50% of the cross-section of the Nb₃Sn conductor that is pure copper must be protected from any poisoning by any Sn leakage through the diffusion barrier that protects the package of niobium and tin from which the Nb₃Sn is formed by a high temperature reaction. These three, somewhat conflicting requirements, mean that optimization of the conductor is complex. The work described in this contract report addresses these conflicting requirements. They show that very sophisticated characterizations can uncover the way to satisfy all 3 requirements and they also suggest that the ultimate optimization of Nb₃Sn is still not yet in sight

Nb3Sn conductor development for the ITER magnets

International Nuclear Information System (INIS)

Mitchell, N.

1997-01-01

The ITER magnet system consists of Toroidal Field (TF) coils, Poloidal Field (PF) coils, the Central Solenoid (CS) and error field correction coils (CC). The conductors for the coils are Nb 3 Sn or NbTi cable in conduit type, forced flow cooled with supercritical helium having a maximum operating current in the range 40-60 kA. To qualify the Nb 3 Sn conductor, two large model coils (energy up to 640 MJ) are being wound by the Home Teams of the Parties to the ITER EDA Agreement. A total of 24 t of strand has been completed for the CS model coil and 4 t for the TF model coil, and fabricated into 7 km of conductor in unit lengths up to 210 m, by an international collaboration involving 12 companies in Europe, Japan, Russia and the USA

Direct measurement of elastic modulus of Nb 3Sn using extracted filaments from superconducting composite wire and resin impregnation method

Science.gov (United States)

Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.

2006-10-01

Young's modulus of Nb3Sn filaments in Nb3Sn/Cu superconducting composite wire was investigated in detail. Nb3Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb3Sn/Nb barrier and bronze. Then, Nb3Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb3Sn filament modulus. The ratio of Nb3Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb3Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values.

Direct measurement of elastic modulus of Nb3Sn using extracted filaments from superconducting composite wire and resin impregnation method

International Nuclear Information System (INIS)

Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.

2006-01-01

Young's modulus of Nb 3 Sn filaments in Nb 3 Sn/Cu superconducting composite wire was investigated in detail. Nb 3 Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb 3 Sn/Nb barrier and bronze. Then, Nb 3 Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb 3 Sn filament modulus. The ratio of Nb 3 Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb 3 Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values

Proof-of-principle demonstration of Nb{sub 3}Sn superconducting radiofrequency cavities for high Q{sub 0} applications

Energy Technology Data Exchange (ETDEWEB)

Posen, S., E-mail: sep93@cornell.edu; Liepe, M.; Hall, D. L. [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States)

2015-02-23

Many future particle accelerators require hundreds of superconducting radiofrequency (SRF) cavities operating with high duty factor. The large dynamic heat load of the cavities causes the cryogenic plant to make up a significant part of the overall cost of the facility. This contribution can be reduced by replacing standard niobium cavities with ones coated with a low-dissipation superconductor such as Nb{sub 3}Sn. In this paper, we present results for single cell cavities coated with Nb{sub 3}Sn at Cornell. Five coatings were carried out, showing that at 4.2 K, high Q{sub 0} out to medium fields was reproducible, resulting in an average quench field of 14 MV/m and an average 4.2 K Q{sub 0} at quench of 8 × 10{sup 9}. In each case, the peak surface magnetic field at quench was well above H{sub c1}, showing that it is not a limiting field in these cavities. The coating with the best performance had a quench field of 17 MV/m, exceeding gradient requirements for state-of-the-art high duty factor SRF accelerators. It is also shown that—taking into account the thermodynamic efficiency of the cryogenic plant—the 4.2 K Q{sub 0} values obtained meet the AC power consumption requirements of state-of-the-art high duty factor accelerators, making this a proof-of-principle demonstration for Nb{sub 3}Sn cavities in future applications.

Performance boundaries in Nb3Sn superconductors

NARCIS (Netherlands)

Godeke, A.

2005-01-01

Superconducting magnets for High Energy Physics, Fusion, Magnetic Resonance Imaging (NMR) and Nuclear Magnetic Resonance, benefit from the extremely high current densities that can be achieved in superconductors compared to normal conducting materials. These magnets are usually constructed starting

Zr-Sn-Nb alloys. Preliminary studies

International Nuclear Information System (INIS)

Danon, C.A.; Arias, D.E.

1993-01-01

Studies of the Zr-Sn-Nb diagram have been started, focussing on the Zr-rich corner, near the composition of Zirlo commercial alloy, Zr-1Sn-1Nb, and with Fe and O contents usual in nuclear grade materials. Three alloys were melted, namely Zr-4Sn-2.4Nb (A), Zr-1Sn-3Nb (B) and Zr-2.1Sn-1Nb (C). α/β transformation temperatures were measured through the variation of electrical resistivity(p) vs temperature (T). Values of 560 deg C, 670 deg C and 750 deg C were measured for the α→α+β reaction and 980 deg C, 910 deg C and 1000 deg C for the α+β→β reaction, for the A, B and C alloys, respectively in that order. Some samples were submitted to heat treatments (62 and 216 hours at 825 deg C, 120 hours at 875 deg C). Optical and scanning electronic microscopy of those samples confirmed our resistivity results. (Author)

Quench performance of Nb3Sn cos-theta coils made of 108/127 RRP strands

International Nuclear Information System (INIS)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.

2007-01-01

A series of 1-m long Nb 3 Sn dipole models has been built at Fermilab in an attempt to refine the wind-and-react technology for Nb3Sn accelerator magnets. Three models made with Powder-in-Tube Nb 3 Sn strand reached their design field of 10 T demonstrating a good reproducibility of magnet quench performance and field quality. Recently a new dipole 'mirror' model based on Nb 3 Sn coil made of improved Restack Rod Process strand was constructed and tested reaching the maximum field above 11 T. This paper describes the parameters of the RRP strand and cable used as well as the design, fabrication and test results of this magnet

Nb3Sn High Field Magnets for the High Luminosity LHC Upgrade Project

Energy Technology Data Exchange (ETDEWEB)

Ambrosio, Giorgio

2015-06-01

The High Luminosity upgrade of the Large Hadron Collider at CERN requires a new generation of high field superconducting magnets. High field large aperture quadrupoles (MQXF) are needed for the low-beta triplets close to the ATLAS and CMS detectors, and high field two-in-one dipoles (11 T dipoles) are needed to make room for additional collimation. The MQXF quadrupoles, with a field gradient of 140 T/m in 150 mm aperture, have a peak coil field of 12.1 T at nominal current. The 11 T dipoles, with an aperture of 60 mm, have a peak coil field of 11.6 T at nominal current. Both magnets require Nb3Sn conductor and are the first applications of this superconductor to actual accelerator magnets.

Development and manufacturing of bronze-processed Ta-added Nb3Sn wires for the ITER

International Nuclear Information System (INIS)

Kikuchi, Kenichi; Seidou, Masahiro; Iwaki, Genzou; Sakai, Syuuji; Moriai, Hidezumi; Nishi, Masataka; Yoshida, Kiyoshi; Isono, Takaaki; Tsuji, Hiroshi.

1997-01-01

Development work to produce a high-performance Nb 3 Sn superconducting wire for the center solenoid coil of the ITER was carried out. The effects of concurrently adding Ti and Ta to bronze-processed Nb 3 Sn wires were examined. In addition, a high-Sn-concentration bronze matrix was applied. Then, the relation between hysteresis loss and filament diameter was examined. Moreover, the cause of wire breakage during processing was elucidated. As a result, a reliable manufacturing process for high-performance Nb 3 Sn superconducting wire was established. (author)

Controlled synthesis of the antiperovskite oxide superconductor Sr3‑x SnO

Science.gov (United States)

Hausmann, J. N.; Oudah, M.; Ikeda, A.; Yonezawa, S.; Maeno, Y.

2018-05-01

A large variety of perovskite oxide superconductors are known, including some of the most prominent high-temperature and unconventional superconductors. However, superconductivity among the oxidation state inverted material class, the antiperovskite oxides, was recently reported for the first time. In this superconductor, Sr3‑x SnO, the unconventional ionic state Sn4‑ is realized and possible unconventional superconductivity due to a band inversion has been discussed. Here, we discuss an improved facile synthesis method, making it possible to control the strontium deficiency in Sr3‑x SnO. Additionally, a synthesis method above the melting point of Sr3SnO is presented. We show temperature dependence of magnetization and electrical resistivity for superconducting strontium deficient Sr3‑x SnO (T c ∼ 5 K) and for Sr3SnO without a superconducting transition in alternating current susceptibility down to 0.15 K. Further, we reveal a significant effect of strontium raw material purity on the superconductivity and achieve substantially increased M/M Meissner (∼1) compared to the highest value reported so far. More detailed characterizations utilizing powder x-ray diffraction and energy-dispersive x-ray spectroscopy show that a minor cubic phase, previously suggested to be another Sr3‑x SnO phase with a slightly larger lattice parameter, is SrO. The improved characterization and controlled synthesis reported herein enable detailed investigations on the superconducting nature and its dependency on the strontium deficiency in Sr3‑x SnO.

Quench performance of Nb3Sn cos-theta coils made of 108/127 RRP strands

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; /Fermilab

2007-07-01

A series of 1-m long Nb{sub 3}Sn dipole models has been built at Fermilab in an attempt to refine the wind-and-react technology for Nb3Sn accelerator magnets. Three models made with Powder-in-Tube Nb{sub 3}Sn strand reached their design field of 10 T demonstrating a good reproducibility of magnet quench performance and field quality. Recently a new dipole 'mirror' model based on Nb{sub 3}Sn coil made of improved Restack Rod Process strand was constructed and tested reaching the maximum field above 11 T. This paper describes the parameters of the RRP strand and cable used as well as the design, fabrication and test results of this magnet.

Pressure effects on topological crystalline insulator SnTe and derived superconductor Sn{sub 0.5}In{sub 0.5}Te

Energy Technology Data Exchange (ETDEWEB)

Maurya, V. K.; Shruti,; Patnaik, S., E-mail: spatnaik@mail.jnu.ac.in [School of Physical Sciences, Jawaharlal Nehru University New Delhi (India); Jha, Rajveer; Awana, V. P. S. [National Physical Laboratory, New Delhi 110012 (India)

2016-05-23

We are reporting decrease in superconducting transition temperature accompanied by increased metallicity in indium doped SnTe superconductor. SnTe is a topological crystalline insulator and superconductivity is achieved by indium substitution in place of tin. With application of hydrostatic pressure we find negative dT{sub c}/dP of ~ -0.6K/GPa upto 2.5 GPa. The overall phenomenon is ascribed to unconventional superconductivity. Decrease in resistivity is also seen in single crystal SnTe with application of pressure but no evidence of superconductivity is observed.

High-field specific heats of A15 V3Si and Nb3Sn

International Nuclear Information System (INIS)

Stewart, G.R.; Brandt, B.L.

1984-01-01

In order to further understand the anomalous behavior of the specific heat of Nb 3 Sn in an 18-T magnetic field discovered by Stewart, Cort, and Webb [Phys. Rev. B 24, 3841 (1981)], we have performed specific-heat measurements on a different sample of Nb 3 Sn at lower fields both in the normal and mixed states, as well as measurement to 19 T on both transforming and nontransforming V 3 Si. The high-field data for V 3 Si indicate that this material behaves quite normally, and that γ/sup trans/ 3 Sn, however, remains anomalous, with both the same ''kink'' in the normal-state field data as observed by Stewart, Cort, and Webb (although at a slightly higher temperature) and unusual mixed-state behavior. The mixed-state specific heat of the V 3 Si samples is as expected, based on earlier work on the mixed-state specific heat of V and Nb

Dimensional Changes of Nb$_{3}$Sn Rutherford Cables During Heat Treatment

CERN Document Server

Rochepault, E; Ambrosio, G; Anerella, M; Ballarino, A; Bonasia, A; Bordini, B; Cheng, D; Dietderich, D R; Felice, H; Garcia Fajardo, L; Ghosh, A; Holik, E F; Izquierdo Bermudez, S; Perez, J C; Pong, I; Schmalzle, J; Yu, M

2016-01-01

In high field magnet applications, Nb$_{3}$Sn coils undergo a heat treatment step after winding. During this stage, coils radially expand and longitudinally contract due to the Nb$_{3}$Sn phase change. In order to prevent residual strain from altering superconducting performances, the tooling must provide the adequate space for these dimensional changes. The aim of this paper is to understand the behavior of cable dimensions during heat treatment and to provide estimates of the space to be accommodated in the tooling for coil expansion and contraction. This paper summarizes measurements of dimensional changes on strands, single Rutherford cables, cable stacks, and coils performed between 2013 and 2015. These samples and coils have been performed within a collaboration between CERN and the U.S. LHC Accelerator Research Program to develop Nb$_{3}$Sn quadrupole magnets for the HiLumi LHC. The results are also compared with other high field magnet projects.

Controlling Cu–Sn mixing so as to enable higher critical current densities in RRP® Nb3Sn wires

Science.gov (United States)

Sanabria, Charlie; Field, Michael; Lee, Peter J.; Miao, Hanping; Parrell, Jeff; Larbalestier, David C.

2018-06-01

Dipole magnets for the proposed Future Circular Collider (FCC) demand specifications significantly beyond the limits of all existing Nb3Sn wires, in particular a critical current density (J c) of more than 1500 A mm‑2 at 16 T and 4.2 K with an effective filament diameter (D eff) of less than 20 μm. The restacked-rod-process (RRP®) is the technology closest to meeting these demands, with a J c (16 T) of up to 1400 A mm‑2, residual resistivity ratio > 100, for a sub-element size D s of 58 μm (which in RRP® wires is essentially the same as D eff). An important present limitation of RRP® is that reducing the sub-element size degrades J c to as low as 900 A mm‑2 at 16 T for D s = 35 μm. To gain an understanding of the sources of this J c degradation, we have made a detailed study of the phase evolution during the Cu–Sn ‘mixing’ stages of the wire heat treatment that occur prior to Nb3Sn formation. Using extensive microstructural quantification, we have identified the critical role that the Sn–Nb–Cu ternary phase (Nausite) can play. The Nausite forms as a well-defined ring between the Sn source and the Cu/Nb filament pack, and acts as an osmotic membrane in the 300 °C–400 °C range—greatly inhibiting Sn diffusion into the Cu/Nb filament pack while supporting a strong Cu counter-diffusion from the filament pack into the Sn core. This converts the Sn core into a mixture of the low melting point (408 °C) η phase (Cu6Sn5) and the more desirable ε phase (Cu3Sn), which decomposes at 676 °C. After the mixing stages, when heated above 408 °C towards the Nb3Sn reaction, any residual η liquefies to form additional irregular Nausite on the inside of the membrane. All Nausite decomposes into NbSn2 on further heating, and ultimately transforms into coarse-grain (and often disconnected) Nb3Sn which has little contribution to current transport. Understanding this critical Nausite reaction pathway has allowed us to simplify the mixing heat treatment to

Tensile Strain Dependence of Critical Current for RHQ-Nb3Al Wires

OpenAIRE

Jin, Xinzhe; Oguro, Hidetoshi; Nakamoto, Tatsushi; Awaji, Satoshi; Ogitsu, Toru; Tsuchiya, Kiyosumi; Yamamoto, Akira; Kikuchi, Akihiro; Takeuchi, Takao

2011-01-01

KEK and NIMS have been jointly developing Nb3Al superconducting wire with a rapid heating and quenching (RHQ) method towards high field accelerator magnets in the Large Hadron Collider (LHC) luminosity upgrade. A15-type superconductors such as Nb3Al and Nb3Sn exhibit strain dependence with respect to their critical currents. Therefore, a thorough understanding of strain behavior is necessary for high field accelerator magnet development, which will be critical for the luminosity upgrade of th...

Degradation mechanism of Nb3Sn composite wires under tensile strain at 4.2 K

International Nuclear Information System (INIS)

Luhman, T.; Suenaga, M.; Welch, D.O.; Kaiho, K.

1978-01-01

Bronze-processed Nb 3 Sn composite wire conductors exhibit changes in their superconducting parameters when strained in tension. This paper describes a detailed study of the effect of strain on critical current and an analysis by optical and SEM techniques of crack formation in the Nb 3 Sn layer under strain. The effect of strain history on both reversible and irreversible changes in critical current and the roles of differential thermal contraction induced residual strains and of Nb 3 Sn cracking are discussed

Quench performance of a 4-m long Nb3Sn shell-type dipole coil

International Nuclear Information System (INIS)

Chlachidze, G.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.

2008-01-01

Fermilab has finished the first phase of Nb 3 Sn technology scale up by testing 2-m and 4-m long shell-type dipole coils in a 'magnetic mirror' configuration. The 2-m long coil, made of Powder-in-Tube (PIT) Nb 3 Sn strand, reached its short sample limit at a field level of 10 T. The 4-m long coil, made of advanced Nb 3 Sn strand based on the Restack Rod Process (RRP) of 108/127 design, has been recently fabricated and tested. Coil test results at 4.5 K and 2.2 K are reported and discussed

Effect of starting materials and processing variables for the production of discontinuous filament Nb3Sn wire

International Nuclear Information System (INIS)

Upadhyay, P.L.; Dew-Hughes, D.

1986-01-01

Discontinuous multifilamentary wires of Nb 3 Sn have been prepared from compacted mixtures of 30 wt. %Nb in Cu, extruded, drawn, annealed, tin plated and reacted. Processing variables include starting materials, extrusion ratio and extrusion temperature. Continuous lengths of wire could be satisfactorily produced from compacts of either ultra-pure Nb (VPN about 95 kg mm -2 ) and Cu powder or from centrifugal arc-cast Nb spheroids (VPN about 120 kg mm -2 ) and tough pitch Cu powder. After a total area reduction of 10 4 : 1, the latter materials resulted in long, unbroken, highly regular filaments of Nb about 6μm in diameter. The high degree of perfection of these filaments is due in part to the uniformity of the initial spheroids, compared to the highly irregular hydride-dehydride Nb powder. However their greater hardness requires that the spheroids be coprocessed in a less-pure Cu matrix. Critical currents were measured on helical specimens involving more than 1m length of wire, in fields up to 15T at 4.2 K, after reaction for various times at different temperatures. Overall current densities of 3 X 10 8 Am -2 were obtained at 12T in the best samples. Further reductions are expected to produce material with improved current densities

X-ray diffraction pattern and morphology of superconducting Nb/sub 3/Sn layer grown on a polycrystalline Nb substrate of (111) main texture

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B [Politechnika Wroclawska (Poland)

1983-01-16

A study is presented on structure and crystallographic orientation of Nb/sub 3/Sn layers formed in the process of interaction of polycrystalline Nb substrate with Cu/sub 0.2/Sn/sub 0.8/ solution at 980 /sup 0/C. Grain structure characterization of Nb/sub 3/Sn layers has been carried out with scanning electron microscopy and TV automatic image analysis. The superconducting layer is divided into a fine-grained FG and coarse-grained CG zone. The X-ray patterns of FG and CG zones did not differ from one another and were the same as in randomly oriented Nb/sub 3/Sn polycrystalline powder.

Comparison of the costs of superconducting accelerator dipoles using NbTi, Nb3Sn and NbTiTa

International Nuclear Information System (INIS)

Hassenzahl, W.

1981-03-01

The present study, which is based on the assumption that future, high-energy accelerators will use superconductors, is a comparison of the costs of 5 to 12 Tesla NbTi, Nb 3 S/sub n/, and NbTiTa accelerator magnets operating at 4.2 K or 1.8 K. The object of this evaluation is not to determine the actual cost of future accelerators, rather, its purpose is to provide some rationale for research on the next generation of superconducting accelerator magnets. Thus, though the actual costs of accelerator magnets may be different from those given here, the comparisons are valid

Effect of strain on the martensitic phase transition in superconducting Nb3Sn

International Nuclear Information System (INIS)

Hoard, R.W.; Scanlan, R.M.; Smith, G.S.; Farrell, C.L.

