This paper deals with recent developments of extensometers working in cryogenic environments down to 4 K capable to transfer accurate, high resolution, and reproducible signals for a variety of engineering measurement tasks such as tensile, fracture, compression, fatigue, flexural, and component tests. Based on strain gauge technology it was possible to manufacture extensometers with resolutions lower than 20 nm. The extensometers foreseen for uniaxial tensile tasks were designed as a twin extensometer system firmly attached onto the specimen and providing for bending during loading by averaging the signals either via software or by special electrical wiring. In particular, for structural component tests, different types of extensometer designs were represented. With the production of a new series of small, low weight, worldwide first twin extensometer system of ∼ 0.5 g mass it was possible to resolve the local strains of fragile Nb3Sn wires. Besides the measurement of distances, it was possible to develo...
{"title":"TRANSDUCERS FOR SUB-MICRON DISPLACEMENT MEASUREMENTS AT CRYOGENIC TEMPERATURES","authors":"A. Nyilas","doi":"10.1063/1.2192330","DOIUrl":"https://doi.org/10.1063/1.2192330","url":null,"abstract":"This paper deals with recent developments of extensometers working in cryogenic environments down to 4 K capable to transfer accurate, high resolution, and reproducible signals for a variety of engineering measurement tasks such as tensile, fracture, compression, fatigue, flexural, and component tests. Based on strain gauge technology it was possible to manufacture extensometers with resolutions lower than 20 nm. The extensometers foreseen for uniaxial tensile tasks were designed as a twin extensometer system firmly attached onto the specimen and providing for bending during loading by averaging the signals either via software or by special electrical wiring. In particular, for structural component tests, different types of extensometer designs were represented. With the production of a new series of small, low weight, worldwide first twin extensometer system of ∼ 0.5 g mass it was possible to resolve the local strains of fragile Nb3Sn wires. Besides the measurement of distances, it was possible to develo...","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59395733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Nakamoto, A. Idesaki, N. Morishita, H. Itoh, T. Kamiya, N. Kimura, Y. Makida, T. Ogitsu, H. Ohhata, A. Yamamoto
Radiation resistance of organic materials used in superconducting magnets for a 50 GeV–750 kW proton beam line for the J‐PARC neutrino experiment was studied with respect to mechanical properties. Specimens cooled at a liquid nitrogen temperature of 77 K were irradiated by gamma rays from 60Co with the maximum dose beyond 10 MGy. The flexural strength of glass‐fiber reinforced plastics (GFRPs), the tear strength of polyimide films and the tensile lap‐shear strength of adhesive films were evaluated. It was verified that the organic materials used in the superconducting magnets have the sufficient radiation resistance, and the degradation of their mechanical properties after the 10 years operation was estimated to be negligible.
{"title":"Mechanical Properties of Organic Materials Used in Superconducting Magnets Irradiated by Gamma Rays at Liquid Nitrogen Temperature","authors":"T. Nakamoto, A. Idesaki, N. Morishita, H. Itoh, T. Kamiya, N. Kimura, Y. Makida, T. Ogitsu, H. Ohhata, A. Yamamoto","doi":"10.1063/1.2192355","DOIUrl":"https://doi.org/10.1063/1.2192355","url":null,"abstract":"Radiation resistance of organic materials used in superconducting magnets for a 50 GeV–750 kW proton beam line for the J‐PARC neutrino experiment was studied with respect to mechanical properties. Specimens cooled at a liquid nitrogen temperature of 77 K were irradiated by gamma rays from 60Co with the maximum dose beyond 10 MGy. The flexural strength of glass‐fiber reinforced plastics (GFRPs), the tear strength of polyimide films and the tensile lap‐shear strength of adhesive films were evaluated. It was verified that the organic materials used in the superconducting magnets have the sufficient radiation resistance, and the degradation of their mechanical properties after the 10 years operation was estimated to be negligible.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192355","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59396261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Hooker, P. Fabian, M. W. Stewart, S. Grandlienard, K. Kano
Inorganic (ceramic) insulation materials are known to have good radiation resistance and desirable electrical and mechanical properties at cryogenic and elevated temperatures. In addition, ceramic materials can withstand the high‐temperature reaction cycle used with Nb3Sn superconductor materials, allowing the insulation to be co‐processed with the superconductor in a wind‐and‐react fabrication process. A critical aspect in the manufacture of ceramic‐based insulation systems is the deposition of suitable fiber‐coating materials that prevent chemical reaction of the fiber and matrix materials, and thus provide a compliant interface between the fiber and matrix, which minimizes the impact of brittle failure of the ceramic matrix. Ceramic insulation produced with CTD‐FI‐202 fiber interfaces have been found to exhibit very high shear and compressive strengths. However, this material is costly to produce. Thus, the goal of the present work is to evaluate alternative, lower‐cost materials and processes. A varie...
