High-temperature superconducting fault-current limiter - optimisation of superconducting elements

International Nuclear Information System (INIS)

2004-01-01

This report summarises the findings of a study initiated to continue the work of a DTI-LINK Collaborative Research Programme 'Enhancing the Properties of Bulk High Temperature Superconductors and their Potential Application as Fault Current Limiters (FCL). Details are given of computer modelling of the quenching process involving the transition from superconducting to normal conducting states undergone by the material when large currents are present. The design of compound elements, and a multi-element model are described along with FCL design covering distribution bus-coupler, embedded generator connection, larger generator connection, hazardous area safety, and interconnection to fault-prone network. The evaluation of thermal loss, test equipment and schedule, the optimised element, installed cost data, and the UK market are considered

Application of RF Superconductivity to High-Current Linac

International Nuclear Information System (INIS)

Chan, K.C.D.

1998-01-01

In 1997, the authors initiated a development program in Los Alamos for high-current superconducting proton-linac technology to build prototypes components of this linac to demonstrate the feasibility. The authors are building 700-MHz niobium cavities with elliptical shapes, as well as power couplers to transfer high RF power to these cavities. The cavities and power couplers will be integrated in cryostats as linac cryomodules. In this paper, they describe the linac design and the status of the development program

Overview of superconducting RF technology and its application to high-current linacs

International Nuclear Information System (INIS)

Delayen, J.R.; Bohn, C.L.

1994-01-01

Superconducting linacs may be a viable option for high-current applications such as copious neutron production like that needed for transmutation of radioactive waste. These linacs must run reliably for many years and allow easy routine maintenance. superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs. However, cost effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement

Superconducting fault current limiter for railway transport

Energy Technology Data Exchange (ETDEWEB)

Fisher, L. M., E-mail: LMFisher@niitfa.ru; Alferov, D. F.; Akhmetgareev, M. R.; Budovskii, A. I.; Evsin, D. V.; Voloshin, I. F.; Kalinov, A. V. [National Technical Physics and Automation Research Institute (Russian Federation)

2015-12-15

A resistive switching superconducting fault current limiter (SFCL) for DC networks with voltage of 3.5 kV and nominal current of 2 kA is developed. The SFCL consists of two series-connected units: block of superconducting modules and high-speed vacuum breaker with total disconnection time not more than 8 ms. The results of laboratory tests of superconducting SFCL modules in current limiting mode are presented. The recovery time of superconductivity is experimentally determined. The possibility of application of SFCL on traction substations of Russian Railways is considered.

Superconducting fault current limiter for railway transport

International Nuclear Information System (INIS)

Fisher, L. M.; Alferov, D. F.; Akhmetgareev, M. R.; Budovskii, A. I.; Evsin, D. V.; Voloshin, I. F.; Kalinov, A. V.

2015-01-01

A resistive switching superconducting fault current limiter (SFCL) for DC networks with voltage of 3.5 kV and nominal current of 2 kA is developed. The SFCL consists of two series-connected units: block of superconducting modules and high-speed vacuum breaker with total disconnection time not more than 8 ms. The results of laboratory tests of superconducting SFCL modules in current limiting mode are presented. The recovery time of superconductivity is experimentally determined. The possibility of application of SFCL on traction substations of Russian Railways is considered

Design and Test of a Thermal Triggered Persistent Current System using High Temperature Superconducting Tapes

Energy Technology Data Exchange (ETDEWEB)

Park, Dong Keun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Kang, Hyoungku [Electro-Mechanical Research Institute, Hyundai Heavy Industries, Yongin (Korea, Republic of); Ahn, Min Cheol [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yang, Seong Eun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yoon, Yong Soo [Department of Electrical Engineering, Ansan College of Technology, 671 Choji-Dong, Danwon-Gu, Ansan, 425-792 (Korea, Republic of); Lee, Sang Jin [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Ko, Tae Kuk [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of)

2006-06-01

A superconducting magnet which is operated in persistent current mode in SMES, NMR, MRI and MAGLEV has many advantages such as high uniformity of magnetic field and reduced thermal loss. A high temperature superconducting (HTS) persistent current switch (PCS) system was designed and tested in this research. The HTS PCS was optimally designed using two different HTS tapes, second generation coated conductor (CC) HTS tape and Bi-2223 HTS tape by the finite element method (FEM) in thermal quench characteristic view. The CC tape is more prospective applicable wire in these days for its high n value and critical current independency from external magnetic field than Bi-2223 tape. Also a prototype PCS system using Bi-2223 tape was manufactured and tested. The PCS system consists of a PCS part, a heater which induces the PCS to quench, and a superconducting magnet. The test was performed in various conditions of transport current. An initial current decay appeared when the superconducting magnet was energized in a PCS system was analyzed. This paper would be foundation of HTS PCS researches.

Current leads for superconducting magnets

International Nuclear Information System (INIS)

Ishibashi, Kenji

1989-01-01

Current leads for superconducting magnets have been studied since 1960's. The technology of current leads may seem to have been established both in theory and experiment before the middle of 1970's. Nevertheless, a wide variety of superconducting magnets have been introduced in the last 15 years, and the demands for special current leads have increased in accordance to the variety. A steady advance has been made in the design theory and fabrication of current leads. This paper describes the recent current lead technology regarding the design theory, safety in accidents, and high current capability. (author)

Superconducting current in a bisoliton superconductivity model

International Nuclear Information System (INIS)

Ermakov, V.N.; Kruchinin, S.P.; Ponezha, E.A.

1991-01-01

It is shown that the transition into a superconducting state with the current which is described by a bisoliton superconductivity model is accompanied by the deformation of the spectrum of one-particle states of the current carriers. The deformation value is proportional to the conducting current force. The residuaby resistance in such state is absent

Theory and application of high temperature superconducting eddy current probes for nondestructive evaluation

Science.gov (United States)

Claycomb, James Ronald

1998-10-01

Several High-T c Superconducting (HTS) eddy current probes have been developed for applications in electromagnetic nondestructive evaluation (NDE) of conducting materials. The probes utilize high-T c SUperconducting Quantum Interference Device (SQUID) magnetometers to detect the fields produced by the perturbation of induced eddy currents resulting from subsurface flaws. Localized HTS shields are incorporated to selectively screen out environmental electromagnetic interference and enable movement of the instrument in the Earth's magnetic field. High permeability magnetic shields are employed to focus flux into, and thereby increase the eddy current density in the metallic test samples. NDE test results are presented, in which machined flaws in aluminum alloy are detected by probes of different design. A novel current injection technique performing NDE of wires using SQUIDs is also discussed. The HTS and high permeability shields are designed based on analytical and numerical finite element method (FEM) calculations presented here. Superconducting and high permeability magnetic shields are modeled in uniform noise fields and in the presence of dipole fields characteristic of flaw signals. Several shield designs are characterized in terms of (1) their ability to screen out uniform background noise fields; (2) the resultant improvement in signal-to-noise ratio and (3) the extent to which dipole source fields are distorted. An analysis of eddy current induction is then presented for low frequency SQUID NDE. Analytical expressions are developed for the induced eddy currents and resulting magnetic fields produced by excitation sources above conducting plates of varying thickness. The expressions derived here are used to model the SQUID's response to material thinning. An analytical defect model is also developed, taking into account the attenuation of the defect field through the conducting material, as well as the current flow around the edges of the flaw. Time harmonic

Analysis of eddy current loss in high-Tc superconducting power cables with respect to various structure of stabilizer

International Nuclear Information System (INIS)

Choi, S. J.; Song, M. K.; Lee, S. J.; Cho, J. W.; Sim, K. D.

2005-01-01

The High-Tc superconducting power cable consists of a multi-layer high-Tc superconducting cable core and a stabilizer which is used to bypass the current at fault time. Eddy current loss is generated in the stabilizer in normal operating condition and affects the whole system. In this paper, the eddy current losses are analyzed with respect to various structure of stabilizer by using opera-3d. Moreover, optimal conditions of the stabilizer are derived to minimize the eddy current losses from the analyzed results. The obtained results could be applied to the design and manufacture of the high-Tc superconducting power cable system.

Large high current density superconducting solenoids for use in high energy physics experiments

International Nuclear Information System (INIS)

Green, M.A.; Eberhard, P.H.; Taylor, J.D.

1976-05-01

Very often the study of high energy physics in colliding beam storage-rings requires a large magnetic field volume in order to detect and analyze charged particles which are created from the collision of two particle beams. Large superconducting solenoids which are greater than 1 meter in diameter are required for this kind of physics. In many cases, interesting physics can be done outside the magnet coil, and this often requires that the amount of material in the magnet coil be minimized. As a result, these solenoids should have high current density (up to 10 9 A m -2 ) superconducting windings. The methods commonly used to stabilize large superconducting magnets cannot be employed because of this need to minimize the amount of material in the coils. A description is given of the Lawrence Berkeley Laboratory program for building and testing prototype solenoid magnets which are designed to operate at coil current densities in excess of 10 9 A m -2 with magnetic stored energies which are as high as 1.5 Megajoules per meter of solenoid length. The coils use intrinsically stable multifilament Nb--Ti superconductors. Control of the magnetic field quench is achieved by using a low resistance aluminum bore tube which is inductively coupled to the coil. The inner cryostat is replaced by a tubular cooling system which carries two phase liquid helium. The magnet coil, the cooling tubes, and aluminum bore tube are cast in epoxy to form a single unified magnet and cryogenic system which is about 2 centimeters thick. The results of the magnet coil tests are discussed

Superconducting current generators

International Nuclear Information System (INIS)

Genevey, P.

1970-01-01

After a brief summary of the principle of energy storage and liberation with superconducting coils,two current generators are described that create currents in the range 600 to 1400 A, used for two storage experiments of 25 kJ and 50 kJ respectively. The two current generators are: a) a flux pump and b) a superconducting transformer. Both could be developed into more powerful units. The study shows the advantage of the transformer over the flux pump in order to create large currents. The efficiencies of the two generators are 95 per cent and 40 to 60 per cent respectively. (author) [fr

High temperature superconducting current lead test facility with heat pipe intercepts

International Nuclear Information System (INIS)

Blumenfeld, P.E.; Prenger, C.; Roth, E.W.; Stewart, J.A.

1998-01-01

A high temperature superconducting (HTS) current lead test facility using heat pipe thermal intercepts is under development at the Superconducting Technology Center at Los Alamos National Laboratory. The facility can be configured for tests at currents up to 1,000 A. Mechanical cryocoolers provide refrigeration to the leads. Electrical isolation is maintained by intercepting thermal energy from the leads through cryogenic heat pipes. HST lead warm end temperature is variable from 65 K to over 90 K by controlling heat pipe evaporator temperature. Cold end temperature is variable up to 30 K. Performance predictions in terms of heat pipe evaporator temperature as a function of lead current are presented for the initial facility configuration, which supports testing up to 200 A. Measurements are to include temperature and voltage gradient in the conventional and HTS lead sections, temperature and heat transfer rate in the heat pipes. as well as optimum and off-optimum performance of the conventional lead sections

High-Tc superconducting electric motors

International Nuclear Information System (INIS)

Schiferl, R.; Stein, J.

1992-01-01

In this paper, the advantages and limitations of using superconductors in motors are discussed. A synchronous motor with a high temperature superconducting field winding for pump and fan drive applications is described and some of its unique design features are identified. A 10,000 horsepower superconducting motor design is presented. The critical field and current density requirements for high temperature superconducting wire in motors is discussed. Finally, recent progress in superconducting wire performance is presented

Highly Sensitive Measurements of the Dark Current of Superconducting Cavities for TESLA Using a SQUID Based Cryogenic Current Comparator

CERN Document Server

Vodel, W; Nietzsche, S

2004-01-01

This contribution presents a Cryogenic Current Comparator (CCC) as an excellent tool for detecting dark currents generated, e.g. by superconducting cavities for the upcoming TESLA project (X-FEL) at DESY. To achieve the maximum possible energy the gradient of the superconducting RF cavities should be pushed close to the physical limit of 50 MV/m. The undesired field emission of electrons (so-called dark current) of the superconducting RF cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. The main component of the CCC is a highly sensitive LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the dark current. For this reason the input coil of the SQUID is connected across a special designed toroidal niobium pick-up coil for the passing electron beam. A noise limited current resolution of nearly 2 pA/√(Hz) with a measu...

Current high-temperature superconducting coils and applications in Japan

International Nuclear Information System (INIS)

Matsushita, T.

2000-01-01

In Japan, four projects for the application of Bi-based superconducting magnets to practical apparatus are currently underway. These projects involve the development of an insert magnet for a 1 GHz nuclear magnetic resonance spectrometer, a magnet for a silicon single-crystal pulling apparatus, a magnet for a magnetic separation system, and a 1 T pulse magnet for a superconducting magnet energy storage system. For example, the magnet for the silicon single-crystal pulling apparatus is of the class with stored energy of 1 MJ to be operated at around 20 K. This review focuses on the present status of the development of these magnets, followed by a discussion of the problems of the present superconducting tapes that need to be overcome for future applications. (author)

Low-Cost Superconducting Wire for Wind Generators: High Performance, Low Cost Superconducting Wires and Coils for High Power Wind Generators

Energy Technology Data Exchange (ETDEWEB)

None

2012-01-01

REACT Project: The University of Houston will develop a low-cost, high-current superconducting wire that could be used in high-power wind generators. Superconducting wire currently transports 600 times more electric current than a similarly sized copper wire, but is significantly more expensive. The University of Houston’s innovation is based on engineering nanoscale defects in the superconducting film. This could quadruple the current relative to today’s superconducting wires, supporting the same amount of current using 25% of the material. This would make wind generators lighter, more powerful and more efficient. The design could result in a several-fold reduction in wire costs and enable their commercial viability of high-power wind generators for use in offshore applications.

Superconducting fault current-limiter with variable shunt impedance

Science.gov (United States)

Llambes, Juan Carlos H; Xiong, Xuming

2013-11-19

A superconducting fault current-limiter is provided, including a superconducting element configured to resistively or inductively limit a fault current, and one or more variable-impedance shunts electrically coupled in parallel with the superconducting element. The variable-impedance shunt(s) is configured to present a first impedance during a superconducting state of the superconducting element and a second impedance during a normal resistive state of the superconducting element. The superconducting element transitions from the superconducting state to the normal resistive state responsive to the fault current, and responsive thereto, the variable-impedance shunt(s) transitions from the first to the second impedance. The second impedance of the variable-impedance shunt(s) is a lower impedance than the first impedance, which facilitates current flow through the variable-impedance shunt(s) during a recovery transition of the superconducting element from the normal resistive state to the superconducting state, and thus, facilitates recovery of the superconducting element under load.

Characterization of superconducting coil for fault current limitation

International Nuclear Information System (INIS)

Polasek, Alexander; Dias, Rodrigo; Niedu, Daniel Brito; Ogasawara, Tsuneharu; Oliveira Filho, Orsino Borges de; Serra, Eduardo Torres; Gomes Junior, George; Amorim, Helio Salim

2010-01-01

The increasing power demand has been raising fault currents up to dangerous levels. Superconducting fault current limiters are a promising solution for this problem. In the present work, we studied a superconducting Bi-2212 coil that is used for fault current limitation. Samples were analyzed by XRD, SEM/EDS and measurement of critical temperature (Tc). The Rietveld method was employed for phase quantification. Relatively high Bi-2212 fractions were found. However, Tc varies from a sample to another one. Variations of local Tc are attributed to variations of oxygen content in Bi- 2212 phase. (author)

Excessive current in wide superconducting films

International Nuclear Information System (INIS)

Volotskaya, V.G.; Sivakov, A.G.; Turutanov, O.G.

1986-01-01

The resistive state of a wide long film due to superconductivity destruction by current is studied. The voltage-independent excess current I 0 is observed on I-V curves at high transport currents. The two-dimensional image of the current-carrying sample obtained by laser scanning technique in this current range indicates that the whole film is in the resistive state. The current I 0 is measured as a function of magnetic field and SHF power

Development of Bi-based high critical current density superconducting tapes

International Nuclear Information System (INIS)

Swaminathan, G.

1995-01-01

In order to achieve the aim of developing suitable superconducting materials the main emphasis has to be made in the following areas viz., synthesizing powders, detailed study of sintering and phase conversion process in relation to the critical current density (J c ) on pellets and optimising of tape processing parameters. The bismuth system has been found to be more favourable for making wires and tapes because of its high transition temperature, good stability, does not require oxygen on cooling and is non-toxic. These have been the most convenient properties which made the BiSCO material the most popular one

A superconducting direct-current limiter with a power of up to 8 MVA

Energy Technology Data Exchange (ETDEWEB)

Fisher, L. M.; Alferov, D. F., E-mail: DFAlferov@niitfa.ru; Akhmetgareev, M. R.; Budovskii, A. I.; Evsin, D. V.; Voloshin, I. F.; Kalinov, A. V. [National Technical Physics and Automation Research Institute (Russian Federation)

2016-12-15

A resistive switching superconducting fault current limiter (SFCL) for DC networks with a nominal voltage of 3.5 kV and a nominal current of 2 kA was developed, produced, and tested. The SFCL has two main units—an assembly of superconducting modules and a high-speed vacuum circuit breaker. The assembly of superconducting modules consists of nine (3 × 3) parallel–series connected modules. Each module contains four parallel-connected 2G high-temperature superconducting (HTS) tapes. The results of SFCL tests in the short-circuit emulation mode with a maximum current rise rate of 1300 A/ms are presented. The SFCL is capable of limiting the current at a level of 7 kA and break it 8 ms after the current-limiting mode begins. The average temperature of HTS tapes during the current-limiting mode increases to 210 K. After the current is interrupted, the superconductivity recovery time does not exceed 1 s.

A superconducting direct-current limiter with a power of up to 8 MVA

Science.gov (United States)

Fisher, L. M.; Alferov, D. F.; Akhmetgareev, M. R.; Budovskii, A. I.; Evsin, D. V.; Voloshin, I. F.; Kalinov, A. V.

2016-12-01

A resistive switching superconducting fault current limiter (SFCL) for DC networks with a nominal voltage of 3.5 kV and a nominal current of 2 kA was developed, produced, and tested. The SFCL has two main units—an assembly of superconducting modules and a high-speed vacuum circuit breaker. The assembly of superconducting modules consists of nine (3 × 3) parallel-series connected modules. Each module contains four parallel-connected 2G high-temperature superconducting (HTS) tapes. The results of SFCL tests in the short-circuit emulation mode with a maximum current rise rate of 1300 A/ms are presented. The SFCL is capable of limiting the current at a level of 7 kA and break it 8 ms after the current-limiting mode begins. The average temperature of HTS tapes during the current-limiting mode increases to 210 K. After the current is interrupted, the superconductivity recovery time does not exceed 1 s.

SQUID based cryogenic current comparator for measurements of the dark current of superconducting cavities

Energy Technology Data Exchange (ETDEWEB)

Vodel, W.; Nietzsche, S.; Neubert, R.; Nawrodt, R. [Friedrich Schiller Univ. Jena (Germany); Peters, A. [GSI Darmstadt (Germany); Knaack, K.; Wendt, M.; Wittenburg, K. [DESY Hamburg (Germany)

2005-07-01

The linear accelerator technology, based on super-conducting L-band (1.3 GHz) is currently under study at DESY (Hamburg, Germany). The two 10 km long main Linacs will be equipped with a total of nearly 20.000 cavities. The dark current due to the emission of electrons in these high gradient field super-conducting cavities is an unwanted particle source. A newly high performance SQUID based measurement system for detecting dark currents is proposed. It makes use of the Cryogenic Current Comparator principle and senses dark currents in the pA range with a measurement bandwidth of up to 70 kHz. The use of a cryogenic current comparator as dark current sensor has some important advantages: -) the measurement of the absolute value of the dark current, -) the non-dependence on the electron trajectories, -) the accurate absolute calibration with an additional wire loop, and -) extremely high resolution.

Analysis of mechanical characteristics of superconducting field coil for 17 MW class high temperature superconducting synchronous motor

International Nuclear Information System (INIS)

Kim, J. H.; Park, S. I.; Im, S. H.; Kim, H. M.

2013-01-01

Superconducting field coils using a high-temperature superconducting (HTS) wires with high current density generate high magnetic field of 2 to 5 [T] and electromagnetic force (Lorentz force) acting on the superconducting field coils also become a very strong from the point of view of a mechanical characteristics. Because mechanical stress caused by these powerful electromagnetic force is one of the factors which worsens the critical current performance and structural characteristics of HTS wire, the mechanical stress analysis should be performed when designing the superconducting field coils. In this paper, as part of structural design of superconducting field coils for 17 MW class superconducting ship propulsion motor, mechanical stress acting on the superconducting field coils was analyzed and structural safety was also determined by the coupling analysis system that is consists of commercial electromagnetic field analysis program and structural analysis program.

High temperature interface superconductivity

International Nuclear Information System (INIS)

Gozar, A.; Bozovic, I.

2016-01-01

Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T_c superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T_c Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

Superconductivity in high energy particle accelerators

International Nuclear Information System (INIS)

Schmueser, P.

2002-08-01

The basics of superconductivity are outlined with special emphasis on the features which are relevant for the application in magnets and radio frequency cavities for high energy particle accelerators. The special properties of superconducting accelerator magnets are described in detail: design principles, magnetic field calculations, magnetic forces, quench performance, persistent magnetization currents and eddy currents. The design principles and basic properties of superconducting cavities are explained as well as the observed performance limitations and the countermeasures. The ongoing research efforts towards maximum accelerating fields are addressed and the coupling of radio frequency power to the particle beam is treated. (orig.)

Modern high-temperature superconductivity

International Nuclear Information System (INIS)

Ching Wu Chu

1988-01-01

Ever since the discovery of superconductivity in 1911, its unusual scientific challenge and great technological potential have been recognized. For the past three-quarters of a century, superconductivity has done well on the science front. This is because sueprconductivity is interesting not only just in its own right but also in its ability to act as a probe to many exciting nonsuperconducting phenomena. For instance, it has continued to provide bases for vigorous activities in condensed matter science. Among the more recent examples are heavy-fermion systems and organic superconductors. During this same period of time, superconductivity has also performed admirably in the applied area. Many ideas have been conceived and tested, making use of the unique characteristics of superconductivity - zero resistivity, quantum interference phenomena, and the Meissner effect. In fact, it was not until late January 1987 that it became possible to achieve superconductivity with the mere use of liquid nitrogen - which is plentiful, cheap, efficient, and easy to handle - following the discovery of supercondictivity above 90 K in Y-Ba-Cu-O, the first genuine quaternary superconductor. Superconductivity above 90 K poses scientific and technological challenges not previously encountered: no existing theories can adequately describe superconductivity above 40 K and no known techniques can economically process the materials for full-scale applications. In this paper, therefore, the author recalls a few events leading to the discovery of the new class of quaternary compounds with a superconducting transition temperature T c in the 90 K range, describes the current experimental status of high-temperature superconductivity and, finally, discusses the prospect of very-high-temperature superconductivity, i.e., with a T c substantially higher than 100 K. 97 refs., 7 figs

Epitaxial YBa2Cu3O7 on biaxially textured (001) Ni: An approach to high critical current density superconducting tapes

International Nuclear Information System (INIS)

Norton, D.P.; Goyal, A.; Budai, J.D.

1997-01-01

In-plane aligned, c-axis oriented YBa 2 Cu 3 O 7 (YBCO) films with superconducting critical current densities, J c , as high as 700,000 amperes per square centimeter at 77 kelvin have been grown on thermo-mechanically, rolled-textured (001) Ni tapes using pulsed-laser deposition. Epitaxial growth of oxide buffer layers directly on biaxially textured Ni, formed by recrystallization of cold-rolled pure Ni, enables the growth of 1.5 micrometer-thick YBCO films with superconducting properties that are comparable to those observed for epitaxial films on single crystal oxide substrates. This result represents a viable approach for producing long-length superconducting tapes for high current, high field applications at 77 kelvin

A current controlled variable delay superconducting transmission line

International Nuclear Information System (INIS)

Anlage, S.M.; Snortland, H.J.; Beasley, M.R.

1989-01-01

The authors present a device concept for a current-controlled variable delay for superconducting transmission line. The device makes use of the change in kinetic inductance of a superconducting transmission line under the application of a DC bias current. The relevant materials parameters and several promising superconducting materials have been identified

Development of high field superconducting magnet

International Nuclear Information System (INIS)

Irie, Fujio; Takeo, Masakatsu.

1986-01-01

Recently, in connection with nuclear fusion research, the development of high field superconducting magnets showed rapid progress. The development of high field magnets of 15 T class by the techniques of winding after heat treatment has been continued in various places, as these techniques are suitable to make large magnets. In 1985, Kyushu University attained the record of 15.5 T. However in high field magnets, there are many problems peculiar to them, and the basic research related to those is demanded. In this report, these general problems, the experience of the design and manufacture in Kyushu University and the related problems are described. The superconducting magnet installed in the Superconducting Magnet Research Center of Kyushu University attained the record of 15.5 T for the first time in March, 1985. In superconducting magnets, very difficult problem must be solved since superconductivity, heat and mechanical force are inter related. The problems of the wire materials for high field, the scale of high field magnets, the condition limiting mean current density, and the development of high field magnets in Kyushu University are described. (Kako, I.)

Cryogenic Current Comparator for Absolute Measurement of the Dark Current of the Superconducting Cavities for Tesla

CERN Document Server

Knaack, K; Wittenburg, K

2003-01-01

A newly high performance SQUID based measurement system for detecting dark currents, generated by superconducting cavities for TESLA is proposed. It makes use of the Cryogenic Current Comparator principle and senses dark currents in the nA range with a small signal bandwidth of 70 kHz. To reach the maximum possible energy in the TESLA project is a strong motivation to push the gradients of the superconducting cavities closer to the physical limit of 50 MV/m. The field emission of electrons (the so called dark current) of the superconducting cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. This contribution describes a Cryogenic Current Comparator (CCC) as an excellent and useful tool for this purpose. The most important component of the CCC is a high performance DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted ...

Fluctuation current in superconducting loops

International Nuclear Information System (INIS)

Berger, Jorge

2012-01-01

A superconducting loop that encloses noninteger flux holds a permanent current. On the average, this current is also present above T c , and has been measured in recent years. We are able to evaluate the permanent current within the TDGL or the Kramer-Watts-Tobin models for loops of general configuration, i.e., we don't require uniform cross section, material or temperature. We can also consider situations in which the width is not negligible in comparison to the radius. Our results agree with experiments. The situations with which we deal at present include fluctuation superconductivity in two-band superconductors, equilibrium thermal fluctuations of supercurrent along a weak link, and ratchet effects.

Fault-current limiter using a superconducting coil

International Nuclear Information System (INIS)

Boenig, H.J.; Paice, D.A.

1982-01-01

A novel circuit, consisting of solid-state diodes and a biased superconducting coil, for limiting the fault currents in three-phase ac systems is presented. A modification of the basic circuit results in a solid-state ac breaker with current-limiting features. The operating characteristics of the fault-current limiter and the ac breaker are analyzed. An optimization procedure for sizing the superconducting coil is derived

High field superconducting magnets

Science.gov (United States)

Hait, Thomas P. (Inventor); Shirron, Peter J. (Inventor)

2011-01-01

A superconducting magnet includes an insulating layer disposed about the surface of a mandrel; a superconducting wire wound in adjacent turns about the mandrel to form the superconducting magnet, wherein the superconducting wire is in thermal communication with the mandrel, and the superconducting magnet has a field-to-current ratio equal to or greater than 1.1 Tesla per Ampere; a thermally conductive potting material configured to fill interstices between the adjacent turns, wherein the thermally conductive potting material and the superconducting wire provide a path for dissipation of heat; and a voltage limiting device disposed across each end of the superconducting wire, wherein the voltage limiting device is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet.

Functional model of a high-current high-voltage superconducting switches

International Nuclear Information System (INIS)

Menke, Kh.; Shishov, Yu.A.

1977-01-01

Considered are problems of superconducting switches (SS) for energy extraction from magnets at a current of several kiloamperes and a voltage of several kilovolts with a time for transition to the normal state of <0.5 ms. SS is made of a wire of 0.5 mm diameter containing 19 strands of Nb-Ti alloy of 65 μm diameter. The wire matrix was etched out, 19 wires of 4.5 m length were braided together. On each of three groups of wires a heater wire of constantan of 0.12 mm diameter and 6 m length was wound. A second heater intended for slow heating during current feeding into the magnet, is wound over the braid. The wires and heaters are parallel connected and impregnated by an epoxy compound. The following main parameters were obtained in SS testing: critical current of 920 A, resistance in the normal state of 2.5 Ohm, and minimum delay time of 0.2 ms at a nominal current of 0.8 of the critical one

Design of high-energy high-current linac with focusing by superconducting solenoids

Energy Technology Data Exchange (ETDEWEB)

Batskikh, G.I.; Belugin, V.M.; Bondarev, B.I. [Moscow Radiotechnical Institute (Russian Federation)] [and others

1995-10-01

The advancement of MRTI design for 1.5 GeV and 250 mA ion CW linac was presented in a previous report. In this new linac version all the way from input to output the ions are focused by magnetic fields of superconducting solenoids. The ion limit current is far beyond the needed value. The linac focusing channel offers major advantages over the more conventional ones. The acceptance is 1.7 times as large for such focusing channel as for quadrupole one. Concurrently, a random perturbation sensitivity for such channel is one order of magnitude smaller than in quadrupole channel. These focusing channel features allow to decrease beam matched radius and increase a linac radiation purity without aperture growth. {open_quotes}Regotron{close_quotes} is used as high power generator in linac main part. But D&W cavities need not be divided into sections connected by RF-bridges which denuded them of high coupling factor.

Conceptual design of current lead for large scale high temperature superconducting rotating machine

International Nuclear Information System (INIS)

Le, T. D.; Kim, J. H.; Park, S. I.; Kim, H. M.

2014-01-01

High-temperature superconducting (HTS) rotating machines always require an electric current of from several hundreds to several thousand amperes to be led from outside into cold region of the field coil. Heat losses through the current leads then assume tremendous importance. Consequently, it is necessary to acquire optimal design for the leads which would achieve minimum heat loss during operation of machines for a given electrical current. In this paper, conduction cooled current lead type of 10 MW-Class HTS rotating machine will be chosen, a conceptual design will be discussed and performed relied on the least heat lost estimation between conventional metal lead and partially HTS lead. In addition, steady-state thermal characteristic of each one also is considered and illustrated.

Progress on the high-current 704 MHz superconducting RF cavity at BNL

International Nuclear Information System (INIS)

Xu, W.; Astefanous, C.; Belomestnykh, S.; Ben-Zvi, I.

2012-01-01

The 704 MHz high current superconducting cavity has been designed with consideration of both performance of fundamental mode and damping of higher order modes. A copper prototype cavity was fabricated by AES and delivered to BNL. RF measurements were carried out on this prototype cavity, including fundamental pass-band and HOM spectrum measurements, HOM studies using bead-pull setup, prototyping of antenna-type HOM couplers. The measurements show that the cavity has very good damping for the higher-order modes, which was one of the main goals for the high current cavity design. 3D cavity models were simulated with Omega3P code developed by SLAC to compare with the measurements. The paper describes the cavity design, RF measurement setups and results for the copper prototype. The progress with the niobium cavity fabrication will also be described.

Limiting currents in superconducting composites

International Nuclear Information System (INIS)

Keilin, V.E.; Romanovskii, V.R.

1992-01-01

In this paper the results of numerical and analytical calculations of the process of current charging into a round superconducting composite with properties homogenized over cross-section are presented. In the numerical solution taken was into account a common proceeding of the thermal and electromagnetic processes. A wire with real volt-ampere characteristics approximated by exponential dependence was considered. The calculations carried out at various rates of current charging, voltampere characteristics, matrix materials, heat transfer coefficients and other parameters showed: the existence of characteristic limiting value of current below which the wire remains in a superconducting state if the current charging ceases and above which changes into a normal state; this current is somewhat less than a quench current; the existence of finite value for limiting current at any low heat transfer from a surface. The analytical solution of the problem is given. It permitted to write the stability criterion from which the dependence of limiting currents on initial parameters follows. The wire nonisothermality, its heat capacity, thermal and electric conductivities are taken into account additionally, as compared to results published earlier

High-temperature superconductivity

International Nuclear Information System (INIS)

Ginzburg, V.L.

1987-07-01

After a short account of the history of experimental studies on superconductivity, the microscopic theory of superconductivity, the calculation of the control temperature and its possible maximum value are presented. An explanation of the mechanism of superconductivity in recently discovered superconducting metal oxide ceramics and the perspectives for the realization of new high-temperature superconducting materials are discussed. 56 refs, 2 figs, 3 tabs

High voltage superconducting switch for power application

International Nuclear Information System (INIS)

Mawardi, O.; Ferendeci, A.; Gattozzi, A.

1983-01-01

This paper reports the development of a novel interrupter which meets the requirements of a high voltage direct current (HVDC) power switch and at the same time doubles as a current limiter. The basic concept of the interrupter makes use of a fast superconducting, high capacity (SHIC) switch that carries the full load current while in the superconducting state and reverts to the normal resistive state when triggered. Typical design parameters are examined for the case of a HVDC transmission line handling 2.5KA at 150KVDC. The result is a power switch with superior performance and smaller size than the ones reported to date

Optimization of Superconducting Focusing Quadrupoles for the HighCurrent Experiment

Energy Technology Data Exchange (ETDEWEB)

Sabbi, GianLuca; Gourlay, Steve; Gung, Chen-yu; Hafalia, Ray; Lietzke, Alan; Martovetski, Nicolai; Mattafirri, Sara; Meinke, Rainer; Minervini, Joseph; Schultz, Joel; Seidl, Peter

2005-09-16

The Heavy Ion Fusion (HIF) program is progressing through a series of physics and technology demonstrations leading to an inertial fusion power plant. The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is exploring the physics of intense beams with high line-charge density. Superconducting focusing quadrupoles have been developed for the HCX magnetic transport studies. A baseline design was selected following several pre-series models. Optimization of the baseline design led to the development of a first prototype that achieved a conductor-limited gradient of 132 T/m in a 70 mm bore, without training, with measured field errors at the 0.1% level. Based on these results, the magnet geometry and fabrication procedures were adjusted to improve the field quality. These modifications were implemented in a second prototype. In this paper, the optimized design is presented and comparisons between the design harmonics and magnetic measurements performed on the new prototype are discussed.

Harmonic current layer method for the design of superconducting quadrupole magnetic field

International Nuclear Information System (INIS)

Zizek, F.

1977-01-01

The magnetic field of a superconducting quadrupole is investigated by the method of harmonic current layers of cylindrical shape. The superconducting winding is replaced by a system of thin current layers with a harmonically distributed density of the surface current along the circumference. The effect of the outer ferromagnetic circuit with an arbitrary constant permeability over the cross section is replaced analogically. The resultant magnetic field is then given by the superposition of the contributions from the individual current layers. The calculation method can be modified for the selection of the geometry of the winding for the latter to meet the demand for the high homogeneity of the gradient of magnetic induction in the working space of the superconducting quadrupole. (author)

Final report: High current capacity high temperature superconducting film based tape for high field magnets

International Nuclear Information System (INIS)

Ying Xin

2000-01-01

The primary goal of the program was to establish the process parameters for the continuous deposition of high quality, superconducting YBCO films on one meter lengths of buffered RABiTS tape using MOCVD and to characterize the potential utility of the resulting tapes in high field magnet applications

Generation of high magnetic fields using superconducting magnets

International Nuclear Information System (INIS)

Kiyoshi, T.; Otsuka, A.; Kosuge, M.; Yuyama, M.; Nagai, H.; Matsumoto, F.