1980-01-01

The connection between the cubic-to-tetragonal martensitic phase transformation and the phenomenon of superconductivity in A15 compounds is being investigated. The degradation of the critical parameters, such as T/sub c/, H/sub c2/, and J/sub c/, with mechanical straining is of particular interest. Low-temperature x-ray diffraction experiments are performed on Nb 3 Sn ribbons (with the bronze layers etched off) mounted on copper and indium sample stages. The cryostat used is unique in that it has a vacuum mechanical insert which allows the superconductor to be placed under both compressive and tensile strains while at low temperatures. Preliminary results indicate that the martensitic phase transition temperature, T/sub m/, increases with compressive strains. Other effects of strain on tetragonal phase production are also discussed

Investigation of mechanical behavior of copper in Nb3Sn superconducting composite wire

International Nuclear Information System (INIS)

Hojo, M.; Matsuoka, T.; Nakamura, M.; Tanaka, M.; Adachi, T.; Ochiai, S.; Miyashita, K.

2004-01-01

The mechanical properties and the thermal residual stress distribution of copper in Nb 3 Sn/Cu composite superconductor were investigated in detail. The stabilizer copper was removed from the composite wire, and the stress-strain behavior of this wire was compared with that of the original composite wire. The subtraction yielded the stress-strain curves of the copper when the Bauschinger effect was taken into account. The tensile test of the composites from which about 30% and 60% of copper was removed suggested the existence of the distribution of the thermal residual stress in the stabilizer copper. When this factor was taken into account, the analytical stress-strain curve agreed well with the experimental stress-strain curve. Thus, the stress-stain behavior of each component was fully understood

Stress-strain effects in alumina-Cu reinforced Nb3Sn wires fabricated by the tube process

International Nuclear Information System (INIS)

Murase, Satoru; Nakayama, Shigeo; Masegi, Tamaki; Koyanagi, Kei; Nomura, Shunji; Shiga, Noriyuki; Kobayashi, Norio; Watanabe, Kazuo.

1997-01-01

In order to fabricate a large-bore, high-field magnet which achieves a low coil weight and volume, a high strength compound superconducting wire is required. For those demands we have developed the reinforced Nb 3 Sn wire using alumina dispersion strengthened copper (alumina-Cu) as a reinforcement material and the tube process of the Nb 3 Sn wire fabrication. The ductility study of the composites which consisted of the reinforcement, Nb tube, Cu, and Cu clad Sn brought a 1 km long alumina-Cu reinforced Nb 3 Sn wire successfully. Using fabricated wires measurements and evaluations of critical current density as parameters of magnetic field, tensile stress, tensile strain, and transverse compressive stress, and those of stress-strain curves at 4.2 K were performed. They showed superior performance such as high 0.3% proof stress (240 MPa at 0.3% strain) and high maximum tolerance stress (320 MPa) which were two times as large as those of conventional Cu matrix Nb 3 Sn wire. The strain sensitivity parameters were obtained for the reinforced Nb 3 Sn wire and the Cu matrix one using the scaling law. Residual stress of the component materials caused by cooling down to 4.2 K from heat-treatment temperature was calculated using equivalent Young's modulus, equivalent yield strength, thermal expansion coefficient and other mechanical parameters. Calculated stress-strain curves at 4.2 K for the reinforced Nb 3 Sn wire and the Cu matrix one based on calculation of residual stress, had good agreement with the experimental values. (author)

Flux pinning in bronze-processed Nb3Sn wires

International Nuclear Information System (INIS)

Suenaga, M.; Welch, D.O.

1980-01-01

The scaling law derived by Kramer for magnetic flux pinning in high magnetic fields was examined for its applicability to the magnetic field dependence of critical-current densities in the bronze processed monofilamentary Nb 3 Sn wires. From this it was concluded that: (1) its prediction for the form of the dependence of critical current on magnetic field and grain size [/J vector /sub c/ x H vector/ approx. h/sup 1/2/(1-h) 2 (1-a 0 √rho) -2 ] was found to be very good in most cases including wires with very small Nb 3 Sn grains (approx. 400 A). It was found very useful in comparison of J/sub c/ for different wires and in extrapolating to obtain H/sub c2/ for these wires. (2) However, it could not account consistently for the anisotropy in critical current of a tape which was measured with H applied perpendicular and parallel to the tape face. (3) The values of kappa 1 which were determined with the scaling law were too small by a factor of 2 to 3, and the trend in the variation with heat-treating time was opposite to that which is reasonably to be expected. That the behavior of kappa 1 is thus seriously in contradiction with the expected behavior for Nb 3 Sn suggests basic faults in the derivation of the scaling equation for critical currents at high magnetic fields

Energy dissipation of composite multifilamentary superconductors for high-current ramp-field magnet applications

International Nuclear Information System (INIS)

Gung, C.Y.

1993-01-01

Energy dissipation, which is also called AC loss, of a composite multifilamentary superconducting wire is one of the most fundamental concerns in building a stable superconducting magnet. Characterization and reduction of AC losses are especially important in designing a superconducting magnet for generating transient magnetic fields. The goal of this thesis is to improve the understanding of AC-loss properties of superconducting wires developed for high-current ramp-field magnet applications. The major tasks include: (1) building an advanced AC-loss measurement system, (2) measuring AC losses of superconducting wires under simulated pulse magnet operations, (3) developing an analytical model for explaining the new AC-loss properties found in the experiment, and (4) developing a computational methodology for comparing AC losses of a superconducting wire with those of a cable for a superconducting pulse magnet. A new experimental system using an isothermal calorimetric method was designed and constructed to measure the absolute AC losses in a composite superconductor. This unique experimental setup is capable of measuring AC losses of a brittle Nb 3 Sn wire carrying high AC current in-phase with a large-amplitude pulse magnetic field. Improvements of the accuracy and the efficiency of this method are discussed. Three different types of composite wire have been measured: a Nb 3 Sn modified jelly-roll (MJR) internal-tin wire used in a prototype ohmic heating coil, a Nb 3 Sn internal-tin wire developed for a fusion reactor ohmic heating coil, and a NbTi wire developed for the magnets in a particle accelerator. The cross sectional constructions of these wires represent typical commercial wires manufactured for pulse magnet applications

Nb3Sn superconducting magnets for electron cyclotron resonance ion sources.

Science.gov (United States)

Ferracin, P; Caspi, S; Felice, H; Leitner, D; Lyneis, C M; Prestemon, S; Sabbi, G L; Todd, D S

2010-02-01

Electron cyclotron resonance (ECR) ion sources are an essential component of heavy-ion accelerators. Over the past few decades advances in magnet technology and an improved understanding of the ECR ion source plasma physics have led to remarkable performance improvements of ECR ion sources. Currently third generation high field superconducting ECR ion sources operating at frequencies around 28 GHz are the state of the art ion injectors and several devices are either under commissioning or under design around the world. At the same time, the demand for increased intensities of highly charged heavy ions continues to grow, which makes the development of even higher performance ECR ion sources a necessity. To extend ECR ion sources to frequencies well above 28 GHz, new magnet technology will be needed in order to operate at higher field and force levels. The superconducting magnet program at LBNL has been developing high field superconducting magnets for particle accelerators based on Nb(3)Sn superconducting technology for several years. At the moment, Nb(3)Sn is the only practical conductor capable of operating at the 15 T field level in the relevant configurations. Recent design studies have been focused on the possibility of using Nb(3)Sn in the next generation of ECR ion sources. In the past, LBNL has worked on the VENUS ECR, a 28 GHz source with solenoids and a sextupole made with NbTi operating at fields of 6-7 T. VENUS has now been operating since 2004. We present in this paper the design of a Nb(3)Sn ECR ion source optimized to operate at an rf frequency of 56 GHz with conductor peak fields of 13-15 T. Because of the brittleness and strain sensitivity of Nb(3)Sn, particular care is required in the design of the magnet support structure, which must be capable of providing support to the coils without overstressing the conductor. In this paper, we present the main features of the support structure, featuring an external aluminum shell pretensioned with water

Improved Fin Designs to Reduce D Effective ln Internal-Tin Nb3Sn

International Nuclear Information System (INIS)

Gregory, Eric

2010-01-01

As interest has moved to higher field properties, we are now aiming to make 2000 A/mm2 at 15 T. With a view to approaching this we inserted Ti into the Sn core in the EG 36 sub-element. The data after testing is shown in Figs 39-42. The 12 T values are lower than when no Ti is present but the 15 T data is higher giving 1800 A/mm2. In summary, while we failed to show that the split sub-element method could yield sufficiently high properties to compete with the other approaches, we did achieve properties at least as high as those obtained by Oxford using the standard internal tin approach.

Quench performance of a 4-m long Nb3Sn shell-type dipole coil

Energy Technology Data Exchange (ETDEWEB)

Chlachidze, G.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; /Fermilab

2008-08-01

Fermilab has finished the first phase of Nb{sub 3}Sn technology scale up by testing 2-m and 4-m long shell-type dipole coils in a 'magnetic mirror' configuration. The 2-m long coil, made of Powder-in-Tube (PIT) Nb{sub 3}Sn strand, reached its short sample limit at a field level of 10 T. The 4-m long coil, made of advanced Nb{sub 3}Sn strand based on the Restack Rod Process (RRP) of 108/127 design, has been recently fabricated and tested. Coil test results at 4.5 K and 2.2 K are reported and discussed.

Radiation behavior of superconductors

International Nuclear Information System (INIS)

Scanlan, R.M.; Raymond, E.L.

1979-01-01

High energy neutron irradiations have been performed on Nb 3 Sn superconductors to assess their behavior in a fusion reactor environment. Irradiations were performed at 4.2 K and property measurements were made without warming the samples. The critical current I/sub c/ increased with irradiation to a level about 50% above the unirradiated value at the highest fluences reached in our experiments. These results are compared with the results of other low temperature irradiations of Nb 3 Sn

Results from the first single cell Nb₃Sn cavity coatings at JLab

Energy Technology Data Exchange (ETDEWEB)

Eremeev, Grigory [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2015-09-01

Nb₃Sn is a promising superconducting material for SRF applications and has the potential to exceed the limitations of niobium. We have used the recently commissioned Nb₃Sn coating system to investigate Nb₃Sn coatings on several single cell cavities by applying the same coating procedure on several different single cells with different history and pre-coating surface preparation. We report on our findings with four 1.5 GHz CEBAF-shape single cell and one 1.3 GHz ILC-shape single cavities that were coated, inspected, and tested.

Extreme and Local 3rd Harmonic Response of Niobium (Nb) Superconductor

Science.gov (United States)

Oripov, Bakhrom; Tai, Tamin; Anlage, Steven

Superconducting Radio Frequency (SRF) cavities are being widely used in new generation particle accelerators. These SRF cavities are based on bulk Nb. Based on the needs of the SRF community to identify defects on Nb surfaces, a novel near-field magnetic microwave microscope was successfully built using a magnetic writer from a conventional magnetic recording hard-disk drive1. This magnetic writer can create an RF magnetic field, localized and strong enough to drive Nb into the vortex state. This probe enables us to locate defects through scanning and mapping of the local electrodynamic response in the multi-GHz frequency range. Recent measurements have shown that 3rd harmonic nonlinear response is far more sensitive to variations in input power and temperature then linear response, thus we mainly study the 3rd harmonic response. Moreover, the superconductor is usually the only source for nonlinear response in our setup, thus there is less chance of having noise or background signal. Understanding the mechanism responsible for this non-linear response is important for improving the performance of SRF cavities. Besides Nb we also study various other superconductors such as MgB2 and the cuprate Bi-Sr-Ca-Cu-O (BSCCO) for potential applications in SRF cavities. This work is funded by US Department of Energy through Grant # DE-SC0012036T and CNAM.

Critical current scaling and the pivot-point in Nb3Sn strands

International Nuclear Information System (INIS)

Tsui, Y; Hampshire, D P

2012-01-01

Detailed measurements are provided of the engineering critical current density (J c ) and the index of transition (n-value) of two different types of advanced ITER Nb 3 Sn superconducting strand for fusion applications. The samples consist of one internal-tin strand (OST) and two bronze-route strands (BEAS I and BEAS II—reacted using different heat treatments). Tests on different sections of these wires show that prior to applying strain, J c is homogeneous to better than 2% along the length of each strand. J c data have been characterized as a function of magnetic field (B ≤ 14.5 T), temperature (4.2 K ≤ T ≤ 12 K) and applied axial strain ( − 1% ≤ ε A ≤ 0.8%). Strain-cycling tests demonstrate that the variable strain J c data are reversible to better than 2% when the applied axial strain is in the range of − 1% ≤ ε A ≤ 0.5%. The wires are damaged when the intrinsic strain (ε I ) is ε I ≥ 0.55% and ε I ≥ 0.23% for the OST and BEAS strands, respectively. The strain dependences of the normalized J c for each type of strand are similar to those of prototype strands of similar design measured in 2005 and 2008 to about 2% which makes them candidate strands for a round-robin interlaboratory comparison. The J c data are described by Durham, ITER and Josephson-junction parameterizations to an accuracy of about 4%. For all of these scaling laws, the percentage difference between the data and the parameterization is larger when J c is small, caused by high B, T or |ε I |. The n-values can be described by a modified power law of the form n=1+rI c s , where r and s are approximately constant and I c is the critical current. It has long been known that pivot-points (or cross-overs) in J c occur at high magnetic field and temperature. Changing the magnetic field or temperature from one side of the pivot-point to the other changes the highest J c sample to the lowest J c sample and vice versa. The pivot-point follows the B–T phase boundary

Quench in a conduction-cooled Nb3Sn SMES magnet

Science.gov (United States)

Korpela, Aki; Lehtonen, Jorma; Mikkonen, Risto; Perälä, Raine

2003-11-01

Due to the rapid development of cryocoolers, conduction-cooled Nb3Sn devices are nowadays enabled. A 0.2 MJ conduction-cooled Nb3Sn SMES system has been designed and constructed. The nominal current of the coil was 275 A at 10 K. The quench tests have been performed and in this paper the experimental data are compared to the computational one. Due to a slow normal zone propagation, Nb3Sn magnets are not necessarily self-protective. In conduction-cooled coils, a thermal interface provides a protection method known as a quench back. The temperature rise in the coil during a quench was measured with a sensor located on the inner radius of the coil. The current decay was also monitored. The measured temperature increased for approximately 15 s after the current had already decayed. This temperature rise is due to the heat conduction from the hot spot. Thus, the measured temperature does not represent the hot-spot temperature. A computational quench model which takes into account quench back and heat conduction after the current decay was developed in order to understand the measured temperatures. According to the results, a quench back due to the eddy current induced heating of the thermal interface of an LTS coil was an adequate protection method.

Development and test of Nb3sn cos-theta coils made of high-jc rrp strands

Energy Technology Data Exchange (ETDEWEB)

Bossert, R.; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Novitski, I.; Pischalnikov, Yu.; Sylvester, C.; Tartaglia, M.; Turrioni, D.; Yamada, R.; Zlobin, A.V.; /Fermilab

2005-10-01

A series of 1-m long Nb3Sn dipole magnets have been built at Fermilab in an attempt to refine the wind-and-react technology for Nb{sub 3}Sn conductor. Models have been made with MJR and PIT strand with varying degrees of success. Subsequently two new dipole ''mirror'' magnets based on RRP Nb{sub 3}Sn coils were constructed and tested. This paper describes the design, fabrication and test results of those magnets.

PERSISTENT CURRENT EFFECT IN 15-16 T NB3SN ACCELERATOR DIPOLES AND ITS CORRECTION

Energy Technology Data Exchange (ETDEWEB)

Kashikhin, V. V. [Fermilab; Zlobin, A. V. [Fermilab

2016-11-08

Nb3Sn magnets with operating fields of 15-16 T are considered for the LHC Energy Doubler and a future Very High Energy pp Collider. Due to large coil volume, high critical current density and large superconducting (SC) filament size the persistent current effect is very large in Nb3Sn dipoles al low fields. This paper presents the results of analysis of the persistent current effect in the 15 T Nb3Sn dipole demonstrator being developed at FNAL, and describes different possibilities of its correction including passive SC wires, iron shims and coil geometry.

Research and development efforts relative to superconducting materials. Final report. [Nb/sub 3/Sn tapes

Energy Technology Data Exchange (ETDEWEB)

Adam, E; Beishcher, P; Marancik, W; Lucariello, R; Young, M

1976-04-01

Three processes for the production of low-loss superconducting tapes of Nb/sub 3/Sn were investigated. They are the rolled-bronze process, the electron beam (EB) bronze deposition process, and the high-rate sputtering process. Shortly after the start of the investigation, effort on the last two processes was suspended because the process-development time that would be needed to arrive at a suitable transmission-line tape appeared most likely to be the shortest with the rolled-bronze process. Long lengths of Nb/sub 3/Sn tapes were prepared by the rolled-bronze process from extruded and rolled bronze-clad niobium billets. Tapes were stabilized by removing the bronze layer after reaction and then coating the exposed Nb/sub 3/Sn with high-purity copper by EB evaporation. Several meters of high quality Nb/sub 3/Sn tapes were produced by the rolled-bronze process. Even when the tapes were stabilized with copper, the losses were as low as 1.8 ..mu..W/cm/sup 2/ at 4.2 K and a surface current density of 500 rms A/cm. Despite early curtailment of the effort on the EB bronze-deposition process, short samples of Nb/sub 3/Sn tapes were produced.

ac loss and dc critical current densities of Nb3Sn tapes by the solid state diffusion process

International Nuclear Information System (INIS)

Suenaga, M.; Klamut, C.; Bussiere, J.F.

1976-01-01

The effects of metallurgical processing on 60 Hz ac losses and dc critical currents in Nb 3 Sn tapes fabricated by the solid state diffusion technique were investigated. An addition of Al to the Cu--Sn alloy for the matrix resulted in large reduction in the ac losses of Nb 3 Sn tapes, but the highest linear critical current densities were observed in Nb 3 Sn tapes produced with a Nb-1 wt percent Zr core in a Cu-13 wt percent Sn matrix. Values of the losses and the critical currents in these tapes can meet the present requirements for the ac superconducting power cables

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

Directory of Open Access Journals (Sweden)

Rui Sun

2016-06-01

Full Text Available We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100 substrates with a TiN buffer layer. A 50-nm-thick (200-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large IcRN product of 3.8 mV, a sharp quasiparticle current rise with a ΔVg of 0.4 mV, and a small subgap leakage current. The junction quality factor Rsg/RN was about 23 for the junction with a Jc of 47 A/cm2 and was about 6 for the junction with a Jc of 3.0 kA/cm2. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200-orientated TiN buffer layer and had a highly crystalline structure with the (200 orientation.

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

Energy Technology Data Exchange (ETDEWEB)

Sun, Rui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Makise, Kazumasa; Terai, Hirotaka [Advanced ICT Research Institute, National Institute of Information and Communications Technology (Japan); Zhang, Lu [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Wang, Zhen, E-mail: zwang@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Shanghai Tech University, Shanghai 201210 (China)

2016-06-15

We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100) substrates with a TiN buffer layer. A 50-nm-thick (200)-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large I{sub c}R{sub N} product of 3.8 mV, a sharp quasiparticle current rise with a ΔV{sub g} of 0.4 mV, and a small subgap leakage current. The junction quality factor R{sub sg}/R{sub N} was about 23 for the junction with a J{sub c} of 47 A/cm{sup 2} and was about 6 for the junction with a J{sub c} of 3.0 kA/cm{sup 2}. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200)-orientated TiN buffer layer and had a highly crystalline structure with the (200) orientation.

Magnetization and loss measurements on Nb3Sn and NbTi strands for ITER and LHC

International Nuclear Information System (INIS)

Foitl, M.

