Shrewsbury, MA, United States
Shrewsbury, MA, United States
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Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2010

Future magnets for Fusion Energy Systems require superconducting cables with improved high critical current carrying capacity at high magnetic fields, 20 Kelvin operation, low AC losses and lower cost. A new method of fabricating a high current cable with 2G HTS tapes has been developed that will improve the engineering current density achievable. Commercial Applications and Other Benefits: Future fusion and related superconducting magnets for HEP applications will become more feasible if this project is successful. Additionally, the technology developed if this project is successful can find application in commercial high field magnets for NMR, FT-ICR, and other analytic magnet applications.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase II | Award Amount: 750.00K | Year: 2011

Future magnets for Fusion Energy Systems require superconducting cables with improved high critical current carrying capacity at high magnetic fields, 20 Kelvin operation, low AC losses and lower cost. A new method of fabricating a high current cable with 2G HTS tapes has been developed that will improve the engineering current density achievable. Commercial Applications and Other Benefits: Future fusion and related superconducting magnets for HEP applications will become more feasible if this project is successful. Additionally, the technology developed if this project is successful can find application in commercial high field magnets for NMR, FT-ICR, and other analytic magnet applications.


Kajbafvala A.,North Carolina State University | Nachtrab W.,Supercon, Inc. | Wong T.,Supercon, Inc. | Schwartz J.,North Carolina State University
Superconductor Science and Technology | Year: 2014

Ag/Al alloys with various Al content (0.50 wt%, 0.75 wt%, 1.00 wt%, and 1.25 wt%) are made by powder metallurgy and used as the outer sheath material for Bi2Sr2CaCu2O8 +x (Bi2212)/Ag/AgAl multifilamentary round wires (RW). Bi2212/Ag/AgAl RW microstructural, mechanical and electrical properties are studied in various conditions, including as-drawn, after internal oxidation, and after partial melt processing (PMP). The results are compared with the behavior of a Bi2212/Ag/Ag0.20Mg wire of the same geometry. The grains in as-drawn Ag/Al alloys are found to be ∼25% smaller than those in the corresponding Ag/0.20 wt%Mg, but after PMP, the Ag/Al and Ag/0.20 wt%Mg grain sizes are comparable. Tensile tests show that Bi2212/Ag/AgAl green wires have yield strength (YS) of ∼115 MPa, nearly 65% higher than that of Bi2212/Ag/Ag0.20Mg. After PMP, the Bi2212/Ag/AgAl YS is about 35% greater than that of Bi2212/Ag/Ag0.20Mg. Furthermore, Bi2212/Ag/AgAl wires exhibit higher ultimate tensile strength and modulus and twice the elongation-to-failure. Atomic resolution high-angle annular dark-field scanning transmission electron microscopy, high resolution transmission electron microscopy and energy dispersive spectroscopy demonstrate the formation of nanosize MgO and Al2O3 precipitates via internal oxidation. Large spherical MgO precipitates are observed on the Ag grain boundaries of Ag/0.20 wt%Mg alloy, whereas the Al2O3 precipitates are distributed homogenously in the dispersion-strengthened (DS) Ag/Al alloy. Furthermore, it is found that less Cu diffused from the Bi2212 filaments in the Bi2212/Ag/Ag0.75Al wire during PMP than from the filaments in the Bi2212/Ag/Ag0.20Mg wire. These results show that DS Ag/Al alloy is a strong candidate for improved Bi2212 wire. © 2014 IOP Publishing Ltd.


Nachtrab W.T.,Supercon, Inc. | Liu X.T.,North Carolina State University | Wong T.,Supercon, Inc. | Schwartz J.,North Carolina State University
IEEE Transactions on Applied Superconductivity | Year: 2011

In this study, we report the effect of cooling from the peak temperature reached during partial melt processing on the critical current for a Bi2212/Ag wire. A single-stage cooling approach is compared to two-stage cooling. For two-stage cooling, the first stage cooling rate and the cooling rate transition temperature were varied to investigate the effects of undercooling on the solidification behavior of the 2212 phase. Two-stage cooling results in higher I c compared to single-stage cooling, and the cooling rate transition temperature was found to have a greater effect on I c than the initial cooling rate. © 2011 IEEE.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2010