2006-01-01

High-field superconducting magnets have opened new frontiers for several kinds of applications, such as fusion reactors, particle accelerators, and nuclear magnetic resonance (NMR) spectrometers. The present record for the highest field in a fully superconducting state is 23.4 T. It was achieved with a combination of NbTi, Nb 3 Sn, and Bi-2212 conductors in 1999. Since high T c (critical temperature) superconductors (HTS) have sufficiently high critical current density even in excess of 30 T, they are promising for use as high-field superconducting magnets. However, several problems still remain to be resolved for practical applications, and the use of HTS coils will be limited to the inner part of a high-field magnet system in the near future. The required technologies to develop a high-field superconducting magnet with a field of up to 28 T have already been established. Such a magnet is certain to provide information to all leading research areas

Abstracts of The First Polish-US Conference on High Temperature Superconductivity

International Nuclear Information System (INIS)

1995-01-01

The current problems in high temperature superconductivity science have been presented at the conference. The two main topics have been mostly represented: superconducting material research and fundamental physical research on superconductivity mechanisms. Superconducting material preparation, chemical composition, magnetic and electrical properties of different type of high temperature superconductors, material structure and its influence on superconducting properties and related problems were included in the first of the general topics. In the range of second general topic of the two listed above, many theoretical models being applied for explanation of superconductivity mechanism in different systems up and below transition temperature were presented

Analysis of persistent current in the superconducting magnets on an EDS Maglev vehicle for high-speed passenger transport

Energy Technology Data Exchange (ETDEWEB)

Azukizawa, Teruo [R and D Center, Toshiba Corp. (Japan)

1996-12-31

In an electrodynamic suspension system using superconducting magnets, an air core system is employed to effectively use strong magnetic fields produced by the superconducting magnets. This paper proposes an analysis method for the fluctuating persistent current in an superconducting soil, considering electromagnetic effects of the conductive cryostat. (HW)

Superconducting quantum interference monitor of charged particle beam current

International Nuclear Information System (INIS)

Gertsev, K.F.; Mikheev, M.S.

1981-01-01

Description and test results of the monitor of charged particle beam current on the base of the high-frequency superconducting quantum interference detector with lead slotted shield are presented. The toroidal superconducting coil, which covers the measured beam has 16 turns wound by the lead belt of 7 mm width with 0.5 mm gaps between the turns. A superconducting low-coupling monitor having two holes and point oxidated niobium contact has been used in the mode of quanta counting of magnetic flux. The lead point shield was 2 mm thick and it had 30 mm aperture. The coefficient of background shielding within 0-200 Hz frequency range constituted more than 10 8 . The threshold current resolution of the monitor had the value less than 01 μA √Hz. The suggested monitor requires helium cooling. The proposed design of the monitor is applicable for mounting on the vacuum chamber when it is surrounded by helium conductor. In other cases mounting of low-powerful autonomic system or cryostat of helium storage up to several weeks is possible [ru

Assessment of the impact of HTSCs on superconducting fault-current limiters

International Nuclear Information System (INIS)

Giese, R.F.; Runde, M.

1992-01-01

The possible impact of nitrogen-cooled superconductors on the design and cost of superconducting fault-current limiters is assessed by considering the technical specifications such devices must meet and by comparing material properties of 77-K and 4-K superconductors. The main advantage of operating superconducting at 77 K is that the refrigeration operating cost is reduced by a factor of up to 25, and the refrigeration capital cost is reduced by a factor of up to 10. The heat capacity at 77 K is several orders of magnitude larger than at 4 K. This phenomenon increases conductor stability against flux jumps but makes switching from the superconducting to normal state slow and difficult. Therefore, a high critical current density, probably at least 10 5 A/cm 2 , is required

Self-triggering superconducting fault current limiter

Science.gov (United States)

Yuan, Xing [Albany, NY; Tekletsadik, Kasegn [Rexford, NY

2008-10-21

A modular and scaleable Matrix Fault Current Limiter (MFCL) that functions as a "variable impedance" device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. The matrix fault current limiter comprises a fault current limiter module that includes a superconductor which is electrically coupled in parallel with a trigger coil, wherein the trigger coil is magnetically coupled to the superconductor. The current surge doing a fault within the electrical power network will cause the superconductor to transition to its resistive state and also generate a uniform magnetic field in the trigger coil and simultaneously limit the voltage developed across the superconductor. This results in fast and uniform quenching of the superconductors, significantly reduces the burnout risk associated with non-uniformity often existing within the volume of superconductor materials. The fault current limiter modules may be electrically coupled together to form various "n" (rows).times."m" (columns) matrix configurations.

A superconducting quadrupole array for transport of multiple high current beams

International Nuclear Information System (INIS)

Faltens, A.; Shuman, D.

1999-01-01

We present a conceptual design of a superconducting quadrupole magnet array for the side-by-side transport of multiple high current particle beams in induction linear accelerators. The magnetic design uses a modified cosine 20 current distribution inside a square cell boundary. Each interior magnet's neighbors serve as the return flux paths and the poles are placed as close as possible to each other to facilitate this. No iron is present in the basic 2-D magnetic design; it will work at any current level without correction windings. Special 1/8th quadrupoles are used along the transverse periphery of the array to contain and channel flux back into the array, making every channel look as part of an infinite array. This design provides a fixed dimension array boundary equal to the quadrupole radius that can be used for arrays of any number of quadrupole channels, at any field level. More importantly, the design provides magnetic field separation between the array and the induction cores which may be surrounding it. Flux linkage between these two components can seriously affect the operation of both of them

Bi-based superconducting fibers with high critical parameters

International Nuclear Information System (INIS)

Huo Yujing; He Yusheng; Liu Menglin; Mao Sining; Cai Liying; Wang Ying; Zhang Jincang; He Aisheng; Wang Jinsong

1991-01-01

Superconducting fibers of Bi(Pb)-Sr-Ca-Cu-O high Tc superconducting materials have been prepared by means of the laser-heated pedestal growth (LHPG) method. The highest zero resistance temperature T c0 reaches is 114K, and the highest critical current density J c (77K, O T) is greater than 5000 A/cm 2 . As-grown superconducting fibers were successfully fabricated without post growth heat treatment. Amorphous materials were used for the first time to make high quality fibers. The influence of growth conditions, thermal treatment and the composition of the fibers were discussed. (author). 5 refs., 7 figs., 3 tabs

Improved critical current densities and compressive strength in porous superconducting structures containing calcium

International Nuclear Information System (INIS)

Walsh, D; Hall, S R; Wimbush, S C

2008-01-01

Templated control of crystallization by biopolymers is a new technique in the synthesis of high temperature superconducting phases. By controlling the way YBa 2 Cu 3 O 7-δ (Y123) materials crystallize and are organized in three dimensions, the critical current density can be improved. In this work, we present the results of doping superconducting sponges with calcium ions, which result in higher critical current densities (J c ) and improved compressive strength compared to that of commercially available Y123, in spite of minor reductions in T c . Y123 synthesis using the biopolymer dextran achieves not only an extremely effective oxygenation of the superconductor but also an in situ template-directing of the crystal morphology producing high J c , homogeneous superconducting structures with nano-scale crystallinity

Current distribution characteristics of superconducting parallel circuits

International Nuclear Information System (INIS)

Mori, K.; Suzuki, Y.; Hara, N.; Kitamura, M.; Tominaka, T.

1994-01-01

In order to increase the current carrying capacity of the current path of the superconducting magnet system, the portion of parallel circuits such as insulated multi-strand cables or parallel persistent current switches (PCS) are made. In superconducting parallel circuits of an insulated multi-strand cable or a parallel persistent current switch (PCS), the current distribution during the current sweep, the persistent mode, and the quench process were investigated. In order to measure the current distribution, two methods were used. (1) Each strand was surrounded with a pure iron core with the air gap. In the air gap, a Hall probe was located. The accuracy of this method was deteriorated by the magnetic hysteresis of iron. (2) The Rogowski coil without iron was used for the current measurement of each path in a 4-parallel PCS. As a result, it was shown that the current distribution characteristics of a parallel PCS is very similar to that of an insulated multi-strand cable for the quench process

Effect of a superconducting coil as a fault current limiter on current density distribution in BSCCO tape after an over-current pulse

International Nuclear Information System (INIS)

Tallouli, M; Yamaguchi, S.; Shyshkin, O.

2017-01-01

The development of power transmission lines based on long-length high temperature superconducting (HTS) tapes is complicated and technically challenging task. A serious problem for transmission line operation could become HTS power cable damage due to over-current pulse conditions. To avoid the cable damage in any urgent case the superconducting coil technology, i.e. superconductor fault current limiter (SFCL) is required. Comprehensive understanding of the current density characteristics of HTS tapes in both cases, either after pure over-current pulse or after over-current pulse limited by SFCL, is needed to restart or to continue the operation of the power transmission line. Moreover, current density distribution along and across the HTS tape provides us with the sufficient information about the quality of the tape performance in different current feeding regimes. In present paper we examine BSCCO HTS tape under two current feeding regimes. The first one is 100A feeding preceded by 900A over-current pulse. In this case none of tape protection was used. The second scenario is similar to the fist one but SFCL is used to limit an over-current value. For both scenarios after the pulse is gone and the current feeding is set up at 100A we scan magnetic field above the tape by means of Hall probe sensor. Then the feeding is turned of and the magnetic field scanning is repeated. Using the inverse problem numerical solver we calculate the corresponding direct and permanent current density distributions during the feeding and after switch off. It is demonstrated that in the absence of SFCL the current distribution is highly peaked at the tape center. At the same time the current distribution in the experiment with SFCL is similar to that observed under normal current feeding condition. The current peaking in the first case is explained by the effect of an opposite electric field induced at the tape edges during the overcurrent pulse decay, and by degradation of

SQUID Based Cryogenic Current Comparator for Measurements of the Dark Current of Superconducting Cavities

CERN Document Server

Vodel, W; Neubert, R; Nietzsche, S

2005-01-01

This contribution presents a LTS-SQUID based Cryogenic Current Comparator (CCC) for detecting dark currents, generated e.g. by superconducting cavities for the upcoming X-FEL project at DESY. To achieve the maximum possible energy the gradients of the superconducting RF cavities should be pushed close to the physical limit of 50 MV/m. The measurement of the undesired field emission of electrons (the so-called dark current) in correlation with the gradient will give a proper value to compare and classify the cavities. The main component of the CCC is a high performance LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted dark current. For this reason the input coil of the SQUID is connected across a special designed toroidal niobium pick-up coil (inner diameter: about 100 mm) for the passing electron beam. A noise limited current resolution of nearly 2 pA/√(Hz) with a measurement bandwidth of up to 70 kHz was achieved without the pick-up coil. Now, ...

Characterization of high-current, high-temperature superconductor current lead elements

International Nuclear Information System (INIS)

Niemann, R.C.; Evans, D.J.; Fisher, B.L.; Brockenborough, W.E.; Roberts, P.R.; Rodenbush, A.J.

1996-08-01

The refrigeration loads of current leads for superconducting magnets can be significantly reduced by using high-temperature superconductor (HTS) leads. An HTS conductor type that is well suited for this application is a laminated sintered stack of HTS powder-in-tube (PIT) tapes. The superconducting elements are normally characterized by their manufacturer by measuring critical currents at 77 K in self field. Additional characterization, which correlates electrical performance at 77 K and at lower temperatures with applied magnetic fields, provides the current lead designer and conductor element manufacturer with critical information. For HTS conductor elements comprising a laminated and sintered stack of Bi-2223 PIT tapes having an alloyed Ag sheath, this characterization uses variable applied fields and operating temperatures

Current Feedthroughs for Superconducting Magnets Operating Below 2 K

CERN Document Server

Benda, V

1998-01-01

For superconducting magnets working in superfluid helium, a thermal and pressure barrier between liquid helium baths at different temperatures, so called "lambda plate", is required. Bus bars connecte d to current leads of magnets to be powered, pass through current feedthroughs. These feedthroughs have to stand high pressure, thermal shock, high voltage, and mechanical stresses, must be leak tight and introduce minimum heat inleak. This article describes a possible solution. Three prototypes were built and measured. Design of this feedthrough and preliminary results are presented.

Transient characteristics of current lead losses for the large scale high-temperature superconducting rotating machine

International Nuclear Information System (INIS)

Le, T. D.; Kim, J. H.; Park, S. I.; Kim, D. J.; Kim, H. M.; Lee, H. G.; Yoon, Y. S.; Jo, Y. S.; Yoon, K. Y.

2014-01-01

To minimize most heat loss of current lead for high-temperature superconducting (HTS) rotating machine, the choice of conductor properties and lead geometry - such as length, cross section, and cooling surface area - are one of the various significant factors must be selected. Therefore, an optimal lead for large scale of HTS rotating machine has presented before. Not let up with these trends, this paper continues to improve of diminishing heat loss for HTS part according to different model. It also determines the simplification conditions for an evaluation of the main flux flow loss and eddy current loss transient characteristics during charging and discharging period.

The discovery of high temperature superconductivity

International Nuclear Information System (INIS)

Muller, K. A.; Bednorz, J.G.

1988-01-01

This article recalls the different stages which led to the display of high temperature superconductivity for Ba, La, Cu, O and the following avalanche of discoveries for other oxides; the numerous theoretical models which tentatively explain the current experimental results are also reviewed. 30 refs

The discovery of high temperature superconductivity

International Nuclear Information System (INIS)

Muller, K.A.; Bednorz, J.G.

1988-01-01

This article recalls the different stages which led to the display of high temperature superconductivity for Ba La Cu O, and the following avalanche of discoveries for other oxides; the numerous theoretical models which tentatively explain the current experimental results are also reviewed [fr

A numerical study on the feasibility evaluation of a hybrid type superconducting fault current limiter applying thyristors

Energy Technology Data Exchange (ETDEWEB)

Nam, Seok Ho; Lee, Woo Seung; Lee, Ji Ho; Hwang, Young Jin; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of)

2013-12-15

Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

A numerical study on the feasibility evaluation of a hybrid type superconducting fault current limiter applying thyristors

International Nuclear Information System (INIS)

Nam, Seok Ho; Lee, Woo Seung; Lee, Ji Ho; Hwang, Young Jin; Ko, Tae Kuk

2013-01-01

Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

Flux-lock type of superconducting fault current limiters: A comprehensive review

Science.gov (United States)

Badakhshan, M.; Mousavi G., S. M.

2018-04-01

Power systems must be developed and extended to supply the continuous enhancement of demands for electrical energy. This development of systems in addition to the integration of distributed generation (DG) units to the power systems results higher capacity of system. Hence, short circuit current of network is confronted with persistent increasing. Since exploration of high temperature superconducting (HTS) materials, superconducting fault current limiters (SFCLs) have attracted a lot of attention all over the world. There are different types of SFCLs. Flux-lock type of SFCL because of its characteristics in fault current limitation is an important category of SFCLs. This paper aims to present a comprehensive review of research activities and applications of Flux-lock type of SFCLs in power systems.

Hybrid superconducting a.c. current limiter extrapolation 63 kV-1 250 A

Science.gov (United States)

Tixador, P.; Levêque, J.; Brunet, Y.; Pham, V. D.

1994-04-01

Following the developement of a.c. superconducting wires a.c. current superconducting limiters have emerged. These limiters limit the fault currents nearly instantaneously, without detection nor order giver and may be suitable for high voltages. They are based on the natural transition from the superconducting state to the normal resistive state by overstepping the critical current of a superconducting coil which limits or triggers the limitation. Our limiter device consists essentially of two copper windings coupled through a saturable magnetic circuit and of a non inductively wound superconducting coil with a reduced current compared to the line current. This design allows a simple superconducting cable and reduced cryogenic losses but the dielectric stresses are high during faults. A small model (150 V/50 A) has experimentally validated our design. An industrial scale current limiter is designed and the comparisons between this design and other superconducting current limiters are given. Les courants de court-circuit sur les grands réseaux électriques ne cessent d'augmenter. Dans ce contexte sont apparus les limiteurs supraconducteurs de courant suite au développement des brins supraconducteurs alternatifs. Ces limiteurs peuvent limiter les courants de défaut presque instantanément, sans détection de défaut ni donneur d'ordre et ils sont extrapolables aux hautes tensions. Ils sont fondés sur la transition naturelle de l'état supraconducteur à l'état normal très résistif par dépassement du courant critique d'un enroulement supraconducteur qui limite ou déclenche la limitation. Notre limiteur est composé de deux enroulements en cuivre couplés par un circuit magnétique saturable et d'une bobine supraconductrice à courant réduit par rapport au courant de la ligne. Cette conception permet un câble supraconducteur simple et des pertes cryogéniques réduites mais les contraintes diélectriques en régime de défaut sont importantes. Une maquette

Superconducting technology for overcurrent limiting in a 25 kA current injection system

Energy Technology Data Exchange (ETDEWEB)

Heydari, Hossein; Faghihi, Faramarz; Sharifi, Reza; Poursoltanmohammadi, Amir Hossein [Center of Excellence for Power System Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of)], E-mail: heydari@iust.ac.ir, E-mail: faramarz_faghihi@ee.iust.ac.ir, E-mail: reza_sharifi@ee.iust.ac.ir, E-mail: amirhosseinp@ee.iust.ac.ir

2008-09-15

Current injection transformer (CIT) systems are within the major group of the standard type test of high current equipment in the electrical industry, so their performance becomes very important. When designing high current systems, there are many factors to be considered from which their overcurrent protection must be ensured. The output of a CIT is wholly dependent on the impedance of the equipment under test (EUT). Therefore current flow beyond the allowable limit can occur. The present state of the art provides an important guide to developing current limiters not only for the grid application but also in industrial equipment. This paper reports the state of the art in the technology available that could be developed into an application of superconductivity for high current equipment (CIT) protection with no test disruption. This will result in a greater market choice and lower costs for equipment protection solutions, reduced costs and improved system reliability. The paper will also push the state of the art by using two distinctive circuits, closed-core and open-core, for overcurrent protection of a 25 kA CIT system, based on a flux-lock-type superconducting fault current limiter (SFCL) and magnetic properties of high temperature superconducting (HTS) elements. An appropriate location of the HTS element will enhance the rate of limitation with the help of the magnetic field generated by the CIT output busbars. The calculation of the HTS parameters for overcurrent limiting is also performed to suit the required current levels of the CIT.

Superconducting technology for overcurrent limiting in a 25 kA current injection system

Science.gov (United States)

Heydari, Hossein; Faghihi, Faramarz; Sharifi, Reza; Poursoltanmohammadi, Amir Hossein

2008-09-01

Current injection transformer (CIT) systems are within the major group of the standard type test of high current equipment in the electrical industry, so their performance becomes very important. When designing high current systems, there are many factors to be considered from which their overcurrent protection must be ensured. The output of a CIT is wholly dependent on the impedance of the equipment under test (EUT). Therefore current flow beyond the allowable limit can occur. The present state of the art provides an important guide to developing current limiters not only for the grid application but also in industrial equipment. This paper reports the state of the art in the technology available that could be developed into an application of superconductivity for high current equipment (CIT) protection with no test disruption. This will result in a greater market choice and lower costs for equipment protection solutions, reduced costs and improved system reliability. The paper will also push the state of the art by using two distinctive circuits, closed-core and open-core, for overcurrent protection of a 25 kA CIT system, based on a flux-lock-type superconducting fault current limiter (SFCL) and magnetic properties of high temperature superconducting (HTS) elements. An appropriate location of the HTS element will enhance the rate of limitation with the help of the magnetic field generated by the CIT output busbars. The calculation of the HTS parameters for overcurrent limiting is also performed to suit the required current levels of the CIT.

Superconducting technology for overcurrent limiting in a 25 kA current injection system

International Nuclear Information System (INIS)

Heydari, Hossein; Faghihi, Faramarz; Sharifi, Reza; Poursoltanmohammadi, Amir Hossein

2008-01-01

Current injection transformer (CIT) systems are within the major group of the standard type test of high current equipment in the electrical industry, so their performance becomes very important. When designing high current systems, there are many factors to be considered from which their overcurrent protection must be ensured. The output of a CIT is wholly dependent on the impedance of the equipment under test (EUT). Therefore current flow beyond the allowable limit can occur. The present state of the art provides an important guide to developing current limiters not only for the grid application but also in industrial equipment. This paper reports the state of the art in the technology available that could be developed into an application of superconductivity for high current equipment (CIT) protection with no test disruption. This will result in a greater market choice and lower costs for equipment protection solutions, reduced costs and improved system reliability. The paper will also push the state of the art by using two distinctive circuits, closed-core and open-core, for overcurrent protection of a 25 kA CIT system, based on a flux-lock-type superconducting fault current limiter (SFCL) and magnetic properties of high temperature superconducting (HTS) elements. An appropriate location of the HTS element will enhance the rate of limitation with the help of the magnetic field generated by the CIT output busbars. The calculation of the HTS parameters for overcurrent limiting is also performed to suit the required current levels of the CIT

Thermal instability and current-voltage scaling in superconducting fault current limiters

Energy Technology Data Exchange (ETDEWEB)

Zeimetz, B [Department of Materials Science and Metallurgy, Cambridge University, Pembroke Street, Cambridge CB1 3QZ (United Kingdom); Tadinada, K [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom); Eves, D E [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom); Coombs, T A [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom); Evetts, J E [Department of Materials Science and Metallurgy, Cambridge University, Pembroke Street, Cambridge CB1 3QZ (United Kingdom); Campbell, A M [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom)

2004-04-01

We have developed a computer model for the simulation of resistive superconducting fault current limiters in three dimensions. The program calculates the electromagnetic and thermal response of a superconductor to a time-dependent overload voltage, with different possible cooling conditions for the surfaces, and locally variable superconducting and thermal properties. We find that the cryogen boil-off parameters critically influence the stability of a limiter. The recovery time after a fault increases strongly with thickness. Above a critical thickness, the temperature is unstable even for a small applied AC voltage. The maximum voltage and maximum current during a short fault are correlated by a simple exponential law.

A high Tc superconducting liquid nitrogen level sensor

International Nuclear Information System (INIS)

Jin, J. X.; Liu, H. K.; Dou, S. X.; Grantham, C.; Beer, J.

1996-01-01

Full text: The dramatic resistance change in the superconducting-normal transition temperature range enables a high T c superconductor to be considered for designing a liquid nitrogen level sensor. A (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire is selected and tested as a continuous liquid nitrogen level sensor to investigate the possibility for this application. The (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire has approximately 110 K critical temperature, with more flexible and stable properties compared with bulk shape ceramic high T c superconductors. The voltage drops across the sensor are tested with different immersion lengths in liquid nitrogen. The accuracy of the HTS sensor is analysed with its dR/dT in the superconducting-normal transition range. The voltage signal is sensitive to liquid nitrogen level change, and this signal can be optimized by controlling the transport current. The problems of the Ag clad superconductor are that the Ag sheath thermal conductivity is very high, and the sensor normal resistance is low. These are the main disadvantages for using such a wire as a continuous level sensor. However, a satisfactory accuracy can be achieved by control of the transport current. A different configuration of the wire sensor is also designed to avoid this thermal influence

Tetracritical point and current circulations in superconducting state

International Nuclear Information System (INIS)

Belyavskij, V.I.; Kopaev, Yu.V.; Smirnov, M.Yu.

2005-01-01

Phase diagram reflecting the key peculiar features of the standard diagram of the cuprate superconductors was studied in terms of the Ginzburg-Landau phenomenology near the tetracritical point resulting from the competition of superconducting and dielectric channels of pairing. Two-component parameter of order the relative phase of which is associated with antiferromagnetic dielectric ordering corresponds to the superconducting pairing at repulsion. In case of slight doping the dielectric order coexists with superconductivity below the temperature of superconducting phase transition and manifests itself as a slight pseudoslit above the mentioned temperature. A segment of pseudoslit region adjacent to the superconducting state corresponds to the matured fluctuations of the order parameter in the form of quasi-stationary states of noncoherent superconducting pairs and may be interpreted as a region of a strong pseudoslit. At increase of doping one observes a phase transition from the coexistence region and the orbital antiferromagnetism to the conventional superconducting state covering the region of matured fluctuations of the order parameter in the form of quasi-stationary states of the noncorrelated orbital circulation currents adjacent to the line of phase transition [ru

Transport currents along c-axis and (a,b) planes in YBCO single domain materials. Critical current densities and normal-superconducting transitions

International Nuclear Information System (INIS)

Porcar, L.; Bourgault, D.; Chaud, X.; Noudem, J.G.; Tournier, R.; Tixador, P.

1998-01-01

High transport currents along the (a,b) planes and along the c-axis have been measured in pulsed current of different pseudo-frequencies. Self field losses and transport current of 8000 A (20000 A cm -2 ) have been measured in Y 1 Ba 2 Cu 3 O 7-δ bars textured by the melting zone technique. Critical currents as high as 500 A (90000 A cm -2 ) along the (a,b) planes or 3000 A (7500 A cm -2 ) along the c-axis have been measured. For both orientations, the transition from the normal state to the superconducting state has been observed. Electric field of 1000 V m -1 and study of the superconducting state recovery are reported. (orig.)

Design and Characteristics Analysis of a Rod Type High-Tc Superconducting Fault Current Limiter through Electromagnetic Analysis

Energy Technology Data Exchange (ETDEWEB)

Hyun, O.B. [Korea Electric Power Research Institute, Taejeon (Korea); Lee, C.J.; Lee, S.J.; Ko, T.K. [Yonsei University, Seoul (Korea)

2001-07-01

The existence of a large air gaps between a High-Tc Superconducting (HTS) tube and an iron core, or between a primary winding and a HTS tube possibly causes magnetic flux leaks, resulting in undesirable voltage drops under normal operation. For this reason optimization of air gaps is essential in designing a high-Tc superconducting fault current limiter (SFCL). In this paper we performed the electromagnetic analysis for the optimization. The inductance L decreases by 20% as the hight of the winding increases from 50 to 200 mm. But, L increases from 5.6 mH to 10.5 mH as the hight of the rod changes from 150 to 400 mm. L is found to be almost constant for the air gap between 5 to 10 mm, but L decreases by 20% as the gap increases from 10 to 20 mm. The computational and experimental results will bo compared. (author). 7 refs., 8 figs., 1 tab.

Modeling and comparison of superconducting linear actuators for highly dynamic motion

Directory of Open Access Journals (Sweden)

Bruyn B.J.H. de

2015-12-01

Full Text Available This paper presents a numerical modeling method for AC losses in highly dynamic linear actuators with high temperature superconducting (HTS tapes. The AC losses and generated force of two actuators, with different placement of the cryostats, are compared. In these actuators, the main loss component in the superconducting tapes are hysteresis losses, which result from both the non-sinusoidal phase currents and movement of the permanent magnets. The modeling method, based on the H-formulation of the magnetic fields, takes into account permanent magnetization and movement of permanent magnets. Calculated losses as function of the peak phase current of both superconducting actuators are compared to those of an equivalent non-cryogenic actuator.

High transition temperature superconducting integrated circuit

International Nuclear Information System (INIS)

DiIorio, M.S.

1985-01-01

This thesis describes the design and fabrication of the first superconducting integrated circuit capable of operating at over 10K. The primary component of the circuit is a dc SQUID (Superconducting QUantum Interference Device) which is extremely sensitive to magnetic fields. The dc SQUID consists of two superconductor-normal metal-superconductor (SNS) Josephson microbridges that are fabricated using a novel step-edge process which permits the use of high transition temperature superconductors. By utilizing electron-beam lithography in conjunction with ion-beam etching, very small microbridges can be produced. Such microbridges lead to high performance dc SQUIDs with products of the critical current and normal resistance reaching 1 mV at 4.2 K. These SQUIDs have been extensively characterized, and exhibit excellent electrical characteristics over a wide temperature range. In order to couple electrical signals into the SQUID in a practical fashion, a planar input coil was integrated for efficient coupling. A process was developed to incorporate the technologically important high transition temperature superconducting materials, Nb-Sn and Nb-Ge, using integrated circuit techniques. The primary obstacles were presented by the metallurgical idiosyncrasies of the various materials, such as the need to deposit the superconductors at elevated temperatures, 800-900 0 C, in order to achieve a high transition temperature

Initial Beam Dynamics Simulations of a High-Average-Current Field-Emission Electron Source in a Superconducting RadioFrequency Gun

Energy Technology Data Exchange (ETDEWEB)

Mohsen, O. [Northern Illinois U.; Gonin, I. [Fermilab; Kephart, R. [Fermilab; Khabiboulline, T. [Fermilab; Piot, P. [Northern Illinois U.; Solyak, N. [Fermilab; Thangaraj, J. C. [Fermilab; Yakovlev, V. [Fermilab

2018-01-05

High-power electron beams are sought-after tools in support to a wide array of societal applications. This paper investigates the production of high-power electron beams by combining a high-current field-emission electron source to a superconducting radio-frequency (SRF) cavity. We especially carry out beam-dynamics simulations that demonstrate the viability of the scheme to form $\\sim$ 300 kW average-power electron beam using a 1+1/2-cell SRF gun.

High Tc superconducting three-terminal device under quasi-particle injection

International Nuclear Information System (INIS)

Hashimoto, K.; Kabasawa, U.; Tonouchi, M.; Kobayashi, T.

1988-01-01

A new type of the current injection type three terminal device was fabricated using the high Tc YBaCuO thin epitaxial films, wherein the hot quasi-particle injection effect on the superconducting current was closely examined. The zero bias drain current was efficiently suppressed by the injection of the hot quasi-particles through the gate electrode. Though it is speculative, a comparison of the experimental results and analyses based on the familiar BCS theory intimates that the main mechanism of the current modulation is the non-equilibrium superconductivity due to accumulation of the excess quasi-particles

High gradient superconducting quadrupoles

International Nuclear Information System (INIS)

Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

1987-07-01

Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

Thermal studies of a superconducting current limiter using Monte-Carlo method

International Nuclear Information System (INIS)

Leveque, J.; Rezzoug, A.

1999-01-01

Considering the increase of the fault current level in electrical network, the current limiters become very interesting. The superconducting limiters are based on the quasi-instantaneous intrinsic transition from superconducting state to normal resistive one. Without detection of default or given order, they reduce the constraints supported by electrical installations above the fault. To avoid the destruction of the superconducting coil, the temperature must not exceed a certain value. Therefore the design of a superconducting coil needs the simultaneous resolution of an electrical equation and a thermal one. This papers deals with a resolution of this coupled problem by the method of Monte-Carlo. This method allows us to calculate the evolution of the resistance of the coil as well as the current of limitation. Experimental results are compared with theoretical ones. (orig.)

Stability of the superconductive operating mode in high current-density devices

International Nuclear Information System (INIS)

Wipf, S.L.

1979-01-01

The superconductive operating mode represents a thermal equilibrium that can tolerate a certain amount of disturbance before it is lost. The basin of attraction (BOA), in many ways equivalent to a potential well, is a measure of the size of disturbance needed to lift the device from the superconductive into a resistive operating mode. The BOA for a simple geometry is calculated and discussed. Experimental results are reported, showing how the concept is used to gain information on the disturbances occurring in a superconducting device

Limiting characteristics of the superconducting fault current limiter applied to the neutral line of conventional transformer

International Nuclear Information System (INIS)

Im, I.G.; Choi, H.S.; Jung, B.I.

2013-01-01

Highlights: •Fault current limiter was used a high-speed interrupter. •High-speed interrupter was operated to bypass to the current limiter line. •The size of the fault current was limited to about 80% after the fault occurred. •The fault current was limited quickly within a half-cycle after the fault occurred. -- Abstract: The increased electricity demands influenced by the recent industrial development make the electric power distribution system more comprehensive, and the risks are high to cause failures to steady state electric line due to the extended range of fault at the time of fault occurrence. Also, the high performance and the high precision electric appliances that sensitive to switching surge and fault current expose vulnerability of reduced life span and increased fault occurrence ratio. Therefore, this thesis analyzed the fault limiting characteristics by the fault types by applying the superconducting fault current limiter to the neutral line of the transformer in order to reduce the fault currents that flow such high performance appliances. A current transformer (CT) that detects the fault current in the simulated power distribution system, a switching control system that is self-developed and a transformer are used in constructing a circuit. When a fault occurs, the initial fault current is restricted by the superconducting fault current limiter and simultaneously detours the fault current by operating the SCR contact of the switching control system through the detection by CT. This thesis analyzed the limiting characteristics of the superconducting fault current limiter that are applied to the neutral line of the transformer by the fault types

Limiting characteristics of the superconducting fault current limiter applied to the neutral line of conventional transformer

Energy Technology Data Exchange (ETDEWEB)

Im, I.G., E-mail: asiligo@gmail.com; Choi, H.S., E-mail: hyosang@chosun.ac.kr; Jung, B.I.

2013-11-15

Highlights: •Fault current limiter was used a high-speed interrupter. •High-speed interrupter was operated to bypass to the current limiter line. •The size of the fault current was limited to about 80% after the fault occurred. •The fault current was limited quickly within a half-cycle after the fault occurred. -- Abstract: The increased electricity demands influenced by the recent industrial development make the electric power distribution system more comprehensive, and the risks are high to cause failures to steady state electric line due to the extended range of fault at the time of fault occurrence. Also, the high performance and the high precision electric appliances that sensitive to switching surge and fault current expose vulnerability of reduced life span and increased fault occurrence ratio. Therefore, this thesis analyzed the fault limiting characteristics by the fault types by applying the superconducting fault current limiter to the neutral line of the transformer in order to reduce the fault currents that flow such high performance appliances. A current transformer (CT) that detects the fault current in the simulated power distribution system, a switching control system that is self-developed and a transformer are used in constructing a circuit. When a fault occurs, the initial fault current is restricted by the superconducting fault current limiter and simultaneously detours the fault current by operating the SCR contact of the switching control system through the detection by CT. This thesis analyzed the limiting characteristics of the superconducting fault current limiter that are applied to the neutral line of the transformer by the fault types.

Computational methods in calculating superconducting current problems

Science.gov (United States)

Brown, David John, II

Various computational problems in treating superconducting currents are examined. First, field inversion in spatial Fourier transform space is reviewed to obtain both one-dimensional transport currents flowing down a long thin tape, and a localized two-dimensional current. The problems associated with spatial high-frequency noise, created by finite resolution and experimental equipment, are presented, and resolved with a smooth Gaussian cutoff in spatial frequency space. Convergence of the Green's functions for the one-dimensional transport current densities is discussed, and particular attention is devoted to the negative effects of performing discrete Fourier transforms alone on fields asymptotically dropping like 1/r. Results of imaging simulated current densities are favorably compared to the original distributions after the resulting magnetic fields undergo the imaging procedure. The behavior of high-frequency spatial noise, and the behavior of the fields with a 1/r asymptote in the imaging procedure in our simulations is analyzed, and compared to the treatment of these phenomena in the published literature. Next, we examine calculation of Mathieu and spheroidal wave functions, solutions to the wave equation in elliptical cylindrical and oblate and prolate spheroidal coordinates, respectively. These functions are also solutions to Schrodinger's equations with certain potential wells, and are useful in solving time-varying superconducting problems. The Mathieu functions are Fourier expanded, and the spheroidal functions expanded in associated Legendre polynomials to convert the defining differential equations to recursion relations. The infinite number of linear recursion equations is converted to an infinite matrix, multiplied by a vector of expansion coefficients, thus becoming an eigenvalue problem. The eigenvalue problem is solved with root solvers, and the eigenvector problem is solved using a Jacobi-type iteration method, after preconditioning the

Development of high electrical resistance persistent current switch for high speed energization system

International Nuclear Information System (INIS)

Jizo, Y.; Furuta, Y.; Nakashima, H.