2001-05-01

this work, magnetization and loss measurements on 20 different strand samples which were taken from different billets supplied by two manufacturers of NbTi strands are reported, which with the use of an Integrating Coil Magnetometer as well as micro Hall sensors magnetization loops of single strands were studied. Variations in the strand magnetization could be either correlated with systematical irregularities in the strand characteristics (e.g. filament diameter) or with variations of the strand's critical current density jC. The second part of this work is related to the annealing process of superconducting magnets manufactured from internal tin Nb3Sn strands to be used for the magnetic confinement of fusion plasma. After the successful generation of plasma burning pulses of several seconds duration (Joint European Torus, JET), magnetic fusion energy research has reached a point where a tokamak burning plasma facility, in which the thermonuclear heating balances transport and radiation losses for periods of 500 s or longer, can be seriously contemplated as a next step. Achieving this goal would be a major step forward, both in science and technology, towards the ultimate goal of magnetic fusion generation of electrical power. Therefore the main objectives of the International Thermonuclear Experimental Reactor (ITER) will be the demonstration of the scientific and technological feasibility of fusion energy on a scale close to that of an eventual thermonuclear power reactor. The magnitude of the magnetic field (∼ 11.8 T) needed to confine stable a plasma of sufficient pressure to generate ∼ 0.5 GW of fusion power is comparable to the limiting magnetic fields that a toroidal superconducting magnet system can produce. In order to achieve the best magnet performance possible, the toroidal field (TF) coils made of superconducting Nb3Sn cable-in-conduit type conductors have to be optimized with respect to the maximum transport current and transient field losses

Comparative cost study of the processes for producing niobium--tin (Nb3Sn) superconducting tapes for their application to power transmission lines. Final report

International Nuclear Information System (INIS)

1976-10-01

This report considers the manufacture of superconducting Nb 3 Sn tapes for ac superconducting transmission cables. The 14 product examples studied are produced by processes involving solid-state diffusion of Sn and Nb and/or physical vapor deposition. Production of 80,000 km per year is assumed, sufficient for 100 km of 3 phase ac line. Results are summarized in a table entitled ''Variants of 6 mm wide Nb 3 Sn Superconducting Tapes with Economics of Manufacture.'' The table identifies the 14 product examples by method of manufacture; by the composition of the layers integrated into the tape; and by the final thickness of Nb used in 12 of the product examples. The estimated fixed capital for plant is listed for each product example together with the estimated costs of manufacture in cents per meter of tape. The total manufacturing cost given is the sum of the costs of raw materials, operating labor, depreciation and other overhead. The depreciation is calculated on a 10 year straight line basis. Stainless steel strip (304L) is used in 6 of the product examples. The final line in the table shows the ''selling price'' which will earn the equivalent of 20 percent p.a. on the total capital, fixed and working, employed at any time during an eleven-year plant life where depreciation is sum of year digits for a 10 year period, investment credit is 10 percent, and income tax is 48 percent. 13 tables, 21 figures

Production and testing of an s-band resonator with a Nb3Sn surface

International Nuclear Information System (INIS)

Peiniger, M.

1983-01-01

This report describes the preparation of a niobium s-band resonator with Nb3Sn surface using a special vapor phase deposition method. High-frequency superconductivity tests were performed on this resonator. Measurements of transition temperature, penetration depth, energy gap, and temperature dependence of surface conductivity of Nb3Sn, and resonator behaviour at high electrical field strengths are reported. (GSCH)

Test results of Nb3Sn ribbons for the Princeton D coil test program

International Nuclear Information System (INIS)

Kaugerts, J.; File, J.; Willard, J.W.

1974-10-01

A previously described D coil test program was modified. Details of a smaller Nb 3 Sn D coil test program are described. Cusp coil tests were made with several Nb 3 Sn composite ribbons. Measurements of both the quench and recovery currents as a function of magnetic field component perpendicular to the wide edge of the ribbon are presented. (auth)

Quench Protection Studies of the 11-T $Nb_3Sn$ Dipole for LHC Upgrades

CERN Document Server

Izquierdo Bermudez, Susana; BAJAS, Hugues; Bajko, Marta; Bordini, Bernardo; Bottura, Luca; Chlachidze, Guram; Karppinen, Mikko; Rysti, Juho; Savary, Frederic; Willering, Gerard; Zlobin, Alexander

2016-01-01

The planned upgrade of the LHC collimation system foresees additional collimators to be installed in the dispersion suppressor areas. Fermilab and CERN are developing an 11 T Nb$_{3}$Sn dipole to replace some 8.33 T-15-m-long Nb-Ti LHC main dipoles providing longitudinal space for the collimators. In case of a quench, the large stored energy and the low copper stabilizer fraction make the protection of the 11 T Nb$_{3}$Sn dipoles challenging. This paper presents the results of quench protection analysis, including quench protection heater design and efficiency, quench propagation and coil heating. The numerical results are compared with the experimental data from the 2-m-long Nb$_{3}$Sn dipole models. The validated model is used to predict the current decay and hot spot temperature under operating conditions in the LHC and the presently foreseen magnet protection scheme is discussed.

Tests results of Nb$_{3}$Sn quadrupole magnets using a shell-based support structure

CERN Document Server

Caspi, S

2009-01-01

In support of the development of a 90 mm aperture Nb$_{3}$Sn superconducting quadrupole for the US LHC Accelerator Research Program (LARP), test results of five quadrupole magnets are compared. All five assemblies used key and bladder technology to compress and support the coils within an iron yoke and an aluminium shell. The first three models (TQS01a, b, c) used Nb$_{3}$Sn MJR conductor and segmented bronze poles. The last two models (TQS02a, b) used Nb$_{3}$Sn RRP conductor, and segmented titanium alloy (TiAl6V4) poles, with no axial gaps during reaction. This presentation summarizes the magnets performance during assembly, cool-down and excitation and compares measurements with design expectations.

Recent status of studies on the neutron irradiation effect focusing on Nb3Sn and Nb3Al strands

International Nuclear Information System (INIS)

Nishimura, Arata

2011-01-01

A fusion reactor generates a lot of 14 MeV neutrons, some of which penetrate shielding blankets, stream out of ports and reach superconducting magnets. Some important studies were performed in the 1970s and a basic understanding of the mechanisms of neutron irradiation effect was established. Advances in the design concept of nuclear fusion reactors led to the need for consistent studies on the neutron irradiation effect of A-15 strands such as Nb 3 Sn and Nb 3 Al, which are strong candidates for fusion reactors. In the early 2000s, a progressive attempt to organize the collaborative research of universities and national institutes was started using a 14 MeV neutron source at Japan Atomic Energy Agency. This paper outlines the neutron irradiation issues related to superconducting magnets for fusion, and a brief history of research on the neutron irradiation effect is provided. In addition, experimental results regarding changes in the superconducting properties of Nb 3 Sn and Nb 3 Al strands by neutron irradiation obtained in the newly established collaborative framework are presented, and general mechanisms for the property changes are introduced. (author)

Magnetization of in situ multifilamentary superconducting Nb3Sn-Cu composites

International Nuclear Information System (INIS)

Shen, S.S.; Verhoeven, J.D.

1980-01-01

Magnetic properties are reported for in situ superconducting Nb 3 Sn composites that have exhibited attractive electrical properties and superior mechanical characteristics. Magnetization measurements were conducted up to 4 T at 4.2 K on a variety of samples of different sizes and twist pitches, and the results are presented in absolute M-H curves and losses per cycle. It is observed that the magnetization of such composites is generally proportional to the size of the wire (approx. 0.25 to 0.51 mm) rather than the fiber size (approx. 10 -7 m), which indicates a strong coupling effect among Nb 3 Sn fibers

Design of Nb3Sn Coils for LARP Long Magnets

International Nuclear Information System (INIS)

Ferracin, Paolo; Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Ferracin, P.; Caspi, S.; Lietzke, A. F.

2007-01-01

The LHC Accelerator Research Program (LARP) has a primary goal to develop, assemble, and test full size Nb 3 Sn quadrupole magnet models for a luminosity upgrade of the Large Hadron Collider (LHC). A major milestone in this development is to assemble and test, by the end of 2009, two 4 m-long quadrupole cold masses, which will be the first Nb 3 Sn accelerator magnet models approaching the length of real accelerator magnets. The design is based on the LARP Technological Quadrupoles (TQ), under development at FNAL and LBNL, with gradient higher than 200 T/m and aperture of 90 mm. The mechanical design will be chosen between two designs presently explored for the TQs: traditional collars and Al-shell based design (preloaded by bladders and keys). The fabrication of the first long quadrupole model is expected to start in the last quarter of 2007. Meanwhile the fabrication of 4 m-long racetrack coils started this year at BNL. These coils will be tested in an Al-shell based supporting structure developed at LBNL. Several challenges have to be addressed for the successful fabrication of long Nb 3 Sn coils. This paper presents these challenges with comments and solutions adopted or under study for these magnets. The coil design of these magnets, including conductor and insulation features, and quench protection studies are also presented

Design of Nb3Sn coils for LARP long magnets

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Dietderich, D.; Feher, S.; Ferracin, P.; Ghosh, A.; Gourlay, S.; Kashikhin, V.V.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Sabbi, G.L.; Schmalzle, J.; Wanderer, P.; Zlobin, A.V.; Fermilab; Brookhaven; LBL, Berkeley; Texas A-M

2006-01-01

The LHC Accelerator Research Program (LARP) has a primary goal to develop, assemble, and test full size Nb 3 Sn quadrupole magnet models for a luminosity upgrade of the Large Hadron Collider (LHC). A major milestone in this development is to assemble and test, by the end of 2009, two 4m-long quadrupole cold masses, which will be the first Nb3Sn accelerator magnet models approaching the length of real accelerator magnets. The design is based on the LARP Technological Quadrupoles (TQ), under development at FNAL and LBNL, with gradient higher than 200 T/m and aperture of 90 mm. The mechanical design will be chosen between two designs presently explored for the TQs: traditional collars and Al-shell based design (preloaded by bladders and keys). The fabrication of the first long quadrupole model is expected to start in the last quarter of 2007. Meanwhile the fabrication of 4m-long racetrack coils started this year at BNL. These coils will be tested in an Al-shell based supporting structure developed at LBNL. Several challenges have to be addressed for the successful fabrication of long Nb 3 Sn coils. This paper presents these challenges with comments and solutions adopted or under study for these magnets. The coil design of these magnets, including conductor and insulation features, and quench protection studies are also presented

Stress distribution and lattice distortions in Nb3Sn multifilament wires under uniaxial tensile loading at 4.2 K

International Nuclear Information System (INIS)

Scheuerlein, C; Flükiger, R; Kadar, J; Bordini, B; Ballarino, A; Bottura, L; Di Michiel, M; Buta, F; Seeber, B; Senatore, C; Siegrist, T; Besara, T

2014-01-01

The lattice parameter changes in three types of Nb 3 Sn superconducting wires during uniaxial stress–strain measurements at 4.2 K have been measured by high-energy synchrotron x-ray diffraction. The nearly-stress-free Nb 3 Sn lattice parameter has been determined using extracted filaments, and the elastic strain in the axial and transverse wire directions in the different wire phases has been calculated. The mechanical properties of the PIT and RRP wire are mainly determined by the properties of Nb 3 Sn and unreacted Nb. This is in contrast to the bronze route wire, where the matrix can carry substantial loads. In straight wires the axial Nb 3 Sn pre-strain is strongest in the bronze route wire, its value being smaller in the PIT and RRP wires. A strong reduction of the non-Cu elastic modulus of about 30% is observed during cool-down from ambient temperature to 4.2 K. The Nb 3 Sn Poisson ratio at 4.2 K measured in the untwisted bronze route wire is 0.35. The present study also shows that the process route has a strong influence on the Nb 3 Sn texture. (paper)

Studies on the condition of obtaining a single phase superconducting Nb/sub 3/Sn layer by Moessbauer spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B [Politechnika Wroclawska (Poland); Chojcan, J [Wroclaw Univ. (Poland)

1983-11-16

The /sup 119/Sn Moessbauer spectroscopy was used to examine the influence of temperature (1153 to 1253 K) and heating time (11 and 22 min) on the formation of the ..beta..-Nb/sub 3/Sn phase in simultaneous processes: peritectic reaction of NbSn/sub 2/ phase decomposition and reactive diffusion of Sn atoms into the Nb1.5%Zr base.

Final Report SBIR Phase I, Improvement of Properties of Tubular Internal-Tin Nb3Sn

International Nuclear Information System (INIS)

Gregory, Eric

2009-01-01

Final report of SBIR to develop an economical process that can produce the best material for high field magnets to be used in the next generation of accelerators. The overall problem is to develop an economical process that can produce material with good properties for high field magnets to be used in the future for High Energy Physics (HEP) applications. The Internal-tin (IT) process, called by some the Restacked Rod process (RRP), for making Nb 3 Sn has been very successful in achieving high J c properties in the high field region. As a result it has been used effectively in several high field magnets. Originally, when this material was processed to give the highest J c it behaved unstably in the low field region and consequently did not perform as well in magnets designed for intermediate field applications. In this field range, the Powder-in-Tube (PIT) material, that has a lower d eff and a high RRR, behaved more reliably. The IT material has been improved to give better stability in the low field range and consequently the process offers a considerable challenge to the PIT process for application in both types of magnets. The PIT material has two principal drawbacks - lower J c and high cost. Work has been carried out to address these two problems and Supergenics I LLC has reported, on a low cost tubular process that is under development. It has fewer problems than the (IT) process in making low d eff materials and is of lower cost than both the IT and PIT processes. At the present stage, the J c 's that have been achieved are similar to those of the PIT material but are below those of the IT material. The purpose of the work proposed here is to improve the properties of the material made by this tubular process that has been described previously.

Analysis of critical current-bend strain relationships in composite Nb3Sn superconducting wires

International Nuclear Information System (INIS)

Luhman, T.; Welch, D.O.

1979-01-01

In order to be used successfully in fusion magnets, Nb 3 Sn conductors must meet several mechanical strain criteria, including tolerance to bending strains encountered during magnet construction. Since Nb 3 Sn is extremely brittle much information has been generated regarding the sensitivity of these conductros to tensile strain. A recent comparison of critical current-bend and tensile test data indicates that the strain required to initiate compound cracking during bending is significantly less than the strain required to do so by tensile of critical current on bending strains in monofilamentary Nb 3 Sn wires is calculated and compared with experimental data. The calculation takes into account a shift in the composite's neutral axis which occurs during bending. The analysis correctly predicts the observed depdndence of the critical current on bending strains

submitter Optimization of Nb$_{3}$Sn Rutherford Cables Geometry for the High Luminosity LHC

CERN Document Server

Fleiter, Jerome; Bonasia, Angelo; Bordini, Bernardo; Richter, David

2017-01-01

The quadrupole and dipole magnets for the LHC High Luminosity (HL-LHC) upgrade will be based on Nb$_{3}$Sn Rutherford cables that operate at 1.9 K and experience magnetic fields of up to about 12 T. An important step in the design of these magnets is the development of the high aspect ratio Nb$_{3}$Sn cables to achieve the nominal field with sufficient margin. The strong plastic deformation of unreacted $Nb_3Sn$ strands during the Rutherford cabling process may induce non negligible $I_c$ and RRR degradation. In this paper, the cabling degradation is investigated as a function of the cable geometry for both PIT and RRP conductors. Based on this analysis, new baseline geometries for both 11 T and QXF magnets of HL-LHC are proposed.

submitter Optimization of Nb$_{3}$Sn Rutherford Cables Geometry for the High Luminosity LHC

CERN Document Server

Fleiter, Jerome; Bonasia, Angelo; Bordini, Bernardo; Richter, David

2017-01-01

The quadrupole and dipole magnets for the LHC High Luminosity (HL-LHC) upgrade will be based on Nb3Sn Rutherford cables that operate at 1.9 K and experience magnetic fields of up to about 12 T. An important step in the design of these magnets is the development of the high aspect ratio Nb3Sn cables to achieve the nominal field with sufficient margin. The strong plastic deformation of unreacted $Nb_3Sn$ strands during the Rutherford cabling process may induce non negligible $I_c$ and RRR degradation. In this paper, the cabling degradation is investigated as a function of the cable geometry for both PIT and RRP conductors. Based on this analysis, new baseline geometries for both 11 T and QXF magnets of HL-LHC are proposed.

Development of an experimental 10 T Nb3Sn dipole magnet for the CERN LHC

NARCIS (Netherlands)

ten Kate, H.H.J.; den Ouden, A.; ter Avest, D.; Wessel, S.; Dubbeldam, R.; van Emden, W.; Daum, C.; Bona, M.; Perin, R.

1991-01-01

An experimental 1-m long twill aperture dipole magnet developed using a high-current Nb3Sn conductor in order to attain a magnetic field well beyond 10 T at 4.2 K is described. The emphasis in this Nb3Sn project is on the highest possible field within the known Large Hadron Collider (LHC)

A High Current Density Low Cost Niobium 3 Tin Titanium Doped Conductor Utilizing A Novel Internal Tin Process

International Nuclear Information System (INIS)

Bruce A Zeitlin

2005-01-01

An internal tin conductor has been developed using a Mono Element Internal Tin (MEIT) with an integral Nb barrier surrounding the Nb filaments. High current densities of 3000 A/mm2+ at 12 T and 1800 A/mm2 at 15 T have been achieved in conductors as small as 0.152 mm with the use of Nb7.5Ta filaments and Ti in the Sn core. In contrast, conductors with pure Nb and Ti in the Sn achieved 2700 A/mm2 at 12 T. Two internal fins, developed and patented on the project, were introduced into the filament array and reduced the effective filament diameter (Deff) by 38%. Additional fins will further reduce Deff The conductor was produced from 152.4 mm diameter billets to produce wire as small as 0.152 mm. The process promises be scaleable to 304 mm diameter billets yielding wire of 0.304 mm diameter. The MEIT process wire was easy to draw with relatively few breaks. The cost of this conductor in large production quantities based on the cost model presented could meet the 1.5 $/kilo amp meter(KAM) target of the HEP community

Effect of Sn addition on the microstructure and superelasticity in Ti-Nb-Mo-Sn alloys.

Science.gov (United States)

Zhang, D C; Yang, S; Wei, M; Mao, Y F; Tan, C G; Lin, J G

2012-09-01

Ti-7.5Nb-4Mo-xSn (x=0-4at%) alloys were developed as the biomedical materials. The effect of the Sn content on the microstructure and superelasticity of the alloys was investigated. It is found that Sn is a strong stabilizer of the β phase, which is effective in suppressing the formation of α″ and ω phases in the alloys. Moreover, the Sn addition has a significant impact on the mechanical properties of the alloys. With the increase of Sn addition, the yield stress of the alloys increase, but their elastic modulus, the fracture strength and the ductility decrease, and the deformation mode of the alloys changes from (322) twining to α″ transformation and then to slip. The Ti-7.5Nb-4Mo-1Sn and Ti-7.5Nb-4Mo-3Sn alloys exhibit a good superelasticity with a high σ(SIM) due to the relatively high athermal ω phases containing or the solution hardening at room temperature. Under the maximum strain of 5%, Ti-7.5Nb-4Mo-3Sn (at%) alloy exhibits higher super elastic stability than that of Ti-7.5Nb-4Mo-1Sn alloy. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development and test of a Nb3Sn racetrack magnet using the react and wind technology

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Barzi, E.; Bauer, P.; Carcagno, R.; Chichili, D.; Ewald, K.; Feher, S.; Imbasciati, L.; Kashikhin, V. V.; Limon, P.; Novitski, I.; Orris, D.; Pischalnikov, Y.; Sylvester, C.; Tartaglia, M.; Tompkins, J.; Yadav, S.; Zlobin, A.V.