{"title":"Interfacial Coatings for Inorganic Composite Insulation Systems","authors":"M. Hooker, P. Fabian, M. W. Stewart, S. Grandlienard, K. Kano","doi":"10.1063/1.2192366","DOIUrl":"https://doi.org/10.1063/1.2192366","url":null,"abstract":"Inorganic (ceramic) insulation materials are known to have good radiation resistance and desirable electrical and mechanical properties at cryogenic and elevated temperatures. In addition, ceramic materials can withstand the high‐temperature reaction cycle used with Nb3Sn superconductor materials, allowing the insulation to be co‐processed with the superconductor in a wind‐and‐react fabrication process. A critical aspect in the manufacture of ceramic‐based insulation systems is the deposition of suitable fiber‐coating materials that prevent chemical reaction of the fiber and matrix materials, and thus provide a compliant interface between the fiber and matrix, which minimizes the impact of brittle failure of the ceramic matrix. Ceramic insulation produced with CTD‐FI‐202 fiber interfaces have been found to exhibit very high shear and compressive strengths. However, this material is costly to produce. Thus, the goal of the present work is to evaluate alternative, lower‐cost materials and processes. A varie...","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192366","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59396690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Linerless composite tanks, using continuous‐graphite‐fiber reinforcement and a polymeric‐resin matrix will enable significant mass savings and increased payload capacity in future launch vehicles. The critical application for which linerless composite tanks show the greatest impact to system performance is in the upper stages of future expendable launch vehicles. Many of these tanks will operate at cryogenic temperatures. The key technical challenge in developing these tanks will be to choose and/or design the material to resist microcracks that may lead to leakage. Microcracks are known to form in the matrix of a composite due to thermal and mechanical stresses transverse to the reinforcing fiber direction. The toughness of the matrix material has the most pronounced impact of all factors on microcracking. This paper presents an approach for characterizing a resin’s “microcracking fracture toughness,” or the resistance of the resin to form microcracks, at cryogenic temperatures. It describes an effort to...
{"title":"Evaluating the Resistance to Microcrack Formation of Composites at Cryogenic Temperatures","authors":"K. Ryan, J. Cronin, S. Arzberger, K. Mallick","doi":"10.1063/1.2192359","DOIUrl":"https://doi.org/10.1063/1.2192359","url":null,"abstract":"Linerless composite tanks, using continuous‐graphite‐fiber reinforcement and a polymeric‐resin matrix will enable significant mass savings and increased payload capacity in future launch vehicles. The critical application for which linerless composite tanks show the greatest impact to system performance is in the upper stages of future expendable launch vehicles. Many of these tanks will operate at cryogenic temperatures. The key technical challenge in developing these tanks will be to choose and/or design the material to resist microcracks that may lead to leakage. Microcracks are known to form in the matrix of a composite due to thermal and mechanical stresses transverse to the reinforcing fiber direction. The toughness of the matrix material has the most pronounced impact of all factors on microcracking. This paper presents an approach for characterizing a resin’s “microcracking fracture toughness,” or the resistance of the resin to form microcracks, at cryogenic temperatures. It describes an effort to...","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192359","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59397036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multifilament Nb3Sn superconductor has been produced by the internal‐tin‐tube approach. In this method tubular niobium filaments containing either solid or powder cores of high tin content are processed into multifilament conductors containing filament diameters as small as 30 μm. The recent emphasis has been on incorporating Nb‐7.5Ta filaments in an effort to raise the upper critical field and hence increase the critical current density. Comparison to recent results with our powder‐in‐tube A15 conductor is made. Niobium‐tantalum tube fabrication, wire processing, filament quality and Nb3Sn microstructure are discussed and the superconducting properties are presented.