1986-01-01

Japanese National Railways is now developing a superconducting magnetically-levitated train system. A persistent current switch is incorporated in the super-conducting magnet used in the magnetically-levitated train. In recent years, the switch has been required to have higher electrical resistance during its off-state in order to realize the high speed energization/de-energization system of the superconducting magnets. The system aims to decrease evaporation volume of liquid helium during the energization/de-energization of the magnet, by means of energizing the superconducting magnet with high current increasing/decreasing rate. Consequently, it would be possible to decrease the dependence of the on-board magnet system upon the ground cooling system. Through the development of a stable superconductive wire material and a coil structure for the persistent current switch using many small model switches which were produced in order to improve their current carrying capacities, the authors have succeeded in manufacturing the high electrical resistance persistent current switch whose electrical resistance was 5 ohms. The switch, of cylindrical shape, has a diameter of about 100mm, a length of about 100mm. These 5 ohm PCSs are now functioning in stable conditions being incorporated in the superconducting magnets of No.2 vehicle of MLU001 at the JNR's Miyazaki test track. Further, the authors are now developing the PCS of still higher resistance values, such as 50 ohms, through studies for stabilization in structural aspects of the winding and obtaining results therefrom

Control of the Superconducting Magnets current Power Supplies of the TJ-II Gyrotrons

International Nuclear Information System (INIS)

Ros, A.; Fernandez, A.; Tolkachev, A.; Catalan, G.

2006-01-01

The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs

Use of high-temperature superconducting films in superconducting bearings

International Nuclear Information System (INIS)

Cansiz, A.

1999-01-01

We have investigated the effect of high-temperature superconductor (HTS) films deposited on substrates that are placed above bulk HTSs in an attempt to reduce rotational drag in superconducting bearings composed of a permanent magnet levitated above the film/bulk HTS combination. According to the critical state model, hysteresis energy loss is inversely proportional to critical current density, J c , and because HTS films typically have much higher J c than that of bulk HTS, the film/bulk combination was expected to reduce rotational losses by at least one order of magnitude in the coefficient of fiction, which in turn is a measure of the hysteresis losses. We measured rotational losses of a superconducting bearing in a vacuum chamber and compared the losses with and without a film present. The experimental results showed that contrary to expectation, the rotational losses are increased by the film. These results are discussed in terms of flux drag through the film, as well as of the critical state model

High-energy neutron irradiation of superconducting compounds

International Nuclear Information System (INIS)

Sweedler, A.R.; Snead, C.L.; Newkirk, L.; Valencia, F.; Geballe, T.H.; Schwall, R.H.; Matthias, B.T.; Corenswit, E.

1975-01-01

The effect of high-energy neutron irradiation (E greater than 1 MeV) at ambient reactor temperatures on the superconducting properties of a variety of superconducting compounds is reported. The materials studied include the A-15 compounds Nb 3 Sn, Nb 3 Al, Nb 3 Ga, Nb 3 Ge and V 3 Si, the C-15 Laves phase HfV 2 , the ternary molybdenum sulfide Mo 3 Pb 0 . 5 S 4 and the layered dichalcogenide NbSe 2 . The superconducting transition temperature has been measured for all of the above materials for neutron fluences up to 5 x 10 19 n/cm 2 . The critical current for multifilamentary Nb 3 Sn has also been determined for fields up to 16 T and fluences between 3 x 10 17 n/cm 2 and 1.1 x 10 19 n/cm 2

JETC (Japanese Technology Evaluation Center) Panel Report on High Temperature Superconductivity in Japan

Science.gov (United States)

Shelton, Duane; Gamota, George

1989-01-01

The Japanese regard success in R and D in high temperature superconductivity as an important national objective. The results of a detailed evaluation of the current state of Japanese high temperature superconductivity development are provided. The analysis was performed by a panel of technical experts drawn from U.S. industry and academia, and is based on reviews of the relevant literature and visits to Japanese government, academic and industrial laboratories. Detailed appraisals are presented on the following: Basic research; superconducting materials; large scale applications; processing of superconducting materials; superconducting electronics and thin films. In all cases, comparisons are made with the corresponding state-of-the-art in the United States.

Effect of coupling currents on the dynamic inductance during fast transient in superconducting magnets

Directory of Open Access Journals (Sweden)

V. Marinozzi

2015-03-01

Full Text Available We present electromagnetic models aiming to calculate the variation of the inductance in a magnet due to dynamic effects such as the variation of magnetization or the coupling with eddy currents. The models are studied with special regard to the calculation of the inductance in superconducting magnets which are affected by interfilament coupling currents. The developed models have been compared with experimental data coming from tests of prototype Nb_{3}Sn magnets designed for the new generation of accelerators. This work is relevant for the quench protection study of superconducting magnets: quench is an unwanted event, when part of the magnet becomes resistive; in these cases, the current should be discharged as fast as possible, in order to maintain the resistive zone temperature under a safe limit. The magnet inductance is therefore a relevant term for the description of the current discharge, especially for the high-field new generation superconducting magnets for accelerators, and this work shows how to calculate the correct value during rapid current changes, providing a mean for simulations of the reached temperature.

Calculation of alternating current losses in stacks and coils made of second generation high temperature superconducting tapes for large scale applications

DEFF Research Database (Denmark)

Zermeno, Victor M. R.; Abrahamsen, Asger Bech; Mijatovic, Nenad

2013-01-01

A homogenization method to model a stack of second generation High Temperature Superconducting tapes under AC applied transport current or magnetic field has been obtained. The idea is to find an anisotropic bulk equivalent for the stack such that the geometrical layout of the internal alternatin...

A Snapshot View of High Temperature Superconductivity 2002

Energy Technology Data Exchange (ETDEWEB)

Schuller, Ivan K. [Univ. of California, San Diego, CA (United States); Bansil, Arun [Northeastern Univ., Boston, MA (United States); Basov, Dimitri N. [Univ. of California, San Diego, CA (United States)

2002-04-05

This report outlines the conclusions of a workshop on High Temperature Superconductivity held April 5-8, 2002 in San Diego. The purpose of this report is to outline and highlight some outstanding and interesting issues in the field of High Temperature Superconductivity. The range of activities and new ideas that arose within the context of High Temperature Superconductors is so vast and extensive that it is impossible to summarize it in a brief document. Thus, this report does not pretend to be all-inclusive and cover all areas of activity. It is a restricted snapshot and it only presents a few viewpoints. The complexity and difficulties with high temperature superconductivity are well illustrated by the Buddhist parable of the blind men trying to describe “experimentally” an elephant. These very same facts clearly illustrate that this is an extremely active field, with many unanswered questions, and with a great future potential for discoveries and progress in many (sometimes unpredictable) directions. It is very important to stress that, independently of any current or future applications, this is a very important area of basic research.

Bipolar programmable current supply for superconducting nuclear magnetic resonance magnets

Science.gov (United States)

Koivuniemi, Jaakko; Luusalo, Reeta; Hakonen, Pertti

1998-09-01

In high resolution continuous-wave nuclear magnetic resonance (NMR) work well-reproducible, linear sweeps of current are needed. We have developed a microcontroller based programmable current supply, tested with superconducting magnets with inductance of 10 mH and 10 H. We achieved a resolution and noise of 4 ppm. The supply has an internal sweep with programmable ramping rate and a possibility for remote operation from a computer with either GPIB or RS232 interface. It is based on an 18-bit D/A converter. The maximum output current is ±10 A, the sweep rate can be set between 1 μA/s-140 mA/s, and the maximum output voltage is ±2.5 V. In work at ultralow temperatures, especially in superconducting quantum interference device NMR, all rf interference to the experiment should be avoided. One of the sources of this kind of unwanted input is the digital switching noise of fast logic devices. We discuss this problem in the context of our design.

Possibility of high temperature superconducting phases in PdH

Science.gov (United States)

Tripodi, Paolo; Di Gioacchino, Daniele; Borelli, Rodolfo; Vinko, Jenny Darja

2003-05-01

Possible new superconducting phases with a high critical transition temperature (Tc) have been found in stable palladium-hydrogen (PdHx) samples for stoichiometric ratio x=H/Pd⩾1, in addition to the well-known low critical transition temperature (0⩽Tc⩽9) when x is in the range (0.75⩽x⩽1.00). Possible new measured superconducting phases with critical temperature in the range 51⩽Tc⩽295 K occur. This Tc varies considerably with every milli part of x when x exceeds unit. A superconducting critical current density Jc⩾6.1×104 A cm-2 has been measured at 77 K with HDC=0 T.

On the superconducting phase diagram of high Tc superconductors

International Nuclear Information System (INIS)

de la Cruz, F.

1990-01-01

The tendency of oxide superconductors to show granularity has been pointed out since the beginning of research on superconductivity in this type of materials. Nevertheless, only very recently the full phase diagram and characteristics of the grains have been determined. In this paper, the authors review and discuss the different critical fields and their relation to the transport of superconducting current. The superconducting response of single crystals of High Tc superconductors is discussed. Special attention is devoted to the behavior of the vortex lattice and, in particular, to the recent discovery of the quenching of H c1 in YBaCuO, several degrees below Tc

Interacting loop-current model of superconducting networks

International Nuclear Information System (INIS)

Chi, C.C.; Santhanam, P.; Bloechl, P.E.

1992-01-01

The authors review their recent approximation scheme to calculate the normal-superconducting phase boundary, T c (H), of a superconducting wire network in a magnetic field in terms of interacting loop currents. The theory is based on the London approximation of the linearized Ginzburg-Landau equation. An approximate general formula is derived for any two-dimensional space-filling lattice comprising tiles of two shapes. Many examples are provided illustrating the use of this method, with a particular emphasis on the fluxoid distribution. In addition to periodic lattices, quasiperiodic lattices and fractal Sierpinski gaskets are also discussed

High temperature superconducting compounds II; Proceedings of the Second Symposium, Anaheim, CA, Feb. 20, 21, 1990

International Nuclear Information System (INIS)

Whang, S.H.; Dasgupta, A.; Laibowitz, R.

1990-01-01

Various topics relevant to the production and implementation of high-temperature superconducting compounds are highlighted including critical current; texturing; ceramics and novel processing; composites; deformation and consolidation; thin films; microstructures; tapes, filaments, and ribbons; and thermodynamics. The thermally activated flux creep, critical current density and current enhancement in high-temperature superconductors are addressed. Also discussed are the phase stability and microstructure of doped superconductors, mechanical considerations in the processing of high-Tc superconductors, fabrication and application of high current density, high RTc superconducting thin films and devices, the effect of substrate temperature and RF biasing on the composition of sputtered Bi-based superconducting thin films, and optical electron microanalysis of cuprate superconductors. The microstructure dependence of critical current density and fabrication of double-layered ribbons from cuprate are also discussed

Superconductivity revisited

CERN Document Server

Dougherty, Ralph

2013-01-01

While the macroscopic phenomenon of superconductivity is well known and in practical use worldwide in many industries, including MRIs in medical diagnostics, the current theoretical paradigm for superconductivity (BCS theory) suffers from a number of limitations, not the least of which is an adequate explanation of high temperature superconductivity. This book reviews the current theory and its limitations and suggests new ideas and approaches in addressing these issues. The central objective of the book is to develop a new, coherent, understandable theory of superconductivity directly based on molecular quantum mechanics.

Eddy current quality control of soldered current-carrying busbar splices of superconducting magnets

CERN Document Server

Kogan, L; Savary, F; Principe, R; Datskov, V; Rozenfel'd, E; Khudjakov, B

2015-01-01

The eddy current technique associated with a U-shaped transducer is studied for the quality control of soldered joints between superconducting busbars ('splices'). Two other quality control techniques, based on X-rays and direct measurement of the electrical resistance, are also studied for comparison. A comparative analysis of the advantages and disadvantages of these three methods in relation to the quality control of soldered superconducting busbar cables enclosed in copper shells is used for benchmarking. The results of inspections with the U-shaped eddy current transducer carried out on several sample joints presenting different types of soldering defects show the potential of this type of nondestructive (ND) quality control technique.

Alternating current losses of a 10 metre long low loss superconducting cable conductor determined from phase sensitive measurements

DEFF Research Database (Denmark)

Olsen, Søren Krüger; Kühle (fratrådt), Anders Van Der Aa; Træholt, Chresten

1999-01-01

The ac loss of a superconducting cable conductor carrying an ac current is small. Therefore the ratio between the inductive (out-of-phase) and the resistive (in-phase) voltages over the conductor is correspondingly high. In vectorial representations this results in phase angles between the current......-in amplifiers can be exploited. In this paper we present the results from ac-loss measurements on a low loss 10 metre long high temperature superconducting cable conductor using such a correction scheme. Measurements were carried out with and without a compensation circuit that could reduce-the inductive...... voltage. The 1 mu V cm(-1) critical current of the conductor was 3240 A at 77 K. At an rms current of 2 kA (50 Hz) the ac loss was derived to be 0.6 +/- 0.15 W m(-1). This is, to the best of our knowledge, the lowest value of ac loss of a high temperature superconducting cable conductor reported so far...

Superconducting high current magnetic Circuit: Design and Parameter Estimation of a Simulation Model

CERN Document Server

Kiefer, Alexander; Reich, Werner Dr

The Large Hadron Collider (LHC) utilizes superconducting main dipole magnets that bend the trajectory of the particle beams. In order to adjust the not completely homogeneous magnetic feld of the main dipole magnets, amongst others, sextupole correctcorrector magnets are used. In one of the 16 corrector magnet circuits placed in the LHC, 154 of these sextupole corrector magnets (MCS) are connected in series. This circuit extends on a 3.35 km tunnel section of the LHC. In 2015, at one of the 16 circuits a fault was detected. The simulation of this circuit is helpful for fnding the fault by applying alternating current at different frequencies. Within this Thesis a PSpice model for the simulation of the superconducting corrector magnet circuit was designed. The physical properties of the circuit and its elements were analyzed and implemented. For the magnets and bus-bars, sub-circuits were created which reflect the parasitic effects of electrodynamics and electrostats. The inductance values and capacitance valu...

Superconducting magnets in high energy physics

International Nuclear Information System (INIS)

Prodell, A.G.

1978-01-01

The applications of superconducting magnets in high energy physics in the last ten years have made feasible developments which are vital to high energy research. These developments include high magnetic field, large volume detectors, such as bubble chambers, required for effective resolution of high energy particle trajectories, particle beam transport magnets, and superconducting focusing and bending magnets for the very high energy accelerators and storage rings needed to pursue the study of interactions between elementary particles. The acceptance of superconductivity as a proven technology in high energy physics was reinforced by the recognition that the existing large accelerators using copper-iron magnets had reached practical limits in terms of magnetic field intensity, cost, space, and energy usage, and that large-volume, high-field, copper-iron magnets were not economically feasible. Some of the superconducting magnets and associated systems being used in and being developed for high energy physics are described

Developmental activities of the 18 GHz high temperature superconducting ECR ion source, PKDELIS, for the high current injector at IUAC

International Nuclear Information System (INIS)

Rodrigues, G.; Lakshmy, P.S.; Mathur, Y.; Ahuja, R.; Dutt, R.N.; Rao, U.K.; Mandal, A.; Kanjilal, D.; Roy, A.

2011-01-01

Various developmental activities of the 18 GHz High Temperature Superconducting ECR Ion Source, PKDELIS have been carried out as a part of the High Current Injector programme. Emittance measurements using a simple technique has given important inputs for the design of downstream accelerators like RFQ, DTL and low beta cavities. The techniques allows for emittance matching by varying the emittance parameters to match with the acceptance of the accelerators. X-ray Beamstrahlung measurements from ECR plasma has shown that it is a diagnostic tool to optimize the production of highly charged ions. The ion optics through the low energy beam transport section has been benchmarked with various codes and given a handle to optimize the transmission. New techniques to improve the extraction efficiency of highly charged ions has been developed. (author)

Imaging of current distributions in superconducting thin film structures

International Nuclear Information System (INIS)

Doenitz, D.

2006-01-01

Local analysis plays an important role in many fields of scientific research. However, imaging methods are not very common in the investigation of superconductors. For more than 20 years, Low Temperature Scanning Electron Microscopy (LTSEM) has been successfully used at the University of Tuebingen for studying of condensed matter phenomena, especially of superconductivity. In this thesis LTSEM was used for imaging current distributions in different superconducting thin film structures: - Imaging of current distributions in Josephson junctions with ferromagnetic interlayer, also known as SIFS junctions, showed inhomogeneous current transport over the junctions which directly led to an improvement in the fabrication process. An investigation of improved samples showed a very homogeneous current distribution without any trace of magnetic domains. Either such domains were not present or too small for imaging with the LTSEM. - An investigation of Nb/YBCO zigzag Josephson junctions yielded important information on signal formation in the LTSEM both for Josephson junctions in the short and in the long limit. Using a reference junction our signal formation model could be verified, thus confirming earlier results on short zigzag junctions. These results, which could be reproduced in this work, support the theory of d-wave symmetry in the superconducting order parameter of YBCO. Furthermore, investigations of the quasiparticle tunneling in the zigzag junctions showed the existence of Andreev bound states, which is another indication of the d-wave symmetry in YBCO. - The LTSEM study of Hot Electron Bolometers (HEB) allowed the first successful imaging of a stable 'Hot Spot', a self-heating region in HEB structures. Moreover, the electron beam was used to induce an - otherwise unstable - hot spot. Both investigations yielded information on the homogeneity of the samples. - An entirely new method of imaging the current distribution in superconducting interference devices

High temperature superconductor current leads

International Nuclear Information System (INIS)

Zeimetz, B.; Liu, H.K.; Dou, S.X.

1996-01-01

Full text: The use of superconductors in high electrical current applications (magnets, transformers, generators etc.) usually requires cooling with liquid Helium, which is very expensive. The superconductor itself produces no heat, and the design of Helium dewars is very advanced. Therefore most of the heat loss, i.e. Helium consumption, comes from the current lead which connects the superconductor with its power source at room temperature. The current lead usually consists of a pair of thick copper wires. The discovery of the High Temperature Superconductors makes it possible to replace a part of the copper with superconducting material. This drastically reduces the heat losses because a) the superconductor generates no resistive heat and b) it is a very poor thermal conductor compared with the copper. In this work silver-sheathed superconducting tapes are used as current lead components. The work comprises both the production of the tapes and the overall design of the leads, in order to a) maximize the current capacity ('critical current') of the superconductor, b) minimize the thermal conductivity of the silver clad, and c) optimize the cooling conditions

Research on DC-RF superconducting photocathode injector for high average power FELs

International Nuclear Information System (INIS)

Zhao Kui; Hao Jiankui; Hu Yanle; Zhang Baocheng; Quan Shengwen; Chen Jiaer; Zhuang Jiejia

2001-01-01

To obtain high average current electron beams for a high average power Free Electron Laser (FEL), a DC-RF superconducting injector is designed. It consists of a DC extraction gap, a 1+((1)/(2)) superconducting cavity and a coaxial input system. The DC gap, which takes the form of a Pierce configuration, is connected to the 1+((1)/(2)) superconducting cavity. The photocathode is attached to the negative electrode of the DC gap. The anode forms the bottom of the ((1)/(2)) cavity. Simulations are made to model the beam dynamics of the electron beams extracted by the DC gap and accelerated by the superconducting cavity. High quality electron beams with emittance lower than 3 π-mm-mrad can be obtained. The optimization of experiments with the DC gap, as well as the design of experiments with the coaxial coupler have all been completed. An optimized 1+((1)/(2)) superconducting cavity is in the process of being studied and manufactured

A Snapshot View of High Temperature Superconductivity 2002

International Nuclear Information System (INIS)

Schuller, Ivan K.; Bansil, Arun; Basov, Dimitri N.

2002-01-01

This report outlines the conclusions of a workshop on High Temperature Superconductivity held April 5-8, 2002 in San Diego. The purpose of this report is to outline and highlight some outstanding and interesting issues in the field of High Temperature Superconductivity. The range of activities and new ideas that arose within the context of High Temperature Superconductors is so vast and extensive that it is impossible to summarize it in a brief document. Thus, this report does not pretend to be all-inclusive and cover all areas of activity. It is a restricted snapshot and it only presents a few viewpoints. The complexity and difficulties with high temperature superconductivity are well illustrated by the Buddhist parable of the blind men trying to describe ''experimentally'' an elephant. These very same facts clearly illustrate that this is an extremely active field, with many unanswered questions, and with a great future potential for discoveries and progress in many (sometimes unpredictable) directions. It is very important to stress that, independently of any current or future applications, this is a very important area of basic research.

Superconducting dc fault current limiter

International Nuclear Information System (INIS)

Cointe, Y.

2007-12-01

Within the framework of the electric power market liberalization, DC networks have many interests compared to alternative ones, but their protections need to use new systems. Superconducting fault current limiters enable by an overstepping of the critical current to limit the fault current to a preset value, lower than the theoretical short-circuit current. For these applications, coated conductors offer excellent opportunities. We worked on the implementation of these materials and built a test bench. We carried out limiting experiments to estimate the quench homogeneity at various short-circuit parameters. An important point is the temperature measurement by deposited sensors on the ribbon, results are in good correlation with the theoretical models. Improved quench behaviours for temperatures close to the critical temperature have been confirmed. Our results enable to better understand the limitation mechanisms of coated conductors. (author)

Gauge Model of High-Tc Superconductivity

International Nuclear Information System (INIS)

Ng, Sze Kui

2012-01-01

A simple gauge model of superconductivity is presented. The seagull vertex term of this gauge model gives an attractive potential between electrons for the forming of Cooper pairs of superconductivity. This gauge model gives a unified description of superconductivity and magnetism including antiferromagnetism, pseudogap phenomenon, stripes phenomenon, paramagnetic Meissner effect, Type I and Type II supeconductivity and high-T c superconductivity. The doping mechanism of superconductivity is found. It is shown that the critical temperature T c is related to the ionization energies of elements and can be computed by a formula of T c . For the high-T c superconductors such as La 2-x Sr x CuO 4 , Y Ba 2 Cu 3 O 7 , and MgB 2 , the computational results of T c agree with the experimental results.

Quenches in large superconducting magnets

International Nuclear Information System (INIS)

Eberhard, P.H.; Alston-Garnjost, M.; Green, M.A.; Lecomte, P.; Smits, R.G.; Taylor, J.D.; Vuillemin, V.

1977-08-01

The development of large high current density superconducting magnets requires an understanding of the quench process by which the magnet goes normal. A theory which describes the quench process in large superconducting magnets is presented and compared with experimental measurements. The use of a quench theory to improve the design of large high current density superconducting magnets is discussed

Possibility of high temperature superconducting phases in PdH

Energy Technology Data Exchange (ETDEWEB)

Tripodi, Paolo; Di Gioacchino, Daniele; Borelli, Rodolfo; Vinko, Jenny Darja

2003-05-15

Possible new superconducting phases with a high critical transition temperature (T{sub c}) have been found in stable palladium-hydrogen (PdH{sub x}) samples for stoichiometric ratio x=H/Pd{>=}1, in addition to the well-known low critical transition temperature (0{<=}T{sub c}{<=}9) when x is in the range (0.75{<=}x{<=}1.00). Possible new measured superconducting phases with critical temperature in the range 51{<=}T{sub c}{<=}295 K occur. This T{sub c} varies considerably with every milli part of x when x exceeds unit. A superconducting critical current density J{sub c}{>=}6.1x10{sup 4} A cm{sup -2} has been measured at 77 K with H{sub DC}=0 T.

Superconducting current generators; Generateurs supraconducteurs de courant

Energy Technology Data Exchange (ETDEWEB)

Genevey, P [Commissariat a l' Energie Atomique, Limeil-Brevannes (France). Centre d' Etudes

1970-07-01

After a brief summary of the principle of energy storage and liberation with superconducting coils,two current generators are described that create currents in the range 600 to 1400 A, used for two storage experiments of 25 kJ and 50 kJ respectively. The two current generators are: a) a flux pump and b) a superconducting transformer. Both could be developed into more powerful units. The study shows the advantage of the transformer over the flux pump in order to create large currents. The efficiencies of the two generators are 95 per cent and 40 to 60 per cent respectively. (author) [French] Apres un rappel succinct du principe de stockage d'energie dans un solenoide supraconducteur et de sa liberation, nous decrivons deux generateurs de courant qui nous ont permis d'obtenir les courants necessaires (600 a 1400 A) aux experiences de stockage d'energie envisagees (27 kJ et 50 kJ): 1) - une pompe a flux, 2) - un transformateur supraconducteur. Ces generateurs sont extrapolables. Cette etude montre que si nous voulons creer un courant intense, le transformateur grace a son rendement eleve (> 95 pour cent) est preferable actuellement aux pompes a flux dont le rendement est de 40 a 60 pour cent. (auteur)

Plasma-enhanced chemical vapor deposition for YBCO film fabrication of superconducting fault-current limiter

Energy Technology Data Exchange (ETDEWEB)

Jun, Byung Hyuk; Kim, Chan Joong

2006-05-15

Since the high-temperature superconductor of oxide type was founded, many researches and efforts have been performed for finding its application field. The YBCO superconducting film fabricated on economic metal substrate with uniform critical current density is considered as superconducting fault-current limiter (SFCL). There are physical and chemical processes to fabricate superconductor film, and it is understood that the chemical methods are more economic to deposit large area. Among them, chemical vapor deposition (CVD) is a promising deposition method in obtaining film uniformity. To solve the problems due to the high deposition temperature of thermal CVD, plasma-enhanced chemical vapor deposition (PECVD) is suggested. This report describes the principle and fabrication trend of SFCL, example of YBCO film deposition by PECVD method, and principle of plasma deposition.

Use of a High-Temperature Superconducting Coil for Magnetic Energy Storage

International Nuclear Information System (INIS)

Fagnard, J-F; Crate, D; Jamoye, J-F; Laurent, Ph; Mattivi, B; Cloots, R; Ausloos, M; Genon, A; Vanderbemden, Ph

2006-01-01

A high temperature superconducting magnetic energy storage device (SMES) has been realised using a 350 m-long BSCCO tape wound as a ''pancake'' coil. The coil is mounted on a cryocooler allowing temperatures down to 17.2 K to be achieved. The temperature dependence of coil electrical resistance R(T) shows a superconducting transition at T = 102.5 K. Measurements of the V(I) characteristics were performed at several temperatures between 17.2 K and 101.5 K to obtain the temperature dependence of the critical current (using a 1 μV/cm criterion). Critical currents were found to exceed 100 A for T < 30 K. An electronic DC-DC converter was built in order to control the energy flow in and out of the superconducting coil. The converter consists of a MOS transistor bridge switching at a 80 kHz frequency and controlled with standard Pulse Width Modulation (PWM) techniques. The system was tested using a 30 V squared wave power supply as bridge input voltage. The coil current, the bridge input and output voltages were recorded simultaneously. Using a 10 A setpoint current in the superconducting coil, the whole system (coil + DC-DC converter) can provide a stable output voltage showing uninterruptible power supply (UPS) capabilities over 1 s

Comparison study of cable geometries and superconducting tape layouts for high-temperature superconductor cables

Science.gov (United States)

Ta, Wurui; Shao, Tianchong; Gao, Yuanwen

2018-04-01

High-temperature superconductor (HTS) rare-earth-barium-copper-oxide (REBCO) tapes are very promising for use in high-current cables. The cable geometry and the layout of the superconducting tapes are directly related to the performance of the HTS cable. In this paper, we use numerical methods to perform a comparison study of multiple-stage twisted stacked-tape cable (TSTC) conductors to find better cable structures that can both improve the critical current and minimize the alternating current (AC) losses of the cable. The sub-cable geometry is designed to have a stair-step shape. Three superconducting tape layouts are chosen and their transport performance and AC losses are evaluated. The magnetic field and current density profiles of the cables are obtained. The results show that arrangement of the superconducting tapes from the interior towards the exterior of the cable based on their critical current values in descending order can enhance the cable's transport capacity while significantly reducing the AC losses. These results imply that cable transport capacity improvements can be achieved by arranging the superconducting tapes in a manner consistent with the electromagnetic field distribution. Through comparison of the critical currents and AC losses of four types of HTS cables, we determine the best structural choice among these cables.

Measuring the critical current in superconducting samples made of NT-50 under pulse irradiation by high-energy particles

International Nuclear Information System (INIS)

Vasilev, P.G.; Vladimirova, N.M.; Volkov, V.I.; Goncharov, I.N.; Zajtsev, L.N.; Zel'dich, B.D.; Ivanov, V.I.; Kleshchenko, E.D.; Khvostov, V.B.

1981-01-01

The results of tests of superconducting samples of an uninsulated wire of the 0.5 mm diameter, containing 1045 superconducting filaments of the 10 μm diameter made of NT-50 superconductor in a copper matrix, are given. The upper part of the sample (''closed'') is placed between two glass-cloth-base laminate plates of the 50 mm length, and the lower part (''open'') of the 45 mm length is immerged into liquid helium. The sample is located perpendicular to the magnetic field of a superconducting solenoid and it is irradiated by charged particle beams at the energy of several GeV. The measurement results of permissible energy release in the sample depending on subcriticality (I/Isub(c) where I is an operating current through the sample, and Isub(c) is a critical current for lack of the beam) and the particle flux density, as well as of the maximum permissible fluence depending on subcriticality. In case of the ''closed'' sample irradiated by short pulses (approximately 1 ms) for I/Isub(c) [ru

Automatic adjustment of bias current for direct current superconducting quantum interference device

International Nuclear Information System (INIS)

Makie-Fukuda, K.; Hotta, M.; Okajima, K.; Kado, H.

1993-01-01

A new method of adjusting the bias current of dc superconducting quantum interference device (SQUID) is described. It is shown that the signal-to-noise ratio of a SQUID magnetometer connected in a flux-locked loop configuration is proportional to the second harmonic of the output signal from the SQUID. A circuit configuration that can automatically optimize a SQUID's bias current by measuring this second harmonic and adjusting the bias current accordingly is proposed

Recovery characteristics of flux-lock type superconducting fault current limiter

International Nuclear Information System (INIS)

Han, T.H.; Choi, H.S.; Lim, S.H.; Lee, N.Y.

2007-01-01

The flux-lock type superconducting fault current limiter (SFCL) has attractive characteristics that the current limiting level can be adjusted by a winding direction and the inductance ratio between two coils. We changed the winding direction and the number of coils to compare the resistive type SFCL with the flux-lock type SFCL. The initial limiting current (I ini ) and quench characteristic were dependent on the winding direction and the inductance ratio of two coils. As a winding number was increased from 21 to 42, I ini and quench characteristic were proportionally increased. In additive polarity winding, I ini was 10.2 A and the quench time (T q ) was 0.53 ms, which was faster than that of a subtractive polarity winding. The consumed energy and recovery characteristics in a superconducting element showed the same tendency. Recovery characteristics in the flux-lock type SFCL were dependent on the consumed energy of a superconducting element. The recovery time was related to a heat energy and it was represented as the consuming time of the heat energy. As the heat energy was shown in H 0.24I 2 Rt, the recovery time was shortened in the following order: a subtractive polarity winding, a resistive type and an additive polarity winding. It was known that the recovery time was proportional to a consumed energy of a superconducting element

High performance superconducting radio frequency ingot niobium technology for continuous wave applications

International Nuclear Information System (INIS)

Dhakal, Pashupati; Ciovati, Gianluigi; Myneni, Ganapati R.

2015-01-01

Future continuous wave (CW) accelerators require the superconducting radio frequency cavities with high quality factor and medium accelerating gradients (≤20 MV/m). Ingot niobium cavities with medium purity fulfill the specifications of both accelerating gradient and high quality factor with simple processing techniques and potential reduction in cost. This contribution reviews the current superconducting radiofrequency research and development and outlines the potential benefits of using ingot niobium technology for CW applications

Superconductivity, intergrain, and intragrain critical current densities of materials

International Nuclear Information System (INIS)

Thompson, J.R.; Brynestad, J.; Kroeger, D.M.; Kim, Y.C.; Sekula, S.T.; Christen, D.K.; Specht, E.D.

1989-01-01

Bulk sintered and powdered samples of the high-temperature superconductive compounds Tl 2 Ca 2 Ba 2 Cu 3 O/sub 1+//sub δ/ (Tl-2:2:2:3) and Tl 2 Ca 2 Ba 2 Cu 2 O/sub 8+//sub δ/ (Tl-2:1:2:2) have been synthesized with phase purity of approximately 90%. The materials were characterized by x-ray-diffraction, metallographic, and electron microprobe analyses. The electronic and superconductive properties were investigated through measurement of the electrical resistivity and the critical current density J/sub c/ using transport methods and by extensive magnetization measurements. Primary results and conclusions are that (1) the intragrain J/sub c/ values were large, much larger than the transport values; (2) both sintered and powdered materials exhibited large flux creep; (3) and the J/sub c/ decreased exponentially with temperature. These features are qualitatively very similar to those found in the corresponding YBa 2 Cu 3 O/sub z/ (with z≅7) series of compounds

Current distribution inside Rutherford-type superconducting cables and impact on performance of LHC dipoles

CERN Document Server

Schreiner, T

2002-01-01

The windings of high--field superconducting accelerator magnets are usually made of Rutherford--type cables. The magnetic field distribution along the axis of such magnets exhibits a periodic modulation with a wavelength equal to the twist pitch length of the cable used in the winding. Such a Periodic Field Pattern (PFP) has already been observed in number of superconducting accelerator magnets. Additional unbalanced currents in individual strands of the cable appear to be causing this effect. The present thesis describes the investigation of the PFPs performed with a Hall probes array inserted inside the aperture of the LHC superconducting dipoles, both in the small--scale model magnets with a length of one meter and in full--scale prototypes and pre--series magnets with fifteen meters of length. The amplitude and the time dependence of this periodic field oscillation have been studied as a function of the magnet current history. One of the main parameters influencing the properties of the PFP is the cross--...

Recent developments in the application of rf superconductivity to high-brightness and high-gradient ion beam accelerators

International Nuclear Information System (INIS)

Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Nichols, G.L.; Roche, C.T.; Sagalovsky, L.