2002-01-01

Fermilab is involved in the development of a high field accelerator magnet for future hadron colliders using Nb 3 Sn superconductor and the react-and-wind technology. The magnet design is based on single-layer common coils wound simultaneously into a laminated mechanical structure and impregnated with epoxy. In order to develop and optimize the fabrication techniques and to study the conductor performance, a magnet with flat racetrack type coils in a common coil configuration was assembled and tested. The coils were wound in the mechanical structure and in situ impregnated following a procedure that will be used in the single-layer common coil. The magnetic and mechanical design of the racetrack magnet, the fabrication techniques and the test results are presented and discussed in this paper

A review of the properties of Nb3Sn and their variation with A15 composition, morphology and strain state

International Nuclear Information System (INIS)

Godeke, A

2006-01-01

Significant efforts can be found throughout the literature to optimize the current-carrying capacity of Nb 3 Sn superconducting wires. The achievable transport current density in wires depends on the A15 composition, morphology and strain state. The A15 sections in wires contain, due to compositional inhomogeneities resulting from solid-state diffusion A15 formation reactions, a distribution of superconducting properties. The A15 grain size can be different from wire to wire, and is also not necessarily homogeneous across the A15 regions. Strain is always present in composite wires, and the strain state changes as a result of thermal contraction differences and Lorentz forces in magnet systems. To optimize the transport properties, it is thus required to identify how composition, grain size and strain state influence the superconducting properties. This is not possible accurately in inhomogeneous and spatially complex systems such as wires. This article therefore gives an overview of the available literature on simplified, well-defined (quasi-)homogeneous laboratory samples. After more than 50 years of research on superconductivity in Nb 3 Sn, a significant amount of results are available, but these are scattered over a multitude of publications. Two reviews exist on the basic properties of A15 materials in general, but no specific review for Nb 3 Sn is available. This article is intended to provide such an overview. It starts with a basic description of the niobium-tin intermetallic. After that, it maps the influence of Sn content on the electron-phonon interaction strength and on the field-temperature phase boundary. The literature on the influence of Cu, Ti and Ta additions will then be summarized briefly. This is followed by a review of the effects of grain size and strain. The article concludes with a summary of the main results. (topical review)

Experimental results and analysis from the 11 T Nb3Sn DS dipole

International Nuclear Information System (INIS)

Chlachidze, G; Novitski, I; Zlobin, A V; Auchmann, B; Karppinen, M

2013-01-01

FNAL and CERN are developing a 5.5-m-long twin-aperture Nb3Sn dipole suitable for installation in the LHC. A 2-m-long single-aperture demonstrator dipole with 60 mm bore, a nominal field of 11 T at the LHC nominal current of 11.85 kA and 20% margin has been developed and tested. This paper presents the results of quench protection analysis and protection heater study for the Nb3Sn demonstrator dipole. Extrapolations of the results for long magnet and operation in LHC are also presented. (author)

Powder-in-tube (PIT) Nb$_{3}$Sn conductors for high-field magnets

CERN Document Server

Lindenhovius, J L H; den Ouden, A; Wessel, W A J; ten Kate, H H J

2000-01-01

New Nb/sub 3/Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment of the conductor lay-out. It uniquely combines a non-copper current density of 2680 A/mm/sup 2/@10 T with an effective filament diameter of about 20 mu m. This binary conductor may be used in a 10 T, wide bore model separator dipole magnet for the LHC, which is being developed by a collaboration of the University of Twente and CERN. A ternary (Nb/7.5wt%Ta)/sub 3/Sn conductor containing 37 filaments is particularly suited for application in extremely high-field superconducting solenoids. This wire features a copper content of 43%, a non-copper current density of 217 A/mm/sup 2/@20 T and a B/sub c2/ of 25.6 T. The main issues and the experimental results of the development program of PIT Nb/sub 3/Sn conductors a...

Comments on Moessbauer-effect studies on 2-MeV proton-irradiated Nb3Sn

International Nuclear Information System (INIS)

Cox, D.E.; Sweedler, A.R.

1979-01-01

In a recent paper, Herber and Kalish have presented 119 Sn Moessbauer data for Nb 3 Sn irradiated by 2-MeV protons which they interpret in terms of a statistical distribution of site defects rather than interchange of Nb and Sn atoms. Further analysis of these data leads to the conclusion that they are in fact quite consistent with the presence of a substantial amount of radiation-induced site-exchange disorder. This is in agreement with the findings of a number of recent diffraction studies

Direct measurements of inter-filament resistance in various multi-filamentary superconducting NbTi and Nb3Sn strands

NARCIS (Netherlands)

Zhou, Chao; Miyoshi, Y.; van Lanen, E.P.A.; Dhalle, Marc M.J.; Nijhuis, Arend

2012-01-01

For a proper characterization of multi-filamentary NbTi and Nb3Sn strands and a better understanding of their performance in short sample tests, as well as for increased understanding of inter-strand current redistribution in cabled conductors, a quantitative knowledge of the inter-filament

To Crack or Not to Crack: Strain in High Temperature Superconductors

International Nuclear Information System (INIS)

Godeke, Arno

2007-01-01

Round wire Bi 2212 is emerging as a viable successor of Nb3Sn in High Energy Physics and Nuclear Magnetic Resonance, to generate magnetic fields that surpass the intrinsic limitations of Nb3Sn. Rather bold claims are made on achievable magnetic fields in applications using Bi 2212, due to the materials' estimated critical magnetic field of 100 Tor higher. High transport currents in high magnetic fields, however, lead to large stress on, and resulting large strain in the superconductor. The effect of strain on the critical properties of Bi-2212 is far from understood, and strain is, as with Nb3Sn, often treated as a secondary parameter in the design of superconducting magnets. Reversibility of the strain induced change of the critical surface of Nb3Sn, points to an electronic origin of the observed strain dependence. Record breaking high field magnets are enabled by virtue of such reversible behavior. Strain effects on the critical surface of Bi-2212, in contrast, are mainly irreversible and suggest a non-electronic origin of the observed strain dependence, which appears to be dominated by the formation of cracks in the superconductor volumes. A review is presented of available results on the effects of strain on the critical surface of Bi-2212, Bi-2223 and YBCO. It is shown how a generic behavior emerges for the (axial) strain dependence of the critical current density, and how the irreversible reduction of the critical current density is dominated by strain induced crack formation in the superconductor. From this generic model it becomes clear that magnets using high temperature superconductors will be strain limited far before the intrinsic magnetic field limitations will be approached, or possibly even before the magnetic field limitation of Nb3Sn can be surpassed. On a positive note, in a very promising recent result from NIST on the axial strain dependence of the critical current density in extremely well aligned YBCO, reversible behavior was observed. This

Progress of metallic superconductors in Japan

Energy Technology Data Exchange (ETDEWEB)

Tachikawa, Kyoji, E-mail: tacsuper@keyaki.cc.u-tokai.ac.jp [Faculty of Engineering, Tokai University, 4-1-1, Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan)

2013-01-15

Highlights: ► Japanese contributions on the R and D of different metallic superconductors are summarized. ► Nb–Ti wires have been developed for MRI, accelerator, MAGLEV train and other applications. ► Multifilamentary Nb{sub 3}Sn wires with excellent performance have been developed for high-field use. ► Long-length Nb{sub 3}Al wires with promising strain tolerance have been fabricated by a new process. -- Abstract: This article overviews the development of metallic superconductors in Japan covering different kinds of alloys and intermetallic compounds. Metallic superconductors have opened many new application areas in science and technology. Japan has been one of the leading countries in the world, both in the research and development and in large-scale manufacturing of metallic superconductors.

Development and test of Nb(3)Sn cos-theta dipoles based on PIT strands

International Nuclear Information System (INIS)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Chichili, D.R.; Elementi, L.; Feher, S.; Kashikhin, V.V.; Lamm, M.J.; Novitski, I.; Pischalnikov, Yu.; Sylvester, C.; Tartaglia, M.; Yamada, R.

2004-01-01

Fermilab is involved in the development of new generation high-field accelerator magnets using state-of-the-art Nb 3 Sn strands produced using different technologies. Two 1-m long models--mirror configuration and dipole magnet--were fabricated recently at Fermilab based on powder-in-tube (PIT) Nb 3 Sn strands with small effective filament size. This paper describes the parameters of superconducting strands and cable, the details of magnet design and fabrication procedure, and reports the results of PIT coil testing

Transverse Load Optimisation in Nb3Sn CICC Design; Influence of Cabling, Void Fraction and Strand Stiffness

NARCIS (Netherlands)

Nijhuis, Arend; Ilyin, Y.

2006-01-01

We have developed a model that describes the transverse load degradation in Nb3Sn CICCs, based on strand and cable properties, and that is capable of predicting how such degradation can be prevented. The Nb3Sn cable in conduit conductors (CICCs) for the International Thermonuclear Experimental

Internal friction and elastic softening in polycrystalline Nb3Sn

International Nuclear Information System (INIS)

Bussiere, J.F.; Faucher, B.; Snead, C.L. Jr.; Welch, D.O.

1981-01-01

The vibrating-reed technique was used to measure internal friction and Young's modulus of polycrystalline Nb 3 Sn in the form of composite Nb/Nb 3 Sn tapes from 6 to 300 K. In tapes with only small residual strain in the A15 layers, a dramatic increase in internal friction with decreasing temperature is observed with an abrupt onset at approx.48 K. The internal friction Q -1 between 6 and 48 K is believed to be associated with stress-induced motion of martensitic-domain walls. In this temperature range, Q -1 is approximately proportional to the square of the tetragonal strain of the martensitic phase; Q -1 α (c/a-1) 2 . With residual compressive strains of approx.0.2%, the internal friction associated with domain-wall motion is considerably reduced. This is attributed to a biasing of domain-wall orientation with residual stress, which reduces wall motion induced by the (much smaller) applied stress. The transformation temperature, however, is unchanged (within +- 1 K) by residual strains of up to 0.2%. Young's modulus exhibits substantial softening on cooling from 300 to 6 K. This softening, is substantially reduced in the presence of small residual compressive strains, indicating a highly nonlinear stress-strain relationship as previously reported for V 3 Si

Peak Fields of Nb$_{3}$Sn Superconducting Undulators and a Scaling Law

CERN Document Server

Kim, S H

2005-01-01

The peak fields on the beam axis and the maximum fields in the conductor of Nb$_{3}$Sn superconducting undulators (SCUs) were calculated for an undulator period length of 16 mm. Using a simple scaling law for SCUs [1], the peak fields, as well as the conductor maximum fields and the current densities, were calculated for a period range of 8 to 32 mm. The critical current densities of commercially available Nb$_{3}$Sn superconducting strands were used for the calculations. The achievable peak fields are limited mainly by the flux-jump instabilities at low fields. The possible or feasible peak field will also be compared with that achieved in prototype development of SCUs.

Measurement of Fast Voltage Transients in High-Performance Nb3Sn Magnets

Energy Technology Data Exchange (ETDEWEB)

Lietzke, A. F.; Sabbi., G. L.; Ferracin, P.; Caspi, S.; Zimmerman, S.; Joseph, J.; Doering, D.; Lizarazo, J.

2008-06-01

The Superconducting Magnet group at Lawrence Berkeley National Laboratory has been developing Nb{sub 3}Sn high-field accelerator magnet technology for the last fifteen years. In order to support the magnet R&D effort, we are developing a diagnostic system that can help identify the causes of performance limiting quenches by recording small flux-changes within the magnet prior to quench-onset. These analysis techniques were applied to the test results from recent Nb{sub 3}Sn magnets. This paper will examine various types of events and their distinguishing characteristics. The present measurement techniques are discussed along with the design of a new data acquisition system that will substantially improve the quality of the recorded signals.

Band Alignments, Valence Bands, and Core Levels in the Tin Sulfides SnS, SnS2, and Sn2S3: Experiment and Theory

OpenAIRE

Whittles, TJ; Burton, LA; Skelton, JM; Walsh, A; Veal, TD; Dhanak, VR

2016-01-01

Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy measurements of single crystal SnS, SnS2, and Sn2S3, with electronic-structure calculations from density functional theory (DFT). Differences in the XPS spectra of the three phases, including...

Status of 11 T 2-in-1 Nb$_3$Sn Dipole Development for LHC

Energy Technology Data Exchange (ETDEWEB)

Zlobin, Alexander [Fermilab; Andreev, Nicolai [Fermilab; Apollinari, Giorgio [Fermilab; Barzi, Emanuela [Fermilab; Bossert, Rodger [Fermilab; Buehler, Marc [Fermilab; Chlachidze, Guram [Fermilab; DiMarco, Joseph [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Turrioni, Daniele [Fermilab; Velev, Gueorgui [Fermilab; Auchmann, Bernhard [CERN; Karppinen, Mikko [CERN; Rossi, Lucio [CERN; Smekens, David [CERN

2014-07-01

The LHC upgrade plans foresee installation of additional collimators in the LHC lattice. To provide the necessary longitudinal space for these collimators, shorter and stronger Nb3Sn dipoles compatible with the LHC lattice and main systems could be used. This paper describes the design and status of the twin-aperture Nb3Sn dipole being developed by FNAL and CERN for the LHC, and reports test results of two collared coils to be used in the first 1 m long twin-aperture dipole model.

Development and test of Nb(3)Sn cos-theta dipoles based on PIT strands

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R.; Chichili, D.R.; Elementi, L.; Feher, S.; Kashikhin, V.V.; Lamm, M.J.; Novitski, I.; Pischalnikov, Yu.; Sylvester, C.; Tartaglia, M.; Yamada, R.; /Fermilab

2004-11-01

Fermilab is involved in the development of new generation high-field accelerator magnets using state-of-the-art Nb{sub 3}Sn strands produced using different technologies. Two 1-m long models--mirror configuration and dipole magnet--were fabricated recently at Fermilab based on powder-in-tube (PIT) Nb{sub 3}Sn strands with small effective filament size. This paper describes the parameters of superconducting strands and cable, the details of magnet design and fabrication procedure, and reports the results of PIT coil testing.

Understanding Irreversible Degradation of Nb3Sn Wires with Fundamental Fracture Mechanics

Energy Technology Data Exchange (ETDEWEB)

Zhai, Yuhu [PPPL; Calzolaio, Ciro [Univ of Geneva; Senatore, Carmine [Univ of Geneva

2014-08-01

Irreversible performance degradation of advanced Nb3Sn superconducting wires subjected to transverse or axial mechanical loading is a critical issue for the design of large-scale fusion and accelerator magnets such as ITER and LHC. Recent SULTAN tests indicate that most cable-in-conduit conductors for ITER coils made of Nb3Sn wires processed by various fabrication techniques show similar performance degradation under cyclic loading. The irreversible degradation due to filament fracture and local strain accumulation in Nb3Sn wires cannot be described by the existing strand scaling law. Fracture mechanic modeling combined with X-ray diffraction imaging of filament micro-crack formation inside the wires under mechanical loading may reveal exciting insights to the wire degradation mechanisms. We apply fundamental fracture mechanics with a singularity approach to study influence of wire filament microstructure of initial void size and distribution to local stress concentration and potential crack propagation. We report impact of the scale and density of the void structure on stress concentration in the composite wire materials for crack initiation. These initial defects result in an irreversible degradation of the critical current beyond certain applied stress. We also discuss options to minimize stress concentration in the design of the material microstructure for enhanced wire performance for future applications.

Preliminary proposal of a Nb3Sn quadrupole model for the low β insertions of the LHC

International Nuclear Information System (INIS)

Ambrosio, G.; Ametrano, F.; Bellomo, G.; Broggi, F.; Rossi, L.; Volpini, G.

1995-09-01

In recent years Nb 3 Sn based conductors have shown wide applicability for superconducting magnets in many research areas like high field solenoids for laboratory experiment, for NMR spectroscopy and high field magnets for fusion. Nb 3 Sn technology is progressing fast, increasing both technical reliability and availability. The Nb 3 Sn technology, which has a higher critical field than NbTi, seems attractive for IR (Insertion Region) quadrupoles of large colliders . In this paper it is proposed the construction of a superconducting quadrupole wound with Nb 3 Sn cable for a second generation IR inner triplet low β quadrupoles, for the Large Hadron Collider at CERN. The low β quadrupoles, control the beam focusing at collision points, therefore a gain in term of focus strength and/or coil aperture can increase significantly machine performance. Two are the main steps for the whole project: 1) design and construction of a 1 metre long quadrupole to demonstrate the actual feasibility, which is the subject of this proposal; 2) study for integration of the quadrupole in the machine and final design of 5 m long quadrupoles finalized to the LHC

Low-field Instabilities in Nb$_{3}$Sn Multifilamentary Wires the Possible Role of Unreacted Nb

CERN Document Server

Devred, A; Celentano, G; Fabbricatore, P; Ferdeghini, C; Greco, M; Gambardella, U

2007-01-01

We report an experimental study aiming to demonstrate the not negligible role of unreacted Nb on the magnetic instabilities in superconducting Nb$_{3}$Sn multifilamentary wires, observable through partial flux jumps at magnetic field values below 0.5 T. The analysed wires were recently developed for use as dipoles required in future high-energy proton accelerators and are based on powder-in-tube technology. We studied both unreacted (only involving Nb filaments) and reacted wires, finding flux jump instabilities in both cases when performing magnetic measurements. The results can be interpreted on the basis of the critical state model and are coherent with the intrinsic stability criterion.

Low critical temperature superconductors for electromagnets

International Nuclear Information System (INIS)

Devred, A.

2002-01-01

After a brief history of the main discoveries in applied superconductivity (section 1), we discuss the structure and properties of NbTi and Nb3 Sn (section 2). Then, we explain why low critical-temperature superconductors are produced under the form of multifilamentary composites (section 3), and we review the manufacturing processes of NbTi and Nb3Sn wires (section 4). We follow by a description of the transition from the superconducting to the normal resistive state of multifilamentary composite wires (section 5) and we detail their magnetization properties section 6). Last, we present the most commonly used cable configurations (section 7) and we provide simple formulae illustrating on a few examples the computation of losses generated under time-varying magnetic fields (section 8). (author)

The effect of transverse loads up to 300 MPa on the critical currents of Nb3Sn cables

International Nuclear Information System (INIS)

Boschman, H.; Verweij, A.P.; Wessel, S.; ten Kate, H.H.J.; van de Klundert, L.J.M.

1991-01-01

In the framework of the development of an experimental 10 T Nb 3 Sn dipole coil for the LHC at CERN the effects of transverse stress on Rutherford type of Nb 3 Sn cables have been investigated. For this purpose a special facility was designed and taken into operation in which the voltage-current behavior of short pieces of Nb 3 Sn cables can be investigated in a background field up to 11 T and an applied stress of 300 MPa. The repulsive Lorentz force of 250 kN, generated by a set of superconducting coils, is used to impress the cable over an area of 20 x 42 mm 2 maximum, in presence of a transport current up to 40 kA. In this paper the testing equipment is described and the first results of the observed critical current degradation of two Nb 3 Sn cables are discussed

Effect of transverse loads up to 300 MPa on the critical currents of Nb3Sn cables

NARCIS (Netherlands)

Boschman, H.; Verweij, A.P.; Verweij, A.P.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.; van de Klundert, L.J.M.; van de Klundert, L.J.M.

1991-01-01

In the framework of the development of an experimental 10-T Nb3Sn dipole coil for the LHC (Large Hadron Collider) at CERN, the effects of transverse stress on Rutherford-type Nb3Sn cable were investigated. For this purpose a special facility was designed and put into operation in which the

Quench Protection Studies of 11T Nb$_3$Sn Dipole Models for LHC Upgrades

Energy Technology Data Exchange (ETDEWEB)

Zlobin, Alexander [Fermilab; Chlachidze, Guram [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Karppinen, Mikko [CERN

2014-07-01

CERN and FNAL are developing 11 T Nb3Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb3Sn dipole coil tested in a magnetic mirror configuration.

Inter-filament resistance, effective transverse resistivity and coupling loss in superconducting multifilamentary NbTi and Nb3Sn strands

NARCIS (Netherlands)

Zhou, Chao; Dhalle, Marc M.J.; Nijhuis, Arend

2012-01-01

The effective transverse resistivity of a range of multi-filamentary Nb3Sn and NbTi strands is measured with a direct four-probe method and the data are compared to the transverse resistivity values obtained from AC coupling loss experiments. Correspondence between both is satisfactory provided that

High-Field Nb3Sn Cos-theta Dipole with Stress Management

Energy Technology Data Exchange (ETDEWEB)

Novitski, Igor [Fermilab; Carmichael, Justin [Fermilab; Kashikhin, Vadim V. [Fermilab; Zlobin, Alexander V. [Fermilab

2017-01-01

Cost-effective superconducting dipole magnets with operating fields up to 16 T are being considered for the LHC en-ergy upgrade (HE-LHC) and a Future Circular Collider (FCC). To demonstrate feasibility of 15 T accelerator quality dipole mag-nets, FNAL as a part of the US-MDP is developing a single-aper-ture Nb3Sn dipole demonstrator based on a 4-layer graded cos-theta coil with 60 mm aperture and cold iron yoke. In parallel, to explore the limit of the Nb3Sn accelerator magnet technology, op-timize magnet design and performance parameters, and reduce magnet cost, magnet design studies are also being performed to push the nominal bore field to 16 T in a 60-mm aperture cos-theta dipole. Results of these studies are reported and discussed in this paper.

New tests on the 40 kA Nb3Sn CEA conductor for ITER applications

International Nuclear Information System (INIS)

Duchateau, J.L.; Bessette, D.; Katheder, H.