{"title":"High Field Nb3Sn Superconductor Fabricated by the Internal‐Tin‐Tube Process","authors":"C. Renaud, T. Wong","doi":"10.1063/1.2192387","DOIUrl":"https://doi.org/10.1063/1.2192387","url":null,"abstract":"Multifilament Nb3Sn superconductor has been produced by the internal‐tin‐tube approach. In this method tubular niobium filaments containing either solid or powder cores of high tin content are processed into multifilament conductors containing filament diameters as small as 30 μm. The recent emphasis has been on incorporating Nb‐7.5Ta filaments in an effort to raise the upper critical field and hence increase the critical current density. Comparison to recent results with our powder‐in‐tube A15 conductor is made. Niobium‐tantalum tube fabrication, wire processing, filament quality and Nb3Sn microstructure are discussed and the superconducting properties are presented.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192387","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Lietzke, S. Mattafirri, A. Mcinturff, M. Nyman, D. Dietderich, S. Gourlay, G. Sabbi
The Superconducting Magnet Group at Lawrence Berkeley National Laboratory has been developing high‐field, brittle‐superconductor, accelerator magnet technology for several years. While recent dramatic increases in Nb3Sn superconducting current density, (Jc = 3000 A/mm2 at 12 Tesla, 4.2 K) have facilitated the achievement of record peak dipole bore‐fields (16 Tesla), the number and size of fast intra‐coil flux‐adjustments of the “flux‐jump” variety have increased with the current density. In 2000, with state‐of‐the art (Jc = 2000 A/mm2 at 12 T) Nb3Sn conductor, the associated coil voltage transients were observed to be large enough to cause nuisance “quench‐detector” magnet‐protection false‐alarms. Subsequent Jc increases have resulted in large enough flux‐jumps to cause premature quenches in some magnets, at currents well below those predicted by their virgin strand superconducting “short‐sample” measurements.This paper will examine various types of quench‐onsets and their distinguishing characteristics. ...
{"title":"Differentiation of Performance‐Limiting Voltage Transients during Nb3Sn Magnet Testing","authors":"A. Lietzke, S. Mattafirri, A. Mcinturff, M. Nyman, D. Dietderich, S. Gourlay, G. Sabbi","doi":"10.1063/1.2192394","DOIUrl":"https://doi.org/10.1063/1.2192394","url":null,"abstract":"The Superconducting Magnet Group at Lawrence Berkeley National Laboratory has been developing high‐field, brittle‐superconductor, accelerator magnet technology for several years. While recent dramatic increases in Nb3Sn superconducting current density, (Jc = 3000 A/mm2 at 12 Tesla, 4.2 K) have facilitated the achievement of record peak dipole bore‐fields (16 Tesla), the number and size of fast intra‐coil flux‐adjustments of the “flux‐jump” variety have increased with the current density. In 2000, with state‐of‐the art (Jc = 2000 A/mm2 at 12 T) Nb3Sn conductor, the associated coil voltage transients were observed to be large enough to cause nuisance “quench‐detector” magnet‐protection false‐alarms. Subsequent Jc increases have resulted in large enough flux‐jumps to cause premature quenches in some magnets, at currents well below those predicted by their virgin strand superconducting “short‐sample” measurements.This paper will examine various types of quench‐onsets and their distinguishing characteristics. ...","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192394","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The critical current of Nb3Sn strands used in Fermilab’s high field magnets was measured at low and high fields under various experimental conditions using the voltage‐current (V‐I) and voltage‐field (V‐H) methods. The strands were commercially produced using Restack Rod Process (RRP) and Powder‐in‐Tube (PIT) technologies. Both round and deformed strands were studied. Measurements were performed at the Fermilab’s Short Sample Test Facility using a 2‐kA sample holder with a low contact resistivity. V‐I characteristics at fields above 10–12T with a smooth transition from the superconducting to normal phase allowed determining strand critical current. V‐I and V‐H measurements at low fields showed premature quenches due to magnetic instability in strands with high critical current density and large effective filament size. The effects of strand deformation and RRR as well as test temperature were studied. This paper describes the Nb3Sn strand parameters, the equipment and measurement methods used, and the res...