1991-01-01

A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high- brightness ion beams. Since the last workshop, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm 2 ) surface areas. Theoretical studies of beam impingement and cumulative beam breakup have also yielded encouraging results. Consequently, a section of superconducting resonators and focusing elements has been designed for tests with high-current deuteron beams. In addition, considerable data pertaining to the rf properties of high-T c superconductors has been collected at rf-field amplitudes and frequencies of interest in connection with accelerator operation. This paper summarizes the recent progress and identifies current and future work in the areas of accelerator technology and superconducting materials which will build upon it

New 30 kA power system at Fermilab and its use for measuring the effects of ripple current on the performance of superconducting high field magnets

Energy Technology Data Exchange (ETDEWEB)

Carcagno, R.; Feher, S.; Garvey, J.; Jaskierny, W.; Lamm, M.; Makulski, A.; Orris, D.F.; Pfeffer, H.; Tartaglia, M.; Tompkins, J.; Wolff, D.; /Fermilab

2004-12-01

A new 30 kA, 30 V dc Power System was designed, built, and commissioned at Fermilab for testing Superconducting High Field Magnets. This system has been successfully supporting operations at the Fermilab Magnet Test Facility since April 2002. It is based on six commercial 150 kW Power Energy Industries power supply modules and the following in-house modules: six 720 Hz filters, two 15 kA/1kV dc solid-state dump switch, and a 3 MJ/30 kA/1 kV dc dump resistor. Additional inhouse electronic components were designed and built to provide precise current regulation and distribution of current and current rate of change. An industrial-type Programmable Logic Controller system was used to provide equipment interlocks and monitoring. This paper summarizes studies on the influence of characteristics of this new power system--such as ripple current--on the performance of High Field Superconducting magnets.

New 30 kA power system at Fermilab and its use for measuring the effects of ripple current on the performance of superconducting high field magnets

International Nuclear Information System (INIS)

Carcagno, R.; Feher, S.; Garvey, J.; Jaskierny, W.; Lamm, M.; Makulski, A.; Orris, D.F.; Pfeffer, H.; Tartaglia, M.; Tompkins, J.; Wolff, D.

2004-01-01

A new 30 kA, 30 V dc Power System was designed, built, and commissioned at Fermilab for testing Superconducting High Field Magnets. This system has been successfully supporting operations at the Fermilab Magnet Test Facility since April 2002. It is based on six commercial 150 kW Power Energy Industries power supply modules and the following in-house modules: six 720 Hz filters, two 15 kA/1kV dc solid-state dump switch, and a 3 MJ/30 kA/1 kV dc dump resistor. Additional in-house electronic components were designed and built to provide precise current regulation and distribution of current and current rate of change. An industrial-type Programmable Logic Controller system was used to provide equipment interlocks and monitoring. This paper summarizes studies on the influence of characteristics of this new power system--such as ripple current--on the performance of High Field Superconducting Magnets

Superconductivity from magnetic elements under high pressure

International Nuclear Information System (INIS)

Shimizu, Katsuya; Amaya, Kiichi; Suzuki, Naoshi; Onuki, Yoshichika

2006-01-01

Can we expect the appearance of superconductivity from magnetic elements? In general, superconductivity occurs in nonmagnetic metal at low temperature and magnetic impurities destroy superconductivity; magnetism and superconductivity are as incompatible as oil and water. Here, we present our experimental example of superconducting elements, iron and oxygen. They are magnetic at ambient pressure, however, they become nonmagnetic under high pressure, then superconductor at low temperature. What is the driving force of the superconductivity? Our understanding in the early stages was a simple scenario that the superconductive state was obtained as a consequence of an emergence of the nonmagnetic states. In both cases, we may consider another scenario for the appearance of superconductivity; the magnetic fluctuation mechanism in the same way as unconventional superconductors

Alternating current losses of a 10 metre long low loss superconducting cable conductor determined from phase sensitive measurements

International Nuclear Information System (INIS)

Krueger Olsen, S.; Kuehle, A.; Traeholt, C.; C Rasmussen, C.; Toennesen, O.; Daeumling, M.; Rasmussen, C.N.; Willen, D.W.A.

1999-01-01

The ac loss of a superconducting cable conductor carrying an ac current is small. Therefore the ratio between the inductive (out-of-phase) and the resistive (in-phase) voltages over the conductor is correspondingly high. In vectorial representations this results in phase angles between the current and the voltage over the cable close to 90 degrees. This has the effect that the loss cannot be derived directly using most commercial lock-in amplifiers due to their limited absolute accuracy. However, by using two lock-in amplifiers and an appropriate correction scheme the high relative accuracy of such lock-in amplifiers can be exploited. In this paper we present the results from ac-loss measurements on a low loss 10 metre long high temperature superconducting cable conductor using such a correction scheme. Measurements were carried out with and without a compensation circuit that could reduce the inductive voltage. The 1 μV cm -1 critical current of the conductor was 3240 A at 77 K. At an rms current of 2 kA (50 Hz) the ac loss was derived to be 0.6±0.15 W m -1 . This is, to the best of our knowledge, the lowest value of ac loss of a high temperature superconducting cable conductor reported so far at these high currents. (author)

Experiment study on an inductive superconducting fault current limiter using no-insulation coils

Science.gov (United States)

Qiu, D.; Li, Z. Y.; Gu, F.; Huang, Z.; Zhao, A.; Hu, D.; Wei, B. G.; Huang, H.; Hong, Z.; Ryu, K.; Jin, Z.

2018-03-01

No-insulation (NI) coil made of 2 G high temperature superconducting (HTS) tapes has been widely used in DC magnet due to its excellent performance of engineering current density, thermal stability and mechanical strength. However, there are few AC power device using NI coil at present. In this paper, the NI coil is firstly applied into inductive superconducting fault current limiter (iSFCL). A two-winding structure air-core iSFCL prototype was fabricated, composed of a primary copper winding and a secondary no-insulation winding using 2 G HTS coated conductors. Firstly, in order to testify the feasibility to use NI coil as the secondary winding, the impedance variation of the prototype at different currents and different cycles was tested. The result shows that the impedance increases rapidly with the current rises. Then the iSFCL prototype was tested in a 40 V rms/ 3.3 kA peak short circuit experiment platform, both of the fault current limiting and recovery property of the iSFCL are discussed.

Josephson current and Andreev level dynamics in nanoscale superconducting weak links

Energy Technology Data Exchange (ETDEWEB)

Brunetti, Aldo

2014-11-15

In this thesis we focus on the interplay between proximity induced superconducting correlations and Coulomb interactions in a Josephson junction: i.e., in a system where two superconductors modeled as two s-wave superconductors at a phase difference φ are contacted by means of a weak link, in our case a quantum dot located in the contact. In the first part we study the Josephson current-phase relation for a multi-level quantum dot tunnel-contacted by two conventional s-waves superconductors. We determine in detail the conditions for observing a finite anomalous Josephson current, i.e. a supercurrent flowing at zero phase difference in a two-level dot with spin-orbit interactions, a weak magnetic (Zeeman) field, and in the presence of Coulomb interactions. This leads to an onset behavior I{sub a}∝sgn(B), interpreted as the sign of an incipient spontaneous breakdown of time-reversal symmetry. Moreover, we will provide conditions for realizing spatially separated - but topologically unprotected - Majorana bound states, whose signature in the system will be detectable via the current-phase relation. In the second part of the thesis, we address the Andreev bound state population dynamics in superconducting weak links (a superconducting 'atomic contact'), in which a poisoning mechanism due to the trapping of single quasiparticles can occur. Our motivation is that quantum coherent superconducting circuits are the most promising candidates for future large-scale quantum information processing devices. Moreover, quasiparticle poisoning has recently been observed in devices which contain a short superconducting weak link with few transport channels. We discuss a novel charge imbalance effect in the continuum quasiparticle population, which is due to phase fluctuations of the environment weakly coupled to the superconducting contact. This coupling enters the system as a transition rate connecting continuum quasiparticles and the Andreev bound state system. The

High-temperature superconducting current leads

Science.gov (United States)

Hull, J. R.

1992-07-01

The use of high-temperature superconductors (HTSs) for current leads to deliver power to devices at liquid helium temperature is near commercial realization. The use of HTSs in this application has the potential to reduce refrigeration requirements and helium boiloff to values significantly lower than the theoretical best achievable with conventional leads. Considerable advantage is achieved by operating these leads with an intermediate temperature heat sink. The HTS part of the lead can be made from pressed and sintered powder. Powder-in-tube fabrication is also possible, however, the normal metal part of the lead acts as a thermal short and cannot provide much stabilization without increasing the refrigeration required. Lead stability favors designs with low current density. Such leads can be manufactured with today's technology, and lower refrigeration results from the same allowable burnout time. Higher current densities result in lower boiloff for the same lead length, but bumout times can be very short. In comparing experiment to theory, the density of helium vapor needs to be accounted for in calculating the expected boiloff. For very low-loss leads, two-dimensional heat transfer and the state of the dewar near the leads may play a dominant role in lead performance.

Characteristic Of Induction Magnetic Field On The Laboratory Scale Superconducting Fault Current Limiter Circuit

International Nuclear Information System (INIS)

Adi, Wisnu Ari; Sukirman, E.; Didin, S.W.; Yustinus, P.M.; Siregar, Riswal H.

2004-01-01

Model construction of the laboratory scale superconducting fault current limiter circuit (SFCL) has been performed. The SFCL is fault current limiter and used as electric network security. It mainly consists of a copper coil, a superconducting ring and an iron core that are concentrically arranged. The SFCL circuit is essentially a transformer where the secondary windings are being replaced by the ring of YBa 2 Cu 3 O 7-x superconductor (HTS). The ring has critical transition temperature Tc = 92 K and critical current Ic = 3.61 A. Characterization of the SFCL circuit is simulated by ANSYS version 5.4 software. The SFCL circuit consists of load and transformer impedances. The results show that the inductions of magnet field flux in the iron core of primer windings and ring disappear to one other before fault state. It means that impedance of the transformer is zero. After the condition a superconductivity behavior of the ring is disappear so that the impedance of the transformer becomes very high. From this experiment, we concluded that the SFCL circuit could work normally if the resultant of induction magnetic in the iron core (transformer) is zero

Low energy current accumulator for high-energy proton rings

International Nuclear Information System (INIS)

Month, M.

1977-01-01

Building current in high-energy p-p colliding beam machines is most appropriately done in a low-energy (small circumference) current accumulator. Three significant factors favor such a procedure: First, large rings tend to be susceptible to unstable longitudinal density oscillations. These can be avoided by pumping up the beam in the accumulator. When the current stack is injected into the storage ring, potentially harmful instability is essentially neutralized. Second, high-field magnets characteristic of future high energy proton rings are designed with superconducting coils within the iron magnetic shield. This means coil construction and placement errors propagate rapidly within the beam aperture. An intermediate ''stacking ring'' allows the minimum use of the superconducting ring aperture. Finally, the coils are vulnerable to radiation heating and possible magnet quenching. By minimizing beam manipulaion in the superconducting environment and using only the central portion of the beam aperture, coil vulnerability can be put at a minimum

Advances in superconductivity: new materials, critical currents and devices

International Nuclear Information System (INIS)

Pinto, R.; Malik, S.K.; Grover, A.K.; Ayyub, P.

1997-01-01

The discovery of superconductivity in the cuprates produced an explosive growth in research, driven by the quest for higher and higher superconducting transition temperatures. In the initial stages, the excitement was tremendous both in the physical sciences and in engineering. However, the complexity of the new materials on the one hand, and the absence of a viable theory on the other, have made further developments much more difficult. It is to be expected therefore, that the early excitement and the subsequent rapid advances have paved the way for more systematic and detailed studies of all aspects of superconductivity. The International Symposium was intended to provide a forum to review the progress in selected areas in superconductivity. The emphasis was on experimental and theoretical studies of the new superconductors, advances in the theoretical understanding, progress in studies of flux pinning and vortex dynamics which affect critical currents, and developments of novel material synthesis methods. Recent developments in the twin areas of thin films and devices were extensively discussed during the symposium. Papers relevant to INIS are indexed separately

Some theories of high temperature superconductivity

International Nuclear Information System (INIS)

Cohen, M.L.

1990-01-01

In this paper a brief review is given of some historical aspects of theoretical research on superconductivity including a discussion of BCS theory and some theoretical proposals for mechanisms which can cause superconductivity at high temperatures

The low-temperature, high-magnetic-field critical current characteristics of Zr-added (Gd, Y)Ba2Cu3Ox superconducting tapes

Energy Technology Data Exchange (ETDEWEB)

Selvamanickam, V; Yao, Y; Chen, Y; Shi, T; Liu, Y; Khatri, ND; Liu, J; Lei, C; Galstyan, E; Majkic, G

2012-10-26

Critical current performances of state-of-the-art Zr-added (Gd, Y)BaCuO tapes have been investigated over a temperature range of 20-77 K, in magnetic fields up to 9 T and over a wide angular range of magnetic field orientations. The peak in critical current that is commonly observed in the field orientation perpendicular to the tape in BaZrO3 (BZO) containing superconducting tapes is found to vanish at 30 K in magnetic fields at 1-9 T. While the critical current of 15% Zr-added tapes was about 40% lower than that of 7.5% Zr-added tapes at 77 K, the pinning force values of the former were found to be 18-23% higher than those of the latter in the temperature range of 20-40 K and in magnetic fields of 3-5 T. The results from this study emphasize the importance of optimization of coated conductor fabrication processes for optimum performance not just in low magnetic fields at 77 K but also at the operating conditions of low temperatures and high magnetic fields that are of interest, especially for rotating superconducting machinery applications.

The low-temperature, high-magnetic-field critical current characteristics of Zr-added (Gd,Y)Ba2Cu3Ox superconducting tapes

International Nuclear Information System (INIS)

Selvamanickam, V; Yao, Y; Shi, T; Liu, Y; Khatri, N D; Liu, J; Galstyan, E; Majkic, G; Chen, Y; Lei, C

2012-01-01

Critical current performances of state-of-the-art Zr-added (Gd, Y)BaCuO tapes have been investigated over a temperature range of 20–77 K, in magnetic fields up to 9 T and over a wide angular range of magnetic field orientations. The peak in critical current that is commonly observed in the field orientation perpendicular to the tape in BaZrO 3 (BZO) containing superconducting tapes is found to vanish at 30 K in magnetic fields at 1–9 T. While the critical current of 15% Zr-added tapes was about 40% lower than that of 7.5% Zr-added tapes at 77 K, the pinning force values of the former were found to be 18–23% higher than those of the latter in the temperature range of 20–40 K and in magnetic fields of 3–5 T. The results from this study emphasize the importance of optimization of coated conductor fabrication processes for optimum performance not just in low magnetic fields at 77 K but also at the operating conditions of low temperatures and high magnetic fields that are of interest, especially for rotating superconducting machinery applications. (paper)

Electromagnetic analysis of a superconducting transformer for high current characterization of cable in conduit conductors in background magnetic field

Science.gov (United States)

Wu, Xiangyang; Tan, Yunfei; Fang, Zhen; Jiang, Donghui; Chen, Zhiyou; Chen, Wenge; Kuang, Guangli

2017-10-01

A large cable-in-conduit-conductor (CICC) test facility has been designed and fabricated at the High Magnetic Field Laboratory of the Chinese Academy of Sciences (CHMFL) in order to meet the test requirement of the conductors which are applied to the future fusion reactor. The critical component of the test facility is an 80 kA superconducting transformer which consists of a multi-turn primary coil and a minor-turn secondary coil. As the current source of the conductor samples, the electromagnetic performance of the superconducting transformer determines the stability and safety of the test facility. In this paper, the key factors and parameters, which have much impact on the performance of the transformer, are analyzed in detail. The conceptual design and optimizing principles of the transformer are discussed. An Electromagnetic-Circuit coupled model built in ANSYS Multiphysics is successfully used to investigate the electromagnetic characterization of the transformer under the dynamic operation condition.

High-temperature superconducting conductors and cables

International Nuclear Information System (INIS)

Peterson, D.E.; Maley, M.P.; Boulaevskii, L.; Willis, J.O.; Coulter, J.Y.; Ullmann, J.L.; Cho, Jin; Fleshler, S.

1996-01-01

This is the final report of a 3-year LDRD project at LANL. High-temperature superconductivity (HTS) promises more efficient and powerful electrical devices such as motors, generators, and power transmission cables; however this depends on developing HTS conductors that sustain high current densities J c in high magnetic fields at temperatures near liq. N2's bp. Our early work concentrated on Cu oxides but at present, long wire and tape conductors can be best made from BSCCO compounds with high J c at low temperatures, but which are degraded severely at temperatures of interest. This problem is associated with thermally activated motion of magnetic flux lines in BSCCO. Reducing these dc losses at higher temperatures will require a high density of microscopic defects that will pin flux lines and inhibit their motion. Recently it was shown that optimum defects can be produced by small tracks formed by passage of energetic heavy ions. Such defects result when Bi is bombarded with high energy protons. The longer range of protons in matter suggests the possibility of application to tape conductors. AC losses are a major limitation in many applications of superconductivity such as power transmission. The improved pinning of flux lines reduces ac losses, but optimization also involves other factors. Measuring and characterizing these losses with respect to material parameters and conductor design is essential to successful development of ac devices

Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor.

Science.gov (United States)

Choi, Seokhwan; Choi, Hyoung Joon; Ok, Jong Mok; Lee, Yeonghoon; Jang, Won-Jun; Lee, Alex Taekyung; Kuk, Young; Lee, SungBin; Heinrich, Andreas J; Cheong, Sang-Wook; Bang, Yunkyu; Johnston, Steven; Kim, Jun Sung; Lee, Jhinhwan

2017-12-01

We explore a new mechanism for switching magnetism and superconductivity in a magnetically frustrated iron-based superconductor using spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single-crystal Sr_{2}VO_{3}FeAs shows that a spin-polarized tunneling current can switch the Fe-layer magnetism into a nontrivial C_{4} (2×2) order, which cannot be achieved by thermal excitation with an unpolarized current. Our tunneling spectroscopy study shows that the induced C_{4} (2×2) order has characteristics of plaquette antiferromagnetic order in the Fe layer and strongly suppresses superconductivity. Also, thermal agitation beyond the bulk Fe spin ordering temperature erases the C_{4} state. These results suggest a new possibility of switching local superconductivity by changing the symmetry of magnetic order with spin-polarized and unpolarized tunneling currents in iron-based superconductors.

Elimination of the induced current error in magnetometers using superconducting flux transformers

International Nuclear Information System (INIS)

Dummer, D.; Weyhmann, W.

1987-01-01

The changing magnetization of a sample in a superconducting flux transformer coupled magnetometer induces a current in the transformer which in turn changes the field at the sample. This ''image'' field and the error caused by it can be eliminated by sensing the current in the loop and nulling it by feedback through a mutual inductance. We have tested the technique on the superconducting transition of indium in an applied magnetic field and shown that the observed width of the transition is greatly reduced by maintaining zero current in the flux transformer

Trapped magnetic field of a superconducting bulk magnet in high- Tc RE-Ba-Cu-O

International Nuclear Information System (INIS)

Fujimoto, Hiroyuki; Yoo, Sang Im; Higuchi, Takamitsu; Nakamura, Yuichi; Kamijo, Hiroki; Nagashima, Ken; Murakami, Masato

1999-01-01

Superconducting magnets made of high-T c superconductors are promising for industrial applications. It is well known that REBa 2 Cu 3 O 7-x and LRE (light rare-earth) Ba 2 Cu 3 O 7-x superconductors prepared by melt processes have a high critical current density, J c , at 77 K and high magnetic fields. Therefore, the materials are very prospective for high magnetic field application as a superconducting permanent/bulk magnet with liquid-nitrogen refrigeration. LREBaCuO bulks, compared with REBaCuO bulks, exhibit a larger J c in high magnetic fields and a much improved irreversibility field, H irr , at 77 K. In this study, we discuss the possibility and trapped field properties of a superconducting bulk magnet, as well as the melt processing for bulk superconductors and their characteristic superconducting properties. One of the applications is a superconducting magnet for the future magnetically levitated (Maglev) train

The spheromak as a prototype for ultra-high-field superconducting magnets

International Nuclear Information System (INIS)

Furth, H.P.; Jardin, S.C.

1987-08-01

In view of current progress in the development of superconductor materials, the ultimate high-field limit of superconducting magnets is likely to be set by mechanical stress problems. Maximum field strength should be attainable by means of approximately force-free magnet windings having favorable ''MHD'' stability properties (so that small winding errors will not grow). Since a low-beta finite-flux-hole spheromak configuration qualifies as a suitable prototype, the theoretical and experimental spheromak research effort of the past decade has served to create a substantial technical basis for the design of ultra-high-field superconducting coils. 11 refs

Magnetic and Superconducting Materials at High Pressures

Energy Technology Data Exchange (ETDEWEB)

Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

2015-03-24

The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

High-Tc cuprate superconductivity in a nutshell

International Nuclear Information System (INIS)

Won, Hyekyung; Haas, Stephan; Parker, David; Maki, Kazumi

2005-01-01

Since the discovery of high-T c cuprate superconductivity in 1986 many new experimental techniques and theoretical concepts have been developed. In particular it was shown that the BCS theory of d-wave superconductivity describes semi-quantitatively the high-T c superconductivity. Furthermore, it was demonstrated that Volovik's approach is extremely useful for finding the quasiparticle properties in the vortex state. Here we survey these developments and forecast future directions. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

HIGH-CURRENT ERL-BASED ELECTRON COOLING FOR RHIC

International Nuclear Information System (INIS)

BEN-ZVI, I.

2005-01-01

The design of an electron cooler must take into account both electron beam dynamics issues as well as the electron cooling physics. Research towards high-energy electron cooling of RHIC is in its 3rd year at Brookhaven National Laboratory. The luminosity upgrade of RHIC calls for electron cooling of various stored ion beams, such as 100 GeV/A gold ions at collision energies. The necessary electron energy of 54 MeV is clearly out of reach for DC accelerator system of any kind. The high energy also necessitates a bunched beam, with a high electron bunch charge, low emittance and small energy spread. The Collider-Accelerator Department adopted the Energy Recovery Linac (ERL) for generating the high-current, high-energy and high-quality electron beam. The RHIC electron cooler ERL will use four Superconducting RF (SRF) 5-cell cavities, designed to operate at ampere-class average currents with high bunch charges. The electron source will be a superconducting, 705.75 MHz laser-photocathode RF gun, followed up by a superconducting Energy Recovery Linac (ERL). An R and D ERL is under construction to demonstrate the ERL at the unprecedented average current of 0.5 amperes. Beam dynamics performance and luminosity enhancement are described for the case of magnetized and non-magnetized electron cooling of RHIC

Calculation of eddy-currents induced in a compact synchrotron superconducting magnet structure during a current ramp

International Nuclear Information System (INIS)

Kalsi, S.; Heese, R.

1991-01-01

Under DARPA sponsorship, a compact Superconducting X-Ray Light Source (SXLS) is being designed and built by the Brookhaven National Laboratory (BNL) with industry participation from Grumman Corporation and General Dynamics. The SXLS machine employs two 180 degree curved 4 tesla superconducting dipole magnets. These magnets are required to produce a dipole field for bending the beam but at the same time they must produce finite amounts of higher multipoles which are required for conditioning the beam. In fact, uniformity of the field to less than 1 part in 10,000 must be maintained under all operating conditions. When a superconducting magnet is ramped from zero to full field, the changing magnetic field produces eddy-currents in the magnet structure which in turn can produce undesirable multipoles. This paper discusses a simple method for estimating these eddy-currents and their effect on the field harmonics. The paper presents the analysis basis and its application to the SXLS magnet support structure and to the beam chamber components

Quark condensation, induced symmetry breaking and color superconductivity at high density

International Nuclear Information System (INIS)

Langfeld, Kurt; Rho, Mannque

1999-01-01

The phase structure of hadronic matter at high density relevant to the physics of compact stars and relativistic heavy-ion collisions is studied in a low-energy effective quark theory. The relevant phases that figure are (1) chiral condensation, (2) diquark color condensation (color superconductivity) and (3) induced Lorentz-symmetry breaking (''ISB''). For a reasonable strength for the effective four-Fermi current-current interaction implied by the low-energy effective quark theory for systems with a Fermi surface we find that the ''ISB'' phase sets in together with chiral symmetry restoration (with the vanishing quark condensate) at a moderate density while color superconductivity associated with scalar diquark condensation is pushed up to an asymptotic density. Consequently, color superconductivity seems rather unlikely in heavy-ion collisions although it may play a role in compact stars. Lack of confinement in the model makes the result of this analysis only qualitative but the hierarchy of the transitions we find seems to be quite robust

Transport critical current measurement apparatus using liquid nitrogen cooled high-T(c) superconducting magnet with variable temperature insert.

Science.gov (United States)

Nishijima, G; Kitaguchi, H; Tshuchiya, Y; Nishimura, T; Kato, T

2013-01-01

We have developed an apparatus to investigate transport critical current (I(c)) as a function of magnetic field and temperature using only liquid nitrogen. The apparatus consists of a (Bi,Pb)(2)Sr(2)Ca(2)Cu(3)O(10) (Bi-2223) superconducting magnet, an outer dewar, and a variable temperature insert (VTI). The magnet, which is operated in depressurized liquid nitrogen, generates magnetic field up to 1.26 T. The sample is also immersed in liquid nitrogen. The pressure in the VTI is controlled from 0.02 to 0.3 MPa, which corresponds to temperature ranging from 66 to 88 K. We have confirmed the long-term stable operation of the Bi-2223 magnet at 1 T. The temperature stability of the sample at high transport current was also demonstrated. The apparatus provides easy-operating I(c) measurement environment for a high-T(c) superconductor up to 500 A in magnetic fields up to 1 T and in temperatures ranging from 66 to 88 K.

Experimental studies of current sharing in parallel driven Graetz bridge units for diurnal superconductive magnetic energy storage

International Nuclear Information System (INIS)

Kustom, R.L.; Akita, S.; Okada, H.; Skiles, J.

1985-01-01

Superconductive Magnetic Energy Storage (SMES) coils for diurnal load leveling and system peaking are envisioned to operate at hundreds of thousands of amperes and a few kilovolts. The interface between the SMES coil and the electric utility is envisioned to be Graetz bridges using SCR switches. Many parallel SCR switches or bridge units will have to operate in parallel because of the high operating current of the coil. Current balancing on parallel Graetz bridges driving a single 8-hy superconducting coil has been achieved on a laboratory model using delay-angle control with an LSI 11/2 microprocessor and external digital control hardware

Spin currents, relativistic effects and the Darwin interaction in the theory of hole superconductivity

International Nuclear Information System (INIS)

Hirsch, J.E.

2005-01-01

The existence of macroscopic spin currents in the ground state of superconductors is predicted within the theory of hole superconductivity. Here it is shown that the electromagnetic Darwin interaction is attractive for spin currents and repulsive for charge currents. It is also shown that the mere existence of spin currents implies that some electrons are moving at relativistic speeds in macroscopic superconductors, which in turn implies that the Darwin interaction plays a fundamental role in stabilizing the superconducting state

Development of an air coil superconducting fault current limiter

Energy Technology Data Exchange (ETDEWEB)

Naeckel, Oliver

2016-07-01

Electrical power grids are the lifeline of technical infrastructure and fundamental for industry and modern lives. Fault Currents can disrupt the continuous supply of electrical energy, cause instable grid conditions and damage electrical equipment. The Air Coil Superconducting Fault Current Limiter (AC-SFCL) is a measure to effectively limit fault currents. The concept is investigated and proven experimentally by designing, building and successfully testing a 60 kV, 400 V, z=6% demonstrator.

State of the art and trends of high-Tc superconductivity

International Nuclear Information System (INIS)

Barone, A.

1990-01-01

In this paper a brief account is given on some aspects of the development of high-T c Superconductivity since the last edition of the SATT Conference. This year significant results have been obtained in the challenging endeavor of increasing high critical current densities and in the context of high-T c junctions. The attention is confined to achievements and perspectives in these two topics

Testing and evaluation of high temperature superconductor current leads

International Nuclear Information System (INIS)

Yadav, Anand; Puntambekar, Avinash; Manekar, M.A.

2009-01-01

National Institute for Inter-disciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research, Trivandrum (formerly Regional Research Laboratory) has accomplished a DAE-BRNS project with Raja Ramanna Centre for Advanced Technology (RRCAT) as principal collaborator for the development of high temperature superconductor (HTS) current leads. These HTS current leads have self-field critical currents (Ic) ranging from 50 A to 1000 A at liquid nitrogen (LN 2 ) temperature. These HTS are made out of silver sheathed Bismuth Strontium Calcium Copper Oxide (BSCCO-2223), for direct application in superconducting (SC) systems involving transportation of high electric currents from power sources at room temperature to superconducting devices at cryogenic temperatures. RRCAT has participated in this project by testing and evaluation of these HTS current leads and carried out actual load trials. In this paper, we will describe the HTS testing setup, tests performed with their testing procedure and the test results. The testing of these HTS has been done with joint effort of Materials Advanced Accelerator Science and Cryogenics Div. and Superconducting Technology Lab (SCT Lab), Advanced Accelerator Module Development Div., using the test facility available at the SCT Lab. (author)

Current contact device for a superconducting magnet coil

International Nuclear Information System (INIS)

Hieronymus, H.

1987-01-01

The invention concerns a current supply device for a superconducting magnet coil to be shortcircuited, with a separating device per coil end, which contains a fixed cooled contact and a moving contact connected to a power supply device and a mechanical actuating device for closing and opening the contacts. When closing the heated contact on to the cooled contact, relatively large quantities of heat can be transferred to the cooled contact and therefore to the connected superconducting coil end and can cause normal conduction there. The invention therefore provides that the mass ratio of the cooled contact to the moving contact is at least 5:1, preferably at least 10:1, and that the cooled contact part is provided, at the end away from the contact area, with means for increasing the area, for example cooling fins and is connected to the coil end has a thermal resistance between the contact area and the coil end of at least 0.2 k/W, preferably at least 0.5 k/W per 1000 A of current to be transmitted. (orig.) [de

Critical currents in multilayered superconducting films

International Nuclear Information System (INIS)

Raffy, Helene

1977-01-01

The superconducting critical currents Isub(c) were measured as a function of magnetic field H and temperature T, on multilayered films. These films consist of alternating layers of two different superconductors S 1 and S 2 being a weaker superconductor acting as a flux pinning barrier region. A strong anisotropy was observed between the two situations where the magnetic field H is applied parallel or perpendicular to the layers. In the case discussed, there is a peak effect in the curves Isub(c)H well defined at the highest temperatures, and disappearing at low temperatures. The anisotropy of the critical current at constant field presents a maximum at a temperature T* close to the critical temperature Tsub(c 2 ) of S 2 [fr

High-temperature superconductivity

International Nuclear Information System (INIS)

Lynn, J.W.

1990-01-01

This book discusses development in oxide materials with high superconducting transition temperature. Systems with Tc well above liquid nitrogen temperature are already a reality and higher Tc's are anticipated. The author discusses how the idea of a room-temperature superconductor appears to be a distinctly possible outcome of materials research

AC Losses and Their Thermal Effect in High Temperature Superconducting Machines

DEFF Research Database (Denmark)

Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan

2015-01-01

In transient operations or fault conditions, high temperature superconducting (HTS) machines suffer AC losses which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate AC losses and their thermal effect in HTS machines is presented....... The method consists of three sub-models that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an AC loss model which has...

Superconductive AC current limiter

International Nuclear Information System (INIS)

Bekhaled, M.

1987-01-01

This patent describes an AC current limiter for a power transport line including a power supply circuit and feeding a load circuit via an overload circuit-breaker member. The limiter comprises a transformer having a primary winding connected in series between the power supply circuit and the load circuit and at least one secondary winding of superconductor material contained in a cryogenic enclosure and short-circuited on itself. The leakage reactance of the transformer as seen from the primary winding is low, and the resistance of the at least one secondary winding when in the non-superconducting state and as seen from the primary is much greater than the nominal impedance of the transformer. The improvement whereby the at least one secondary winding of the transformer comprises an active winding in association with a set of auxiliary windings. The set of auxiliary windings is constituted by an even number of series-connected auxiliary windings wound in opposite directions, with the total number of turns in one direction being equal to the total number of turns in the opposite direction, and with the thermal capacity of the secondary winding as a whole being sufficiently high to limit the expansion thereof to a value which remains small during the time it takes the circuit-breaking member to operate

The formation of Cooper pairs and the nature of superconducting currents

International Nuclear Information System (INIS)

Weisskopf, V.F.

1979-12-01

A simple physical explanation is given for the formation of Cooper pairs in a superconducting metal, for the origin of the attractive force causing the binding of the pairs, for the forming of a degenerate Bose gas by the Cooper pairs, for the finite energy gap that prevents the ensemble of electrons to change its quantum state at low temperatures, and for the existence of permanent currents in a superconducting wire. (orig.)

The formation of Cooper pairs and the nature of superconducting currents

International Nuclear Information System (INIS)

Weisskopf, V.F.

1981-01-01

A simple physical explanation is given for the formation of Cooper pairs in a superconducting metal, for the origin of the attractive force causing the binding of the pairs, for the forming of a degenerate Bose gas by the Cooper pairs, for the finite energy gap that prevents the ensemble of electrons from changing its quantum state at low temperatures, and for the existence of permanent currents in a superconducting wire. (author)

Impurity band Mott insulators: a new route to high Tc superconductivity

Directory of Open Access Journals (Sweden)

Ganapathy Baskaran

2008-01-01

Full Text Available Last century witnessed the birth of semiconductor electronics and nanotechnology. The physics behind these revolutionary developments is certain quantum mechanical behaviour of 'impurity state electrons' in crystalline 'band insulators', such as Si, Ge, GaAs and GaN, arising from intentionally added (doped impurities. The present article proposes that certain collective quantum behaviour of these impurity state electrons, arising from Coulomb repulsions, could lead to superconductivity in a parent band insulator, in a way not suspected before. Impurity band resonating valence bond theory of superconductivity in boron doped diamond, recently proposed by us, suggests possibility of superconductivity emerging from impurity band Mott insulators. We use certain key ideas and insights from the field of high-temperature superconductivity in cuprates and organics. Our suggestion also offers new possibilities in the field of semiconductor electronics and nanotechnology. The current level of sophistication in solid state technology and combinatorial materials science is very well capable of realizing our proposal and discover new superconductors.

Non-equilibrium properties of Josephson critical current in Nb-based three terminal superconducting tunnel devices

International Nuclear Information System (INIS)

Ammendola, G.; Parlato, L.; Peluso, G.; Pepe, G.

1998-01-01

Tunnel quasi-particle injection into a superconducting film provides useful information on the non-equilibrium state inside the perturbed superconductor as well as on the potential application to electronic devices. Three terminal injector-detector superconducting devices have a long history in non-equilibrium superconductivity. In the recent past non-equilibrium phenomena have attracted again considerable attention because of many superconducting based detectors involve processes substantially non-equilibrium in nature. The possibility of using a stacked double tunnel junction to study the influence of non-equilibrium superconductivity on the Josephson critical current is now considered. An experimental study of the effect of quasi-particle injection on the Josephson current both in steady-state and pulsed experiments down to T=1.2 K is presented using 3 terminal Nb-based stacked double tunnel devices. The feasibility of a new class of particle detectors based on the direct measurement of the change in the Josephson current following the absorption of a X-ray quantum is also discussed in terms of non-equilibrium theories. (orig.)

Calculation of eddy-currents induced in a compact synchrotron superconducting magnet structure during a current ramp

International Nuclear Information System (INIS)

Kalsi, S.