1994-01-01

New tests have been performed on the 40 kA CEA Nb 3 Sn conductor in the Sultan III facility. The aim of these tests is to obtain key experimental data on the behaviour of Nb 3 Sn conductors for fusion applications under high field and large transport current. The 40 kA Nb 3 Sn CEA conductor has a shape and an internal arrangement of the superconducting wires which is very similar to the ITER conductors. The level of the ac losses experienced by these conductors under varying fields influences deeply their design. The basic experiment consists of producing field pulses on the conductor by means of a coil installed in the bore of the Sultan magnet and recording the integrated voltage obtained on pick-up coils placed on the conductor as a function of time. (author) 4 refs.; 5 figs.; 2 tabs

Introduction of Nonlinear Properties Into Hierachical Models of Nb3Sn Strands

International Nuclear Information System (INIS)

Collins, B.; Krishnan, J.; Arbelaez, D.; Ferracin, P.; Prestemon, S.O.; Godeke, A.; Dietderich, D.R.; Zohdi, T.I.

2011-01-01

The development of computational models representing Rutherford cable formation and deformation is necessary to investigate the strain state in the superconducting filaments in Nb 3 Sn magnets. The wide variety of length scales within accelerator magnets suggests usage of a hierarchical structure within the model. As part of an ongoing investigation at LBNL, a three-dimensional simplified nonlinear multiscale model is developed as a way to extend previous linear elastic versions. The inclusion of plasticity models into the problem formulation allows an improved representation of strand behavior compared to the linear elastic model. This formulation is applied to a single Nb 3 Sn strand to find its effective properties as well as the strain state in the conductor under loading.

Electrical Resistance of Nb$_{3}$Sn/Cu Splices Produced by Electromagnetic Pulse Technology and Soft Soldering

CERN Document Server

Schoerling, D; Scheuerlein, C; Atieh, S; Schaefer, R

2011-01-01

The electrical interconnection of Nb$_{3}$Sn/Cu strands is a key issue for the construction of Nb$_{3}$Sn based damping ring wigglers and insertion devices for third generation light sources. We compare the electrical resistance of Nb$_{3}$Sn/Cu splices manufactured by solid state welding using Electromagnetic Pulse Technology (EMPT) with that of splices produced by soft soldering with two different solders. The resistance of splices produced by soft soldering depends strongly on the resistivity of the solder alloy at the operating temperature. By solid state welding splice resistances below 10 nOhm can be achieved with 1 cm strand overlap length only, which is about 4 times lower than the resistance of Sn96Ag4 soldered splices with the same overlap length. The comparison of experimental results with Finite Element simulations shows that the electrical resistance of EMPT welded splices is determined by the resistance of the stabilizing copper between the superconducting filaments and confirms that welding of ...

An exponential scaling law for the strain dependence of the Nb3Sn critical current density

International Nuclear Information System (INIS)

Bordini, B; Alknes, P; Bottura, L; Rossi, L; Valentinis, D

2013-01-01

The critical current density of the Nb 3 Sn superconductor is strongly dependent on the strain applied to the material. In order to investigate this dependence, it is a common practice to measure the critical current of Nb 3 Sn strands for different values of applied axial strain. In the literature, several models have been proposed to describe these experimental data in the reversible strain region. All these models are capable of fitting the measurement results in the strain region where data are collected, but tend to predict unphysical trends outside the range of data, and especially for large strain values. In this paper we present a model of a new strain function, together with the results obtained by applying the new scaling law on relevant datasets. The data analyzed consisted of the critical current measurements at 4.2 K that were carried out under applied axial strain at Durham University and the University of Geneva on different strand types. With respect to the previous models proposed, the new scaling function does not present problems at large strain values, has a lower number of fitting parameters (only two instead of three or four), and is very stable, so that, starting from few experimental points, it can estimate quite accurately the strand behavior in a strain region where there are no data. A relationship is shown between the proposed strain function and the elastic strain energy, and an analogy is drawn with the exponential form of the McMillan equation for the critical temperature. (paper)

Magnetic and Structural Design of a 15 T $Nb_3Sn$ Accelerator Depole Model

Energy Technology Data Exchange (ETDEWEB)

Kashikhin, V. V. [Fermilab; Andreev, N. [Fermilab; Barzi, E. [Fermilab; Novitski, I. [Fermilab; Zlobin, A. V. [Fermilab

2015-01-01

Hadron Colliders (HC) are the most powerful discovery tools in modern high energy physics. A 100 TeV scale HC with a nominal operation field of at least 15 T is being considered for the post-LHC era. The choice of a 15 T nominal field requires using the Nb3Sn technology. Practical demonstration of this field level in an accelerator-quality magnet and substantial reduction of the magnet costs are the key conditions for realization of such a machine. FNAL has started the development of a 15 T $Nb_{3}Sn$ dipole demonstrator for a 100 TeV scale HC. The magnet design is based on 4-layer shell type coils, graded between the inner and outer layers to maximize the performance. The experience gained during the 11-T dipole R&D campaign is applied to different aspects of the magnet design. This paper describes the magnetic and structural designs and parameters of the 15 T $Nb_3Sn$ dipole and the steps towards the demonstration model.

Impact of Nb vacancies and p-type doping of the NbCoSn-NbCoSb half-Heusler thermoelectrics.

Science.gov (United States)

Ferluccio, Daniella A; Smith, Ronald I; Buckman, Jim; Bos, Jan-Willem G

2018-02-07

The half-Heuslers NbCoSn and NbCoSb have promising thermoelectric properties. Here, an investigation of the NbCo 1+y Sn 1-z Sb z (y = 0, 0.05; 0 ≤ z ≤ 1) solid-solution is presented. In addition, the p-type doping of NbCoSn using Ti and Zr substitution is investigated. Rietveld analysis reveals the gradual creation of Nb vacancies to compensate for the n-type doping caused by the substitution of Sb in NbCoSn. This leads to a similar valence electron count (∼18.25) for the NbCo 1+y Sn 1-z Sb z samples (z > 0). Mass fluctuation disorder due to the Nb vacancies strongly decreases the lattice thermal conductivity from 10 W m -1 K -1 (z = 0) to 4.5 W m -1 K -1 (z = 0.5, 1). This is accompanied by a transition to degenerate semiconducting behaviour leading to large power factors, S 2 /ρ = 2.5-3 mW m -1 K -2 and figures of merit, ZT = 0.25-0.33 at 773 K. Ti and Zr can be used to achieve positive Seebeck values, e.g. S = +150 μV K -1 for 20% Zr at 773 K. However, the electrical resistivity, ρ 323K = 27-35 mΩ cm, remains too large for these materials to be considered useful p-type materials.

Superconductors by powder metallurgy techniques

International Nuclear Information System (INIS)

Pickus, M.R.; Wang, J.L.F.

1976-05-01

Fabrication methods for Nb 3 Sn type compounds are described. Information is included on the Bell Telephone process, the General Electric tape process, superconductor stability, the bronze process, powder metallurgy multifilamentary tapes and wires, and current assessment of powder metallurgy superconducting wire

Wide-band operation of quasi-optical distributed superconductor/insulator/superconductor mixers with epitaxial NbN/AlN/NbN junctions

International Nuclear Information System (INIS)

Kohjiro, S; Shitov, S V; Wang, Z; Uzawa, Y; Miki, S; Kawakami, A; Shoji, A

2004-01-01

For the optimum design of integrated receivers operating above the gap frequency of Nb, we have designed, fabricated and tested NbN-based quasi-optical superconductor/insulator/superconductor (SIS) mixers. The mixer chip incorporates a resonant half-wavelength epitaxial NbN/AlN/NbN junction, a twin-slot antenna and their coupling circuits. We adopted two kinds of coupling circuit between the antenna and the SIS junction: one is an in-phase feed with a length of 95 μm and the other is an anti-phase feed of 30 μm length. It was found that the anti-phase mixer reveals a 3 dB bandwidth of 43% of the centre frequency; the uncorrected double-sideband receiver noise temperature T RX = 691 K at 0.91 THz and T RX = 844 K at 0.80 THz, while 17% and T RX = 1250 K at 0.79 THz for the in-phase version. Possible reasons for this difference are discussed, which could be transmission loss and its robustness with respect to the variation of junction parameters. These experimental results suggest the NbN-based distributed mixer with the anti-phase feed is a better candidate for wide-band integrated receivers operating above 0.7 THz

Preliminary proposal of a Nb{sub 3}Sn quadrupole model for the low {beta} insertions of the LHC

Energy Technology Data Exchange (ETDEWEB)

Ambrosio, G; Ametrano, F; Bellomo, G; Broggi, F; Rossi, L; Volpini, G [Milan Univ. (Italy). Dip. di Fisica; [INFN, Sezione di Milano (Italy). Laboratorio Acceleratori e Superconduttivita` Applicata

1995-09-01

In recent years Nb{sub 3}Sn based conductors have shown wide applicability for superconducting magnets in many research areas like high field solenoids for laboratory experiment, for NMR spectroscopy and high field magnets for fusion. Nb{sub 3}Sn technology is progressing fast, increasing both technical reliability and availability. The Nb{sub 3}Sn technology, which has a higher critical field than NbTi, seems attractive for IR (Insertion Region) quadrupoles of large colliders . In this paper it is proposed the construction of a superconducting quadrupole wound with Nb{sub 3}Sn cable for a second generation IR inner triplet low {beta} quadrupoles, for the Large Hadron Collider at CERN. The low {beta} quadrupoles, control the beam focusing at collision points, therefore a gain in term of focus strength and/or coil aperture can increase significantly machine performance. Two are the main steps for the whole project: (1) design and construction of a 1 metre long quadrupole to demonstrate the actual feasibility, which is the subject of this proposal; (2) study for integration of the quadrupole in the machine and final design of 5 m long quadrupoles finalized to the LHC.

Test Results for HD1, a 16 Tesla Nb3Sn Dipole Magnet

International Nuclear Information System (INIS)

Lietzke, A.F.; Bartlett, S.; Bish, P.; Caspi, S.; Chiesa, L.; Dietderich, D.; Ferracin, P.; Gourlay, S.A.; Goli, M.; Hafalia, R.R.; Higley, H.; Hannaford, R.; Lau, W.; Liggens, N.; Mattafirri, S.; McInturff, A.; Nyman, M.; Sabbi, G.; Scanlan, R.; Swanson, J.

2003-01-01

The Superconducting Magnet Group at Lawrence Berkeley National Laboratory has been developing the technology for using brittle superconductor in high-field accelerator magnets. HD1, the latest in a series of magnets, contains two, double-layer Nb 3 Sn flat racetrack coils. This single-bore dipole configuration, using the highest performance conductor available, was designed and assembled for a 16 tesla conductor/structure/pre-stress proof-of-principle. With the combination of brittle conductor and high Lorentz stress, considerable care was taken to predict the magnet's mechanical responses to pre-stress, cool-down, and excitation. Subsequent cold testing satisfied expectations: Training started at 13.6 T, 83% of 'short-sample', achieved 90% in 10 quenches, and reached its peak bore field (16 T) after 19 quenches. The average plateau, ∼92% of 'short-sample', appeared to be limited by 'stick-slip' conductor motions, consistent with the 16.2 T conductor 'lift-off' pre-stress that was chosen for this first test. Some lessons learned and some implications for future conductor and magnet technology development are presented and discussed.

Josephson effects in Nb3Sn microbridges

International Nuclear Information System (INIS)

Lee, T.W.; Falco, C.M.

1981-01-01

Josephson effects in long narrow Nb/sub 3/Sn microbridges at temperatures up to 17 K were studied. These microbridges are formed by photolithographic techniques and subsequently subjected to controlled electrical discharges to modifY the intrinsic T/sub c/ of the bridge region. The bridges exhibit 10 GHz microwave steps in their I-V characteristics whose amplitudes are in agreement with the Resistively Shunted Junction (RSJ) model. I-V characteristics can be fit assuming an effective temperature approximately 15 K above the bath temperature. Structures in the I-V characteristics in the absence of microwaves were also investigated. It was demonstrated that phase-slip centers are induced at weak superconducting positions along the bridge when the S-N boundarY of an expanding hot spot reaches within a thermal healing distance. The critical current of the phase-slip center thus formed exhibits a temperature dependence (1-T/T/sub c/)/one-half/ insteady of the usual mean field result (1-T/T/sub c/)/sup 3/2/. 12 refs

The effect of Sn on autoclave corrosion performance and corrosion mechanisms in Zr–Sn–Nb alloys

International Nuclear Information System (INIS)

Wei, J.; Frankel, P.; Polatidis, E.; Blat, M.; Ambard, A.; Comstock, R.J.; Hallstadius, L.; Hudson, D.; Smith, G.D.W.; Grovenor, C.R.M.; Klaus, M.; Cottis, R.A.; Lyon, S.; Preuss, M.

2013-01-01

The desire to improve the corrosion resistance of Zr cladding material for high burn-up has resulted in a general trend among fuel manufacturers to develop alloys with reduced levels of Sn. While commonly accepted, the reason for the improved corrosion performance observed for low-tin zirconium alloys in high-temperature aqueous environments remains unclear. High-energy synchrotron X-ray diffraction was used to characterize the oxides formed by autoclave exposure on Zr–Sn–Nb alloys with tin concentration ranging from 0.01 to 0.92 wt.%. The alloys studied included the commercial alloy ZIRLO® (ZIRLO® is a registered trademark of Westinghouse Electric Company LLC in the USA and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited.) and two variants of ZIRLO with significantly lower tin levels, referred to here as A-0.6Sn and A-0.0Sn. The nature of the oxide grown on tube samples from each alloy was investigated via cross-sectional scanning electron microscopy. Atom probe analysis of ZIRLO demonstrated that the tin present in the alloy passes into the oxide as it forms, with no significant difference in the Sn/Zr ratio between the two. Synchrotron X-ray diffraction measurements on the oxides formed on each alloy revealed that the monoclinic and tetragonal oxide phases display highly compressive in-plane residual stresses with the magnitudes dependent on the phase and alloy. The amount of tetragonal phase present and, more importantly, the level of tetragonal-to-monoclinic phase transformation both decrease with decreasing tin levels, suggesting that tin is a tetragonal oxide phase stabilizing element. It is proposed that in Zr–Nb–Sn alloys with low Sn, the tetragonal phase is mainly stabilized by very small grain size and therefore remains stable throughout the corrosion process. In contrast, alloys with higher tin levels can in addition grow larger, stress stabilized, tetragonal grains that

Investigate the effect of anisotropic order parameter on the specific heat of anisotropic two-band superconductors

International Nuclear Information System (INIS)

Udomsamuthirun, P.; Peamsuwan, R.; Kumvongsa, C.

2009-01-01

The effect of anisotropic order parameter on the specific heat of anisotropic two-band superconductors in BCS weak-coupling limit is investigated. An analytical specific heat jump and the numerical specific heat are shown by using anisotropic order parameters, and the electron-phonon interaction and non-electron-phonon interaction. The two models of anisotropic order parameters are used for numerical calculation that we find little effect on the numerical results. The specific heat jump of MgB 2 , Lu 2 Fe 3 Si 5 and Nb 3 Sn superconductors can fit well with both of them. By comparing the experimental data with overall range of temperature, the best fit is Nb 3 Sn, MgB 2 , and Lu 2 Fe 3 Si 5 superconductors.

Development of a large aperture Nb3Sn racetrack quadrupole magnet

International Nuclear Information System (INIS)

Ferracin, Paolo; Bartlett, Scott E.; Caspi, Shlomo; Dietderich, Daniel R.; Gourlay, Steven A.; Hannaford, Charles R.; Hafalia, AurelioR.; Lietzke, Alan F.; Mattafirri, Sara; McInturff, Alfred D.; Nyman, Mark; Sabbi, Gianluca

2005-01-01

The U.S. LHC Accelerator Research Program (LARP), a collaboration between BNL, FNAL, LBNL, and SLAC, has among its major objectives the development of advanced magnet technology for an LHC luminosity upgrade. The LBNL Superconducting Magnet Group supports this program with a broad effort involving design studies, Nb 3 Sn conductor development, mechanical models, and basic prototypes. This paper describes the development of a large aperture Nb 3 Sn racetrack quadrupole magnet using four racetrack coils from the LBNL Subscale Magnet (SM) Program. The magnet provides a gradient of 95 T/m in a 110 mm bore, with a peak field in the conductor of 11.2 T. The coils are prestressed by a mechanical structure based on a pre-tensioned aluminum shell, and axially supported with aluminum rods. The mechanical behavior has been monitored with strain gauges and the magnetic field has been measured. Results of the test are reported and analyzed

Magnetic Parameters Of A NB3SN Superconducting Magnet For A 56 HGz ECR Ion Source

International Nuclear Information System (INIS)

Ferracin, P.; Caspi, S.; Felice, H.; Leitner, D.; Lyneis, C.M.; Prestemon, S.; Sabbi, G.L.; Todd, D.S.

2009-01-01

Third generation Electron Cyclotron Resonance (ECR) ion sources operate at microwave frequencies between 20 and 30 GHz and employ NbTi superconducting magnets with a conductor peak field of 6-7 T. A significant gain in performance can be achieved by replacing NbTi with Nb 3 Sn, allowing solenoids and sextupole coils to reach a field of 15 T in the windings. In this paper we describe the design of a Nb 3 Sn superconducting magnet for a fourth generation ECR source operating at a microwave frequency of 56 GHz. The magnet design features a configuration with an internal sextupole magnet surrounded by three solenoids. A finite element magnetic model has been used to investigate conductor peak fields and the operational margins. Results of the numerical analysis are presented and discussed.

MAGNETIC PARAMETERS OF A NB3SN SUPERCONDUCTING MAGNET FOR A 56 HGz ECR ION SOURCE

Energy Technology Data Exchange (ETDEWEB)

Ferracin, P.; Caspi, S.; Felice, H.; Leitner, D.; Lyneis, C. M.; Prestemon, S.; Sabbi, G. L.; Todd, D. S.

2009-05-04

Third generation Electron Cyclotron Resonance (ECR) ion sources operate at microwave frequencies between 20 and 30 GHz and employ NbTi superconducting magnets with a conductor peak field of 6-7 T. A significant gain in performance can be achieved by replacing NbTi with Nb{sub 3}Sn, allowing solenoids and sextupole coils to reach a field of 15 T in the windings. In this paper we describe the design of a Nb{sub 3}Sn superconducting magnet for a fourth generation ECR source operating at a microwave frequency of 56 GHz. The magnet design features a configuration with an internal sextupole magnet surrounded by three solenoids. A finite element magnetic model has been used to investigate conductor peak fields and the operational margins. Results of the numerical analysis are presented and discussed.

Design Concept and Parameters of a 15 T $Nb_{3}Sn$ Dipole Demonstrator for a 100 TEV Hadron Collider

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A. V. [Fermilab; Andreev, N. [Fermilab; Barzi, E. [Fermilab; Kashikhin, V. V. [Fermilab; Novitski, I. [Fermilab

2015-06-01

FNAL has started the development of a 15 T $Nb_{3}Sn$ dipole demonstrator for a 100 TeV scale hadron collider. This paper describes the design concept and parameters of the 15 T $Nb_{3}Sn$ dipole demonstrator. The dipole magnetic, mechanical and quench protection concept and parameters are presented and discussed.

Improved superconductor for transmission line applications, phase I. Final report, January 1, 1975--June 30, 1975

International Nuclear Information System (INIS)

Braginski, A.I.; Mauser, S.F.; Roland, G.W.; Burghardt, R.R.; Daniel, M.R.; Janocko, M.A.

1975-01-01

The analysis of an existing superconducting power transmission cable design indicated that economic benefits in the area of refrigeration can be derived from the substitution of Nb 3 Ge superconductor for the presently planned Nb 3 Sn. However, the cost of Nb 3 Ge must be comparable to that of Nb 3 Sn, which is achievable when preparing Nb 3 Ge by the chemical vapor deposition. Alternatively, technical benefits can be obtained. The most essential and prerequisite requirement is that the Nb 3 Ge critical current density be improved significantly over the present state-of-the art. Other properties of Nb 3 Ge are generally suitable for the transmission line application and/or require only moderate improvements. (auth)

Steering Charge Kinetics of Tin Niobate Photocatalysts: Key Roles of Phase Structure and Electronic Structure.