This proposal describes an innovative high strength silver alloy for use in making Bi2212/Ag round wire conductor. Bi2212 is a high field superconductor that has the highest Jc of any practical superconductor at fields above 20 T. NbTi and Nb3Sn, which are currently the primary materials currently used for high field magnets, are limited to about 10.5 T and 18 T respectively. To generate magnetic fields greater than 20 T, a new high field conductor such as Bi2212 is needed. However, Bi2212 is brittle compound that can be easily damaged, and its critical current is very strain sensitive. The Bi2212 compound is contained in a silver matrix in the wire. The silver matrix is chemically compatible with the Bi2212 ceramic, and it aids in processing the conductor. However, silver is a low strength, low stiffness material. It provides little in the way of mechanical support for the conductor during either magnet fabrication or operation. High field magnets are subject to large stresses. These stresses can exceed the yield strength of the silver matrix, causing degradation of conductor thus limiting the usefulness of Bi2212 for high field magnets resulting in the need to use more costly approaches for producing high magnetic fields. This proposal seeks to develop a high strength, high modulus silver alloy for manufacturing Bi2212 round wire multifilament conductor. The silver is strengthened by a fine dispersion of Al2O3 particles producing an alloy having high strength and stiffness. The Al2O3 particles are chemically inert to Bi2212, and strengthen the silver matrix even after high temperature processing. The increased strength and stiffness provided by the silver alloy results in greater resistance to mechanical stresses and electromagnetic forces. These attributes provide for less complex magnet design, resulting in reduced costs with the benefit of higher performance. Potential applications include particle accelerators and high field NMR magnets. Commercial applications and other benefits: A high field superconductor such as Bi2212 will find its primary application in accelerator magnets for high energy physics. The other major application for the technology is high field nuclear magnetic resonance systems for imaging complex organic compounds and biological materials


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1.00M | Year: 2010

Future magnets for High Energy Physics (HEP) require superconductors with improved high critical current carrying capacity at high magnetic fields, decreased effective filament sizes and lower cost. An improved method of fabricating such superconductors is being investigated using the Internal Tin Tube (ITT) Process that will improve the critical current density achievable. In Phase I, Sn-Ta alloys were fabricated by melt diffusion of mixed powders. The alloys were rolled to foil and placed at the interface between the niobium and the high tin copper-clad tin cores of ITT monofilaments. Thick Nb3Sn layers were formed after heat treatment. Fine grained Nb3Sn was observed in composites containing the alloys, but not in a control composite that did not contain Sn-Ta alloy. In Phase II, the Sn-Ta alloy homogeneity will be improved. The alloy compostion and thickness will be optimized. The process will be scaled-up to a commercial level, with conductor lengths and filament sizes suitable for high energy physics applications. Commercial Applications and Other Benefits: Future accelerator and related superconducting magnets for HEP applications will become more feasible if this project is successful. Additionally, the technology developed if this project is successful can find application in commercial high field magnets for NMR, FT-ICR, and other analytic magnet applications.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2011

The high energy physics community seeks high performance multifilament superconducting wire for use in magnets operating in the range of 12-15T or higher. Nb3Sn conductors fabricated by the internal tin (IT) method presently represent the state-of-the-art for these applications. The internal tin tube (ITT) method holds the promise to compete with such conductors if their performance can be raised to a sufficiently high level. One problem with ITT conductors is that it is difficult to avoid the formation of large-grained Nb3Sn. This is an impediment to high performance. Sn-B alloys formed by melt diffusion of powders have been shown to result in thick layers of fine grained Nb3Sn when reacted with niobium in jelly roll composites. In the proposed project, Sn-B powder mixtures will be employed as the tin source in multifilamentary ITT composites. It is anticipated that high performance can be achieved by virtue of the fine Nb3Sn grain size that can be achieved using this technique. Commercial Applications and Other Benefits: High performance multifilamentary Nb3Sn will find application in high energy physics particle accelerators and magnetic confinement fusion machines. Commercially, such conductor will find application in high frequency NMR magnets by taking advantage of the higher critical current density in order to reduce the size and overall cost of the magnet system.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1.00M | Year: 2011