1991-01-01

Under DARPA sponsorship, a compact Superconducting X-Ray Light Source (SXSL) is being designed and built by the Brookhaven National Laboratory (BNL) with industry participation from Grumman Corporation and General Dynamics. The SXLS machine employs two 180 degrees curved 4 telsa superconducting dipole magnets. These magnets are required to produce a dipole field for bending the beam but at the same time they must produce finite amounts of higher multipoles which are required for conditioning the beam. In fact uniformity of the field to less than 1 part in 10,000 must be maintained under all operating conditions. When a superconducting magnet is ramped from zero to full field, the changing magnetic field produces eddy-currents in the magnet structure which in turn can produce undesirable multipoles. This paper discusses a simple method for estimating these eddy-currents and their effect on the field harmonics. The paper present the analysis basis and its application to the SXLS magnet support structure and to the beam chamber components. 5 figs., 1 tab

Introduction to superconductivity and high-Tc materials

International Nuclear Information System (INIS)

Cyrot, M.; Pavuna, D.

1991-01-01

What sets this book apart from other introductions to superconductivity and high-T c materials is its pragmatic approach. In this book the authors describe all relevant superconducting phenomena and rely on the macroscopic Ginzburg-Landau theory to derive the most important results. Examples are chosen from selected conventional superconductors like NbTi and compared to those high-T c materials. The text should be of interest to non-specialists in superconductivity either as a textbook for those entering the field (one semester course) or as researchers in advanced technologies and even some managers of interdisciplinary research projects

Improvement in operational characteristics of KEPCO’s line-commutation-type superconducting hybrid fault current limiter

International Nuclear Information System (INIS)

Yim, S.-W.; Park, B.-C.; Jeong, Y.-T.; Kim, Y.-J.; Yang, S.-E.; Kim, W.-S.; Kim, H.-R.; Du, H.-I.

2013-01-01

Highlights: ► A line-commutation type hybrid FCL was modified for 1st peak current limitation. ► A superconducting module of current limitation and fault detection was fabricated. ► The superconducting module was applied to a hybrid FCL system and tested. ► 7.4 kA p fault current was limited to 4.3 kA p at the first-half cycle by the FCL. -- Abstract: A 22.9 kV class hybrid fault current limiter (FCL) developed by Korea Electric Power Corporation and LS Industrial Systems in 2006 operates using the line commutation mechanism and begins to limit the fault current after the first half-cycle. The first peak of the fault current is available for protective coordination in the power system. However, it also produces a large electromagnetic force and imposes a huge stress on power facilities such as the main transformer and gas-insulated switchgear. In this study, we improved the operational characteristics of the hybrid FCL in order to reduce the first peak of the fault current. While maintaining the structure of the hybrid FCL system, we developed a superconducting module that detects and limits the fault current during the first half-cycle. To maintain the protective coordination capacity, the hybrid FCL was designed to reduce the first peak value of the fault current by up to approximately 30%. The superconducting module was also designed to produce a minimum AC loss, generating a small, uniform magnetic field distribution during normal operation. Performance tests confirmed that when applied to the hybrid FCL, the superconducting module showed successful current limiting operation without any damage

Inductive fault current limiter based on multiple superconducting rings of small diameter

International Nuclear Information System (INIS)

Osorio, M R; Cabo, L; Veira, J A; Vidal, F

2004-01-01

We present a fault current limiter prototype based on the use of a secondary comprised of an array of magnetic cores of small sections, each one of them with several superconducting rings. The main advantage of this configuration is that it is easier to make small diameter superconducting rings which, in addition, are more homogeneous and allow better refrigeration. We then present detailed measurements that show that, in addition to these advantages, this prototype offers the same limitation performances than when using a unique core and a superconducting ring with an equivalent area as the array of small section cores

Current limiting experiment with 600 V/100A rectification type superconducting fault current limiter; 600 V-100A kyu seiryugata chodendo genryuki no genryu shiken

Energy Technology Data Exchange (ETDEWEB)

Matsuzaki, J.; Tsurunaga, K.; Urata, M. [Toshiba Corp., Tokyo (Japan); Okuma, T.; Sato, Y.; Iwata, Y. [Tokyo Electric Power Co., Inc., Tokyo (Japan)

1999-06-07

The rectification type current limiter with the current-limiting system of the new type which combined rectifier circuits with the direct current reactor has been proposed until now, and it has succeeded in the current-limiting test by the normal conduction reactor by the 6.6kV class model vessel. Since the loss of the conductor becomes fundamentally the zero, in the same current limiter, by using superconducting wire rod, because direct current always flows in the reactor, making into low-loss becomes possible. In this report, this paper describes cut-off characteristic of 600V/100A rectification type superconductive current limiter using the metal type superconductive conductor. (NEDO)

Engineering design of a high-temperature superconductor current lead

International Nuclear Information System (INIS)

Niemann, R.C.; Cha, Y.S.; Hull, J.R.; Daugherty, M.A.; Buckles, W.E.

1993-01-01

As part of the US Department of Energy's Superconductivity Pilot Center Program, Argonne National Laboratory and Superconductivity, Inc., are developing high-temperature superconductor (HTS) current leads suitable for application to superconducting magnetic energy storage systems. The principal objective of the development program is to design, construct, and evaluate the performance of HTS current leads suitable for near-term applications. Supporting objectives are to (1) develop performance criteria; (2) develop a detailed design; (3) analyze performance; (4) gain manufacturing experience in the areas of materials and components procurement, fabrication and assembly, quality assurance, and cost; (5) measure performance of critical components and the overall assembly; (6) identify design uncertainties and develop a program for their study; and (7) develop application-acceptance criteria

Engineering design of a high-temperature superconductor current lead

Science.gov (United States)

Niemann, R. C.; Cha, Y. S.; Hull, J. R.; Daugherty, M. A.; Buckles, W. E.

As part of the US Department of Energy's Superconductivity Pilot Center Program, Argonne National Laboratory and Superconductivity, Inc., are developing high-temperature superconductor (HTS) current leads suitable for application to superconducting magnetic energy storage systems. The principal objective of the development program is to design, construct, and evaluate the performance of HTS current leads suitable for near-term applications. Supporting objectives are to (1) develop performance criteria; (2) develop a detailed design; (3) analyze performance; (4) gain manufacturing experience in the areas of materials and components procurement, fabrication and assembly, quality assurance, and cost; (5) measure performance of critical components and the overall assembly; (6) identify design uncertainties and develop a program for their study; and (7) develop application-acceptance criteria.

Calculation of persistent currents in superconducting magnets

Directory of Open Access Journals (Sweden)

C. Völlinger

2000-12-01

Full Text Available This paper describes a semianalytical hysteresis model for hard superconductors. The model is based on the critical state model considering the dependency of the critical current density on the varying local field in the superconducting filaments. By combining this hysteresis model with numerical field computation methods, it is possible to calculate the persistent current multipole errors in the magnet taking local saturation effects in the magnetic iron parts into consideration. As an application of the method, the use of soft magnetic iron sheets (coil protection sheets mounted between the coils and the collars for partial compensation of the multipole errors during the ramping of the magnets is investigated.

Recovery time of high temperature superconducting tapes exposed in liquid nitrogen

International Nuclear Information System (INIS)

Sheng, Jie; Zeng, Weina; Yao, Zhihao; Zhao, Anfeng; Hu, Daoyu; Hong, Zhiyong

2016-01-01

Highlights: • A novel method based on a sequence of AC pulses is presented. • Liquid nitrogen temperature is used as criterion to judge whether the sample has recovered. • Recovery time of some tape doesn't increase with the amplitude of fault current. • This phenomenon is caused by boiling heat transfer process of liquid nitrogen. • This phenomenon can be used in optimizing both the limiting rate and reclosing system. - Abstract: The recovery time is a crucial parameter to high temperature superconducting tapes, especially in power applications. The cooperation between the reclosing device and the superconducting facilities mostly relies on the recovery time of the superconducting tapes. In this paper, a novel method is presented to measure the recovery time of several different superconducting samples. In this method criterion used to judge whether the sample has recovered is the liquid nitrogen temperature, instead of the critical temperature. An interesting phenomenon is observed during the testing of superconducting samples exposed in the liquid nitrogen. Theoretical explanations of this phenomenon are presented from the aspect of heat transfer. Optimization strategy of recovery characteristics based on this phenomenon is also briefly discussed.

Design prospect of remountable high-temperature superconducting magnet

Energy Technology Data Exchange (ETDEWEB)

Hashizume, Hidetoshi, E-mail: hidetoshi.hashizume@qse.tohoku.ac.jp; Ito, Satoshi

2014-10-15

The remountable (mountable and demountable repeatedly) high-temperature superconducting (HTS) magnet has been proposed for huge and complex superconducting magnets in future fusion reactors to fabricate and repair easily the magnet and access inner structural components. This paper summarizes progress in R and D activities of mechanical joints of HTS conductors in terms of the electrical resistance and heat transfer performance at the joint region. The latest experimental results show the low joint resistance, 4 nΩ under 70 kA current condition using REBCO HTS conductor with mechanical lap joint system, and for the cooling system the maximum heat flux of 0.4 MW/m{sup 2} is removed by using bronze sintered porous media with sub-cooled liquid nitrogen. These values indicate that there is large possibility to design the remountable HTS magnet for fusion reactors.

Sample of superconducting wiring (Niobium Titanium)

CERN Multimedia

About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resistan...

Sample of superconducting wiring (Niobium Titanium)

CERN Multimedia

About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resista...

A new hybrid protection system for high-field superconducting magnets

CERN Document Server

Ravaioli, E; Kirby, G; ten Kate, H H J; Verweij, A P

2014-01-01

The new generation of high-field superconducting accelerator magnets poses a challenge concerning the protection of the magnet coil in the case of a quench. The very high stored energy per unit volume requires a fast and efficient quench heating system in order to avoid damage due to overheating. A new protection system for superconducting magnets is presented, comprising a combination of a novel coupling-loss induced quench (CLIQ) system and conventional quench heaters. CLIQ can provoke a very fast transition to the normal state in coil windings by introducing coupling loss and thus heat in the coil's conductor. The advantage of the hybrid protection system is a global transition, resulting in a much faster current decay, a significantly lower hot-spot temperature, and a more homogeneous temperature distribution in the magnet's coil.

Passivation of Flexible YBCO Superconducting Current Lead With Amorphous SiO2 Layer

Science.gov (United States)

Johannes, Daniel; Webber, Robert

2013-01-01

Adiabatic demagnetization refrigerators (ADR) are operated in space to cool detectors of cosmic radiation to a few 10s of mK. A key element of the ADR is a superconducting magnet operating at about 0.3 K that is continually energized and de-energized in synchronism with a thermal switch, such that a piece of paramagnetic salt is alternately warm in a high magnetic field and cold in zero magnetic field. This causes the salt pill or refrigerant to cool, and it is able to suck heat from an object, e.g., the sensor, to be cooled. Current has to be fed into and out of the magnets from a dissipative power supply at the ambient temperature of the spacecraft. The current leads that link the magnets to the power supply inevitably conduct a significant amount of heat into the colder regions of the supporting cryostat, resulting in the need for larger, heavier, and more powerful supporting refrigerators. The aim of this project was to design and construct high-temperature superconductor (HTS) leads from YBCO (yttrium barium copper oxide) composite conductors to reduce the heat load significantly in the temperature regime below the critical temperature of YBCO. The magnet lead does not have to support current in the event that the YBCO ceases to be superconducting. Cus - tomarily, a normal metal conductor in parallel with the YBCO is a necessary part of the lead structure to allow for this upset condition; however, for this application, the normal metal can be dispensed with. Amorphous silicon dioxide is deposited directly onto the surface of YBCO, which resides on a flexible substrate. The silicon dioxide protects the YBCO from chemically reacting with atmospheric water and carbon dioxide, thus preserving the superconducting properties of the YBCO. The customary protective coating for flexible YBCO conductors is silver or a silver/gold alloy, which conducts heat many orders of magnitude better than SiO2 and so limits the use of such a composite conductor for passing current

Quantitative analysis of Josephson-quasiparticle current in superconducting single-electron transistors

International Nuclear Information System (INIS)

Nakamura, Y.; Chen, C.D.; Tsai, J.S.

1996-01-01

We have investigated Josephson-quasiparticle (JQP) current in superconducting single-electron transistors in which charging energy E C was larger than superconducting gap energy Δ and junction resistances were much larger than R Q ≡h/4e 2 . We found that not only the shapes of the JQP peaks but also their absolute height were reproduced quantitatively with a theory by Averin and Aleshkin using a Josephson energy of Ambegaokar-Baratoff close-quote s value. copyright 1996 The American Physical Society

Photocathodes inside superconducting cavities. Studies on the feasibility of a superconducting photoelectron source of high brightness. External report

International Nuclear Information System (INIS)

Michalke, A.

1992-01-01

We have done studies and experiments to explore the feasibility of a photoemission RF gun with a superconducting accelerator cavity. This concept promises to provide an electron beam of high brightness in continuous operation. It is thus of strong interest for a free-electron-laser or a linear collider based on a superconducting accelerator. In a first step we studied possible technical solutions for its components, especially the material of the photocathode and the geometrical shape of the cavity. Based on these considerations, we developed the complete design for a prototype electron source. The cathode material was chosen to be alkali antimonide. In spite of its sensitivity, it seems to be the best choice for a gun with high average current due to its high quantum efficiency. The cavity shape was at first a reentrant-type single cell of 500 MHz. It is now replaced by a more regular two-and-half cell shape, an independent half cell added for emittance correction. Its beam dynamics properties are investigated by numerical simulations; we estimated a beam brightness of about 5x10 11 A/(m.rad) 2 . But the mutual interactions between alkali antimonide photocathode and superconducting cavity must be investigated experimentally, because they are completely unkown. (orig.)

High-Density Superconducting Cables for Advanced ACTPol

Science.gov (United States)

Pappas, C. G.; Austermann, J.; Beall, J. A.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Henderson, S. W.; Ho, S. P.; Koopman, B. J.; Li, D.; McMahon, J.; Nati, F.; Niemack, M. D.; Niraula, P.; Salatino, M.; Schillaci, A.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Vavagiakis, E. M.; Ward, J. T.; Wollack, E. J.

2016-07-01

Advanced ACTPol (AdvACT) is an upcoming Atacama Cosmology Telescope (ACT) receiver upgrade, scheduled to deploy in 2016, that will allow measurement of the cosmic microwave background polarization and temperature to the highest precision yet with ACT. The AdvACT increase in sensitivity is partly provided by an increase in the number of transition-edge sensors (TESes) per array by up to a factor of two over the current ACTPol receiver detector arrays. The high-density AdvACT TES arrays require 70 \\upmu m pitch superconducting flexible cables (flex) to connect the detector wafer to the first-stage readout electronics. Here, we present the flex fabrication process and test results. For the flex wiring layer, we use a 400-nm-thick sputtered aluminum film. In the center of the cable, the wiring is supported by a polyimide substrate, which smoothly transitions to a bare (uncoated with polyimide) silicon substrate at the ends of the cable for a robust wedge wire-bonding interface. Tests on the first batch of flex made for the first AdvACT array show that the flex will meet the requirements for AdvACT, with a superconducting critical current above 1 mA at 500 mK, resilience to mechanical and cryogenic stress, and a room temperature yield of 97 %.

Critical current measurements of high-temperature superconducting short samples at a wide range of temperatures and magnetic fields

Science.gov (United States)

Ma, Hongjun; Liu, Huajun; Liu, Fang; Zhang, Huahui; Ci, Lu; Shi, Yi; Lei, Lei

2018-01-01

High-Temperature Superconductors (HTS) are potential materials for high-field magnets, low-loss transmission cables, and Superconducting Magnetic Energy Storage (SMES) due to their high upper critical magnetic field (Hc2) and critical temperature (Tc). The critical current (Ic) of HTS, which is one of the most important parameters for superconductor application, depends strongly on the magnetic fields and temperatures. A new Ic measurement system that can carry out accurate Ic measurement for HTS short samples with various temperatures (4.2-80 K), magnetic fields (0-14 T), and angles of the magnetic field (0°-90°) has been developed. The Ic measurement system mainly consists of a measurement holder, temperature-control system, background magnet, test cryostat, data acquisition system, and DC power supply. The accuracy of temperature control is better than ±0.1 K over the 20-80 K range and ±0.05 K when measured below 20 K. The maximum current is over 1000 A with a measurement uncertainty of 1%. The system had been successfully used for YBa2Cu3O7-x(YBCO) tapes Ic determination with different temperatures and magnetic fields.

Critical current measurements of high-temperature superconducting short samples at a wide range of temperatures and magnetic fields.

Science.gov (United States)

Ma, Hongjun; Liu, Huajun; Liu, Fang; Zhang, Huahui; Ci, Lu; Shi, Yi; Lei, Lei

2018-01-01

High-Temperature Superconductors (HTS) are potential materials for high-field magnets, low-loss transmission cables, and Superconducting Magnetic Energy Storage (SMES) due to their high upper critical magnetic field (H c2 ) and critical temperature (T c ). The critical current (I c ) of HTS, which is one of the most important parameters for superconductor application, depends strongly on the magnetic fields and temperatures. A new I c measurement system that can carry out accurate I c measurement for HTS short samples with various temperatures (4.2-80 K), magnetic fields (0-14 T), and angles of the magnetic field (0°-90°) has been developed. The I c measurement system mainly consists of a measurement holder, temperature-control system, background magnet, test cryostat, data acquisition system, and DC power supply. The accuracy of temperature control is better than ±0.1 K over the 20-80 K range and ±0.05 K when measured below 20 K. The maximum current is over 1000 A with a measurement uncertainty of 1%. The system had been successfully used for YBa 2 Cu 3 O 7-x (YBCO) tapes I c determination with different temperatures and magnetic fields.

AmpaCity. Superconducting cables and fault current limiters for the energy supply in conurbations

International Nuclear Information System (INIS)

Merschel, F.; Noe, M.; Stemmle, M.; Hobl, A.; Sauerbach, O.

2013-01-01

In 2013 RWE Germany is working jointly with cable manufacturer Nexans and with the scientific support of the Karlsruhe Institute of Technology (KIT) to install world's longest superconducting cable in the downtown area electricity grid of Essen. The AmpaCity project is partly funded by the German Federal Ministry of Economics and Technology and is playing an exemplary role in the further development of electricity grids in major cities worldwide. The project consortium presents AmpaCity as a convincing system solution especially with respect to economics and security of supply. Components of the system are a superconducting three-phase AC cable with two terminations and one connection joint in combination with a fault current limiter, which is also based on superconducting materials. The superconducting system is designed for 10 kV nominal voltage and 40 MW nominal power. It will replace a 110 kV cable system of equal capacity. At the same time, the project partners are paving the way for high failsafe performance, as the cable in conjunction with the fault current limiter cannot be overloaded by short circuit currents in the event of faults in the grid. Planning and follow up on the civil works in Essen posed a major challenge. Cable laying in the inner city, with various crossings of major highways, tramways, as well as already dense cable routes necessitated very thorough preparation and coordination. The civil works in Essen started in April 2013. At around the same time, after the cable had passed the type test, it went into production. Cable laying is scheduled for late summer. After commissioning, planned for the end of 2013, the field trial will run for at least two years under real grid conditions, to demonstrate this technology's suitability for wider deployment.

Colloquium: High pressure and road to room temperature superconductivity

Science.gov (United States)

Gor'kov, Lev P.; Kresin, Vladimir Z.

2018-01-01

This Colloquium is concerned with the superconducting state of new high-Tc compounds containing hydrogen ions (hydrides). Recently superconductivity with the record-setting transition temperature of Tc=203 K was reported for sulfur hydrides under high pressure. In general, high pressure serves as a path finding tool toward novel structures, including those with very high Tc . The field has a rich and interesting history. Currently, it is broadly recognized that superconductivity in sulfur hydrides owes its origin to the phonon mechanism. However, the picture differs from the conventional one in important ways. The phonon spectrum in sulfur hydride is both broad and has a complex structure. Superconductivity arises mainly due to strong coupling to the high-frequency optical modes, although the acoustic phonons also make a noticeable contribution. A new approach is described, which generalizes the standard treatment of the phonon mechanism and makes it possible to obtain an analytical expression for Tc in this phase. It turns out that, unlike in the conventional case, the value of the isotope coefficient (for the deuterium-hydrogen substitution) varies with the pressure and reflects the impact of the optical modes. The phase diagram, that is the pressure dependence of Tc , is rather peculiar. A crucial feature is that increasing pressure results in a series of structural transitions, including the one which yields the superconducting phase with the record Tc of 203 K. In a narrow region near P ≈150 GPa the critical temperature rises sharply from Tc≈120 to ≈200 K . It seems that the sharp structural transition, which produces the high-Tc phase, is a first-order phase transition caused by interaction between the order parameter and lattice deformations. A remarkable feature of the electronic spectrum in the high-Tc phase is the appearance of small pockets at the Fermi level. Their presence leads to a two-gap spectrum, which can, in principle, be observed with the

Anisotrophic currents and flux jumps in high-T-c superconducting films with self-organized arrays of planar defects

DEFF Research Database (Denmark)

Yurchenko, V.V.; Qviller, A.J.; Mozhaev, P.B.

2010-01-01

Regular arrays of planar defects with a period of a few nanometers can be introduced in superconducting YBa2Cu3O7-delta (YBCO) thin films by depositing them on vicinal (also called miscut or tilted) substrates. This results in the anisotropy of critical currents flowing in the plane of the film. ...

Status and prospects on development of yttrium-based high-temperature superconducting coated conductor

International Nuclear Information System (INIS)

Izumi, Teruo; Yanagi, Nagato

2017-01-01

Development of a large-sized large-current conductor using a high-temperature superconducting wire rod based on copper oxide has been started worldwide for the purpose of applying it as an option of a magnet for a nuclear fusion prototype reactor. There is yttrium-based thin film wire rod as a promising candidate. Japan is leading the development of this wire rod for many years, aiming to apply it to power equipment and the like. This paper explained the history of wire rod development, basic superconducting properties and manufacturing method, and latest achievements, and overviewed the feasibility of application to nuclear fusion reactor magnets. At present, the use of niobium-based low-temperature superconducting wire rod that is used in ITER is the basic idea. On the other hand, the development of wire rod using a copper oxide type high-temperature superconductor (HTS) has also been started. HTS wire rod is evaluated as suitable for application to nuclear fusion magnets due to its superior critical current characteristics and high mechanical rigidity up to high magnetic fields at high temperatures of yttrium. As current development progress, there are development of high-quality wire rod in the magnetic field and development of low AC loss wire rod. As future prospects, cost reduction due to mass production and improvement of yield, and investigation of low-resistance connection technology are being studied. The remaining future challenges of yttrium-based HTS are improvement of the anisotropy, influence on neutron irradiation, and problem of activation. (A.O.)

Simulation of the d.c. critical current in superconducting sintered ceramics

International Nuclear Information System (INIS)

Riedinger, R.; Habig, P.; Hlil, E.K.; Arnaud, M.; Boulesteix, C.

1990-01-01

The new superconducting high-T c sintered ceramics can be described in some case as a lattice of interconnected rods, in other cases as a more or less random packing of parallelepiped crystallites; their size is about a few microns. The d.c. critical current at zero voltage of such a material is not related to the critical current of the bulk material, but to its granular structure. Indeed, the critical current between two adjacent cells is governed by the critical current of the weak link between them; this link behaves within some limits as a Josephson junction, the critical current of which is known. For our present problem, the system can be modeled as a lattice of Josephson junctions. We present here results for the d.c. critical current at zero voltage of lattices of identical Josephson junctions in two dimensions. The influence of the finiteness of size of the sample is examined. The relationship with normal conductivity simulations and percolation is discussed

Critical current degradation in superconducting niobium-titanium alloys in external magnetic fields under loading

International Nuclear Information System (INIS)

Bojko, V.S.; Lazareva, M.B.; Starodubov, Ya.D.; Chernyj, O.V.; Gorbatenko, V.M.

1992-01-01

The effect of external magnetic fields on the stress at which the critical current starts to degrade (the degradation threshold σ 0 e ) under mechanical loads in superconducting Nb-Ti alloys is studied and a possible mechanism of realization of the effect observed is proposed.It is assumed that additional stresses on the transformation dislocation from the external magnetic fields are beneficial for the growth of martensite inclusions whose superconducting parameters (critical current density j k and critical temperature T k ) are lower then those in the initial material.The degradation threshold is studied experimentally in external magnetic fields H up to 7 T.The linear dependence σ 0 e (H) is observed.It is shown that external magnetic fields play an important role in the critical current degradation at the starting stages of deformation.This fact supports the assumption that the degradation of superconducting parameters under loading are due to the phenomenon of superelasticity,i.e. a reversible load-induced change in the martensite inclusions sizes rather than the reversible mechanical twinning.The results obtained are thought to be important to estimating superconducting solenoid stability in a wide range of magnetic fields

Magnetic response and critical current properties of mesoscopic-size YBCO superconducting samples

International Nuclear Information System (INIS)

Lisboa-Filho, P N; Deimling, C V; Ortiz, W A

2010-01-01

In this contribution superconducting specimens of YBa 2 Cu 3 O 7-δ were synthesized by a modified polymeric precursor method, yielding a ceramic powder with particles of mesoscopic-size. Samples of this powder were then pressed into pellets and sintered under different conditions. The critical current density was analyzed by isothermal AC-susceptibility measurements as a function of the excitation field, as well as with isothermal DC-magnetization runs at different values of the applied field. Relevant features of the magnetic response could be associated to the microstructure of the specimens and, in particular, to the superconducting intra- and intergranular critical current properties.

Magnetic response and critical current properties of mesoscopic-size YBCO superconducting samples

Energy Technology Data Exchange (ETDEWEB)

Lisboa-Filho, P N [UNESP - Universidade Estadual Paulista, Grupo de Materiais Avancados, Departamento de Fisica, Bauru (Brazil); Deimling, C V; Ortiz, W A, E-mail: plisboa@fc.unesp.b [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos (Brazil)

2010-01-15

In this contribution superconducting specimens of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} were synthesized by a modified polymeric precursor method, yielding a ceramic powder with particles of mesoscopic-size. Samples of this powder were then pressed into pellets and sintered under different conditions. The critical current density was analyzed by isothermal AC-susceptibility measurements as a function of the excitation field, as well as with isothermal DC-magnetization runs at different values of the applied field. Relevant features of the magnetic response could be associated to the microstructure of the specimens and, in particular, to the superconducting intra- and intergranular critical current properties.

Energy of magnetic moment of superconducting current in magnetic field

International Nuclear Information System (INIS)

Gurtovoi, V.L.; Nikulov, A.V.

2015-01-01

Highlights: • Quantization effects observed in superconducting loops are considered. • The energy of magnetic moment in magnetic field can not be deduced from Hamiltonian. • This energy is deduced from a history of the current state in the classical case. • It can not be deduced directly in the quantum case. • Taking this energy into account demolishes agreement between theory and experiment. - Abstract: The energy of magnetic moment of the persistent current circulating in superconducting loop in an externally produced magnetic field is not taken into account in the theory of quantization effects because of identification of the Hamiltonian with the energy. This identification misleads if, in accordance with the conservation law, the energy of a state is the energy expended for its creation. The energy of magnetic moment is deduced from a creation history of the current state in magnetic field both in the classical and quantum case. But taking this energy into account demolishes the agreement between theory and experiment. Impartial consideration of this problem discovers the contradiction both in theory and experiment

Short Circuits of a 10 MW High Temperature Superconducting Wind Turbine Generator

NARCIS (Netherlands)

Song, X.; Polinder, H.; Liu, D.; Mijatovic, Nenad; Holbøll, Joachim; Jensen, Bogi Bech

Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen at

Trapped magnetic field of a superconducting bulk magnet in high- T sub c RE-Ba-Cu-O

CERN Document Server

Fujimoto, H; Higuchi, T; Nakamura, Y; Kamijo, H; Nagashima, K; Murakami, M

1999-01-01

Superconducting magnets made of high-T sub c superconductors are promising for industrial applications. It is well known that REBa sub 2 Cu sub 3 O sub 7 sub - sub x and LRE (light rare-earth) Ba sub 2 Cu sub 3 O sub 7 sub - sub x superconductors prepared by melt processes have a high critical current density, J sub c , at 77 K and high magnetic fields. Therefore, the materials are very prospective for high magnetic field application as a superconducting permanent/bulk magnet with liquid-nitrogen refrigeration. LREBaCuO bulks, compared with REBaCuO bulks, exhibit a larger J sub c in high magnetic fields and a much improved irreversibility field, H sub i sub r sub r , at 77 K. In this study, we discuss the possibility and trapped field properties of a superconducting bulk magnet, as well as the melt processing for bulk superconductors and their characteristic superconducting properties. One of the applications is a superconducting magnet for the future magnetically levitated (Maglev) train.

Alternating current loss calculation in a high-TC superconducting transmission cable considering the magnetic field distribution

International Nuclear Information System (INIS)

Noji, H; Haji, K; Hamada, T

2003-01-01

We have calculated the alternating current (ac) losses of a 114 MVA high-T C superconducting (HTS) transmission cable using an electric-circuit (EC) model. The HTS cable is fabricated by Tokyo Electric Power Company and Sumitomo Electric Industries, Ltd. The EC model is comprised of a resistive part and an inductive part. The resistive part is obtained by the approximated Norris equation for a HTS tape. The Norris equation indicates hysteresis losses due to self-fields. The inductive part has two components, i.e. inductances related to axial fields and those related to circumferential fields. The layer currents and applied fields of each layer were calculated by the EC model. By using both values, the ac losses of the one-phase HTS cable were obtained by calculation considering the self-field, the axial field and the circumferential field of the HTS tape. The measured ac loss transporting 1 kA rms is 0.7 W m -1 ph -1 , which is equal to the calculation. The distribution of each layer loss resembles in shape the distribution of the circumferential field in each layer, which indicates that the circumferential fields strongly influence the ac losses of the HTS cable

Signature of the Collaboration agreement contract between CERN and IASS on High Current, Long Distance Superconducting Power Transmission Lines signed Dr.Steve Myers Director of Acc Tech and Prof. Carlo Rubbia.

CERN Multimedia

Maximilien Brice

2012-01-01

Signature of the Collaboration agreement contract between CERN and IASS on High Current, Long Distance Superconducting Power Transmission Lines signed Dr.Steve Myers Director of Acc Tech and Prof. Carlo Rubbia.

Permanent magnet design for high-speed superconducting bearings

Science.gov (United States)

Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

1996-01-01

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

Research briefing on high-temperature superconductivity

Science.gov (United States)

1987-10-01

The research briefing was prepared in response to the exciting developments in superconductivity in ceramic oxide materials announced earlier in 1987. The panel's specific charge was to examine not only the scientific opportunities in high-temperature superconductivity but also the barriers to commercial exploitation. While the base of experimental knowledge on the superconductors is growing rapidly, there is as yet no generally accepted theoretical explanation of their behavior. The fabrication and processing challenges presented by the materials suggest that the period or precommercial exploration for applications will probably extend for a decade or more. Near term prospects for applications include magnetic shielding, the voltage standard, superconducting quantum interference devices, infrared sensors, microwave devices, and analog signal processing. The panel also identified a number of longer-term prospects in high-field and large-scale applications, and in electronics. The United States' competitive position in the field is discussed, major scientific and technological objectives for research and development identified, and concludes with a series of recommendations.

Contribution to the study of superconducting magnets using high transition temperature superconducting materials

International Nuclear Information System (INIS)

Lecrevisse, Thibault

2012-01-01

The new industrial superconductors using high critical temperature compounds offer new possibilities for superconducting magnetism. Indeed they allow higher magnetic field with the same classical cryogenics at 4.2 K on one hand, and on the other hand they also pave the way for superconducting magnets working between 10 K and 30 K. The high temperature superconductors are then needed in order to produce magnetic fields higher than 16 T (case of HTS dipole insert for Large Hadron Collider at CERN) or to increase the specific density stored in one SMES (Superconducting Magnetic Energy Storage, in the case of the SuperSMES ANR Project).Nevertheless the indisputable assets (critical temperature, critical magnetic field, mechanical stresses) brought by the use of High critical temperature superconductors like YBCO, used in superconducting magnets, require to solve some challenges. Their behavior is still badly understood, especially during the resistive transitions. To succeed in protecting these conductors we need a new reflection on protection schemes designed to avoid the thermal and mechanical damages. The answer to the question: 'Can we use those materials in the long run inside superconducting magnets?' is now inescapable.Some answers are given here. The use of the conductors is approached through various experimental studies to understand the material (electrical characterization and modeling of the critical surface) and to define the key stages of high critical temperature superconducting magnets manufacturing (work on the junctions between conductors and pancakes). This study led to the creation of two coils in order to identify the issues related to the use of YBCO tapes. A numerical thermo-electrical model of the high critical temperature superconductor has been developed and a numerical code based on the CEA software CASTEM (Finish Elements Model) allowed to study the resistive transition (or quench) behavior of those conductor and coil. The code has been

Permanent magnet design for high-speed superconducting bearings

International Nuclear Information System (INIS)

Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

1996-01-01

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs

High-Density Superconducting Cables for Advanced ACTPol

Science.gov (United States)

Pappas, C. G.; Austermann, J.; Beall, J. A.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Henderson, S. W.; Ho, S. P.; Koopman, B. J.; Li, D.;

Origin of the Nonsinusoidal current-phase relation of a superconducting bridge

International Nuclear Information System (INIS)

Sugahara, M.

1977-01-01

The current-phase relation of a long superconducting bridge is investigated with the use of the Aslamazov-Larkin model and the Ginzburg-Landau equation. The feedback effect of the supercurrent to the phase difference in the weak link is taken into consideration. The derived nonsinusoidal current-phase relation explains the experiments of Jackel et al. very well

Direct Observation of High-Temperature Superconductivity in One-Unit-Cell FeSe Films

International Nuclear Information System (INIS)

Zhang Wen-Hao; Zhang Jin-Song; Li Fang-Sen; Guo Ming-Hua; Ding Hao; Tang Chen-Jia; Wang Qing-Yan; He Ke; Ji Shuai-Hua; Chen Xi; Sun Yi; Zhao Yan-Fei; Xing Ying; Wang Hui-Chao; Zhang Hui-Min; Peng Jun-Ping; Li Zhi; Wang Meng; Fujita Takeshi; Hirata Akihiko

2014-01-01

We prepared one-unit-cell (1-UC) thick FeSe films on insulating SrTiO 3 substrates with non-superconducting FeTe protection layers by molecular beam epitaxy for ex situ studies. By direct transport and magnetic measurements, we provide definitive evidence for high temperature superconductivity in the 1-UC FeSe films with an onset T C above 40 K and an extremely large critical current density J C ∼1.7×10 6 A/cm 2 at 2 K, which are much higher than T C ∼8 K and J C ∼10 4 A/cm 2 for bulk FeSe, respectively. Our work may pave the way to enhancing and tailoring superconductivity by interface engineering. (express letter)

Simulation of Field Dependence of Critical Current Densities of Bulk High Tc Superconducting Materials regarding Thermally Activated Flux Motion

Science.gov (United States)

Santosh, M.; Naik, S. Pavan Kumar; Koblischka, M. R.