Science.gov (United States)

Huang, Shushu; Wang, Chunyan; Sun, Hao; Wang, Xiaojing; Su, Yiguo

2018-05-23

Tin niobate photocatalysts with the phase structures of froodite (SnNb 2 O 6 ) and pyrochlore (Sn 2 Nb 2 O 7 ) were obtained by a facile solvothermal method in order to explore the impact of phase structure and electronic structure on the charge kinetics and photocatalytic performance. By employing tin niobate as a model compound, the effects of phase structure over electronic structure, photocatalytic activity toward methyl orange solution and hydrogen evolution were systematically investigated. It is found that the variation of phase structure from SnNb 2 O 6 to Sn 2 Nb 2 O 7 accompanied with modulation of particle size and band edge potentials that has great consequences on photocatalytic performance. In combination with the electrochemical impedance spectroscopy (EIS), transient photocurrent responses, transient absorption spectroscopy (TAS), and the analysis of the charge-carrier dynamics suggested that variation of electronic structure has great impacts on the charge separation and transfer rate of tin niobate photocatalysts and the subsequent photocatalytic performance. Moreover, the results of the X-ray photoelectron spectroscopy (XPS) indicated that the existent of Sn 4+ species in Sn 2 Nb 2 O 7 could result in a decrease in photocatalytic activity. Photocatalytic test demonstrated that the SnNb 2 O 6 (froodite) catalyst possesses a higher photocatalytic activity toward MO degradation and H 2 evolution compared with the sample of Sn 2 Nb 2 O 7 (pyrochlore). On the basis of spin resonance measurement and trapping experiment, it is expected that photogenerated holes, O 2 -• , and OH • active species dominate the photodegradation of methyl orange.

Critical current, electro-mechanical properties and specific heat of bronze Nb{sub 3}Sn conductors

Energy Technology Data Exchange (ETDEWEB)

Uglietti, D.; Seeber, B.; Abacherli, V.; Flukiger, R. [Geneva Univ., Groupe Applique de Physique (GAP) (Switzerland); Wang, X.Y.; Junod, A.; Flukiger, R. [Geneva Univ., Dept. Phys. Mat. Condensee (DPMC) (Switzerland)

2004-07-01

The fabrication process leading to a Nb{sub 3}Sn wire by using the bronze route with 15.4 wt per cent of Sn is described. The critical current density, J{sub c}, is studied as a function of the applied magnetic field, B, up to 25 T; the uniaxial strain, {epsilon}, was measured up to 17. In the second part our device for measuring I{sub c}({epsilon}) is presented. The device is based on the concept of the Walters spring (WASP), which allows to measure long length wires (voltage taps distance up to 50 cm), up to 1000 A and to obtain an absolute measurement of the strain value. It is thus possible to measure the voltage-current relation of technical superconducting wires and tapes down to 0.01 {mu}V/cm, an important requirement for the characterisation in view of applications like NMR high field magnets which require persistent mode operation with high current densities. Finally specific heat measurements on Nb{sub 3}Sn wires prepared at GAP have allowed to determine for the first time the overall distribution of T{sub c} in the filaments. The onset of T{sub c} was observed at 17.2 K, the T{sub c} distribution being centred at 15.9 K. This analysis confirms the reduction of T{sub c} due to the Ti addition and the presence of a distribution of Sn in Nb{sub 3}Sn bronze wires. (authors)

Novel phases and superconductivity of tin sulfide compounds

Science.gov (United States)

Gonzalez, Joseph M.; Nguyen-Cong, Kien; Steele, Brad A.; Oleynik, Ivan I.

2018-05-01

Tin sulfides, SnxSy, are an important class of materials that are actively investigated as novel photovoltaic and water splitting materials. A first-principles evolutionary crystal structure search is performed with the goal of constructing the complete phase diagram of SnxSy and discovering new phases as well as new compounds of varying stoichiometry at ambient conditions and pressures up to 100 GPa. The ambient phase of SnS2 with P 3 ¯ m 1 symmetry remains stable up to 28 GPa. Another ambient phase, SnS, experiences a series of phase transformations including α-SnS to β-SnS at 9 GPa, followed by β-SnS to γ-SnS at 40 GPa. γ-SnS is a new high-pressure metallic phase with P m 3 ¯ m space group symmetry stable up to 100 GPa, which becomes a superconductor with a maximum Tc = 9.74 K at 40 GPa. Another new metallic compound, Sn3S4 with I 4 ¯ 3 d space group symmetry, is predicted to be stable at pressures above 15 GPa, which also becomes a superconductor with relatively high Tc = 21.9 K at 30 GPa.

High field Nb3Sn Axicell insert coils for the Mirror Fusion Test Facility-B (MFTF-B) axicell configuration. Final report

International Nuclear Information System (INIS)

Baldi, R.W.; Tatro, R.E.; Scanlan, R.M.

1984-03-01

Two 12-tesla superconducting insert coils are being designed by General Dynamics Convair Division for the axicell regions of MFTF-B for Lawrence Livermore National Laboratory. A major challenge of this project is to ensure that combined fabrication and operational strains induced in the conductor are within stringent limitations of the relatively brittle Nb 3 Sn superconductor filaments. These coils are located in the axicell region of MFTF-B. They have a clear-bore diameter of 36.195cm (14.25 inches) and consist of 27 double pancakes (i.e., 54 pancakes per coil) would on an electrically insulated 304LN stainless steel/bobbin helium vessel. Each pancake has 57 turns separated by G-10CR insulation. The complete winding bundle has 4.6 million ampere-turns and uniform current density of 2007 A/cm 2 . In conjunction with the other magnets in the system, they produce a 12-tesla central field and a 12.52-tesla peak field. A multifilamentary Nb 3 Sn conductor was selected to meet these requirements. The conductor consists of a monolithic insert soldered into a copper stabilizer. Sufficient cross-sectional area and work-hardening of the copper stabilizer has been provided for the conductor to self-react the electromagnetic Lorentz force induced hoop stresses with normal operational tensile strains less than 0.07 percent

GaN/NbN epitaxial semiconductor/superconductor heterostructures

Science.gov (United States)

Yan, Rusen; Khalsa, Guru; Vishwanath, Suresh; Han, Yimo; Wright, John; Rouvimov, Sergei; Katzer, D. Scott; Nepal, Neeraj; Downey, Brian P.; Muller, David A.; Xing, Huili G.; Meyer, David J.; Jena, Debdeep

2018-03-01

Epitaxy is a process by which a thin layer of one crystal is deposited in an ordered fashion onto a substrate crystal. The direct epitaxial growth of semiconductor heterostructures on top of crystalline superconductors has proved challenging. Here, however, we report the successful use of molecular beam epitaxy to grow and integrate niobium nitride (NbN)-based superconductors with the wide-bandgap family of semiconductors—silicon carbide, gallium nitride (GaN) and aluminium gallium nitride (AlGaN). We apply molecular beam epitaxy to grow an AlGaN/GaN quantum-well heterostructure directly on top of an ultrathin crystalline NbN superconductor. The resulting high-mobility, two-dimensional electron gas in the semiconductor exhibits quantum oscillations, and thus enables a semiconductor transistor—an electronic gain element—to be grown and fabricated directly on a crystalline superconductor. Using the epitaxial superconductor as the source load of the transistor, we observe in the transistor output characteristics a negative differential resistance—a feature often used in amplifiers and oscillators. Our demonstration of the direct epitaxial growth of high-quality semiconductor heterostructures and devices on crystalline nitride superconductors opens up the possibility of combining the macroscopic quantum effects of superconductors with the electronic, photonic and piezoelectric properties of the group III/nitride semiconductor family.

Powder-in-Tube (PIT) Nb3Sn conductors for high-field magnets

NARCIS (Netherlands)

Lindenhovius, J.H.; Hornsveld, E.M.; den Ouden, A.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.

2000-01-01

New Nb3Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment

Development of Nb$_3$Sn coatings by magnetron sputtering for SRF cavities

CERN Document Server

Rosaz, G.; Leaux, F.; Motschmann, F.; Mydlarz, Z.; Taborelli, M.; Vollenberg, W.

2016-01-01

Cost and energy savings are an integral requirement in the design of future particle accelerators. Very low losses SRF accelerating systems, together with high-efficiency cryogenics systems, have the potential of low running costs. The association to the capital cost reduction allowed by thin films coated copper cavities may represent the best overall cost-performance compromise. This strategy has been applied for instance in LEP, the LHC and HIE-ISOLDE with the niobium thin films technology. New materials must be considered to improve the quality factor of the cavities, such as Nb$_{3}$Sn, which could also ideally operate at higher temperature thus allowing further energy savings. The study considers the possibility to coat a copper resonator with an Nb$_{3}$Sn layer by means of magnetron sputtering using an alloyed target. We present the impact of the process parameters on the as-deposited layer stoichiometry. The latter is in good agreement with previous results reported in the literature and can be tuned ...

Self-field instabilities in high-$J_{c}$ Nb$_{3}$Sn strands the effect of copper RRR

CERN Document Server

Bordini, B

2009-01-01

High critical current density (Jc) Nb$_{3}$Sn conductor is the best candidate for next generation high field (> 10 T) accelerator magnets. Although very promising, state of the art high-Jc Nb$_{3}$Sn strands suffer of magneto-thermal instabilities that can severely limit the strand performance. Recently it has been shown that at 1.9 K the self field instability is the dominating mechanism that limits the performance of strands with a low (<10) Residual Resistivity Ratio (RRR) of the stabilizing copper. At CERN several state of the art high–Jc Nb$_{3}$Sn wires have been tested at 4.2 K and 1.9 K to study the effects on strand self-field instability of: RRR and strand impregnation with stycast. To study the effect of the RRR value on magneto-thermal instabilities, a new 2-D finite element model was also developed at CERN. This model simulates the whole development of the flux jump in the strand cross section also taking into account the heat and current diffusion in the stabilizing copper. In this paper th...

Preparation, composition, and solid state investigations of TiN, ZrN, NbN, and compounds from the pseudobinary systems NbN-NbC, NbN-TiC, and NbN-TiN

International Nuclear Information System (INIS)

Christensen, A.N.; Fregerslev, S.

1977-01-01

Single crystals of the cubic phases TiN, ZrN, delta-NbN and of compounds from the pseudobinary systems NbN-NbC, NbN-TiC, and NbN-TiN were obtained by zone melting, zone annealing and annealing of the metal carbides in nitrogen gas of 2 MPa. Single crystals of the tetragonal phase gamma-NbN were obtained in a similar way by annealing of niobium. The nitrides are non-stochiometric. TiN was obtained in the composition range TiNsub(0.99) to TiNsub(0.50), ZrN in the range ZrNsub(1.00) to ZrNsub(0.63), and in niobium nitrides were obtained in the composition range NbNsub(0.90) to NbNsub(0.69). The compounds from the pseudobinary systems have up to 35% vacant sites in the nitrogen-carbon sublattice. TiN and ZrN have only vacant sites in the nitrogen sublattice. A correlation is found between the unit cell parameters for titanium nitride and zirconium nitride and the nitrogen-metal ratios. (orig.) [de

High temperature resistive phase transition in A15 high temperature superconductors

International Nuclear Information System (INIS)

Chu, C.W.; Huang, C.Y.; Schmidt, P.H.; Sugawara, K.

1976-01-01

Resistive measurements were made on A15 high temperature superconductors. Anomalies indicative of a phase transition were observed at 433 0 K in a single crystal Nb 3 Sn and at 485 0 K in an unbacked Nb 3 Ge sputtered thin film. Results are compared with the high temperature transmission electron diffraction studies of Nb 3 Ge films by Schmidt et al. A possible instability in the electron energy spectrum is discussed

Superconductors for pulsed rf accelerators

International Nuclear Information System (INIS)

Campisi, I.E.; Farkas, Z.D.

1985-04-01

The choice of superconducting materials for accelerator rf cavities has been determined in the past only in part by basic properties of the superconductors, such as the critical field, and to a larger extent by criteria which include fabrication processes, surface conditions, heat transfer capabilities and so on. For cw operated cavities the trend has been toward choosing materials with higher critical temperatures and lower surface resistance, from Lead to Niobium, from Niobium to Nb 3 Sn. This trend has been dictated by the specific needs of storage ring cw system and by the relatively low fields which could be reached without breakdown. The work performed at SLAC on superconducting cavities using microsecond long high power rf pulses has shown that in Pb, Nb, and Nb 3 Sn fields close to the critical magnetic fields can be reached without magnetic breakdown

Temperature compensation effects of TiO2 on Ca[(Li1/3Nb2/3)0.8Sn0.2]O3-δ microwave dielectric ceramic

Science.gov (United States)

Hu, Mingzhe; Wei, Huanghe; Xiao, Lihua; Zhang, Kesheng; Hao, Yongde

2017-10-01

The crystal structure and dielectric properties of TiO2-modified Ca[(Li1/3Nb2/3)0.8Sn0.2]O3-δ microwave ceramics are investigated in the present paper. The crystal structure is probed by XRD patterns and their Rietveld refinement, results show that a single perovskite phase is formed in TiO2-modified Ca[(Li1/3Nb2/3)0.8Sn0.2]O3-δ ceramics with the crystal structure belonging to the orthorhombic Pbnm 62 space group. Raman spectra results indicate that the B-site order-disorder structure transition is a key point to the dielectric loss of TiO2-modified Ca[(Li1/3Nb2/3)0.8Sn0.2]O3-δ ceramics at microwave frequencies. After properly modified by TiO2, the large negative temperature coefficient of Ca[(Li1/3Nb2/3)0.8Sn0.2]O3-δ ceramic can be compensated and the optimal microwave dielectric properties can reach 𝜀r = 25.66, Qf = 18,894 GHz and TCF = -6.3 ppm/∘C when sintered at 1170∘C for 2.5 h, which manifests itself for potential use in microwave dielectric devices for modern wireless communication.

Quench protection studies of 11T 2-in-1 Nb$_{3}$Sn dipole models for LHC upgrades

OpenAIRE

Zlobin, AV; Chlachidze, G; Nobrega, F; Novitski, I; Karppinen, M

2014-01-01

CERN and FNAL are developing 11 T Nb3Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb3Sn dipole coil ...

Neutron irradiation effects on in situ Nb3Sn superconducting wires

International Nuclear Information System (INIS)

Hirano, Y.; Fukumoto, M.; Kodaka, H.; Nishijima, S.; Okada, T.; Yoshida, H.

1985-01-01

Three types of ''in situ'' Nb 3 Sn conductors have been studied to determine the detrimental effects of neutron irradiation on critical temperature, critical current and AC losses. It was found that at fluences of 10 18 n/cm 2 , the critical temperature is degraded by approximately 10%. Degradation of AC loss is discussed in comparison with that of critical current density

High field Nb/sub 3/Sn Axicell insert coils for the Mirror Fusion Test Facility-B (MFTF-B) axicell configuration. Final report

Energy Technology Data Exchange (ETDEWEB)

Baldi, R.W.; Tatro, R.E.; Scanlan, R.M.; Agarwal, K.L.; Bailey, R.E.; Burgeson, J.E.; Kim, I.K.; Magnuson, G.D.; Mallett, B.D.; Pickering, J.L.

1984-03-01

Two 12-tesla superconducting insert coils are being designed by General Dynamics Convair Division for the axicell regions of MFTF-B for Lawrence Livermore National Laboratory. A major challenge of this project is to ensure that combined fabrication and operational strains induced in the conductor are within stringent limitations of the relatively brittle Nb/sub 3/Sn superconductor filaments. These coils are located in the axicell region of MFTF-B. They have a clear-bore diameter of 36.195cm (14.25 inches) and consist of 27 double pancakes (i.e., 54 pancakes per coil) would on an electrically insulated 304LN stainless steel/bobbin helium vessel. Each pancake has 57 turns separated by G-10CR insulation. The complete winding bundle has 4.6 million ampere-turns and uniform current density of 2007 A/cm/sup 2/. In conjunction with the other magnets in the system, they produce a 12-tesla central field and a 12.52-tesla peak field. A multifilamentary Nb/sub 3/Sn conductor was selected to meet these requirements. The conductor consists of a monolithic insert soldered into a copper stabilizer. Sufficient cross-sectional area and work-hardening of the copper stabilizer has been provided for the conductor to self-react the electromagnetic Lorentz force induced hoop stresses with normal operational tensile strains less than 0.07 percent.

Quench protection studies of 11T 2-in-1 Nb$_{3}$Sn dipole models for LHC upgrades

CERN Document Server

Zlobin, AV; Nobrega, F; Novitski, I; Karppinen, M

2014-01-01

CERN and FNAL are developing 11 T Nb$_{3}$Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb$_{3}$Sn dipole coil tested in a magnetic mirror configuration.

Influence of two-stage annealing treatment on critical current of bronze-processed multifilamentary Nb/sub 3/Sn superconducting materials

International Nuclear Information System (INIS)

Ochiai, S.; Osamura, K.; Ryoji, M.

1987-01-01

The influence of changes of volume fraction of Nb/sub 3/Sn, grain size and upper critical magnetic field due to two-stage annealing treatment (low temperature annealing to form fine grains + high temperature annealing to raise upper critical magnetic field) on overall critical current and critical current density were studied at magnetic field of 3-15 T. When annealing temperature was low (773-923 K) and the volume fraction of Nb/sub 3/Sn was low in first stage annealing, second stage annealing could raise the overall critical current over the range of the applied magnetic field due to increase in upper critical magnetic field H/sub c2/ and volume fraction of Nb/sub 3/Sn accompanying with reduction in Sn concentration in the bronze matrix, which played a role to reduce residual strain in Nb/sub 3/Sn, leading to high H/sub c2/ although the loss in pinning force arose from the coarsening of the grains. When the annealing temperature was high (973 K) and the Nb/sub 3/Sn was formed until the Sn was consumed in the first stage, second stage annealing could not raise the critical current due to increase in grain size and no effective increase in H/sub c2/. The critical current density at low magnetic fields below several Teslas was reduced by the second stage annealing due to increase in grain size but that at high fields was raised due to increase in high H/sub c2/. The reverse two-stage annealing treatment (high temperature annealing in the first stage+low temperature annealing in the second stage) reduced the H/sub c2/ slightly with increasing second stage annealing temperature and time. The critical current density at low magnetic fields was determined mainly by the grain size and that at high fields was determined by the combination of the upper critical field and grain size

Performance of the first short model 150 mm aperture Nb$_3$Sn Quadrupole MQXFS for the High-Luminosity LHC upgrade

CERN Document Server

Chlachidze, G; Anerella, M; Bossert, R; Cavanna, E; Cheng, D; Dietderich, D; DiMarco, J; Felice, H; Ferracin, P; Ghosh, A; Grosclaude, P; Guinchard, M; Hafalia, A R; Holik, E; Izquierdo Bermudez, S; Krave, S; Marchevsky, M; Nobrega, F; Orris, D; Pan, H; Perez, J C; Prestemon, S; Ravaioli, E; Sabbi, G L; Salmi, T; Schmalzle, J; Stoynev, S; Strauss, T; Sylvester, C; Tartaglia, M; Todesco, E; Vallone, G; Velev, G; Wanderer, P; Wang, X; Yu, M

2017-01-01

The US LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb$_{3}$Sn magnets for the High-Luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb$_{3}$Sn quadrupoles for the LHC interaction regions (IR). These magnets will replace the present 70 mm aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity by a factor of 5. Over the past decade LARP successfully fabricated and tested short and long models of 90 mm and 120 mm aperture Nb$_{3}$Sn quadrupoles. Recently the first short model of 150 mm diameter quadrupole MQXFS was built with coils fabricated both by the LARP and CERN. The magnet performance was tested at Fermilab’s vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence studies.

Performance of the first short model 150 mm aperture Nb$_3$Sn Quadrupole MQXFS for the High- Luminosity LHC upgrade

Energy Technology Data Exchange (ETDEWEB)

Chlachidze, G.; et al.

2016-08-30

The US LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb3Sn magnets for the High-Luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb3Sn quadrupoles for the LHC interaction regions (IR). These magnets will replace the present 70 mm aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity by a factor of 5. Over the past decade LARP successfully fabricated and tested short and long models of 90 mm and 120 mm aperture Nb3Sn quadrupoles. Recently the first short model of 150 mm diameter quadrupole MQXFS was built with coils fabricated both by the LARP and CERN. The magnet performance was tested at Fermilab’s vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence studies.