{"title":"Effect of Temperature and Deformation on Nb3Sn Strands Instabilities","authors":"E. Barzi, L. D. Frate, D. Turrioni, A. Zlobin","doi":"10.1063/1.2192396","DOIUrl":"https://doi.org/10.1063/1.2192396","url":null,"abstract":"The critical current of Nb3Sn strands used in Fermilab’s high field magnets was measured at low and high fields under various experimental conditions using the voltage‐current (V‐I) and voltage‐field (V‐H) methods. The strands were commercially produced using Restack Rod Process (RRP) and Powder‐in‐Tube (PIT) technologies. Both round and deformed strands were studied. Measurements were performed at the Fermilab’s Short Sample Test Facility using a 2‐kA sample holder with a low contact resistivity. V‐I characteristics at fields above 10–12T with a smooth transition from the superconducting to normal phase allowed determining strand critical current. V‐I and V‐H measurements at low fields showed premature quenches due to magnetic instability in strands with high critical current density and large effective filament size. The effects of strand deformation and RRR as well as test temperature were studied. This paper describes the Nb3Sn strand parameters, the equipment and measurement methods used, and the res...","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192396","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In support of a collaboration between SuperPower, Inc., Nexans SuperConductors GmbH, American Electric Power Company, Inc., and EPRI to develop an HTS matrix fault current limiter, Oak Ridge National Laboratory is carrying out thermal property studies on samples of the bulk HTS elements that will be used in the device. The HTS samples are 2.5‐cm‐diam, 1.6‐mm‐wall tubes of Bi‐2212 MCP, a special melt‐cast 2212 material provided by Nexans. Since these tubes will have to dissipate considerable heat during a high‐current fault, accurate measurements of their thermal properties are required for design and engineering analysis. Results will be reported for heat capacity tests over a range from 80 K to 300 K.
{"title":"Thermal Property Measurements on Bulk Bi‐2212 MCP Fault Current Limiter Materials","authors":"S. Schwenterly, D. Hazelton, H. Walter, F. Breuer","doi":"10.1063/1.2192425","DOIUrl":"https://doi.org/10.1063/1.2192425","url":null,"abstract":"In support of a collaboration between SuperPower, Inc., Nexans SuperConductors GmbH, American Electric Power Company, Inc., and EPRI to develop an HTS matrix fault current limiter, Oak Ridge National Laboratory is carrying out thermal property studies on samples of the bulk HTS elements that will be used in the device. The HTS samples are 2.5‐cm‐diam, 1.6‐mm‐wall tubes of Bi‐2212 MCP, a special melt‐cast 2212 material provided by Nexans. Since these tubes will have to dissipate considerable heat during a high‐current fault, accurate measurements of their thermal properties are required for design and engineering analysis. Results will be reported for heat capacity tests over a range from 80 K to 300 K.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192425","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59399526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Watanabe, G. Nishijima, S. Awaji, Y. Hikichi, T. Hasegawa
Practical multifilamentary Ag/Bi2Sr2CaCu2O8 round wires 1 mm in diameter exhibit critical current properties without anisotropy in fields up to 30 T and 4.2 K. We concentrate on the development of a Ag/Bi2Sr2CaCu2O8 insert coil by a wind‐and‐react method for a high field NMR superconducting magnet. Hastelloy cloth was used for the insulation for the wind‐and‐react process. A φ0.05 mm Hastelloy X (Hx) filament was knitted into a braid tube, and has a high mechanical strength and a good tolerance to oxidization at high temperature. We fabricated multifilamentary Ag/Bi2Sr2CaCu2O8 wires with Hx cloth, and heat‐treated them at around 890 °C in an oxygen atmosphere. It was found that the surface of Hx cloth is oxidized enough for a good electric insulation. Multifilamentary Ag/Bi2Sr2CaCu2O8 wires with oxidized Hx cloth insulation have the critical current of 720 A at 4.2 K in a self field.