2017-07-01

In the upcoming generation, bulk high temperature superconductors (HTS) will play a crucial and a promising role in numerous industrial applications ranging from Maglev trains to magnetic resonance imaging, etc. Especially, the bulk HTS as permanent magnets are suitable due to the fact that they can trap magnetic fields being several orders of magnitude higher than those of the best hard ferromagnets. The bulk HTS LREBa2Cu3O7-δ (LREBCO or LRE-123, LRE: Y, Gd, etc.,) materials could obtain very powerful compact superconducting super-magnets, which can be operated at the cheaper liquid nitrogen temperature or below due to higher critical temperatures (i.e., ∼90 K). As a result, the new advanced technology can be utilized in a more attractive manner for a variety of technological and medical applications which have the capacity to revolutionize the field. An understanding of the magnetic field dependence of the critical current density (J c(H)) is important to develop better adapted materials. To achieve this goal, a variety of Jc (H) behaviours of bulk LREBCO samples were modelled regarding thermally activated flux motion. In essence, the Jc (H) curves follows a certain criterion where an exponential model is applied. However, to fit the complete Jc (H) curve of the LRE-123 samples an unique model is necessary to explain the behavior at low and high fields. The modelling of the various superconducting materials could be understood in terms of the pinning mechanisms.

Theory, analysis and applications of the operation of the superconducting transformer supplying a direct current to a non-dissipative superconducting charge circuit

International Nuclear Information System (INIS)

Sole, J.

1967-01-01

The author derives the very simple equations governing the operation of a transformer with superconducting windings supplying direct current to a non-dissipative superconducting charge circuit. An analysis of the various possible modes of operation with direct or slowly varying current raises the problem of the magnetic core. The study. leads to a conclusion which a priori might be surprising: the elimination of the magnetic core and the use of a primary super-conductor. An example of a possible realization of such a transformer is given as an indication, and the present prospects for different applications are considered. (author) [fr

Superconductive properties, interaction mechanisms, materials preparation and electronic transport in high-Tc superconductors

International Nuclear Information System (INIS)

Saemann-Ischenko, G.

1993-01-01

The final report is composed of eight chapters dealing with the following aspects: I. Mixed state, critical currents, anisotropy, intrinsic and extrinsic pinning. II. Microwave properties and far-infrared reflectivity of epitactic HTSC films. III. Hall effect at the states of normal conductivity and superconductivity, magnetoresistance, superconducting fluctuation phenomena. IV. Effects of the nuclear and the electronic energy loss. V. Scanning electron microscopy. VI. p- and n-doped high-Tc superconductors: Charge symmetry and magnetism. VII. Preparation methods. VIII. Electrochemical examinations of HTSC films and HTSC monocrystals at low temperatures. (orig./MM) [de

Conventional superconductivity at 203 K at high pressures

Energy Technology Data Exchange (ETDEWEB)

Drozdov, Alexander; Eremets, Mikhail; Troyan, Ivan [Max-Planck-Institut fuer Chemie, Hahn-Meitner-Weg 1, 55128 Mainz (Germany); Ksenofontov, Vadim; Shylin, Sergii [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitet Mainz, Staudingerweg 9, 55099 Mainz (Germany)

2016-07-01

A search for high, room temperature conventional superconductivity is promising as the Bardeen-Cooper-Schrieffer (BCS) theory in the Eliashberg formulation puts no apparent limits on T{sub c}. Materials with light elements are especially favorable as they provide high frequencies in the phonon spectrum. However only a moderately high T{sub c} = 39 K has been found in this search in MgB{sub 2}. We systematically studied metallic hydrogen and covalent hydrogen dominant compounds and found the record T{sub c} of 203 K at pressure 140 GPa in sulfur hydride. We proved occurrence of superconductivity by the sharp drop of the resistivity to zero; the decrease of T{sub c} with magnetic field; the pronounce isotope shift of T{sub c} in D{sub 2}S which evidences of a major role of phonons in the superconductivity; and the magnetic susceptibility measurements. The X-ray diffraction data confirmed that the superconductive phase has the predicted bcc structure. This phase can be considered as an atomic hydrogen superconductor stabilized by sulfur.

High-T{sub c} cuprate superconductivity in a nutshell

Energy Technology Data Exchange (ETDEWEB)

Won, Hyekyung [Department of Physics, Hallym University, Chuncheon 200-702 (Korea); Haas, Stephan; Parker, David; Maki, Kazumi [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States)

2005-02-01

Since the discovery of high-T{sub c} cuprate superconductivity in 1986 many new experimental techniques and theoretical concepts have been developed. In particular it was shown that the BCS theory of d-wave superconductivity describes semi-quantitatively the high-T{sub c} superconductivity. Furthermore, it was demonstrated that Volovik's approach is extremely useful for finding the quasiparticle properties in the vortex state. Here we survey these developments and forecast future directions. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

State of the art of superconducting fault current limiters and their application to the electric power system

International Nuclear Information System (INIS)

Morandi, Antonio

2013-01-01

Highlights: ► The state of the art of superconducting fault current limiters is reviewed. ► An innovative concept of FCL is discussed and the potential of MgB 2 is outlined. ► The use of FCL to allow more interconnection of MV bus-bar is discussed. ► The use of FCL to increase the immunity from voltage dips is discussed. ► The use of FCL to integrate more distributed generation is pointed out. -- Abstract: Modern electric power systems are becoming more and more complex in order to meet new needs. Nowadays a high power quality is mandatory and there is the need to integrate increasing amounts of on-site generation. All this translates in more sophisticated electric network with intrinsically high short circuit rate. This network is vulnerable in case of fault and special protection apparatus and procedures needs to be developed in order to avoid costly or even irreversible damage. A superconducting fault current limiter (SFCL) is a device with a negligible impedance in normal operating conditions that reliably switches to a high impedance state in case of extra-current. Such a device is able to increase the short circuit power of an electric network and to contemporarily eliminate the hazard during the fault. It can be regarded as a key component for future electric power systems. In this paper the state of the art of superconducting fault current limiters mature for applications is briefly resumed and the potential impact of this device on the paradigm of design and operation of power systems is analyzed. In particular the use of the FCL as a mean to allow more interconnection of MV bus-bars as well an increased immunity with respect to the voltage disturbances induced by critical customer is discussed. The possibility to integrate more distributed generation in the distribution grid is also considered

Aharanov--Bohm currents in thin superconducting cylinders

International Nuclear Information System (INIS)

Kunstatter, G.; Revzen, M.; Trainor, L.E.H.

1983-01-01

The Aharanov--Bohm effect is the influence of classically inaccessible electromagnetic fields on quantum wave functions. In this paper we consider the Ginsburg--Landau (GL) equations for the stationary states of a thin, superconducting cylinder in the presence of a curl-free, static electromagnetic potential corresponding to zero fields. We solve the GL equations explicitly to obtain self-consistent solutions for the current density, the induced field and the free energy in a well-defined and accessible approximation. The analysis makes quantitative predictions which can, in principle, be experimentally tested to provide a clear and convincing demonstration of the Aharanov--Bohm effect

Overlap junctions for high coherence superconducting qubits

Science.gov (United States)

Wu, X.; Long, J. L.; Ku, H. S.; Lake, R. E.; Bal, M.; Pappas, D. P.

2017-07-01

Fabrication of sub-micron Josephson junctions is demonstrated using standard processing techniques for high-coherence, superconducting qubits. These junctions are made in two separate lithography steps with normal-angle evaporation. Most significantly, this work demonstrates that it is possible to achieve high coherence with junctions formed on aluminum surfaces cleaned in situ by Ar plasma before junction oxidation. This method eliminates the angle-dependent shadow masks typically used for small junctions. Therefore, this is conducive to the implementation of typical methods for improving margins and yield using conventional CMOS processing. The current method uses electron-beam lithography and an additive process to define the top and bottom electrodes. Extension of this work to optical lithography and subtractive processes is discussed.

A study on the development of high Tc superconducting materials

International Nuclear Information System (INIS)

Won, D. Y.; Hong, G. Y.; Lee, H. G.; Lee, H. J.; Kim, C. J.; Kwon, S. C.; Kim, K. B.; Kang, Y. H.; Chang, I. S.; Choi, M. J.

1992-01-01

The major work of this project aims to develop the frictionless superconducting bearing with a high speed. The high magnetization YBaCuO bulk superconductor was prepared by Quasi-melt process. The frictionless superconducting magnetic bearing standed a rotating bar with a speed of 75,000 rpm, which were operated by an electric controller. The low temperature chemical vapor deposition technique was developed. YBaCuO superconducting film showing a superconductivity above 77K was successfully prepared at 650 deg C. Effect of oxygen partial pressure, substrate, deposition temperature on the film properties were also investigated. (Author)

Possible universal cause of high-Tc superconductivity in different metals

International Nuclear Information System (INIS)

Amusia, M.Ya.; Shaginyan, V.R.

2002-01-01

Using the theory of the high temperature superconductivity based on the idea of the fermion condensation quantum phase transition (FCQPT) it is shown that neither the d-wave pairing symmetry, nor the pseudogap phenomenon, nor the presence of the Cu-O 2 planes are of decisive importance for the existence of the high-T c superconductivity. The analysis of recent experimental data on this type of superconductivity in different materials is carried out. It is shown that these facts can be understood within the theory of superconductivity based on the FCQPT. The main features of a room-temperature superconductor are discussed [ru

A new measurement tool for characterization of superconducting rf accelerator cavities using high-performance LTS SQUIDs

Energy Technology Data Exchange (ETDEWEB)

Vodel, W [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Neubert, R [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Nietzsche, S [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Seidel, P [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Knaack, K [DESY Hamburg (Germany); Wittenburg, K [DESY Hamburg (Germany); Peters, A [Heidelberger Ionenstrahl-Therapiezentrum, Heidelberg (Germany)

2007-11-15

This paper presents a new system to measure very low currents in an accelerator environment, using a cryogenic current comparator (CCC). In principle a CCC is a conventional current transformer using the high-performance SQUID technology to sense the magnetic fields caused by the beam current. Since the system is sensitive on a pA level, it is an optimum device to detect dark currents of superconducting cavities. The system presented here is designed for the test facilities of the superconducting accelerator modules for the European XFEL at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg. Measurements in a quiet environment showed that an intrinsic noise level of the CCC of 40 pA Hz{sup -1/2} could be achieved.

RE-Ba-Cu-O for high functional superconducting permanent magnet

International Nuclear Information System (INIS)

Yoo, S.I.; Higuchi, T.; Sakai, N.; Murakami, M.; Fujimoto, H.

1998-01-01

Among various potential applications of melt-textured RE-Ba-Cu-O (REBCO, RE: rare earth elements) superconductors, we have examined the bulk application as the superconducting permanent magnet, especially for the magnetically-levitated (MAGLEV) train. Compared with Y-Ba-Cu-O (YBCO), oxygen-controlled melt-growth (OCMG)-processed LREBCO (LRE: light rare earth elements) bulk superconductors are more promising for this application because of larger critical current density (J c ) values in high field and higher irreversibility field (B irr ) within the range of the liquid nitrogen refrigeration (63-77 K), implying that even higher trapped fields (B t ) are achievable in principle. In this paper, material requirements of superconducting bulks for the MAGLEV train are first presented and then processing aspects for the fabrication of good LREBCO bulks are described. (orig.)

Modal bifurcation in a high-Tc superconducting levitation system

International Nuclear Information System (INIS)

Taguchi, D; Fujiwara, S; Sugiura, T

2011-01-01

This paper deals with modal bifurcation of a multi-degree-of-freedom high-T c superconducting levitation system. As modeling of large-scale high-T c superconducting levitation applications, where plural superconducting bulks are often used, it can be helpful to consider a system constituting of multiple oscillators magnetically coupled with each other. This paper investigates nonlinear dynamics of two permanent magnets levitated above high-T c superconducting bulks and placed between two fixed permanent magnets without contact. First, the nonlinear equations of motion of the levitated magnets were derived. Then the method of averaging was applied to them. It can be found from the obtained solutions that this nonlinear two degree-of-freedom system can have two asymmetric modes, in addition to a symmetric mode and an antisymmetric mode both of which also exist in the linearized system. One of the backbone curves in the frequency response shows a modal bifurcation where the two stable asymmetric modes mentioned above appear with destabilization of the antisymmetric mode, thus leading to modal localization. These analytical predictions have been confirmed in our numerical analysis and experiments of free vibration and forced vibration. These results, never predicted by linear analysis, can be important for application of high-T c superconducting levitation systems.

Non-superconducting persistent currents. Des courants permanents mais pas supraconducteurs

Energy Technology Data Exchange (ETDEWEB)

Benoit, A; Mailly, D

1993-03-01

Forecasted ten years ago a quantum effect is evidenced: persistent currents in small non-superconducting loops in a magnetic field at low temperature. The loop (diameter 2.5 micrometer) is etched in a semiconducting structure GaAs/GaAlAs, where the coherence length is 25 [mu]m, the current is measured with a squid on the same chip, a value of 4 nano amps is found which agrees well with the theoretical value of 5 nA.

The development of superconducting equipment

CERN Document Server

Ueda, T; Hiue, H

2003-01-01

Fuji Electric has been developing various types of superconducting equipment for over a quarter of a century. This paper describes the development results achieved for superconducting equipment and especially focuses on large-capacity current leads and superconducting transmission systems, the development of which is being promoted for application to the field of nuclear fusion. High temperature superconductor (HTS) is becoming the mainstream in the field of superconductivity, and the HTS floating coil and conduction-cooled HTS transformed are also introduced as recent developments for devices that utilize this technology. (author)

Superconducting joint of Bi-2223/Ag superconducting tapes by diffusion bonding

International Nuclear Information System (INIS)

Guo Wei; Zou Guisheng; Wu Aiping; Wang Yanjun; Bai Hailin; Ren Jialie

2009-01-01

61-Filaments Bi-2223/Ag superconducting tapes have been joined by diffusion bonding. The critical currents (I C s) of the joints are obtained by using standard four probe method under no magnetic field in the liquid nitrogen. The microstructures of the joints are evaluated by the electron microscope in electron backscatter diffraction mode and the phase compositions of the superconducting cores of the joint and the original tape are determined by X-ray diffraction (XRD). The results show diffusion bonding is effective bonding technique for HTS tapes, and the bonding time is reduced greatly from hundreds of hours to a few hours, and the bonding pressure also changes from 140-4000 MPa to 3 MPa. Furthermore, the diffusion bonding joints sustain superconducting properties, and the critical current ratios (CCR O ) of the joints are in the range of 35%-80%. Microstructures of the typical joint display a good bonding and some defects existed in traditional method are avoided. XRD results show that the phase compositions of the superconducting cores have no obvious changes before and after diffusion bonding, which offers physical and material bases for high superconducting property of the joints.

Pair Fermi contour and high-temperature superconductivity

CERN Document Server

Belyavsky, V I

2002-01-01

The holes superconducting coupling with the pair high summarized pulse and the relative motion low pulses is considered with an account of the quasi-two-dimensional electron structure of the HTSC-cuprates with the clearly-pronounced nesting of the Fermi contour. The superconducting energy gap and the condensation energy are determined and their dependences on the doping level are qualitatively studied. It is shown that the energy gap takes place in some holes concentration area, limited on both sides. The superconducting state, whereby the condensation energy is positive, originates in the more narrower doping interval inside this area. The hole pair redistribution in the pulse space constitutes the cause of the superconducting state origination by the holes repulsive screened Coulomb interaction. The coupling mechanism discussed hereby, males it possible to explain qualitatively not only the phase diagram basic peculiarities but also the key experimental facts, related to the cuprate HTSC-materials

Numerical solution of High-kappa model of superconductivity

Energy Technology Data Exchange (ETDEWEB)

Karamikhova, R. [Univ. of Texas, Arlington, TX (United States)

1996-12-31

We present formulation and finite element approximations of High-kappa model of superconductivity which is valid in the high {kappa}, high magnetic field setting and accounts for applied magnetic field and current. Major part of this work deals with steady-state and dynamic computational experiments which illustrate our theoretical results numerically. In our experiments we use Galerkin discretization in space along with Backward-Euler and Crank-Nicolson schemes in time. We show that for moderate values of {kappa}, steady states of the model system, computed using the High-kappa model, are virtually identical with results computed using the full Ginzburg-Landau (G-L) equations. We illustrate numerically optimal rates of convergence in space and time for the L{sup 2} and H{sup 1} norms of the error in the High-kappa solution. Finally, our numerical approximations demonstrate some well-known experimentally observed properties of high-temperature superconductors, such as appearance of vortices, effects of increasing the applied magnetic field and the sample size, and the effect of applied constant current.

Microwave dynamics of high aspect ratio superconducting nanowires studied using self-resonance

Science.gov (United States)

Santavicca, Daniel F.; Adams, Jesse K.; Grant, Lierd E.; McCaughan, Adam N.; Berggren, Karl K.

2016-06-01

We study the microwave impedance of extremely high aspect ratio (length/width ≈ 5000) superconducting niobium nitride nanowires. The nanowires are fabricated in a compact meander geometry that is in series with the center conductor of a 50 Ω coplanar waveguide transmission line. The transmission coefficient of the sample is measured up to 20 GHz. At high frequency, a peak in the transmission coefficient is seen. Numerical simulations show that this is a half-wave resonance along the length of the nanowire, where the nanowire acts as a high impedance, slow wave transmission line. This resonance sets the upper frequency limit for these nanowires as inductive elements. Fitting simulations to the measured resonance enables a precise determination of the nanowire's complex sheet impedance at the resonance frequency. The real part is a measure of dissipation, while the imaginary part is dominated by kinetic inductance. We characterize the dependence of the sheet resistance and sheet inductance on both temperature and current and compare the results to recent theoretical predictions for disordered superconductors. These results can aid in the understanding of high frequency devices based on superconducting nanowires. They may also lead to the development of novel superconducting devices such as ultra-compact resonators and slow-wave structures.

Characteristics of persistent-current mode of HTS coil on superconducting electromagnet

International Nuclear Information System (INIS)

Lee, C.Y.; Kim, J.; Han, Y.J.; Kang, B.; Chung, Y.D.; Yoon, Y.S.; Chu, S.Y.; Hwang, Y.J.; Jo, H.C.; Jang, J.Y.; Ko, T.K.

2011-01-01

The levitation gap of an electromagnetic suspension (EMS) system affects the current decay rate of superconducting electromagnet. The presence of iron core provides a significant benefit in the PCM performance of SC coil. The increased levitation gap of the EMS model with the SC-EM could negatively affect the design of SC-EM operated in PCM. This paper investigates the way in which the levitation gap of an electromagnetic suspension (EMS) system affects the current decay rate of superconducting electromagnet (SC-EM) operated in persistence-current mode (PCM). Using inductance analyzed from the magnetic circuit of an EMS model, the current decay rate caused by the variation in the levitation gap was simulated. In order to experimentally verify the simulation results, we fabricated a small-scale EMS model with SC coil operated in PCM and measured the current decay rates at different levitation gaps. The result showed that the presence of iron core provides a significant benefit in the PCM performance of SC coil, but the benefit decreased as the levitation gap increases. This study revealed that the increased levitation gap of the EMS model with the SC-EM could negatively affect the design of SC-EM operated in PCM.

Superconductivity: materials and applications

International Nuclear Information System (INIS)

Duchateau, J.L.; Kircher, F.; Leveque, J.; Tixador, P.

2008-01-01

This digest paper presents the different types of superconducting materials: 1 - the low-TC superconductors: the multi-filament composite as elementary constituent, the world production of NbTi, the superconducting cables of the LHC collider and of the ITER tokamak; 2 - the high-TC superconductors: BiSrCaCuO (PIT 1G) ribbons and wires, deposited coatings; 3 - application to particle physics: the the LHC collider of the CERN, the LHC detectors; 4 - applications to thermonuclear fusion: Tore Supra and ITER tokamaks; 5 - NMR imaging: properties of superconducting magnets; 6 - applications in electrotechnics: cables, motors and alternators, current limiters, transformers, superconducting energy storage systems (SMES). (J.S.)

Superconductivity in power engineering

International Nuclear Information System (INIS)

1989-01-01

This proceedings volume presents 24 conference papers and 15 posters dealing with the following aspects: 1) Principles and elementary aspects of high-temperature superconductivity (3 plenary lectures); 2) Preparation, properties and materials requirements of metallic or oxide superconductors (critical current behaviour, soldered joints, structural studies); 3) Magnet technology (large magnets for thermonuclear fusion devices; magnets for particle accelerators and medical devices); 4) Magnetic levitation and superconductivity; 5) Cryogenics; 6) Energy storage systems using superconducting coils (SMES); 7) Superconducting power transmission cables, switches, transformers, and generator systems for power plant; 8) Supporting activities, industrial aspects, patents. There are thirty-eight records in the ENERGY database relating to individual conference papers. (MM) [de

Determination of the electromagnetic field in a high-Tc linear superconducting resonator

International Nuclear Information System (INIS)

Trotel, A.; Sautrot, S.; Pyee, M.

1994-01-01

In this paper, the electromagnetic field configuration in a linear SHTC resonator is described. Two areas are considered: 1) the superconducting strip, 2) the dielectric around the strip. The calculation is based on the current density given by Bowers for an infinite superconducting line. The current density in the resonator is defined by these relations and the resonance conditions. (orig.)

Improvement in operational characteristics of KEPCO’s line-commutation-type superconducting hybrid fault current limiter

Science.gov (United States)

Yim, S.-W.; Park, B.-C.; Jeong, Y.-T.; Kim, Y.-J.; Yang, S.-E.; Kim, W.-S.; Kim, H.-R.; Du, H.-I.

2013-01-01

A 22.9 kV class hybrid fault current limiter (FCL) developed by Korea Electric Power Corporation and LS Industrial Systems in 2006 operates using the line commutation mechanism and begins to limit the fault current after the first half-cycle. The first peak of the fault current is available for protective coordination in the power system. However, it also produces a large electromagnetic force and imposes a huge stress on power facilities such as the main transformer and gas-insulated switchgear. In this study, we improved the operational characteristics of the hybrid FCL in order to reduce the first peak of the fault current. While maintaining the structure of the hybrid FCL system, we developed a superconducting module that detects and limits the fault current during the first half-cycle. To maintain the protective coordination capacity, the hybrid FCL was designed to reduce the first peak value of the fault current by up to approximately 30%. The superconducting module was also designed to produce a minimum AC loss, generating a small, uniform magnetic field distribution during normal operation. Performance tests confirmed that when applied to the hybrid FCL, the superconducting module showed successful current limiting operation without any damage.

Magnetic imaging of superconducting tapes to determine current flow

Energy Technology Data Exchange (ETDEWEB)

Brown, G. W. (Geoffrey W.); Hawley, M. E. (Marilyn E.); Foltyn, S. R. (Stephen R.); Mueller, F. M. (Fred M.)

2001-01-01

We have developed a magnetic imaging system that uses magnetoresistive read heads from computer hard disk drives to map the transport-current-induced magnetic field at the surface of superconducting tapes at liquid nitrogen temperature. Transport current pathways are determined from the 2-dimensional magnetic field maps using established inversion schemes. We examined the current flow in pulsed-laser-deposited YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} a films patterned on single crystal SrTiO{sub 3} substrates and on a textured yttria-stabilized-zirconia layer deposited on an Inconel ribbon by ion beam assisted deposition. The transport current densities in all cases were consistent with the Critical State Model. For the Inconel-based sample, the transport current density maps have allowed us to observe defects and determine the region that limits the current carrying capacity of the structure.

Critical current properties in superconducting melt processed Y-Ba-Cu-O

International Nuclear Information System (INIS)

Matsushita, Teruo

1993-01-01

The critical current density in bulk superconducting Y-Ba-Cu-O has been remarkably improved by employing the so-called melt process. However, its value is still far below those reported in single-crystalline thin films. Important key factors that determine the critical current density are the flux pinning mechanism and defective structures such as cracks or weak links. In this article, these factors in melt-processed Y-Ba-Cu-O are argued from various measurements of the critical current density on the microstructure dependence, the magnetic field dependence, the temperature dependence, the history effect, the longitudinal field effect and the imaginary ac susceptibility. As for the pinning mechanism, it is concluded that the dominant pinning centers in the high temperature region around 77 K are normal 211 (Y 2 BaCuO 5 ) particles, while small defects such as lattice defects or oxygen deficiencies seem to be dominant in the lower temperature region. It is suggested that much finer normal particles should be introduced in order to improve the critical current density especially at higher temperatures. From the rapid decrease of the critical current density with elevating temperature below 30 K, some kind of weak links are considered to still remain in these materials. However, the observed critical current density did not depend on the history of application of the magnetic field and a large enhancement of the critical current density was observed in the longitudinal field geometry at 4.2 K. These results suggest that the weak links in these materials are of much different kind from those at large angle grain boundaries in sintered polycrystalline materials. From the X-ray diffraction measurements, a domain structure of a mean domain size of about 100 μm was found. These domain boundaries may cause weak links in melt-processed Y-Ba-Cu-O. It is also shown that the typical size of channels of flowing current can be obtained by the imaginary ac susceptibility

Active superconducting DC fault current limiter based on flux compensation

International Nuclear Information System (INIS)

Shi Jing; Tang Yuejin; Wang, Chen; Zhou Yusheng; Li Jingdong; Ren Li; Chen Shijie

2006-01-01

With the extensive application of DC power systems, suppression of DC fault current is an important subject that guarantees system security. This paper presents an active superconducting DC fault current limiter (DC-SFCL) based on flux compensation. The DC-SFCL is composed of two superconducting windings wound on a single iron core, the primary winding is in series with DC power system, and the second winding is connected with AC power system through a PWM converter. In normal operating state, the flux in the iron core is compensated to zero, and the SFCL has no influence on DC power system. In the case of DC system accident, through regulating the active power exchange between the SFCL's second winding and the AC power system, the current on the DC side can be limited to different level complying with the system demand. Moreover, the PWM converter that interface the DC system and AC system can be controlled as a reactive power source to supply voltage support for the AC side, which has little influence on the performance of SFCL. Using MATLAB SIMULINK, the mathematic model of the DC-SFCL is created, simulation results validate the dynamics of system, and the performance of DC-SFCL is confirmed

High-field superconducting window-frame beam-transport magnets

International Nuclear Information System (INIS)

Allinger, J.; Carroll, A.; Danby, G.; DeVito, B.; Jackson, J.; Leonhardt, W.; Prodell, A.; Skarita, J.

1982-01-01

The window-frame design for high-field superconducting beam-transport magnets was first applied to two, 2-m-long, 4-T modules of an 8 0 bending magent which has operated for nine years in the primary proton beam line at the Brookhaven National Laboratory Alternating Gradient Synchrotron (AGS). The design of two 1.5-m long, 7.6-cm cold-bore superconducting windowframe magnets, described in this paper, intended for the external proton beam transport system at the AGS incorporated evolutionary changes. These magnets generated a maximum aperture field of 6.8 T with a peak field in the dipole coil of 7.1 T. Measured fields are very accurate and are compared to values calculated using the computer programs LINDA and POISSON. Results of quench-propagation studies demonstrate the excellent thermal stability of the magnets. The magnets quench safely without energy extraction at a maximum current density, J = 130 kA/cm 2 in the superconductor, corresponding to J = 57.6 kA/cm 2 overall the conductor at B = 6.7 T

Status of RF superconductivity at Argonne

International Nuclear Information System (INIS)

Shepard, K.W.

1990-01-01

Development of a superconducting slow-wave structures began at Argonne National Laboratory (ANL) in 1971, and led to the first superconducting heavy-ion linac (ATLAS - the Argonne Tandem-Linac Accelerator System). The Physics Division at ANL has continued to develop superconducting RF technology for accelerating heavy-ions, with the result that the linac has been in an almost continuous process of upgrade and expansion. In 1987, the Engineering Physics Division at ANL began developing of superconducting RF components for the acceleration of high-brightness proton and deuterium beams. The two divisions collaborate in work on several applications of RF superconductivity, and also in work to develop the technology generally. The present report briefly describes major features of the superconducting heavy-ion linac (very-low-velocity superconducting linac, positive ion injector), proton accelerating structures (superconducting resonant cavities for acceleration of high-current proton and deuteron beams, RF properties of oxide superconductors), and future work. Both divisions expect to continue a variety of studies, frequently in collaboration, to advance the basic technology of RF superconductivity. (N.K.)

Mechanisms of conventional and high Tc superconductivity

International Nuclear Information System (INIS)

Kresin, V.L.; Morawitz, H.; Wolf, S.A.

1993-01-01

This book gives a careful and objective review of theories of superconductivity in traditional superconductors, organics, and high Tc cuprates. Of course, the authors do still present their own theories of cuprate superconductivity, but only in the final chapter after other possibilities have been discussed. The book should be especially useful for researchers entering the field of high Tc superconductivity. The reviews of photon mediated pairing and strong coupling theory are very welcome, since much of this material has not been reviewed since the classic 1969 volume edited by Parks. In particular the authors dispel the various myths that phonon mediated pairing leads to upper bounds on Tc. In addition to phonon mediated pairing the book discussed in detail pairing due to exchange of acoustic (demon) plasmons, excitons, or magnetic fluctuations. There have been so many diverse mechanisms based on strong correlation and large U Hubbard models that a book like this can only discuss a limited selection of the main contenders. In particular here the emphasis on Fermi liquid based models no doubt reflects the authors' own point of view. A whole chapter discusses the concepts of induced superconductivity, in the proximity effect, and its application to materials with several different electronic subsystems

Current redistribution effects on superconducting d.c, and microwave measurements

International Nuclear Information System (INIS)

Barra, M; Cassinese, A; Vaglio, R

2006-01-01

In the last two decades, non conventional behavior of the d.c. transport properties of superconductors, with the appearance of anomalous peaks at the transition, have been investigated and interpreted in different ways. In several cases it was recognized that the behavior can be due to current redistribution effects related to the non-homogeneous nature of the measured superconducting sample. In this paper we will briefly review and discuss these effects and, referring to simple concentrated constant equivalent circuits, we will show that sample non-homogeneity can produce the observed features. Then, in the same framework, by performing specific simulations on planar resonators, we will show that anomalous peaks in temperature dependence of the resonant frequency and of the extracted surface reactance can occur at the transition temperature of minority, lower Tc, superconducting phases

Japan. Superconductivity for Smart Grids

Energy Technology Data Exchange (ETDEWEB)

Hayakawa, K.

2012-11-15

Currently, many smart grid projects are running or planned worldwide. These aim at controlling the electricity supply more efficiently and more stably in a new power network system. In Japan, especially superconductivity technology development projects are carried out to contribute to the future smart grid. Japanese cable makers such as Sumitomo Electric and Furukawa Electric are leading in the production of high-temperature superconducting (HTS) power cables. The world's largest electric current and highest voltage superconductivity proving tests have been started this year. Big cities such as Tokyo will be expected to introduce the HTS power cables to reduce transport losses and to meet the increased electricity demand in the near future. Superconducting devices, HTS power cables, Superconducting Magnetic Energy Storage (SMES) and flywheels are the focus of new developments in cooperations between companies, universities and research institutes, funded by the Japanese research and development funding organization New Energy and Industrial Technology Development Organization (NEDO)

Korea's developmental program for superconductivity

Science.gov (United States)

Hong, Gye-Won; Won, Dong-Yeon; Kuk, Il-Hyun; Park, Jong-Chul

1995-04-01

Superconductivity research in Korea was firstly carried out in the late 70's by a research group in Seoul National University (SNU), who fabricated a small scale superconducting magnetic energy storage system under the financial support from Korea Electric Power Company (KEPCO). But a few researchers were involved in superconductivity research until the oxide high Tc superconductor was discovered by Bednorz and Mueller. After the discovery of YBaCuO superconductor operating above the boiling point of liquid nitrogen (77 K)(exp 2), Korean Ministry of Science and Technology (MOST) sponsored a special fund for the high Tc superconductivity research to universities and national research institutes by recognizing its importance. Scientists engaged in this project organized 'High Temperature Superconductivity Research Association (HITSRA)' for effective conducting of research. Its major functions are to coordinate research activities on high Tc superconductivity and organize the workshop for active exchange of information. During last seven years the major superconductivity research has been carried out through the coordination of HITSRA. The major parts of the Korea's superconductivity research program were related to high temperature superconductor and only a few groups were carrying out research on conventional superconductor technology, and Korea Atomic Energy Research Institute (KAERI) and Korea Electrotechnology Research Institute (KERI) have led this research. In this talk, the current status and future plans of superconductivity research in Korea will be reviewed based on the results presented in interim meeting of HITSRA, April 1-2, 1994. Taejeon, as well as the research activity of KAERI.

Model for an irreversible bias current in the superconducting qubit measurement process

International Nuclear Information System (INIS)

Hutchinson, G. D.; Williams, D. A.; Holmes, C. A.; Stace, T. M.; Spiller, T. P.; Barrett, S. D.; Milburn, G. J.; Hasko, D. G.

2006-01-01

The superconducting charge-phase ''quantronium'' qubit is considered in order to develop a model for the measurement process used in the experiment of Vion et al. [Science 296, 886 (2002)]. For this model we propose a method for including the bias current in the readout process in a fundamentally irreversible way, which to first order is approximated by the Josephson junction tilted-washboard potential phenomenology. The decohering bias current is introduced in the form of a Lindblad operator and the Wigner function for the current-biased readout Josephson junction is derived and analyzed. During the readout current pulse used in the quantronium experiment we find that the coherence of the qubit initially prepared in a symmetric superposition state is lost at a time of 0.2 ns after the bias current pulse has been applied, a time scale that is much shorter than the experimental readout time. Additionally we look at the effect of Johnson-Nyquist noise with zero mean from the current source during the qubit manipulation and show that the decoherence due to the irreversible bias current description is an order of magnitude smaller than that found through adding noise to the reversible tilted-washboard potential model. Our irreversible bias current model is also applicable to persistent-current-based qubits where the state is measured according to its flux via a small-inductance direct-current superconducting quantum interference device

Superconducting cyclotron deflector conditioning status - an experience with high voltage

International Nuclear Information System (INIS)

Ghosh, Subhash; Chattopadhyay, Subrata; Bhattacharjee, Tanushyam; De, Anirban; Paul, Santanu; Pal, Gautam; Saha, Subimal; Mallik, C.; Bhandari, R.K.

2009-01-01

In this paper we report about the status of the electrostatic deflector which will be used in K500 superconducting cyclotron at VECC, Kolkata. For extraction of beams from superconducting cyclotron we have to achieve 130 kV/cm. Titanium and tungsten are used for anode and septum respectively. The deflector fits within the median plane of the superconducting magnet. We report here the voltage limit, sparking rates, dark current levels and the effects observed on conditioning. For commissioning of the superconducting cyclotron, the plan is to accelerate Neon beam of 50 MeV/n for which the required extraction voltage is 81 kV/cm and we reached up to 110 kV/cm. The conditioning test chamber is maintained at a pressure of 8.0 x 10 -7 mbar. (author)

Critical current enhancement driven by suppression of superconducting fluctuation in ion-gated ultrathin FeSe

Science.gov (United States)

Harada, T.; Shiogai, J.; Miyakawa, T.; Nojima, T.; Tsukazaki, A.