Formation of hydrothermal tin deposits: Raman spectroscopic evidence for an important role of aqueous Sn(IV) species

Science.gov (United States)

Schmidt, Christian

2018-01-01

The speciation of tin and the solubility of cassiterite in H2O + HCl were determined at temperatures to 600 °C using in situ Raman spectroscopy. In addition, information on the fluid-melt partition of Sn was obtained at 700 °C and indicated a preference of the fluid only at HCl concentrations that are much higher than in fluids exsolved from natural felsic melts. Dissolution of cassiterite generally resulted in formation of Sn(IV) species unless reduced conditions were generated by hydrogen permeation or carbohydrates in the starting material. The prevalent aqueous Sn(IV) species was [SnCl4(H2O)2]0, with additional [SnCl3(H2O)3]+ and [SnCl5(H2O)]-. The only detectable Sn(II) species was very likely [Sn(II)Cl3]-. Cassiterite solubility increased with HCl concentration and was generally high in H2O+HCl fluids, with no strong dependencies on temperature, pressure, or the oxidation state of tin in the fluid. The Sn(IV) concentrations at 500 and 600 °C determined from the integrated ν1[Sn(IV)sbnd Cl] band intensity are in good agreement with literature data on the cassiterite solubility in H2O + HCl at oxygen fugacities along the hematite-magnetite buffer. The combined results from previous experimental studies and this study demonstrate that HCl molality is a crucial parameter for hydrothermal mobilization and transport of tin and for cassiterite precipitation, and that pH, pressure and temperature are less important. Current models on hydrothermal tin deposit formation need to be augmented to include Sn(IV)sbnd Cl complexes as significant tin-transporting species. Irrespective of the oxidation state of tin in the fluid, cassiterite precipitates due to reaction of the hydrothermal fluid with the wall rock (greisen or skarn formation), dilution (mixing with meteoric water) or a decrease in the HCl activity in the aqueous liquid by boiling. A redox reaction is only required for tin transported as Sn(II) to be converted to Sn(IV).

Creep properties of annealed Zr-Nb-O and stress-relieved Zr-Nb-Sn-Fe cladding tubes and their performance comparison

International Nuclear Information System (INIS)

Ko, S.; Hong, S.I.; Kim, K.T.

2010-01-01

Creep properties of annealed Zr-Nb-O and stress-relieved Zr-Nb-Sn-Fe cladding tubes were studied and compared. The creep rates of the annealed Zr-Nb-O alloy were found to be greater than those of the stress-relieved Zr-Nb-Sn-Fe alloy. Zr-Nb-O alloy was found to have stress exponents of 5-7 independent of stress level whereas Zr-Nb-Sn-Fe alloy exhibited the transition of the stress exponent from 6.5 to 7.5 in the lower stress region to ∼4.2 in the higher stress region. The reduction of stress exponent at high stresses in Zr-Nb-Sn-Fe can be explained in terms of the dynamic solute-dislocation effect caused by Sn atoms. The constancy of stress exponent without the transition was observed in Zr-Nb-O alloy, supporting that the decrease of the stress exponent with increasing stress in Zr-Nb-Sn-Fe is associated with Sn atoms. The difference of creep life between annealed Zr-Nb-O and stress-relieved Zr-Nb-Sn-Fe is not large considering the large difference of strength level between annealed Zr-Nb-O and annealed stress-relieved Zr-Nb-Sn-Fe. The better-than-expected creep life of annealed Zr-Nb-O alloy can be attributable to the combined effects of creep ductility enhancement associated with softening and the decreased contribution of grain boundary diffusion due to the increased grain size.

An alkaline tin(II) halide compound Na{sub 3}Sn{sub 2}F{sub 6}Cl: Synthesis, structure, and characterization

Energy Technology Data Exchange (ETDEWEB)

Gong, Pifu [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Luo, Siyang [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Huang, Qian; Yang, Yi [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Jiang, Xingxing [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Liang, Fei [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Chen, Chuangtian [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Lin, Zheshuai, E-mail: zslin@mail.ipc.ac.cn [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China)

2017-04-15

A new alkali tin(II) halide compound, Na{sub 3}Sn{sub 2}F{sub 6}Cl, is synthesized by hydrothermal method. This compound crystallizes trigonally in space group of R-3c (167), and processes a zero-dimensional (0D) structure consisted of Na{sup +} cations, Cl{sup −} anions and the isolated [SnF{sub 3}]{sup -} trigonal pyramids in which the stereochemically active 5s{sup 2} lone pair electrons are attached to the Sn{sup 2+} cations. Interestingly, the [SnF{sub 3}]{sup −} trigonal pyramids are parallel arranged in the a-b plane, while oppositely arranged in line with rotation along the c- axis. Moreover, the energy bandgap, thermal stability and electronic structure of Na{sub 3}Sn{sub 2}F{sub 6}Cl are characterized and the results reveal that this compound has and indirect bandgap of 3.88 eV and is stable under 270 °C. - Graphical abstract: A zero-dimensional alkaline tin halide compound, Na{sub 3}Sn{sub 2}F{sub 6}Cl, is synthesized by hydrothermal method. Interestingly, both the anions and cations coordinating polyhedra exhibit order arranged with the [SnF{sub 3}]{sup -} trigonal pyramids rotating along the c- axis.

Validation of Finite-Element Models of Persistent-Current Effects in Nb3Sn Accelerator Magnets

International Nuclear Information System (INIS)

Wang, X.; Ambrosio, G.; Chlachidze, G.; Collings, E. W.; Dietderich, D. R.; DiMarco, J.; Felice, H.; Ghosh, A. K.; Godeke, A.; Gourlay, S. A.; Marchevsky, M.; Prestemon, S. O.; Sabbi, G.; Sumption, M. D.; Velev, G. V.; Xu, X.; Zlobin, A. V.

2015-01-01

Persistent magnetization currents are induced in superconducting filaments during the current ramping in magnets. The resulting perturbation to the design magnetic field leads to field quality degradation, in particular at low field where the effect is stronger relative to the main field. The effects observed in NbTi accelerator magnets were reproduced well with the critical-state model. However, this approach becomes less accurate for the calculation of the persistent-current effects observed in Nb 3 Sn accelerator magnets. Here a finite-element method based on the measured strand magnetization is validated against three state-of-art Nb3Sn accelerator magnets featuring different subelement diameters, critical currents, magnet designs and measurement temperatures. The temperature dependence of the persistent-current effects is reproduced. Based on the validated model, the impact of conductor design on the persistent current effects is discussed. The performance, limitations and possible improvements of the approach are also discussed

Fabrication and Analysis of 150 mm Aperture Nb$_{3}$Sn LARP MQXF Coils

CERN Document Server

Holik, E F; Anerella, M; Bossert, R; Cavanna, E; Cheng, D; Dietderich, D R; Ferracin, P; Ghosh, A K; Izquierdo Bermudez, S; Krave, S; Nobrega, A; Perez, J C; Pong, I; Rochepault; Sabbi, G L; Schmalzle, J; Yu, M

2016-01-01

The US LHC Accelerator Research Program (LARP) and CERN are combining efforts for the HiLumi-LHC upgrade to design and fabricate 150 mm aperture, interaction region quadrupoles with a nominal gradient of 130 T/m using Nb$_{3}$Sn. To successfully produce the necessary long MQXF triplets, the HiLumi-LHC collaboration is systematically reducing risk and design modification by heavily relying upon the experience gained from the successful 120 mm aperture LARP HQ program. First generation MQXF short (MQXFS) coils were predominately a scaling up of the HQ quadrupole design allowing comparable cable expansion during Nb$_{3}$Sn formation heat treatment and increased insulation fraction for electrical robustness. A total of 13 first generation MQXFS coils were fabricated between LARP and CERN. Systematic differences in coil size, coil alignment symmetry, and coil length contraction during heat treatment are observed and likely due to slight variances in tooling and insulation/cable systems. Analysis of coil cross sect...

Electron microscopic observation at low temperature on superconductors

International Nuclear Information System (INIS)

Yokota, Yasuhiro; Hashimoto, Hatsujiro; Yoshida, Hiroyuki.

1991-01-01

The authors have observed superconducting materials with a high resolution electron microscope at liquid helium temperature. First, observation was carried out on Nb system intermetallic compounds such as Nb 3 Al and Nb 3 Sn of Al 5 type and Nb 3 Ge of 11 type at extremely low temperature. Next, the observation of high temperature superconductive ceramics in the state of superconductivity was attempted. In this paper, first the development of the liquid helium sample holder for a 400 kV electron microscope to realize the observation is reported. Besides, the sample holder of Gatan Co. and an extremely low temperature, high resolution electron microscope with a superconducting lens are described. The purpose of carrying out the electron microscope observation of superconductors at low temperature is the direct observation of the crystalline lattice image in the state of superconductivity. Also the structural transformation from tetragonal crystals to rhombic crystals in Al 5 type superconductors can be observed. The results of observation are reported. (K.I.)

VAMAS Nb3Sn test conductor

International Nuclear Information System (INIS)

Anon.

1994-01-01

A bronze-process Nb 3 Sn conductor was measured as part of the second VAMAS (Versailles Project on Advanced Materials and Standards) international critical-current round robin. The conductor specifications are given in Table 15. The critical current was measured as a function of magnetic field and axial tensile strain. The measured data are presented in Table 16 and in Figs. 23 and 24. The I c and J c values are based on an electric field criterion (E c ) of 1 μV/cm. In the first VAMAS round robin tests, differences in the test specimens' axial strain, caused by variations in the thermal contraction of different test fixtures, was a major source of interlaboratory variation in the critical-current data. Consequently, electromechanical characterization of the test specimen is important for data interpretation and error analysis. In the second round robin, the test apparatus and procedure were more rigidly specified. This increased experimental control reduced the critical-current variation by a factor of 3.5. The results of our measurements will be published in the final VAMAS report

DESIGN, FABRICATION AND TEST OF THE REACT AND WIND, NB(3)SN, LDX FLOATING COIL CONDUCTOR

International Nuclear Information System (INIS)

SMITH, B.A.; MICHAEL, P.C.; MINERVINI, J.V.; TAKAYASU, M.; SCHULTZ, J.H.; GREGORY, E.; PYON, T.; SAMPSON, W.B.; GHOSH, A.; SCANLAN, R.

2000-01-01

The Levitated Dipole Experiment (LDX) is a novel approach for studying magnetic confinement of a fusion plasma. In this approach, a superconducting ring coil is magnetically levitated for up to 8 hours a day in the center of a 5 meter diameter vacuum vessel. The levitated coil, with on-board helium supply, is called the gloating Coil (F-Coil). Although the maximum field at the coil is only 5.3 tesla, a react-and-wind Nb 3 Sn conductor was selected because the relatively high critical temperature will enable the coil to remain levitated while it warms from 5 K to 10 K. Since pre-reacted Nb 3 Sn tape is no longer commercially available, a composite conductor was designed that contains an 18 strand Nb 3 Sn Rutherford cable. The cable was reacted and then soldered into a structural copper channel that completes the conductor and also provides quench protection. The strain state of the cable was continuously controlled during fabrication steps such as: soldering into the copper channel, spooling, and coil winding, to prevent degradation of the critical current. Measurements of strand and cable critical currents are reported, as well as estimates of the effect of fabrication, winding and operating strains on critical current

Mechanical behavior of Nb{sub 3}Sn strands under transverse electromagnetic loads

Energy Technology Data Exchange (ETDEWEB)

Ru, Yanyun; Yong, Huadong, E-mail: yonghd@lzu.edu.cn; Zhou, Youhe

2016-11-15

Highlights: • The contact forces between the strands under transverse electromagnetic load are considered. • The indentation depth for two-dimensional contact problem is calculated. • The strand damage for different layers is presented. • We discuss the effect of bending wavelength on the Nb{sub 3}Sn strand. - Abstract: The performance of Nb{sub 3}Sn cable-in-conduit-conductor (CICC) shows a significant degradation with increasing electromagnetic load in the International Thermonuclear Experimental Reactor (ITER). As the strand is under the compression caused by adjacent strands, the strand damage may occur for high contact force. In this paper, we present a 3D helix model based on the TEMLOP and FEMCAM to simulate the contact force among the strands under transverse load. The maximum linear strain and indentation depth induced by contact stress are calculated with two-dimensional contact model of cylinder. The numerical results are compared with the experimental values. Finally, the indentation depth is discussed for different layers and cross angles based on two models. With the increasing of layer number, the degradation of performance will occur. The short bending wavelength leads to small indentation depth.

Magnetic and mechanical design of a 130 mm aperture Nb{sub 3}Sn dipole magnet

Energy Technology Data Exchange (ETDEWEB)

Felice, H.; Vedrine, P. [CEA Saclay, DAPNIA/SACM/LEAS, F-91191 Gif Sur Yvette, (France); Mailfert, A. [LEM, F-54500 Vandoeuvre Les Nancy, (France)

2007-07-01

For the next generation of dipoles for accelerators, two main challenges come into play. In one hand, high dipolar fields in the range of 13 to 15 T are targeted. In the other hand, large apertures (above 80 mm) are required in the interaction regions. These two requirements lead to two issues. First, a new superconductor has to replace the NbTi as its limits have been reached around 10 T with the LHC. The superconducting material liable to be its successor is the Nb{sub 3}Sn. However, it is a very mechanical stress sensitive material. Up to now, a mechanical stress of 150 MPa is supposed to degrade its critical properties. Second, large aperture dipole can not be considered with the well-known cosine theta design. Indeed, above 88 mm, azimuthal Lorentz forces in this magnetic configuration produces mechanical stresses on the coil midplane higher than the acceptable limit. In this paper, an alternative coil arrangement based on intersecting ellipses and limiting the mechanical stresses is proposed for a 130 mm aperture dipole. The first part of this paper is dedicated to the magnetic study of this magnet. We can underline the fact that the field quality required in particle accelerators can be reached with a bore field of about 13 T. The second part deals with the mechanical structure of the magnet which is necessary to withstand the Lorentz forces involved and to apply pre-stress. (authors)

Development of multifilamentary NbTi and Nb3Sn composite conductors with very fine filaments

International Nuclear Information System (INIS)

Ogasawara, T.; Hubota, T.; Makiura, T.; Oda, Y.; Okon, H.; Yasohama, K.

1986-01-01

A NbTi multifilamentary composite conductor with about 10,000 filaments has been manufactured in long lengths. A filament diameter of 0.52 μm, a twist pitch of 1.13 mm, a strand diameter of 0.1 mm and a Cu/CuNi mixed matrix result in strongly reduced a.c. losses. The hysteresis loss and the coupling loss are 73 kW/m 3 and 56 kW/m 3 for a 50 Hz magnetic field with an amplitude of 1.5 T. From three strands a conductor was formed with a twist pitch of 2.4 mm. Several small coils were wound and operated at 50 Hz. One of the coils generated a maximum field of 1.52 T(center) at an operating current of the same size as the static critical current. Similarily the construction of a Nb 3 Sn multifilamentary composite conductor with about 280,000 sub-micron filaments for a.c. use was tried

Effect of annealing temperature on microstructure and superelastic properties of a Ti-18Zr-4.5Nb-3Sn-2Mo alloy.

Science.gov (United States)

Fu, Jie; Kim, Hee Young; Miyazaki, Shuichi

2017-01-01

In this study a new superelastic Ti-18Zr-4.5Nb-3Sn-2Mo alloy was prepared by adding 2at% of Mo as a substitute for Nb to the Ti-18Zr-11Nb-3Sn alloy, and heat treatment at different temperatures was conducted. The temperature dependence of superelasticity and annealing texture was investigated. Texture showed a dependence of annealing temperature: the specimen annealed at 923K for 0.3ks exhibited {113} β β type texture which was similar to the deformation texture, while specimens annealed at 973, 1073K, and 1173K showed {001} β β type recrystallization texture which was preferable for recovery strain. The largest recovery strain of 6.2%, which is the same level as that of the Ti-18Zr-11Nb-3Sn alloy, was obtained in the specimen annealed at 1173K for 0.3ks due to the well-developed {001} β β type recrystallization texture. The Ti-18Zr-3Nb-3Sn-2Mo alloy presented a higher tensile strength compared with the Ti-18Zr-11Nb-3Sn alloy when heat treated at 1173K for 0.3ks, which was due to the solid solution strengthening effect of Mo. Annealing at 923K for 0.3ks was effective in obtaining a good combination of a high strength as 865MPa and a large recovery strain as 5.6%. The high recovery strain was due to the high stress at which the maximum recovery stain was obtained which was attributed to the small grain size formed at low annealing temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Superconductors with low critical temperature for electro-magnets

International Nuclear Information System (INIS)

Devred, A.

2002-07-01

Among the superconductors with low critical temperature that are used to build magnets, NbTi has reached a development state that allows a massive production for big equipment of physics and an industrial production in the domain of medicine imaging. The material that might challenge the supremacy of NbTi is Nb 3 Sn but some technical difficulties have yet to be overcome. This report begins with a review of the different industrial processes used to produce superconducting wires based on the NbTi and Nb 3 Sn materials. The transition from the superconducting state to the resistive normal state is described for both materials, the magnetizing of multi-wire superconducting cables is also presented. The author details the different patterns of wires in cables and proposes a formulary that allows the determination, in some simple cases,of energy losses that are generated in a superconducting cable by a variable magnetic field. (A.C.)

Low critical temperature superconductors for electromagnets; Supraconducteurs a basse temperature critique pour electroaimants

Energy Technology Data Exchange (ETDEWEB)

Devred, A

2002-07-01

After a brief history of the main discoveries in applied superconductivity (section 1), we discuss the structure and properties of NbTi and Nb3 Sn (section 2). Then, we explain why low critical-temperature superconductors are produced under the form of multifilamentary composites (section 3), and we review the manufacturing processes of NbTi and Nb3Sn wires (section 4). We follow by a description of the transition from the superconducting to the normal resistive state of multifilamentary composite wires (section 5) and we detail their magnetization properties section 6). Last, we present the most commonly used cable configurations (section 7) and we provide simple formulae illustrating on a few examples the computation of losses generated under time-varying magnetic fields (section 8). (author)

The preparation of Nb3Ge thin film superconductors in a UHV evaporation and sputter device

International Nuclear Information System (INIS)

Krevet, B.; Schauer, W.; Wuechner, F.

1978-10-01

Thin film techniques like evaporation or sputtering are remarkbly suitable to vary the metallurgical and physical properties of superconductors in a wide range. In the case of the A15-compound Nb 3 Ge only these preparation techniques allow us to produce a metastable pure phase in stoichiometric composition and to study its superconducting properties. The presen report describes two UHV-plants to produce superconducting films by multisource coevaporation and cosputtering. Of special importance are the constancy, monitoring and control of the evaporation rate, and the thermalization of the sputter components on the other hand. The experimental methods used are explained in detail and discussed together with the results of Nb 3 Ge films. With the preparation parameters suitably chosen both techniques allow to prepare reproducibly Nb 3 Ge films with 21 K transition temperature (onset); under optimized conditions Tc values up to 22.3 K have been reached. (orig.) [de

Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi_{2}Se_{3}

Directory of Open Access Journals (Sweden)

Tomoya Asaba

2017-01-01

Full Text Available The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi_{2}Se_{3} is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb-doped Bi_{2}Se_{3}. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi_{2}Se_{3}.

Flux-assisted synthesis of SnNb2O6 for tuning photocatalytic properties

KAUST Repository

Noureldine, Dalal

2014-01-01

A flux-assisted method was used to synthesize SnNb2O6 as a visible-light-responsive metal oxide photocatalyst. The role of flux was investigated in detail using different flux to reactant molar ratios (1 : 1, 3 : 1, 6 : 1, 10 : 1, and 14 : 1) and different reaction temperatures (300, 500, and 600 °C). The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), the Brunauer-Emmett-Teller method (BET), and high resolution scanning transmission electron microscopy (HRTEM). Flux-assisted synthesis led to tin niobate particles of platelet morphology with smooth surfaces. The synthesized crystal showed a 2D anisotropic growth along the (600) plane as the flux ratio increased. The particles synthesized with a high reactant to flux ratio (1 : 10 or higher) exhibited slightly improved photocatalytic activity for hydrogen evolution from an aqueous methanol solution under visible radiation (λ > 420 nm). The photo-deposition of platinum and PbO2 was examined to gain a better understanding of electrons and hole migration pathways in these layered materials. The HR-STEM observation revealed that no preferential deposition of these nanoparticles was observed depending on the surface facets of SnNb 2O6. This journal is © the Partner Organisations 2014.