This proposal describes an innovative high strength silver alloy for making Bi2212/Ag round wire conductor. To generate magnetic fields greater than 20 T, a new high field superconductor such as Bi2212 is needed. However, Bi2212 is brittle ceramic that can be easily damaged, and its critical current is very strain sensitive. The Bi2212 compound is contained in a silver matrix that is chemically compatible with the Bi2212 ceramic. Silver provides very little mechanical support for the superconductor during either magnet fabrication or operation. High field magnets are subject to large stresses, which can exceed the yield strength of the silver matrix, causing degradation of the superconductor, and necessitating more expensive approaches for making high field amgnets. This proposal seeks to develop a high strength, high modulus silver alloy for manufacturing Bi2212 round wire multifilament conductor. The silver is strengthened by a fine dispersion of alumina particles that are chemically inert to Bi2212 and produce an alloy having high strength and stiffness even after high temperature processing. The increased strength and stiffness provided by the silver alloy results in greater resistance to mechanical stresses and electromagnetic forces. These attributes simplify magnet design, resulting in reduced costs with the added benefit of higher performance. Potential applications include particle accelerators and high field NMR magnets. Phase I demonstrated the feasibility of all the critical aspects of the technology: production of an silver/alumina composite, fabrication of tubes from the composite and a Bi2212 conductor using a silver/alumina composite tube. The Phase II plan includes research to further refine the basic alloy formulation, develop improved processing technology, advance the production technology for making tubes, and a full scale demonstration for making a Bi2212 production conductor. Commercial Applications and Other Benefits: A high field superconductor such as Bi2212 will find its primary application in accelerator magnets for high energy physics. The other major application for the technology is high field nuclear magnetic resonance systems for imaging complex organic compounds and biological materials.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2012

The internal tin tube (ITT) process is potentially the lowest cost approach for manufacturing Nb3Sn superconductors. A present, multifilament conductors made by the ITT process are of necessity cold processed to wire. Since the filaments are not metallurgically bonded to each other, they can move relative to one another during wire drawing. To maximize high field performance, the conductor is made from an Nb-7.5Ta alloy. The high strength of this alloy increases the difficulty in cold processing the wire. The result is a high incidence of filament defects causing wire breakage, which limits product yield and increases the cost of the conductor. This proposal investigates a new method for fabricating ITT Nb3Sn superconductor that could eliminate the difficulty in producing this material, while making it more cost effective. Copper clad Nb-7.5Ta tubes will be fabricated via tube extrusion and drawing. The drawn tubes will be tightly bundled to form a restack array and vacuum annealed at ~1000 C to diffusion bond the subelements. When the subelements in the wire are metallurgically bonded, the wire can be more cost-effectively processed and the risk of wire breakage is reduced. Commercial applications and other benefits: Multifilamentary Nb3Sn has its major application in high energy physics particle accelerators and magnetic confinement fusion machines. These machines are very expensive to build and operate, and must be run at maximum performance to be effective. Reducing the cost and increasing the reliability of the superconductor strand used to fabricate the magnets for these machines will lower their overall cost. Additionally, a lower cost Nb3Sn superconductor resulting from improve manufacturing would benefit the manufacture of high field NMR magnets which are used for exploration of new molecules and chemical compounds for advanced materials and biological and pharmaceutical applications.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2012

Future magnets for Fusion Energy Systems require superconducting cables with improved high critical current carrying capacity at high magnetic fields, 20 kelvin operation, low AC losses and lower cost. The second generation high temperature superconductors are manufactured in tape form that has differing transverse resistivity from the top compared to the bottom of the conductor. An new method of fabricating a high current joints with 2G HTS tapes has been developed that will avoid this asymmetrical electrical behavior and allow uniform current distribution. Commercial Applications and Other Benefits: Future fusion and related superconducting magnets for HEP applications will become more feasible if this project is successful. Additionally, the technology developed if this project is successful can find application in commercial high field magnets for NMR, FT-ICR, and other analytic magnet applications.

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