2018-05-01

The framework of phase transition, such as superconducting transition, occasionally depends on the dimensionality of materials. Superconductivity is often weakened in the experimental conditions of two-dimensional thin films due to the fragile superconducting state against defects and interfacial effects. In contrast to this general trend, superconductivity in the thin limit of FeSe exhibits an opposite trend, such as an increase in critical temperature (T c) and the superconducting gap exceeding the bulk values; however, the dominant mechanism is still under debate. Here, we measured thickness-dependent electrical transport properties of the ion-gated FeSe thin films to evaluate the superconducting critical current (I c) in the ultrathin FeSe. Upon systematically decreasing the FeSe thickness by the electrochemical etching technique in the Hall bar-shaped electric double-layer transistors, we observed a dramatic enhancement of I c reaching about 10 mA and corresponding to about 107 A cm‑2 in the thinnest condition. By analyzing the transition behavior, we clarify that the suppressed superconducting fluctuation is one of the origins of the large I c in the ion-gated ultrathin FeSe films. These results indicate the existence of a robust superconducting state possibly with dense Cooper pairs at the thin limit of FeSe.

A vibrating wire parallel to a high temperature superconducting slab. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

Saif, A G; El-sabagh, M A [Department of Mathematic and Theoretical physics, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)

1996-03-01

The power losses problem for an idealized high temperature type II superconducting system of a simple geometry is studied. This system is composed of a vibrating normal conducting wire (two wires) carrying a direct current parallel to an uniaxial anisotropic type II superconducting slab (moving slab). First, the electromagnetic equation governing the dynamics of this system, and its solutions are obtained. Secondly, a modified anisotropic london equation is developed to study these systems in the case of the slab moving. Thirdly, it is found that, the power losses is dependent on the frequency, london penetration depth, permeability, conductivity, velocity, and the distance between the normal conductors and the surfaces of the superconducting slab. Moreover, the power losses decreases as the distance between the normal conductors and the surface of the superconducting slab decreases; and increases as the frequency, the london penetration depth, permeability, conductivity, and velocity are increased. These losses along the versor of the anisotropy axis is increased as {lambda}{sub |}| increases. Moreover, it is greater than the power losses along the crystal symmetry direction. In the isotropic case as well as the slab thickness tends to infinity, agreement with previous results are obtained. 2 figs.

Superconducting spoke cavities for high-velocity applications

Energy Technology Data Exchange (ETDEWEB)

Hopper, Christopher S. [Old Dominion U.; Delayen, Jean R. [Old Dominion U., JLAB

2013-10-01

To date, superconducting spoke cavities have been designed, developed, and tested for particle velocities up to {beta}{sub 0}~0.6, but there is a growing interest in possible applications of multispoke cavities for high-velocity applications. We have explored the design parameter space for low-frequency, high-velocity, double-spoke superconducting cavities in order to determine how each design parameter affects the electromagnetic properties, in particular the surface electromagnetic fields and the shunt impedance. We present detailed design for cavities operating at 325 and 352 MHz and optimized for {beta}{sub 0}~=0.82 and 1.

Superconductivity in Layered Organic Metals

Directory of Open Access Journals (Sweden)

Jochen Wosnitza

2012-04-01

Full Text Available In this short review, I will give an overview on the current understanding of the superconductivity in quasi-two-dimensional organic metals. Thereby, I will focus on charge-transfer salts based on bis(ethylenedithiotetrathiafulvalene (BEDT-TTF or ET for short. In these materials, strong electronic correlations are clearly evident, resulting in unique phase diagrams. The layered crystallographic structure leads to highly anisotropic electronic as well as superconducting properties. The corresponding very high orbital critical field for in-plane magnetic-field alignment allows for the occurrence of the Fulde–Ferrell– Larkin–Ovchinnikov state as evidenced by thermodynamic measurements. The experimental picture on the nature of the superconducting state is still controversial with evidence both for unconventional as well as for BCS-like superconductivity.

Hybrid superconducting magnetic suspensions

International Nuclear Information System (INIS)

Tixador, P.; Hiebel, P.; Brunet, Y.; Chaud, X.; Gautier-Picard, P.

1996-01-01

Superconductors, especially high T c ones, are the most attractive materials to design stable and fully passive magnetic suspensions which have to control five degrees of freedom. The hybrid superconducting magnetic suspensions present high performances and a simple cooling mode. They consist of a permanent magnet bearing, stabilized by a suitable magnet-superconductor structure. Several designs are given and compared in terms of forces and stiffnesses. The design of the magnet bearing plays an important part. The superconducting magnetic bearing participates less in levitation but must provide a high stabilizing stiffness. This is achieved by the magnet configuration, a good material in term of critical current density and field cooling. A hybrid superconducting suspension for a flywheel is presented. This system consists of a magnet thrust bearing stabilized by superconductors interacting with an alternating polarity magnet structure. First tests and results are reported. Superconducting materials are magnetically melt-textured YBaCuO

Design and construction of a high temperature superconducting power cable cryostat for use in railway system applications

International Nuclear Information System (INIS)

Tomita, M; Muralidhar, M; Suzuki, K; Fukumoto, Y; Ishihara, A; Akasaka, T; Kobayashi, Y

2013-01-01

The primary objective of the current effort was to design and test a cryostat using a prototype five-meter long high temperature Bi 2 Sr 2 Ca 2 Cu 3 O y (Bi-2223) superconducting dc power cable for railway systems. To satisfy the safety regulations of the Govt of Japan a mill sheet covered by super-insulation was used inside the walls of the cryostat. The thicknesses of various walls in the cryostat were obtained from a numerical analysis. A non-destructive inspection was utilized to find leaks under vacuum or pressure. The cryostat target temperature range was around 50 K, which is well below liquid nitrogen temperature, the operating temperature of the superconducting cable. The qualification testing was carried out from 77 down to 66 K. When using only the inner sheet wire, the maximum current at 77.3 K was 10 kA. The critical current (I c ) value increased with decreasing temperature and reached 11.79 kA at 73.7 K. This is the largest dc current reported in a Bi 2 Sr 2 Ca 2 Cu 3 O y or YBa 2 Cu 3 O y (Y-123) superconducting prototype cable so far. These results verify that the developed DC superconducting cable is reliable and fulfils all the requirements necessary for successful use in various power applications including railway systems. The key issues for the design of a reliable cryogenic system for superconducting power cables for railway systems are discussed. (paper)

Superconducting nanostructured materials

International Nuclear Information System (INIS)

Metlushko, V.

1998-01-01

Within the last year it has been realized that the remarkable properties of superconducting thin films containing a periodic array of defects (such as sub-micron sized holes) offer a new route for developing a novel superconducting materials based on precise control of microstructure by modern photolithography. A superconductor is a material which, when cooled below a certain temperature, loses all resistance to electricity. This means that superconducting materials can carry large electrical currents without any energy loss--but there are limits to how much current can flow before superconductivity is destroyed. The current at which superconductivity breaks down is called the critical current. The value of the critical current is determined by the balance of Lorentz forces and pinning forces acting on the flux lines in the superconductor. Lorentz forces proportional to the current flow tend to drive the flux lines into motion, which dissipates energy and destroys zero resistance. Pinning forces created by isolated defects in the microstructure oppose flux line motion and increase the critical current. Many kinds of artificial pinning centers have been proposed and developed to increase critical current performance, ranging from dispersal of small non-superconducting second phases to creation of defects by proton, neutron or heavy ion irradiation. In all of these methods, the pinning centers are randomly distributed over the superconducting material, causing them to operate well below their maximum efficiency. We are overcome this drawback by creating pinning centers in aperiodic lattice (see Fig 1) so that each pin site interacts strongly with only one or a few flux lines

Current Redistribution around the Superconducting-to-normal Transition in Superconducting Nb-Ti Rutherford Cables

CERN Document Server

Willering, G P; ten Kate, H H J

2008-01-01

Sufficient thermal-electromagnetic stability against external heat sources is an essential design criterion for superconducting Rutherford cables, especially if operated close to the critical current. Due to the complex phenomena contributing to stability such as helium cooling, inter-strand current and heat transfer, its level is difficult to quantify. In order to improve our understanding, many stability tests were performed on different cable samples, each incorporating several point-like heaters. The current redistribution around the heat front is measured after inducing a local normal zone in one strand of the cable. By using voltage taps, expansion of the normal zone is monitored in the initially quenched strand as well as in adjacent strands. An array of Hall probes positioned at the cable edge is used to scan the selffield generated by the cable by which it becomes possible to estimate the inter-strand current transfer. In this paper it is demonstrated that two different stability regimes can be disti...

Superconducting RF activities at Cornell University

International Nuclear Information System (INIS)

Kirchgessner, J.; Moffat, D.; Padamsee, H.; Rubin, D.; Sears, J.; Shu, Q.S.

1990-01-01

This paper outlines the RF superconductivity research and development work that has taken place at Cornell Laboratory of Nuclear Studies over the past years. The work that has been performed since the last RF superconductivity workshop is emphasized together with a discussion of the direction of future efforts. Past work is summarized first, focusing on research and development activities in the area of RF superconductivity. Superconducting TeV linear collider is then discussed focusing on the application of superconducting RF to a future TeV linear collider. Linear collider structure development is then described centering on the development of a simpler (thereby cheaper) structure for a TeV linear collider. B-factory with superconducting RF is outlined focusing on the formulation of a conceptual design for a B-factory. B-factory structure development is discussed in relation to the advancement in the capability of SC cavities to carry beam currents of several amperes necessary for a high luminosity storage ring. High gradients are discussed as the key to the realization of a high energy superconducting linac or a superconducting RF B-factory. (N.K.)

High-current pulses from inductive energy stores

International Nuclear Information System (INIS)

Wipf, S.L.

1981-01-01

Superconducting inductive energy stores can be used for high power pulse supplies if a suitable current multiplication scheme is used. The concept of an inductive Marx generator is superior to a transformer. A third scheme, a variable flux linkage device, is suggested; in multiplying current it also compresses energy. Its function is in many ways analogous to that of a horsewhip. Superconductor limits indicate that peak power levels of TW can be reached for stored energies above 1 MJ

Electric currents in REBaCuO superconducting tapes

Czech Academy of Sciences Publication Activity Database

Jirsa, Miloš; Rameš, Michal; Ďuran, Ivan; Melíšek, T.; Kováč, P.; Viererbl, L.

2017-01-01

Roč. 30, č. 4 (2017), 1-8, č. článku 045010. ISSN 0953-2048 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:68378271 ; RVO:61389021 Keywords : superconducting tapes * REBaCuO * critical currents * induction and transport * pinning force density * magnetic relaxation * neutron irradiation Subject RIV: BM - Solid Matter Physics ; Magnetism; BL - Plasma and Gas Discharge Physics (UFP-V) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Fluids and plasma physics (including surface physics) (UFP-V) Impact factor: 2.878, year: 2016

Strongly enhanced current densities in Sr0.6K0.4Fe2As2 + Sn superconducting tapes

Science.gov (United States)

Lin, He; Yao, Chao; Zhang, Xianping; Zhang, Haitao; Wang, Dongliang; Zhang, Qianjun; Ma, Yanwei; Awaji, Satoshi; Watanabe, Kazuo

2014-03-01

Improving transport current has been the primary topic for practical application of superconducting wires and tapes. However, the porous nature of powder-in-tube (PIT) processed iron-based tapes is one of the important reasons for low critical current density (Jc) values. In this work, the superconducting core density of ex-situ Sr0.6K0.4Fe2As2 + Sn tapes, prepared from optimized precursors, was significantly improved by employing a simple hot pressing as an alternative route for final sintering. The resulting samples exhibited optimal critical temperature (Tc), sharp resistive transition, small resistivity and high Vickers hardness (Hv) value. Consequently, the transport Jc reached excellent values of 5.1 × 104 A/cm2 in 10 T and 4.3 × 104 A/cm2 in 14 T at 4.2 K, respectively. Our tapes also exhibited high upper critical field Hc2 and almost field-independent Jc. These results clearly demonstrate that PIT pnictide wire conductors are very promising for high-field magnet applications.

High temperature superconductivity: Hope of a new technology

International Nuclear Information System (INIS)

Anon.

1989-01-01

Following the sensational report in 1986 from the IBM laboratory in Rueschlikon, Switzerland, that superconductivity - that permanent flow of current at temperatures close to absolute zero - is also possible at higher temperatures, the waves of enthusiasm among scientists at first rose high. They talked of a revolution in electrotechnology, especially since superconductors at room temperature seemed to have almost come within reach. In the meantime their thoughts on the matter are much more down to earth. What are the realistic fields of application for the 'new superconductors'? The questions are discussed by scientists, politicians and engineers. (orig.) [de

Protection for low current superconducting coils wound with insulated strand cable

International Nuclear Information System (INIS)

Satti, J.

1980-09-01

The insulated strand cable concept for winding of low current superconducting coil leads to an ideal quench protection by induction coupling. A superconducting secondary loop was made within a cable of a 6.2 Henry dipole coil. When quenching occurred, current was induced in the secondary strand above the critical value. The normal strand quenched the whole cable due to good thermal contact. The secondary loop works as a heater turned on as the wire becomes normal throughout the coil. With a well spread quench, the energy dissipation density is decreased thus preventing local burnout. The mechanism is possible because of close coupling that is present in the insulated cable as in bifilar winding. For the coil tested a 12 strand cable was used, thus a favorable 11 to 1 turn ratio was obtained for the primary to secondary. The superconductor in the secondary had a lower resistance until the critical current was achieved. A theoretical explanation is described for a simplified circuit. Test on the dipole coil with four individual shells showed that the one shell protected with the induced coupling heater always had a more rapid reduction of current. The induced coupling heater tested and explained in this paper works automatically and does not rely on mechanical or electrical devices

Microscopic Superconductivity and Room Temperature Electronics of High-Tc Cuprates

International Nuclear Information System (INIS)

Liu Fusui; Chen Wanfang

2008-01-01

This paper points out that the Landau criterion for macroscopic superfluidity of He II is only a criterion for microscopic superfluidity of 4 He, extends the Landau criterion to microscopic superconductivity in fermions (electron and hole) system and system with Cooper pairs without long-range phase coherence. This paper gives another three non-superconductive systems that are of microscopic superconductivity. This paper demonstrates that one application of microscopic superconductivity is to establish room temperature electronics of the high-T c cuprates

Quasiparticles in the superconducting state of high-Tc metals

International Nuclear Information System (INIS)

Amusia, M.Ya.; Shaginyan, V.R.

2003-01-01

The behavior of quasiparticles in the superconducting state of high-T c metals within the framework of the theory of superconducting state based on the fermion condensation quantum phase transition is considered. It is shown that the behavior coincides with the behavior of Bogoliubov quasiparticles, whereas the maximum value of the superconducting gap and other exotic properties are determined by the presence of the fermion condensate. If at low temperatures the normal state is recovered by the application of a magnetic field suppressing the superconductivity, the induced state can be viewed as Landau-Fermi liquid. These observations are in good agreement with recent experimental facts [ru

Experimental study of gas-cooled current leads for superconducting magnets

International Nuclear Information System (INIS)

Warren, R.P.

1978-04-01

Design details and experimental test results from several design variations of the gas-cooled, copper current leads used in conjunction with the superconducting dipole magnets for ESCAR (Experimental Superconducting Accelerator Ring) are reported. Thermal acoustic oscillations, which were experienced with an initial design, were eliminated in subsequent designs by a reduction of the hydraulic diameter. The occurrence of these oscillations is in general agreement with the stability analysis of Rott but the observed gas flow dependence is not in agreement with some other recently reported results for leads operated supercritical phase coolant. An empirically determined correlation was obtained by plotting lead resistance vs. enthalpy gain of the coolant gas. The resulting family of curves can be reduced to a single line on a plot of effective resistivity vs. the product of current and cross-sectional area divided by the product of the square of the mass flow of the coolant and the lead length. This correlation, which should be applicable to other designs of copper current leads in which ideal heat transfer to the coolant gas is approached, predicts that the enthalpy gain of the coolant, and therefore the peak lead temperature, is proportional to the cube of the ratio of current to coolant mass flow. The effective value of the strongly temperature-dependent kinematic viscosity of the coolant gas was found to vary linearly with the effective resistivity of the lead

Misfit dislocations and phase transformations in high-T sub c superconducting films

CERN Document Server

Gutkin, M Y

2002-01-01

A theoretical model is suggested that describes the effects of misfit stresses on defect structures, phase content and critical transition temperature T sub c in high-T sub c superconducting films. The focus is placed on the exemplary case of YBaCuO films deposited onto LaSrAlO sub 4 substrates. It is theoretically revealed here that misfit stresses are capable of inducing phase transformations controlled by the generation of misfit dislocations in growing cuprate films. These transformations, in the framework of the suggested model, account for experimental data on the influence of the film thickness on phase content and critical temperature T sub c of superconducting cuprate films, reported in the literature. The potential role of stress-assisted phase transformations in suppression of critical current density across grain boundaries in high-T sub c superconductors is briefly discussed.

Current status of high-T{sub c} wire

Energy Technology Data Exchange (ETDEWEB)

Vase, Per [Nordic Superconductor Technologies A/S, Priorparken 685, DK 2605 Broendby (Denmark); Fluekiger, Rene [Departement de Physique de la Matiere Condensee, Universite de Geneve (Switzerland); Leghissa, Martino [Siemens AG, Corporate Technology, Erlangen (Germany); Glowacki, Bartek [Department of Material Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

2000-07-01

This paper is the result of the work of a SCENET (The European Network for Superconductivity) material working group's efforts on giving values for present and future expected performance of high-temperature superconducting (HTS) wires and tapes. The purpose of the work is to give input to the design of HTS applications like power cables, motors, current leads, magnets, transformers and generators. The current status performance values are supposed to be used in the design of today's prototypes and the future values for the design of fully commercial HTS applications of the future. We focus on what is expected to be the relevant parameters for HTS application design. The most successful technique by far for making HTS tapes has been on the (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) material by the powder-in-tube (PIT) technique and this paper therefore focuses on giving the current status and expected future performance for Bi-2223 tapes. (author)

Superconductivity

CERN Document Server

Thomas, D B

1974-01-01

A short general review is presented of the progress made in applied superconductivity as a result of work performed in connection with the high-energy physics program in Europe. The phenomenon of superconductivity and properties of superconductors of Types I and II are outlined. The main body of the paper deals with the development of niobium-titanium superconducting magnets and of radio-frequency superconducting cavities and accelerating structures. Examples of applications in and for high-energy physics experiments are given, including the large superconducting magnet for the Big European Bubble Chamber, prototype synchrotron magnets for the Super Proton Synchrotron, superconducting d.c. beam line magnets, and superconducting RF cavities for use in various laboratories. (0 refs).

Current leads for superconducting solenoids in a transportable Dewar flask for currents up to 1kA

International Nuclear Information System (INIS)

Shirshov, L.S.

1981-01-01

A simple design of the current lead for currents up to 1 kA into a transportable helium dewar with 22 mm neck diameter is described. The lead characteristics have been studied at various conditions. Examples of pulse superconducting solenoid usage, parmitting to achieve the magnetic field up to 3.3 T are given. The 1% field homogeneity has been obtained on a length of 90 mm [ru

High-frequency properties of superconducting Y-Ba-Cu-oxide thin films

International Nuclear Information System (INIS)

Ramakrishnan, E.S.; Su, M.; Howng, W.

1992-01-01

rf and microwave properties of superconducting YBa 2 Cu 3 O 7-x thin films were measured and analyzed using a coplanar resonator structure. The films were developed by sequential electron-beam evaporation of the metals followed by postanneal processing. dc properties of the films were obtained from resistance-temperature and current-voltage measurements to evaluate the transition temperature and current densities. High-frequency properties were measured from 70 to 10 K and in the frequency range 1--3 GHz to determine the film characteristics as compared to pure copper films on the same substrates

The quest for high-gradient superconducting cavities

International Nuclear Information System (INIS)

Padamsee, H.

1999-01-01

Superconducting RF cavities excel in applications requiring continuous waves or long pulse voltages. Since power losses in the walls of the cavity increase as the square of the accelerating voltage, copper cavities become uneconomical as demand for high continuous wave voltage grows with particle energy. For these reasons, RF superconductivity has become an important technology for high energy and high luminosity accelerators. The state of art in performance of sheet metal niobium cavities is best represented by the statistics of more than 300 5-cell, 1.5-GHz cavities built for CEBAF. Key aspects responsible for the outstanding performance of the CEBAF cavities set are the anti-multipactor, elliptical cell shape, good fabrication and welding techniques, high thermal conductivity niobium, and clean surface preparation. On average, field emission starts at the electric field of 8.7 MV/m, but there is a large spread, even though the cavities received nominally the same surface treatment and assembly procedures. In some cavities, field emission was detected as low as 3 MV/m. In others, it was found to be as high as 19 MV/m. As we will discuss, the reason for the large spread in the gradients is the large spread in emitter characteristics and the random occurrence of emitters on the surface. One important phenomenon that limits the achievable RF magnetic field is thermal breakdown of superconductivity, originating at sub-millimeter-size regions of high RF loss, called defects. Simulation reveal that if the defect is a normal conducting region of 200 mm radius, it will break down at 5 MV/m. Producing high gradients and high Q in superconducting cavities demands excellent control of material properties and surface cleanliness. The spread in gradients that arises from the random occurrence of defects and emitters must be reduced. It will be important to improve installation procedures to preserve the excellent gradients now obtained in laboratory test in vertical cryostats

A study on metastable superconducting magnets

International Nuclear Information System (INIS)

Koyama, Kenichi

1976-01-01

It is important to construct superconducting magnets as cheap as possible. One of the methods to achieve such a purpose is to save the superconducting material and operate the magnets at a high current density. Therefore it is useful to investigate the requirements for the operation of metastable superconducting magnets which can work at a current higher than the recovery current. Using the theory of flux jump, we introduce a ''stable current'' below which no flux jump can occur. On a rough approximation, it is given by I sub(s) =√A P sub(i) H sub(e) T sub(o) f(x)/rho where A : cross-section of the composite conductor. P sub(i) : total perimeter of all the superconducting cores. h sub(e) : effective heat transfer coefficient to the liquid helium through the stabilizer. T sub(o) : a characteristic temperature of the superconducting cores. f(x) : a characteristic function for the relative core radius x. rho : effective resistivity of the composite. Then it is shown that superconducting magnets can operate without unexpected normal transitions in the region enclosed by the two curves of I sub(s) and I sub(c). Next, we discuss the characteristics of our saddle shaped superconducting magnet for an one-KW MHD generator. We found that, 1) the magnet does safely operate in the metastable state; 2) the characteristics of the magnet are consistent with our theoretical results. (auth.)

The impact of high temperature superconductivity on the electric power sector

International Nuclear Information System (INIS)

Wolsky, A.M.

1996-01-01

The progress and prospects for the application of high temperature superconductivity to the Electric Power Sector has been the topic of an IEA Implementing Agreement, begun in 1990. The present Task Members are Canada, Denmark, Finland, Germany, Israel, Italy, Japan, Netherlands, Norway, Sweden, Switzerland, Turkey, United Kingdom and the United States. As a result of the Implementing Agreement, work has been done by the Operating Agent with the full participation of all the member countries. This work has facilitated the exchange of information among experts in all countries and has documented relevant assessments. Further, this work has examined the status of high amperage conductor, fault-current limiters, superconducting magnetic energy storage, cables, rotating machines, refrigeration, and studies of the power system. The Task Members find more progress toward applications than many expected five years ago and the grounds for further international collaboration to hasten the use of superconductors in the power sector, early in the 21st century

Thermal studies of a superconducting current limiter using Monte-Carlo method

Science.gov (United States)

Lévêque, J.; Rezzoug, A.

1999-07-01

Considering the increase of the fault current level in electrical network, the current limiters become very interesting. The superconducting limiters are based on the quasi-instantaneous intrinsic transition from superconducting state to normal resistive one. Without detection of default or given order, they reduce the constraints supported by electrical installations above the fault. To avoid the destruction of the superconducting coil, the temperature must not exceed a certain value. Therefore the design of a superconducting coil needs the simultaneous resolution of an electrical equation and a thermal one. This papers deals with a resolution of this coupled problem by the method of Monte-Carlo. This method allows us to calculate the evolution of the resistance of the coil as well as the current of limitation. Experimental results are compared with theoretical ones. L'augmentation des courants de défaut dans les grands réseaux électriques ravive l'intérêt pour les limiteurs de courant. Les limiteurs supraconducteurs de courants peuvent limiter quasi-instantanément, sans donneur d'ordre ni détection de défaut, les courants de court-circuit réduisant ainsi les contraintes supportées par les installations électriques situées en amont du défaut. La limitation s'accompagne nécessairement de la transition du supraconducteur par dépassement de son courant critique. Pour éviter la destruction de la bobine supraconductrice la température ne doit pas excéder une certaine valeur. La conception d'une bobine supraconductrice exige donc la résolution simultanée d'une équation électrique et d'une équation thermique. Nous présentons une résolution de ce problème electrothermique par la méthode de Monte-Carlo. Cette méthode nous permet de calculer l'évolution de la résistance de la bobine et du courant de limitation. Des résultats expérimentaux sont comparés avec les résultats théoriques.

Superconductivity

International Nuclear Information System (INIS)

Palmieri, V.

1990-01-01

This paper reports on superconductivity the absence of electrical resistance has always fascinated the mind of researchers with a promise of applications unachievable by conventional technologies. Since its discovery superconductivity has been posing many questions and challenges to solid state physics, quantum mechanics, chemistry and material science. Simulations arrived to superconductivity from particle physics, astrophysic, electronics, electrical engineering and so on. In seventy-five years the original promises of superconductivity were going to become reality: a microscopical theory gave to superconductivity the cloth of the science and the level of technological advances was getting higher and higher. High field superconducting magnets became commercially available, superconducting electronic devices were invented, high field accelerating gradients were obtained in superconductive cavities and superconducting particle detectors were under study. Other improvements came in a quiet progression when a tornado brought a revolution in the field: new materials had been discovered and superconductivity, from being a phenomenon relegated to the liquid Helium temperatures, became achievable over the liquid Nitrogen temperature. All the physics and the technological implications under superconductivity have to be considered ab initio

Superconducting property measuring system by magnetization method

International Nuclear Information System (INIS)

Ikisawa, K.; Mori, T.; Takasu, N.

1988-01-01

Superconducting property measuring system (CMS-370B) for high temperature oxide superconductor has been developed. This system adopts magnetization measurement. The superconducting properties are able to be measured automatically and continuously changing the temperature and external magnetic field. The critical current density as a function of temperature and magnetic field of high temperature superconductor YBa 2 Cu 3 O 7-y (YBCO) has been measured. This paper reports how it was confirmed that this system having the high performance and the accuracy gave the significant contribution to the superconducting material development

System considerations for airborne, high power superconducting generators

International Nuclear Information System (INIS)

Southall, H.L.; Oberly, C.E.

1979-01-01

The design of rotating superconducting field windings in high power generators is greatly influenced by system considerations. Experience with two superconducting generators designed to produce 5 and 20 Mw resulted in a number of design restrictions. The design restrictions imposed by system considerations have not prevented low weight and high voltage power generation capability. The application of multifilament Nb;sub 3;Sn has permitted a large thermal margin to be designed into the rotating field winding. This margin permits the field winding to remain superconducting under severe system operational requirements. System considerations include: fast rotational startup, fast ramped magnetic fields, load induced transient fields and airborne cryogen logistics. Preliminary selection of a multifilament Nb;sub 3;Sn cable has resulted from these considerations. The cable will carry 864 amp at 8.5K and 6.8 Tesla. 10 refs

Superconductivity in Spain. Midas program

International Nuclear Information System (INIS)

Yndurain, F.

1996-01-01

The different activities in the field of applied superconductivity carried out in Spain under the auspices of the MIDAS program are reported. Applications using both low- and high-temperature superconductors are considered. In the low temperature superconductors case, the design and construction of a 1 mega joule SMES (Superconducting Magnetic Energy Storage) unit, as well as the fabrication of voltage and resistance standards, are reviewed. Developments involving the design and fabrication of an inductive current fault limited and mono- and multi-filamentary wires and tapes using high-temperature superconductors are discussed. Finally, the prospects for the application of superconductivity technology to electric power systems for the electric utilities is considered. (author)

The stability of high-Tc BSCCO/Ag superconducting microcomposites in water, some inorganic solutions and organic solvents

International Nuclear Information System (INIS)

Gao, W.; Chen, J.; Yang, C.O.; McNabb, D.; Sande, J. vander

1992-01-01

Bi(Pb)-Sr-Ca-Cu-O/Ag (BSCCO/Ag) superconducting microcomposites with zero-resistance temperatures from 102 to 108 K and critical current densities of ∝600 A/cm 2 at 77 K were produced by oxidation and annealling of metallic precursor alloys. The stabilities and degradation behavior of BSCCO/Ag specimens in various environments were studied by a combination of mass loss measurement, electrical transport measurement and microstructural observation. The environmental conditions used in the present work were moist air, distilled water, aqueous solutions of NaCl, NaOH and acetic acid, and organic solvents methanol and acetone. Although there is a general tendency toward a decrease in critical current density after a long exposure to most of the testing conditions, the specimens containing a high percent of Ag (≥70 wt.%) showed very little decrease in Tc and J c up to 200 days of exposure in moist air and distilled water, and up to 20 days in NaCl solution, methanol and acetone. It was found that the superconducting ''2223'' phase is stable in water, neutral solutions and the organic solvents, reacts very slowly with basic solutions, and dissolves rapidly in acidic solutions. Some non-superconducting Ca-rich oxides dissolve in water and neutral and basic solutions and therefore damage the connection of the superconducting grains in low-Ag containing specimens. The excellent stability of the BSCCO/Ag superconducting microcomposites containing high Ag provides an important advantage for their potential industrial application. (orig.)

Optimal design of superconducting fault detector for superconductor triggered fault current limiters

International Nuclear Information System (INIS)

Yim, S.-W.; Kim, H.-R.; Hyun, O.-B.; Sim, J.; Park, K.B.; Lee, B.W.

2008-01-01

We have designed and tested a superconducting fault detector (SFD) for a 22.9 kV superconductor triggered fault current limiters (STFCLs) using Au/YBCO thin films. The SFD is to detect a fault and commutate the current from the primary path to the secondary path of the STFCL. First, quench characteristics of the Au/YBCO thin films were investigated for various faults having different fault duration. The rated voltage of the Au/YBCO thin films was determined from the results, considering the stability of the Au/YBCO elements. Second, the recovery time to superconductivity after quench was measured in each fault case. In addition, the dependence of the recovery characteristics on numbers and dimension of Au/YBCO elements were investigated. Based on the results, a SFD was designed, fabricated and tested. The SFD successfully detected a fault current and carried out the line commutation. Its recovery time was confirmed to be less than 0.5 s, satisfying the reclosing scheme in the Korea Electric Power Corporation (KEPCO)'s power grid

Rated-voltage enhancement by fast-breaking of the fault current for a resistive superconducting fault current limiter component

International Nuclear Information System (INIS)

Park, C.-R.; Kim, M.-J.; Yu, S.-D.; Yim, S.-W.; Kim, H.-R.; Hyun, O.-B.

2010-01-01

Performance of a resistive superconducting fault current limiter (SFCL) component is usually limited by temperature rise associated with energy input by fault current application during a fault. Therefore, it is expected that short application of the fault current may enhance the power ratings of the component. This can be accomplished by a combination of a HTS component and a mechanical switch. The fast switch (FS) developed recently enables the fault duration to be as short as 1/2 cycle after a fault. Various second-generation (2G) high temperature superconductors (HTS) and YBCO thin films have been tested. The relation between the rated voltage V and the fault duration time t was found to be V 2 ∼ t -1 . Based upon the relation, we predict that when the FS break the fault current within 1/2 cycle after a fault, the amount of HTS components required to build an SFCL can be reduced by as much as about 60%, of that when breaking the fault current at three cycles.

Alternative designs of high-temperature superconducting synchronous generators

OpenAIRE

Goddard, K. F.; Lukasik, B.; Sykulski, J. K.

2010-01-01

This paper discusses the different possible designs of both cored and coreless superconducting synchronous generators using high-temperature superconducting (HTS) tapes, with particular reference to demonstrators built at the University of Southampton using BiSCCO conductors. An overview of the electromagnetic, thermal, and mechanical issues is provided, the advantages and drawbacks of particular designs are highlighted, the need for compromises is explained, and practical solutions are offer...

Superconducting coil manufacturing method for low current dc beam line magnets

International Nuclear Information System (INIS)

Satti, J.A.

1977-01-01

A method of manufacturing superconducting multipole coils for 40 to 50 kG dc beam line magnets with low current is described. Small coils were built and tested successfully to short sample characteristics. The coils did not train after the first cooldown. The coils are porous and well cooled to cope with mechanical instability and energy deposited in the coil from the beam particles. The coils are wound with insulated strand cable. The cable is shaped rectangularly for winding simplicity and good tolerances. After the coil is wound, the insulated strands are electrically connected in series. This reduces the operating current and, most important, improves the coil quench propagation due to heat conduction of one strand adjacent to the other. A well distributed quench allows the magnet energy to distribute more uniformly to the copper in the superconductor wire, giving self-protected coils. A one-meter long, 43 kG, 6-inch bore tube superconducting dipole is now being fabricated. The porous coil design and coil winding methods are discussed

Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

International Nuclear Information System (INIS)

Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X

2003-01-01

The current density J(ρ, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F SBM z exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E c (J/J c ) n and the material law B = μ 0 H. The magnetic levitation force F SBM z is dominated by the remnant current density J' 2 (ρ, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F SBM z . Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F SBM z

Spontaneous and persistent currents in superconductive and mesoscopic structures (Review)

Science.gov (United States)

Kulik, I. O.

2004-07-01

We briefly review aspects of superconductive persistent currents in Josephson junctions of the S/I/S, S/O/S and S/N/S types, focusing on the origin of jumps in the current versus phase dependences, and discuss in more detail the persistent and the "spontaneous" currents in Aharonov-Bohm mesoscopic and nanoscopic (macromolecular) structures. A fixed-number-of-electrons mesoscopic or macromolecular conducting ring is shown to be unstable against structural transformation removing spatial symmetry (in particular, azimuthal periodicity) of its electron-lattice Hamiltonian. In the case when the transformation is blocked by strong coupling to an external azimuthally symmetric environment, the system becomes bistable in its electronic configuration at a certain number of electrons. Under such a condition, the persistent current has a nonzero value even at an (almost) zero applied Aharonov-Bohm flux and results in very high magnetic susceptibility dM/dH at small nonzero fields, followed by an oscillatory dependence at larger fields. We tentatively assume that previously observed oscillatory magnetization in cyclic metallo-organic molecules by Gatteschi et al. can be attributed to persistent currents. If this proves correct, it may present an opportunity for (and, more generally, macromolecular cyclic structures may suggest the possibility of) engineering quantum computational tools based on the Aharonov-Bohm effect in ballistic nanostructures and macromolecular cyclic aggregates.

Experience of superconducting current feeders system of SST-1

International Nuclear Information System (INIS)

Gupta, N.C.; Garg, A.; Sonara, D.