Contribution to the design of superconducting Nb3Sn dipole windings for particle accelerator

International Nuclear Information System (INIS)

Felice, H.

2006-10-01

Improvement of particle accelerators relies on complex technologies such as the design and fabrication of superconducting magnets. A key parameter in magnet design is the mechanical pre-stress, applied at room temperature to insure compression of the coil during excitation. In dipole magnets, high field and high mechanical stresses in windings combined with the Nb 3 Sn stress sensitivity ask the question of the limit of the mechanical stress that the Nb 3 Sn can undergo without degradation. This limit estimated around 150 MPa is still discussed and has to be investigated. Whatever its value, preliminary studies show that conventional cosine theta design induces mechanical stresses (> 200 MPa) in large aperture (> 130 mm) and high field configurations, which underscore the need of alternative coil arrangements. The first part of this thesis gives an introduction to the issues and challenges encountered by the designers of superconducting ma nets. The second part is devoted to the study of large aperture (88, 130 and 160 mm) and high field (13 T) dipoles based on intersecting ellipses. After a theoretical study, a 2D magnetic design is detailed for each aperture and a mechanical study is developed for the 130 mm aperture dipole. In the last part, an experimental device dedicated to the study of the influence of the pre-stress on the training of sub-scale Nb 3 Sn dipole and to the investigation of the mechanical stress limit is presented. The design of this magnet is detailed and the result of the first test carried out with the structure is reported. (author)

Specific heat of Nb3Sn and V2Zr compounds irradiated with high fluences fast neutrons

International Nuclear Information System (INIS)

Kar'kin, A.E.; Mirmel'shtejn, A.V.; Arkhipov, V.E.; Goshchitskij, B.N.

1987-01-01

Specific heat of Nb 3 Sn (structure A15) and V 2 Zr (C15) specimens irradiated with high fluences of bast neutrons has been measured. It is shown that in these compounds the temperature reduction of superconducting transition T c under neutron irradiation is accompanied with high decrease of N(E F ). Phonon spectrum of the irradiated V 2 Zr (amorphous phase) on the whole is harder, than at an initial state, for irradiated Nb 3 Sn state (disordered crystalline structure) phonon spectrum is differ weakly from initial one. General regularities of parameter change of electron and phonon subsystems for A15 compounds investigated here and earlier (V 3 Si, Mo 3 Si, Mo 3 Ge) have been analysed

Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands

CERN Document Server

Bordini, B; Fehér, S; Rossi, L; Zlobin, A V

2008-01-01

Recent advancements in the critical current density (Jc) of Nb$_{3}$Sn conductors, coupled with a large effective filament size, have drawn attention to the problem of magnetothermal instabilities. At low magnetic fields, the quench current of such high Jc Nb$_{3}$Sn strands is significantly lower than their critical current because of the above-mentioned instabilities. An adiabatic model to calculate the minimum current at which a strand can quench due to magneto-thermal instabilities is developed. The model is based on an 'integral' approach already used elsewhere [1]. The main difference with respect to the previous model is the addition of the self-field effect that allows to describe premature quenches of non-magnetized Nb$_{3}$Sn strands and to better calculate the quench current of strongly magnetized strands. The model is in good agreement with experimental results at 4.2 K obtained at Fermilab using virgin Modified Jelly Roll (MJR) strands with a low Residual Resistivity Ratio (RRR) of the stabilizin...

Manufacturing development of the Westinghouse Nb3Sn coil for the Large Coil Test Program

International Nuclear Information System (INIS)

Young, J.L.; Vota, T.L.; Singh, S.K.

1983-01-01

The Westinghouse Nb 3 Sn Magnet for the Oak Ridge National Laboratory Large Coil Program (LCP) is currently well into the manufacturing phase. This paper identifies the manufacturing processes and development tasks for his unique, advanced coil

Voltage current characteristics of type III superconductors

International Nuclear Information System (INIS)

Dorofejev, G.L.; Imenitov, A.B.; Klimenko, E.Y.

1980-01-01

An adequate description of voltage-current characteristics is important in order to understand the nature of high critical current for the electrodynamic construction of type-III superconductors and for commercial superconductor specification. Homogeneous monofilament and multifilament Nb-Ti, Nb-Zr,Nb 3 Sn wires were investigated in different ranges of magnetic field, temperature and current. The shape of the voltage-current characteristics of multifilament wires, and the parameter's dependence on temperature and magnetic field may be explained qualitatively by the longitudinal heterogeneous nature of the filaments. A method of attaining the complete specification of the wire's electro-physical properties is proposed. It includes the traditional description of a critical surface (i.e. the surface corresponding to a certain conventional effective resistivity in T,B,J-space) and a description of any increasing parameter that depends on B and T. (author)

Voltage current characteristics of type III superconductors

Energy Technology Data Exchange (ETDEWEB)

Dorofeiev, G L; Imenitov, A B; Klimenko, E Y [Gosudarstvennyi Komitet po Ispol' zovaniyu Atomnoi Ehnergii SSSR, Moscow. Inst. Atomnoi Ehnergii

1980-06-01

An adequate description of voltage-current characteristics is important in order to understand the nature of high critical current for the electrodynamic construction of type-III superconductors and for commercial superconductor specification. Homogeneous monofilament and multifilament Nb-Ti, Nb-Zr,Nb/sub 3/Sn wires were investigated in different ranges of magnetic field, temperature and current. The shape of the voltage-current characteristics of multifilament wires, and the parameter's dependence on temperature and magnetic field may be explained qualitatively by the longitudinal heterogeneous nature of the filaments. A method of attaining the complete specification of the wire's electro-physical properties is proposed. It includes the traditional description of a critical surface (i.e. the surface corresponding to a certain conventional effective resistivity in T,B,J-space) and a description of any increasing parameter that depends on B and T.

Analytical model of the critical current of a bent Nb3Sn strand

International Nuclear Information System (INIS)

Koizumi, Norikiyo; Murakami, Haruyuki; Hemmi, Tsutomu; Nakajima, Hideo

2011-01-01

The critical current performance of a large Nb 3 Sn cable-in-conduit conductor (CICC) was degraded by periodic bending of strands due to a large transverse electromagnetic force. The degradation of each strand due to this bending should be evaluated in calculations of the critical current of a CICC, but a suitable model has not been developed yet. Therefore, the authors have developed a new analytical model which takes into account plastic deformation of copper and bronze and filament breakage. The calculated results were compared with test results for uniformly bent Nb 3 Sn bronze-route strands. The calculated results assuming a high transverse resistance model (HTRM) show good agreement with the test results, a finding which confirms the validity of the model. Because of a much shorter calculation time than for numerical simulation, the developed model seems much more practical for use in calculating the critical current performance of a Nb 3 Sn CICC. In addition, simulation results show that since the neutral axis of a bent strand shifts to the compressive side due to plastic deformation of the copper and bronze, and/or filament breakage, the strand is elongated by bending. This elongation may enhance the strand's critical current performance. Moreover, the calculated results indicate that the dependence of the critical current on the bending strain is affected by the bending history if the strand is excessively bent, especially when filaments are broken. In a real magnet, since a strand in a CICC is normally subject to the maximum electromagnetic force prior to an evaluation of its performance at a lower electromagnetic force, the effect of over-bending should be taken into account in calculations of its critical current performance, especially when filament breakage occurs.

Transverse load optimization in Nb3Sn CICC design; influence of cabling, void fraction and strand stiffness

International Nuclear Information System (INIS)

Nijhuis, A; Ilyin, Y

2006-01-01

We have developed a model that describes the transverse load degradation in Nb 3 Sn CICCs, based on strand and cable properties, and that is capable of predicting how such degradation can be prevented. The Nb 3 Sn cable in conduit conductors (CICCs) for the International Thermonuclear Experimental Reactor (ITER) show a significant degradation in their performance with increasing electromagnetic load. Not only do the differences in the thermal contraction of the composite materials affect the critical current and temperature margin, but mostly electromagnetic forces cause significant transverse strand contact and bending strain in the Nb 3 Sn layers. Here, we present the model for transverse electro-magnetic load optimization (TEMLOP) and report the first results of computations for the ITER type of conductors, based on the measured properties of the internal tin strand used for the toroidal field model coil (TFMC). As input, the model uses data describing the behaviour of single strands under periodic bending and contact loads, measured with the TARSIS set-up, enabling a discrimination in performance reduction per specific load and strand type. The most important conclusion of the model computations is that the problem of the severe degradation of large CICCs can be drastically and straightforwardly improved by increasing the pitch length of subsequent cabling stages. It is the first time that an increase of the pitches has been proposed and no experimental data are available yet to confirm this beneficial outcome of the TEMLOP model. Larger pitch lengths will result in a more homogeneous distribution of the stresses and strains in the cable by significantly moderating the local peak stresses associated with the intermediate-length twist pitches. The twist pitch scheme of the present conductor layout turns out to be unfortunately close to a worst-case scenario. The model also makes clear that strand bending is the dominant mechanism causing degradation. The

Effect of bronze on the compression of Nb3Sn in multifilamentary conductors

International Nuclear Information System (INIS)

Rupp, G.

1978-01-01

Nb 3 Sn in multifilamentary conductors is subject to compressive strain as a result of the relatively small thermal contraction of the filaments as compared to bronze. The critical current Isub(c) is consequently degraded. The critical current increases, when an external tensile stress is applied, and passes through a maximum. The ratio of the maximum critical current to the initial critical current increases with the flux density and reaches a value of two at a flux density of 16 T for technical conductors. The strain epsilonsub(m), at which Isub(c) maximum is reached, lies between 0.4% and 0.7% for the conductors investigated and depends on the material parameters. For a constant ratio of bronze to filament cross section this strain epsilonsub(m) is reduced as the Nb 3 Sn layer thickness is increased and can be determined approximately by a graphical method from the stress-strain diagram. Epsilonsub(m) is to a large extent dependent on the metallurgical properties of bronze, which vary to a considerable extent depending upon the heat treatment. (author)

Nb3Sn accelerator magnet technology scale up using cos-theta dipole coils

Energy Technology Data Exchange (ETDEWEB)

Nobrega, F.; Andreev, N.; Ambrosio, G.; Barzi, E.; Bossert, R.; Carcagno, R.; Chlachidze, G.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; /Fermilab

2007-06-01

Fermilab is working on the development of Nb{sub 3}Sn accelerator magnets using shell-type dipole coils and the wind-and-react method. As a part of the first phase of technology development, Fermilab built and tested six 1 m long dipole model magnets and several dipole mirror configurations. The last three dipoles and two mirrors reached their design fields of 10-11 T. The technology scale up phase has started by building 2 m and 4 m dipole coils and testing them in a mirror configuration in which one of the two coils is replaced by a half-cylinder made of low carbon steel. This approach allows for shorter fabrication times and extensive instrumentation preserving almost the same level of magnetic field and Lorentz forces in the coils as in a complete dipole model magnet. This paper presents details on the 2 m (HFDM07) and 4 m long (HFDM08) Nb{sub 3}Sn dipole mirror magnet design and fabrication technology, as well as the magnet test results which are compared with 1 m long models.

Nb3Sn accelerator magnet technology scale up using cos-theta dipole coils

International Nuclear Information System (INIS)

Nobrega, F.; Andreev, N.; Ambrosio, G.; Barzi, E.; Bossert, R.; Carcagno, R.; Chlachidze, G.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Fermilab

2007-01-01

Fermilab is working on the development of Nb 3 Sn accelerator magnets using shell-type dipole coils and the wind-and-react method. As a part of the first phase of technology development, Fermilab built and tested six 1 m long dipole model magnets and several dipole mirror configurations. The last three dipoles and two mirrors reached their design fields of 10-11 T. The technology scale up phase has started by building 2 m and 4 m dipole coils and testing them in a mirror configuration in which one of the two coils is replaced by a half-cylinder made of low carbon steel. This approach allows for shorter fabrication times and extensive instrumentation preserving almost the same level of magnetic field and Lorentz forces in the coils as in a complete dipole model magnet. This paper presents details on the 2 m (HFDM07) and 4 m long (HFDM08) Nb 3 Sn dipole mirror magnet design and fabrication technology, as well as the magnet test results which are compared with 1 m long models

Microscopic superconducting parameters from tunneling in A15 Nb-Sn

International Nuclear Information System (INIS)

Rudman, D.A.; Beasley, M.R.

1984-01-01

High-quality tunnel junctions have been fabricated on thin films of A15 Nb-Sn (20--25 at. %) using oxidized a-Si tunnel barriers and Pb counterelectrodes. These junctions have been used to measure changes in the gap, the transition temperature T/sub c/, and the tunneling density of states with composition in this important high-T/sub c/ superconductor. With the use of the proximity-effect-modified data reduction scheme developed by Arnold and Wolf, values for α 2 F(ω) and μ( are obtained. As the Sn content approaches stoichiometry, the lowest-energy phonon branch in α 2 F(ω) both increases in weight and shifts to lower energy. These two effects combine to produce the increases in lambda as stoichiometry is approached, and at the same time can account for the observed increase in 2Δ/k/sub B/T/sub c/. The values of μ( remain essentially constant as a function of composition, and hence show no evidence for an increased Coulomb interaction with increasing disorder as recently proposed by Anderson et al

Influence of heating rates on in situ resistance measurements of a bronze route Nb-Sn-Cu-Ta multifilamentary conductor

International Nuclear Information System (INIS)

Tan, K.S.; Hopkins, S.C.; Glowacki, B.A.

2004-01-01

The superconducting properties of a bronze process multifilamentary conductor are controlled by the structure, dimensions and composition of the intermetallic layers, which are strongly influenced by the details of the heat treatments applied to the conductor. It has previously been reported that the electrical resistivity of a Vacuumschmelze bronze process conductor varies during heat treatment, and that analysis of the conductor as a set of parallel resistors allows the features of the resistivity variation to be assigned to the progress of Nb 3 Sn intermetallic phase formation. The behaviour of NSP2 Nb-Sn-Cu-Ta bronze process multifilamentary conductors (Imperial Metal Industries) is now reported as a function of the heating rate, in preparation for more complex non-isothermal heat treatment procedures. It is shown that the resistance of the wire measured in situ by an alternating current (AC) technique can be used to observe the progress of the formation of Nb 3 Sn, and that the comparison of resistometric measurements at different heating rates can give an indication of other processes (such as recovery and recrystallisation) occurring at lower temperatures during the heating up process prior to isothermal annealing. In addition, this wire containing only about 1% of copper was carefully chosen because of the broken tantalum barriers around individual copper filaments. Therefore, the resistometric measurements were used to attempt to detect the diffusion of tin from the bronze matrix into the copper filaments at lower temperatures without noticeable influence on Nb 3 Sn phase formation. Treating the NSP2 wire as a set of parallel resistors also permits estimates to be made of the intermetallic layer thicknesses from resistometric measurements, and these are shown to be in good agreement with estimates from scanning electron microscopy. The difference in critical temperature, T c , between wires heated at different rates, with the presence of the bronze matrix

Magnetic Analysis of a Single-Aperture 11T Nb3Sn Demonstrator Dipole for LHC Upgrades

Energy Technology Data Exchange (ETDEWEB)

Auchmann, B. [CERN; Karppinen, M. [CERN; Kashikhin, V. [Fermilab; Zlobin, A. V. [Fermilab

2012-05-01

The planned upgrade of the LHC collimation system foresees additional collimators to be installed in the dispersion suppressor areas around points 2, 3, and 7. The necessary longitudinal space for the collimators could be provided by replacing some 8.33-T 15-m-long NbTi LHC main dipoles with shorter 11-T Nb3Sn dipoles compatible with the LHC lattice and main systems. To demonstrate this possibility, in 2011 Fermilab and CERN started a joint R&D program with the goal of building a 5.5-m-long tw in-aperture dipole prototype suitable for installation in the LHC by 2014. The first step of this program is the development of a 2-m-long single-aperture demonstration dipole with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and 60-m m bore with ~20% margin. This paper presents the results of magnetic analysis of the single-aperture Nb3Sn demonstrator dipole for the LHC collimation system upgrade.

Nb3Sn Quadrupoles Designs For The LHC Upgrades

International Nuclear Information System (INIS)

Felice, Helene

2008-01-01

In preparation for the LHC luminosity upgrades, high field and large aperture Nb 3 Sn quadrupoles are being studied. This development has to incorporate all the relevant features for an accelerator magnet like alignment and cooling channels. The LARP HQ model is a high field and large bore quadrupole that will meet these requirements. The 2-layer coils are surrounded by a structure based on key and bladder technology with supporting iron yoke and aluminum shell. This structure is aimed at pre-stress control, alignment and field quality. We present here the magnetic and mechanical design of HQ, along with recent progress on the development of the first 1-meter model.

Measurement of inter-strand contact resistance in epoxy impregnated Nb3Sn Rutherford cables

International Nuclear Information System (INIS)

Giorgio Ambrosio

2003-01-01

An apparatus for the measurement, under transverse pressure, of the inter-strand contact resistance in epoxy-impregnated Nb 3 Sn Rutherford cables has been recently assembled at Fermilab. Procedures have been developed to instrument and measure samples extracted from Nb 3 Sn coils. Samples were extracted from coils fabricated with the Wind-and-React and the React-and-Wind technology, both presently under development at Fermilab. A ceramic binder is used to improve the insulation and to simplify the fabrication of coils using the Wind-and-React technology. Synthetic oil is used to prevent sintering during the heat treatment of coils to be wound after reaction. In order to evaluate the effects of the ceramic binder and of the synthetic oil on the inter-strand resistance, measurements of samples extracted from coils were compared with measurements of cable stacks with varying characteristics. In this paper we describe the apparatus, the sample preparation, the measurement procedure, and the results of the first series of tests

Fabrication and Test of a 1 m Long Single-Aperture 11 T Nb$_3$Sn Dipole for LHC Upgrades

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A. V. [Fermilab; Andreev, N. [Fermilab; Apollinari, G. [Fermilab; Barzi, E. [Fermilab; Bossert, R. [Fermilab; Chlachidze, G. [Fermilab; DiMarco, J. [Fermilab; Nobrega, F. [Fermilab; Novitski, I. [Fermilab; Turrioni, D. [Fermilab; Velev, G. [Fermilab; Auchmann, B. [CERN; Karppinen, M. [CERN; Rossi, L. [CERN; Smekens, D. [CERN

2013-06-01

FNAL and CERN are carrying out a joint R&D program with the goal of building a 5.5-m long twin-aperture Nb$_3$Sn dipole prototype suitable for installation in the LHC. An important part of the program is the development and test of a series of short single-aperture demonstration dipoles with a nominal field of 11 T at the LHC nominal current of 11.85 kA and 20% margin. This paper describes design features and test results of a 1 m long single-aperture Nb3Sn demonstrator dipole.

Costs of magnets for large fusion power reactors: Phase I, cost of superconductors for dc magnets

International Nuclear Information System (INIS)

Powell, J.R.

1972-01-01

Projections are made for dc magnet conductor costs for large fusion power reactors. A mature fusion economy is assumed sometime after 2000 A. D. in which approximately 90,000 MW(e) of fusion reactors are constructed/year. State of the art critical current vs. field characteristics for superconductors are used in these projections. Present processing techniques are used as a basis for the design of large plants sized to produce approximately one-half of the conductor needed for the fusion magnets. Multifilamentary Nb-Ti, Pb-Bi in glass fiber, GE Nb 3 Sn tape, Linde plasma sprayed Nb 3 Sn tape, and V 3 Ga tape superconductors are investigated, together with high purity aluminum cryoconductor. Conductor costs include processing costs [capital (equipment plus buildings), labor, and operating] and materials costs. Conductor costs are compared for two sets of material costs: current (1971 A. D.) costs, and projected (after 2000 A. D.) costs. (U.S.)