{"title":"Oxidized Hastelloy Cloth Insulation for a Wind‐and‐React Processed Ag/Bi2Sr2CaCu2O8 Superconducting Magnet","authors":"K. Watanabe, G. Nishijima, S. Awaji, Y. Hikichi, T. Hasegawa","doi":"10.1063/1.2192413","DOIUrl":"https://doi.org/10.1063/1.2192413","url":null,"abstract":"Practical multifilamentary Ag/Bi2Sr2CaCu2O8 round wires 1 mm in diameter exhibit critical current properties without anisotropy in fields up to 30 T and 4.2 K. We concentrate on the development of a Ag/Bi2Sr2CaCu2O8 insert coil by a wind‐and‐react method for a high field NMR superconducting magnet. Hastelloy cloth was used for the insulation for the wind‐and‐react process. A φ0.05 mm Hastelloy X (Hx) filament was knitted into a braid tube, and has a high mechanical strength and a good tolerance to oxidization at high temperature. We fabricated multifilamentary Ag/Bi2Sr2CaCu2O8 wires with Hx cloth, and heat‐treated them at around 890 °C in an oxygen atmosphere. It was found that the surface of Hx cloth is oxidized enough for a good electric insulation. Multifilamentary Ag/Bi2Sr2CaCu2O8 wires with oxidized Hx cloth insulation have the critical current of 720 A at 4.2 K in a self field.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192413","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59399559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Gregory, B. Zeitlin, M. Tomsic, X. Wu, X. Peng, M. Sumption, E. Collings
In the past much of the emphasis in the development of Nb3Sn superconductors for High Energy Physics has been on improving the non‐Cu critical current density, (Jc), at 12 T. More recently the focus has shifted to improving the matrix residual resistivity ratio, (RRR), and decreasing the ac losses. In addition, the field of interest has risen to the 15–18 T range. Piece length and cost are also factors that are assumed not to deteriorate as the other properties are improved. In this paper we have emphasized reduction of losses by changing the conductor design. This has been explored both by the introduction of fins of various types and also by simply increasing the number of subelements using a tubular process, which has the potential of a low cost approach. The effect of these changes on the ease with which the multi‐subelementary material can be made is explored and discussed.
{"title":"Various Methods of Reducing AC Losses and Improving Stability of Internal‐Tin Nb3Sn Superconductors","authors":"E. Gregory, B. Zeitlin, M. Tomsic, X. Wu, X. Peng, M. Sumption, E. Collings","doi":"10.1063/1.2192432","DOIUrl":"https://doi.org/10.1063/1.2192432","url":null,"abstract":"In the past much of the emphasis in the development of Nb3Sn superconductors for High Energy Physics has been on improving the non‐Cu critical current density, (Jc), at 12 T. More recently the focus has shifted to improving the matrix residual resistivity ratio, (RRR), and decreasing the ac losses. In addition, the field of interest has risen to the 15–18 T range. Piece length and cost are also factors that are assumed not to deteriorate as the other properties are improved. In this paper we have emphasized reduction of losses by changing the conductor design. This has been explored both by the introduction of fins of various types and also by simply increasing the number of subelements using a tubular process, which has the potential of a low cost approach. The effect of these changes on the ease with which the multi‐subelementary material can be made is explored and discussed.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192432","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59399687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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