2014-01-01

The superconducting current feeder system for SST-1 which has been installed and commissioned recently along with SST-1, felicitates to energize the SST-1. The CFS consists of ten pairs of 10,000 Ampere (A) rating helium vapor cooled conventional current leads, interconnecting Cu-SC joints, three numbers of cryo-compatible SC feeders ducts, current leads assembly chamber, hydraulic network and three numbers of joint boxes operated at different current rating to charge Toroidal Field and Poloidal Field coils separately. During the last three campaigns, it was possible to achieve a controlled cool down up to 4 K and showed its rated operational performance. Actively cooled liquid nitrogen shield showed temperature profile in the temperature range of 80-85K and the whole system was evacuated up to 6x10 -6 mbar. The measured LHe consumption rates from TF VCCL were 0.3 g/s and 0.35 g/s at zero current and 1 kA respectively. (author)

Superconducting toroidal field coil current densities for the TFCX

International Nuclear Information System (INIS)

Kalsi, S.S.; Hooper, R.J.

1985-04-01

A major goal of the Tokamak Fusion Core Experiment (TFCX) study was to minimize the size of the device and achieve lowest cost. Two key factors influencing the size of the device employing superconducting magnets are toroidal field (TF) winding current density and its nuclear heat load withstand capability. Lower winding current density requires larger radial build of the winding pack. Likewise, lower allowable nuclear heating in the winding requires larger shield thickness between the plasma and coil. In order to achieve a low-cost device, it is essential to maximize the winding's current density and nuclear heating withhstand capability. To meet the above objective, the TFCX design specification adopted as goals a nominal winding current density of 3500 A/cm 2 with 10-T peak field at the winding and peak nuclear heat load limits of 1 MW/cm 3 for the nominal design and 50 MW/cm 3 for an advanced design. This study developed justification for these current density and nuclear heat load limits

Imaging of current distributions in superconducting thin film structures; Abbildung von Stromverteilungen in supraleitenden Duennfilmstrukturen

Energy Technology Data Exchange (ETDEWEB)

Doenitz, D.

2006-10-31

Local analysis plays an important role in many fields of scientific research. However, imaging methods are not very common in the investigation of superconductors. For more than 20 years, Low Temperature Scanning Electron Microscopy (LTSEM) has been successfully used at the University of Tuebingen for studying of condensed matter phenomena, especially of superconductivity. In this thesis LTSEM was used for imaging current distributions in different superconducting thin film structures: - Imaging of current distributions in Josephson junctions with ferromagnetic interlayer, also known as SIFS junctions, showed inhomogeneous current transport over the junctions which directly led to an improvement in the fabrication process. An investigation of improved samples showed a very homogeneous current distribution without any trace of magnetic domains. Either such domains were not present or too small for imaging with the LTSEM. - An investigation of Nb/YBCO zigzag Josephson junctions yielded important information on signal formation in the LTSEM both for Josephson junctions in the short and in the long limit. Using a reference junction our signal formation model could be verified, thus confirming earlier results on short zigzag junctions. These results, which could be reproduced in this work, support the theory of d-wave symmetry in the superconducting order parameter of YBCO. Furthermore, investigations of the quasiparticle tunneling in the zigzag junctions showed the existence of Andreev bound states, which is another indication of the d-wave symmetry in YBCO. - The LTSEM study of Hot Electron Bolometers (HEB) allowed the first successful imaging of a stable 'Hot Spot', a self-heating region in HEB structures. Moreover, the electron beam was used to induce an - otherwise unstable - hot spot. Both investigations yielded information on the homogeneity of the samples. - An entirely new method of imaging the current distribution in superconducting interference

Current sharing effect on the current instability and allowable temperature rise of composite high-TC superconductors

International Nuclear Information System (INIS)

Romanovskii, V.R.; Watanabe, K.; Awaji, S.; Nishijima, G.; Takahashi, Ken-ichiro

2004-01-01

To understand the basic mechanisms of the thermal runaway phenomenon, the limiting margin of the current instability, which may spontaneously occur in composite high-T C superconductors like multifilament Bi-based wire or tape, is derived under DC magnetic field. The current sharing and allowable temperature rise effects were considered. A static zero-dimensional model was utilized to describe the basic formulae dealing with the peculiarities of the non-isothermal change of superconducting composite voltage-current characteristic. The boundary of allowable stable values of the temperature, electric field and current are derived analytically. It was shown that permissible values of the current and electric field might be higher than those determined by use of the standard critical current criterion. In consequence of this feature, the noticeable allowable temperature rise of the composite superconductor before its transition to the normal state may be seen. The criterion for complete thermal stability condition is written describing the state when temperature of the composite equals critical temperature of a superconductor and the transport current flows stably only in matrix. The performed analysis also proves the existence of value of the volume fraction of a superconductor in composite at which its current-carrying capacity has minimum. These peculiarities are due to the stable current redistribution between superconductor and stabilizing matrix. Therefore, the current sharing not only leads to the matrix/superconductor ratio effect on the stable operating characteristics of the composite high-T C superconductors but also becomes important in the adequate description of quench process in the high-T C superconducting magnets

High-T/sub c/ superconductor and its use in superconducting magnets

International Nuclear Information System (INIS)

Green, M.A.

1988-02-01

Many of the proposed uses for the high-T/sub c/ superconductor involve the creation of a magnetic field using superconducting coils. This report will assess what is known about the high-T/sub c/ superconductors and take a realistic look at their potential use in various kinds of superconducting magnets. Based on what is known about the high-T/sub c/ superconductors, one can make a ''wish list'' of things that will make such materials useful for magnets. Then, the following question is asked. If one had a high-T/sub c/ superconductor with the same properties as modern niobium-titanium superconductor, how would the superconductor work in a magnet environment? Finally, this report will show the potential impact of the ideal high-T/sub c/ superconductor on: 1) accelerator dipole and quadrupole magnets, 2) superconducting magnets for use in space, and 3) superconducting solenoids for magnetic resonance imaging. 78 refs., 11 tabs

Many-body problems in high temperature superconductivity

International Nuclear Information System (INIS)

Yu Lu.

1991-10-01

In this brief review the basic experimental facts about high T c superconductors are outlined. The superconducting properties of these superconductors are not very different from those of the ordinary superconductors. However, their normal state properties cannot be described by the standard Fermi liquid (FL) theory. Our current understanding of the strongly correlated models is summarized. In one dimension these systems behave like a ''Luttinger liquid'', very much distinct from the FL. In spite of the enormous efforts made in two-dimensional studies, the question of FL vs non-FL behaviour is still open. The numerical results as well as various approximation schemes are discussed. Both the single hole problem in a quantum antiferromagnet and finite doping regime are considered. (author). 104 refs, 9 figs

Insulation model of power lead for 66 kV class superconducting fault current limiter; Chodendo genryuki denryu rido yo zetsuen no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Sakai, M.; Fukuda, A.; Shimada, M.; Urata, M. [Toshiba Corp., Tokyo (Japan); Okuma, T.; Sato, Y.; Iwata, Y. [Tokyo Electric Power Co. Ink., Tokyo (Japan)

1999-06-07

We advance the development of high-temperature superconductivity current limiter using the normal conduction transition. Since the rated voltage is high with 66kV, we desire that solid insulation which consists of main insulating layer and multiple layers in semiconductive layer is conducted to the current lead which connects the ordinary temperature and very low temperature division. And, it is necessary to sufficiently decrease the void, since crack proof and dielectric strength lower, when large bubble exists in the main insulating layer. We use ethylene propylene rubber for the solid insulation of superconducting cable. Though filler has entered the EP-rubber, the formability lowers, when we put filler in, and the void becomes easy to be generated. Then, we produced the current lead insulation model using the EP-rubber without filler, and we carried out crack-resistant test and withstand voltage test. (NEDO)

Design of a low temperature superconducting coil to be applied to current regulators

International Nuclear Information System (INIS)

Garcia-Tabares, L.; Grau Carles, A

1998-05-01

We study the magnetic design and the cryogenic stability of a superconducting coil cooled with liquid helium, which works both in DC and AC modes. In DC mode, we obtain the maximum quench current; while in AC mode, we analyze Joule losses produced by the superconductor magnetization and the generation of eddy currents inside the copper matrix. (Author)

A study on the development of high Tc superconducting materials

International Nuclear Information System (INIS)

Won, Dong Yeon; Lee, Hee Gyoun; Kim, Chan Joong

1990-01-01

The microstructure, crystal structure and formation kinetics for the superconducting phases were studied in the lead-doped BiSrCaCuO system. The formation kinetics was also investigated in the samples with different Pb/Bi ratio and it was observed that the 30 % Pb addition is most perferable for the formation of the high T c phase. The formation of the high T c phase was delayed by the excessive addition of Pb. The lattice parameter (c) of the unit cell of both low T c and high T c phases increased with increasing Pb content. Superconducting thin film was sucessfully prepared by chemical vapor deposition (CVD). Film deposited on MgO substrate showed a T c , onset of 85 K and did not reach to zero resistivity down to 77 K. Superconducting 124 phase in Y-system, which is more stable than 123 phase at high temperature showed a T c , onser of 84 K. Additionally, 0.1 mole of Pb, Sn and Ca was substituted for yttrium in 124 phase, respectively. For Pb and Sn-subsituted specimens, 124 phase was formed and for Ca substituted specimen, 124 phase was not formed and revealed no superconductivity down to 77 K. For Sn-substituted specimens, 124 phase was formed but showed no superconductivity down to 77 K. (author)

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Science.gov (United States)

Gabovich, Alexander M.; Voitenko, Alexander I.

2016-10-01

The state of the art concerning tunnel measurements of energy gaps in cuprate oxides has been analyzed. A detailed review of the relevant literature is made, and original results calculated for the quasiparticle tunnel current J(V) between a metallic tip and a disordered d-wave superconductor partially gapped by charge density waves (CDWs) are reported, because it is this model of high-temperature superconductors that becomes popular owing to recent experiments in which CDWs were observed directly. The current was calculated suggesting the scatter of both the superconducting and CDW order parameters due to the samples' intrinsic inhomogeneity. It was shown that peculiarities in the current-voltage characteristics inherent to the case of homogeneous superconducting material are severely smeared, and the CDW-related features transform into experimentally observed peak-dip-hump structures. Theoretical results were used to fit data measured for YBa2Cu3O7-δ and Bi2Sr2CaCu2O8+δ. The fitting demonstrated a good qualitative agreement between the experiment and model calculations. The analysis of the energy gaps in high-Tc superconductors is important both per se and as a tool to uncover the nature of superconductivity in cuprates not elucidated so far despite of much theoretical effort and experimental progress.

Superconducting technology program Sandia 1996 annual report

International Nuclear Information System (INIS)

Roth, E.P.

1997-02-01

Sandia's Superconductivity Technology Program is a thallium-based high-temperature superconductor (HTS) research and development program consisting of efforts in powder synthesis and process development, open-system thick film conductor development, wire and tape fabrication, and HTS motor design. The objective of this work is to develop high-temperature superconducting conductors (wire and tape) capable of meeting requirements for high-power electrical devices of interest to industry. The research efforts currently underway are: (1) Process development and characterization of thallium-based high-temperature superconducting closed system wire and tape, (2) Investigation of the synthesis and processing of thallium-based thick films using two-zone processing, and (3) Cryogenic design of a 30K superconducting motor. This report outlines the research that has been performed during FY96 in each of these areas

Superconducting wires and methods of making thereof

Energy Technology Data Exchange (ETDEWEB)

Xu, Xingchen; Sumption, Michael D.; Peng, Xuan

2018-03-13

Disclosed herein are superconducting wires. The superconducting wires can comprise a metallic matrix and at least one continuous subelement embedded in the matrix. Each subelement can comprise a non-superconducting core, a superconducting layer coaxially disposed around the non-superconducting core, and a barrier layer coaxially disposed around the superconducting layer. The superconducting layer can comprise a plurality of Nb.sub.3Sn grains stabilized by metal oxide particulates disposed therein. The Nb.sub.3Sn grains can have an average grain size of from 5 nm to 90 nm (for example, from 15 nm to 30 nm). The superconducting wire can have a high-field critical current density (J.sub.c) of at least 5,000 A/mm.sup.2 at a temperature of 4.2 K in a magnetic field of 12 T. Also described are superconducting wire precursors that can be heat treated to prepare superconducting wires, as well as methods of making superconducting wires.

Magnetic levitation systems using a high-Tc superconducting bulk magnet

Energy Technology Data Exchange (ETDEWEB)

Ohsaki, Hiroyuki [Dept. of Electrical Engineering, Univ. of Tokyo (Japan); Kitahara, Hirotaka [Dept. of Electrical Engineering, Univ. of Tokyo (Japan); Masada, Eisuke [Dept. of Electrical Engineering, Univ. of Tokyo (Japan)

1996-12-31

Recent development of high-performance high-Tc bulk superconductors is making their application for electromagnetic force use feasible. We have studied electromagnetic levitation systems using high-Tc bulk superconducting material. In this paper, after an overview of superconducting magnetic levitation systems, with an emphasis on high-Tc bulk superconductor applications, experimental results of a high-Tc bulk EMS levitation and FEM analysis results of magnetic gradient levitation using bulk superconductor are described. Problems to be solved for their application are also discussed. (orig.)

Record high-average current from a high-brightness photoinjector

Energy Technology Data Exchange (ETDEWEB)

Dunham, Bruce; Barley, John; Bartnik, Adam; Bazarov, Ivan; Cultrera, Luca; Dobbins, John; Hoffstaetter, Georg; Johnson, Brent; Kaplan, Roger; Karkare, Siddharth; Kostroun, Vaclav; Li Yulin; Liepe, Matthias; Liu Xianghong; Loehl, Florian; Maxson, Jared; Quigley, Peter; Reilly, John; Rice, David; Sabol, Daniel [Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853 (United States); and others

2013-01-21

High-power, high-brightness electron beams are of interest for many applications, especially as drivers for free electron lasers and energy recovery linac light sources. For these particular applications, photoemission injectors are used in most cases, and the initial beam brightness from the injector sets a limit on the quality of the light generated at the end of the accelerator. At Cornell University, we have built such a high-power injector using a DC photoemission gun followed by a superconducting accelerating module. Recent results will be presented demonstrating record setting performance up to 65 mA average current with beam energies of 4-5 MeV.

Superconducting magnetic shielding apparatus and method

Science.gov (United States)

Clem, John R.; Clem, John R.

1983-01-01

Disclosed is a method and apparatus for providing magnetic shielding around a working volume. The apparatus includes a hollow elongated superconducting shell or cylinder having an elongated low magnetic pinning central portion, and two high magnetic pinning end regions. Transition portions of varying magnetic pinning properties are interposed between the central and end portions. The apparatus further includes a solenoid substantially coextensive with and overlying the superconducting cylinder, so as to be magnetically coupled therewith. The method includes the steps passing a longitudinally directed current through the superconducting cylinder so as to depin magnetic reservoirs trapped in the cylinder. Next, a circumferentially directed current is passed through the cylinder, while a longitudinally directed current is maintained. Depinned magnetic reservoirs are moved to the end portions of the cylinder, where they are trapped.

Superconducting magnetic shielding apparatus and method

Science.gov (United States)

Clem, J.R.

1982-07-09

Disclosed is a method and apparatus for providing magnetic shielding around a working volume. The apparatus includes a hollow elongated superconducting shell or cylinder having an elongated low magnetic pinning central portion, and two high magnetic pinning end regions. Transition portions of varying magnetic pinning properties are interposed between the central and end portions. The apparatus further includes a solenoid substantially coextensive with and overlying the superconducting cylinder, so as to be magnetically coupled therewith. The method includes the steps passing a longitudinally directed current through the superconducting cylinder so as to depin magnetic reservoirs trapped in the cylinder. Next, a circumferentially directed current is passed through the cylinder, while a longitudinally directed current is maintained. Depinned magnetic reservoirs are moved to the end portions of the cylinder, where they are trapped.

Review of progress in superconducting high-beta structures

International Nuclear Information System (INIS)

Sundelin, R.M.

1992-01-01

During the past two years, there has been substantial progress in superconducting high-beta cavities in a number of areas. Understanding of the Q-disease, which occurs when a cavity is held for prolonged periods near 100 K, has advanced, and techniques for mitigating this problem have improved. Progress has been made in the use of high peak power processing to suppress field emission. Cell geometries have improved to reduce the ratio of peak surface electric field to accelerating field, and trapped mode behavior has been found to permit use of nine cells for some applications. The operating experience base for cavities installed in accelerators has increased substantially, as has the performance experience base for industrially manufactured cavities, including both solid niobium and sputter-coated copper. Additional applications for superconducting cavities have been identified. Progress has been made toward the design and construction of a Tera-Electron-Volt Superconducting Linear Accelerator (TESLA) test bed. (author). 25 refs., 1 fig

Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

Energy Technology Data Exchange (ETDEWEB)

Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X [Department of Physics, Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871 (China)

2003-04-01

The current density J({rho}, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F{sup SBM}{sub z} exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E{sub c}(J/J{sub c}){sup n} and the material law B = {mu}{sub 0}H. The magnetic levitation force F{sup SBM}{sub z} is dominated by the remnant current density J'{sub 2}({rho}, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F{sup SBM}{sub z}. Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F{sup SBM}{sub z}.

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

High-Tc superconducting microbolometer for terahertz applications

Science.gov (United States)

Ulysse, C.; Gaugue, A.; Adam, A.; Kreisler, A. J.; Villégier, J.-C.; Thomassin, J.-L.

2002-05-01

Superconducting hot electron bolometer mixers are now a competitive alternative to Schottky diode mixers in the terahertz frequency range because of their ultra wideband (from millimeter waves to visible light), high conversion gain, and low intrinsic noise level. High Tc superconductor materials can be used to make hot electron bolometers and present some advantage in term of operating temperature and cooling. In this paper, we present first a model for the study of superconducting hot electron bolometers responsivity in direct detection mode, in order to establish a firm basis for the design of future THz mixers. Secondly, an original process to realize YBaCuO hot electron bolometer mixers will be described. Submicron YBaCuO superconducting structures are expitaxially sputter deposited on MgO substrates and patterned by using electron beam lithography in combination with optical lithography. Metal masks achieved by electron beam lithography are insuring a good bridge definition and protection during ion etching. Finally, detection experiments are being performed with a laser at 850 nm wavelength, in homodyne mode in order to prove the feasibility and potential performances of these devices.

Processing of flexible high-Tc superconducting wires

International Nuclear Information System (INIS)

Lee, B.I.; Modi, V.

1989-01-01

Wires superconducting at temperatures above 77 K are produced by using YBa 2 Cu 3 O 7 materials. Flexibility was obtained by support from prefabricated fibers or a metallic coating on the extruded YBa 2 Cu 3 O 7 wires. The microstructure, the T c and the critical current densities of the wires were determined. Processing variables and steps are described

High-temperature superconducting nanowires for photon detection

Energy Technology Data Exchange (ETDEWEB)

Arpaia, R. [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg (Sweden); CNR SPIN Institute – Superconductors, Innovative Materials and Devices, UOS–Napoli, I-80100 Napoli (Italy); Dipartimento di Fisica, Università degli Studi di Napoli ‘Federico II’, I-80125 Napoli (Italy); Ejrnaes, M. [CNR SPIN Institute – Superconductors, Innovative Materials and Devices, UOS–Napoli, I-80100 Napoli (Italy); Parlato, L. [CNR SPIN Institute – Superconductors, Innovative Materials and Devices, UOS–Napoli, I-80100 Napoli (Italy); Dipartimento di Fisica, Università degli Studi di Napoli ‘Federico II’, I-80125 Napoli (Italy); Tafuri, F. [CNR SPIN Institute – Superconductors, Innovative Materials and Devices, UOS–Napoli, I-80100 Napoli (Italy); Dipartimento di Ingegneria Industriale e dell’Informazione, Seconda Università di Napoli, I-81031 Aversa, CE (Italy); Cristiano, R. [CNR SPIN Institute – Superconductors, Innovative Materials and Devices, UOS–Napoli, I-80100 Napoli (Italy); Golubev, D. [Low Temperature Laboratory (OVLL), Aalto University School of Science, P.O. Box 13500, FI-00076 Aalto (Finland); Sobolewski, Roman, E-mail: roman.sobolewski@rochester.edu [Institute of Electron Technology, PL-02668 Warszawa (Poland); Department of Electrical and Computer Engineering and Laboratory for Laser Energetics, University of Rochester, NY 14627-0231 (United States); Bauch, T.; Lombardi, F. [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg (Sweden); and others

2015-02-15

Highlights: • Homogeneous YBCO nanowires have been fabricated for photon detection applications. • Serial-parallel nanowire configuration leads to a large detector active area. • The YBCO nanowires exhibit critical current densities up to 106 A/cm{sup 2}. • The devices have been excited using a 1550-nm wavelength, pulsed laser irradiation. • Photoresponse signals have been measured and analyzed from 4 K up to the device T{sub c}. - Abstract: The possible use of high-temperature superconductors (HTS) for realizing superconducting nanowire single-photon detectors is a challenging, but also promising, aim because of their ultrafast electron relaxation times and high operating temperatures. The state-of-the-art HTS nanowires with a 50-nm thickness and widths down to 130 nm have been fabricated and tested under a 1550-nm wavelength laser irradiation. Experimental results presenting both the amplitude and rise times of the photoresponse signals as a function of the normalized detector bias current, measured in a wide temperature range, are discussed. The presence of two distinct regimes in the photoresponse temperature dependence is clearly evidenced, indicating that there are two different response mechanisms responsible for the HTS photoresponse mechanisms.

Theory of high temperature superconductivity

International Nuclear Information System (INIS)

Srivastava, C.M.

1989-01-01

This paper develops a semi-empirical electronic band structure for a high T c superconductor like YBa 2 Cu 3 O 6 - δ . The author accounts for the electrical transport properties on the model based on the correlated electron transfer arising from the electron-phonon interaction. The momentum pairing leading to the superconducting phase amongst the mobile charge carriers is shown

High intensity neutrino source superconducting solenoid cyrostat design

Energy Technology Data Exchange (ETDEWEB)

Page, T.M.; Nicol, T.H.; Feher, S.; Terechkine, I.; Tompkins, J.; /Fermilab

2006-06-01

Fermi National Accelerator Laboratory (FNAL) is involved in the development of a 100 MeV superconducting linac. This linac is part of the High Intensity Neutrino Source (HINS) R&D Program. The initial beam acceleration in the front end section of the linac is achieved using room temperature spoke cavities, each of which is combined with a superconducting focusing solenoid. These solenoid magnets are cooled with liquid helium at 4.5K, operate at 250 A and have a maximum magnetic field strength of 7.5 T. The solenoid cryostat will house the helium vessel, suspension system, thermal shield, multilayer insulation, power leads, instrumentation, a vacuum vessel and cryogenic distribution lines. This paper discusses the requirements and detailed design of these superconducting solenoid cryostats.

High-temperature superconducting phase in rare earth alloys

International Nuclear Information System (INIS)

Vedyaev, A.V.; Molodykh, O.Eh.; Savchenko, M.A.; Stefanovich, A.V.

1984-01-01

A possibility of high-temperature superconducting phase existence in rare e arth alloys with aluminium: TbAl-NdAl is predicted. Such a phase is shown t o exist at t approximately 40 k, however its existence is possible only in a nar row temperature range and it might be metastable. A possibility of a supercondu cting phase occurrence in spin glass is studied. It is shown that the first kin d phase transition to superconducting state may first occur under definite condi tions in the system. But the phase in question will be a low-temperature one be cause of rather inefficient elctron-phonon interaction. Further temperature dec rease would lead to an appearance of magnetic order and to disappearance of the superconductivity

Application of High-Temperature Superconducting Thin-Film Devices to Electro-Optical and Electronic Warfare Systems

Science.gov (United States)

1990-02-01

superconducting dispersive (chirp) delay line. Bt currents (IB 1 and 1B 2) control states of write junctions (gates 1 and 2). (Counter) clockwise currents...Gavaler, and "S. A. Reihle, "Superconductive Convolver with June- A. I. Braginski, "Optical Response of Epitaxial Films tion Ring Nlixers," IELT Trans

Temperature dependence of the current to sustain a normal hotspot in superconducting microbridges

International Nuclear Information System (INIS)

Yamaguchi, Y.; Ishii, C.

1981-01-01

A modification of the boundary condition to determine the SN boundary in the hotspot model of superconducting microbridges is proposed and successfully applied to the interpretation of recent measurements of the hotspot-sustaining current by Mizuno and Aomine. It is shown that suppression of the order parameter due to the applied current gives rise to an additional temperature dependence of the hotspot-sustaining current in the extreme vicinity of the transition temperature. (orig.)

THE NIOBIUM-THORIUM EUTECTIC ALLOY AS A HIGH-FIELD, HIGH-CURRENT SUPERCONDUCTOR

Energy Technology Data Exchange (ETDEWEB)

Cline, H. E.; Rose, R. M.; Wulff, J.

1963-03-15

Niobium-thorium eutectic alloys having fine acicuiar microstructures were produced by fast cooling frorn a vacuum melt. Although the solidified material was normal, continuity between the superconducting niobium-rich phase, which was essentially pure niobium, was attained by plastic deformation at room temperature. The resulting wire was tested for critical current at 4.2 deg K, in transverse magnetic fields up to 82.5 kilogauss; at the highest field, critical current densities of slightly more than 10/sup 4/ amps per square centimeter were observed. The critical current density was independent of applied field from 20 kilogauss to the highest field used; the level of critical current density depended on diameter in a manner that suggested dependence on cold work. It was concluded that the cold work reduced the thickness of the needles of niobium below the superconducting penetration depth, and brought them sufficiently close together to allow the superconducting correlation to interconnect the niobium, in the manner suggested by Cooper; furthermore, the constant critical current region may possibly extend to considerably higher fields. (auth)

A conceptual design of high-temperature superconducting isochronous cyclotron magnet

International Nuclear Information System (INIS)

Jiao, F.; Tang, Y.; Li, J.; Ren, L.; Shi, J.

2011-01-01

A design of High-temperature superconducting (HTS) isochronous cyclotron magnet is proposed. The maximum magnetic field of cyclotron main magnet reaches 3 T. Laying the HTS coil aboard the magnetic pole will raise the availability of the magnetic Field. Super-iron structure can provide a high uniformity and high gradient magnetic field. Super-iron structure can raise the availability of the HTS materials. Along with the development of High-temperature superconducting (HTS) materials, the technology of HTS magnet is becoming increasingly important in the Cyclotron, which catches growing numbers of scholars' attentions. Based on the analysis of the problems met in the process of marrying superconducting materials with ferromagnetic materials, this article proposes a design of HTS isochronous cyclotron magnet. The process of optimization of magnet and the methods of realizing target parameters are introduced after taking finite element software as analyzing tools.

Study on lower hybrid current drive efficiency at high density towards long-pulse regimes in Experimental Advanced Superconducting Tokamak

International Nuclear Information System (INIS)

Li, M. H.; Ding, B. J.; Zhang, J. Z.; Gan, K. F.; Wang, H. Q.; Zhang, L.; Wei, W.; Li, Y. C.; Wu, Z. G.; Ma, W. D.; Jia, H.; Chen, M.; Yang, Y.; Feng, J. Q.; Wang, M.; Xu, H. D.; Shan, J. F.; Liu, F. K.; Peysson, Y.

2014-01-01

Significant progress on both L- and H-mode long-pulse discharges has been made recently in Experimental Advanced Superconducting Tokamak (EAST) with lower hybrid current drive (LHCD) [J. Li et al., Nature Phys. 9, 817 (2013) And B. N. Wan et al., Nucl. Fusion 53, 104006 (2013).]. In this paper, LHCD experiments at high density in L-mode plasmas have been investigated in order to explore possible methods of improving current drive (CD) efficiency, thus to extend the operational space in long-pulse and high performance plasma regime. It is observed that the normalized bremsstrahlung emission falls much more steeply than 1/n e-av (line-averaged density) above n e-av  = 2.2 × 10 19  m −3 indicating anomalous loss of CD efficiency. A large broadening of the operating line frequency (f = 2.45 GHz), measured by a radio frequency (RF) probe located outside the EAST vacuum vessel, is generally observed during high density cases, which is found to be one of the physical mechanisms resulting in the unfavorable CD efficiency. Collisional absorption of lower hybrid wave in the scrape off layer (SOL) may be another cause, but this assertion needs more experimental evidence and numerical analysis. It is found that plasmas with strong lithiation can improve CD efficiency largely, which should be benefited from the changes of edge parameters. In addition, several possible methods are proposed to recover good efficiency in future experiments for EAST

High power density superconducting motor for control applications

International Nuclear Information System (INIS)

Lopez, J; Granados, X; Lloberas, J; Torres, R; Grau, J; Maynou, R; Bosch, R

2008-01-01

A high dynamics superconducting low power motor for control applications has been considered for design. The rotor is cylindrical with machined bulks that generate the field by trapping flux in a four poles configuration. The toothless iron armature is wound by copper, acting iron only as magnetic screen. Details of the magnetic assembling, cryogenics and electrical supply conditioning will be reported. Improvements due to the use of a superconducting set are compared with performances of equivalent conventional motors

Proposal of 99.99%-aluminum/7N01-Aluminum clad beam tube for high energy booster of Superconducting Super Collider

International Nuclear Information System (INIS)

Ishimaru, Hajime

1994-01-01

Proposal of 99.99% pure aluminum/7N01 aluminum alloy clad beam tube for high energy booster in Superconducting Super Collider is described. This aluminum clad beam tube has many good performances, but a eddy current effect is large in superconducting magnet quench collapse. The quench test result for aluminum clad beam tube is basically no problem against magnet quench collapse. (author)

Superconducting fault current limiter using high-resistive YBCO tapes

Energy Technology Data Exchange (ETDEWEB)

Yazawa, T. [Power and Industrial System R and D Center, Toshiba Corporation, 2-4 Suehiro, Tsurumi, Yokohama 230-0045 (Japan)], E-mail: takashi.yazawa@toshiba.co.jp; Koyanagi, K.; Takahashi, M.; Ono, M.; Toba, K.; Takigami, H.; Urata, M. [Power and Industrial System R and D Center, Toshiba Corporation, 2-4 Suehiro, Tsurumi, Yokohama 230-0045 (Japan); Iijima, Y.; Saito, T. [Fujikura Ltd., 1-5-1 Kiba, Koto, Tokyo 135-0042 (Japan); Ameniya, N. [Yokohama National University, 79-1 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Shiohara, Y. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto, Tokyo 135-0062 (Japan)

2008-09-15

One of the programs in the Ministry of Economy and Trade and Industry (METI) project regarding R and D on YBCO conductor is to evaluate the applicability of the developed conductor toward several applications. This paper focuses on a fault current limiter (FCL) as one of the expected power applications. YBCO tape conductors with ion beam assisted deposition (IBAD) substrate are used in this work. In order to obtain high resistance of the conductor, which is preferable to an FCL, the thickness of the protecting layer made of silver was decreased as possible. Then high-resistive metal stabilizing layer is attached on the silver layer to improve stability. Obtaining the relevant current limiting performance on short sample experiments, model coils were developed to aim the 6.6 kV-class FCL. Short circuit experiments were implemented with a short circuit generator. The coil successfully restricted the short circuit current over 17 kA to about 700 A by the applied voltage of 3.8 kV, which is nominal phase-to-ground voltage. The experimental results show good agreement with computer analyses and show promising toward the application.

Spin dynamics in high-TC superconducting cuprates

International Nuclear Information System (INIS)

Bourges, Ph.

2003-07-01

This work is dedicated to the detailed investigations of the magnetic resonance peak in the superconducting state of cuprates. The existence of such a peak could be the signature of a mechanism linked to magnetism that could explain high critical temperature superconductivity. Inelastic neutron scattering is an adequate tool for the understanding of cuprate properties because it reveals magnetic fluctuations whose behaviour and variety depend strongly on temperature and on the level of doping. The last part of this work is dedicated to the study of spin dynamics in YBa 2 Cu 3 O 6+x system

Superconducting magnetic energy storage and superconducting self-supplied electromagnetic launcher

Science.gov (United States)

Ciceron, Jérémie; Badel, Arnaud; Tixador, Pascal

2017-10-01

Superconductors can be used to build energy storage systems called Superconducting Magnetic Energy Storage (SMES), which are promising as inductive pulse power source and suitable for powering electromagnetic launchers. The second generation of high critical temperature superconductors is called coated conductors or REBCO (Rare Earth Barium Copper Oxide) tapes. Their current carrying capability in high magnetic field and their thermal stability are expanding the SMES application field. The BOSSE (Bobine Supraconductrice pour le Stockage d'Energie) project aims to develop and to master the use of these superconducting tapes through two prototypes. The first one is a SMES with high energy density. Thanks to the performances of REBCO tapes, the volume energy and specific energy of existing SMES systems can be surpassed. A study has been undertaken to make the best use of the REBCO tapes and to determine the most adapted topology in order to reach our objective, which is to beat the world record of mass energy density for a superconducting coil. This objective is conflicting with the classical strategies of superconducting coil protection. A different protection approach is proposed. The second prototype of the BOSSE project is a small-scale demonstrator of a Superconducting Self-Supplied Electromagnetic Launcher (S3EL), in which a SMES is integrated around the launcher which benefits from the generated magnetic field to increase the thrust applied to the projectile. The S3EL principle and its design are presented. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

Superconductivity of high Tc Scientific revolution?

International Nuclear Information System (INIS)

Marquina, J.E.; Ridaura, R.; Gomez, R.; Marquina, V.; Alvarez, J.L.

1997-01-01

A short history of superconductivity, since its discovery by Bednorz and Muller to the development of new materials with high transition temperatures, is presented. Further evolvements are analyzed in terms of T.s. Kuhn conceptions expressed in his book. The Structure of Scientific Revolutions. (Author) 4 refs

Critical current measurement in superconducting rings using an automatic inductive technique

International Nuclear Information System (INIS)

Gonzalez-Jorge, H.; Linares, B.; Quelle, I.; Carballo, E.; Romani, L.; Domarco, G.

2007-01-01

A measurement technique was developed to identify the critical current of superconducting rings. It is based on the detection of the voltage on a secondary coil when the current induced in the superconductor by a primary one go beyond to the critical value. The technique uses a DC power supply to control the AC current circulating by the primary circuit. Such circuit mainly consists on an AC power supply which gives a constant AC voltage, a primary inducting coil and a control coil with iron core. The AC current circulating by this circuit is modified with the change in the impedance of the control coil due to the fact of the DC current supplied by the power supply in parallel with it

The high current bus-bars of the LHC from conception to manufacture

CERN Document Server

Belova, L; Perinet-Marquet, J-L; Urpin, C

2006-01-01

The main magnets of the LHC are series-connected electrically in different excitation circuits by means of superconducting bus-bars, carrying a maximum current of 13 kA. These superconducting bus-bars consist of a superconducting cable thermally and electrically coupled to a copper section all along length. The function of the copper section is essentially to provide an alternative path for the magnet current in case the superconducting cable loses its superconductivity and returns to normal state because of a transient system disturbance or normal zone propagation coming from the neighboring magnets. When a superconducting bus-bar quenches to normal state its temperature must always stay below a safe values of about 100 ° C while the copper is conducting. With regard to that, a quench signal is initiated, which in turn triggers the ramping down of the current from 13000 A to 0....

Modal bifurcation in a high-T{sub c} superconducting levitation system

Energy Technology Data Exchange (ETDEWEB)

Taguchi, D; Fujiwara, S; Sugiura, T, E-mail: sugiura@mech.keio.ac.jp [Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, kohoku-ku, Yokohama 223-8522 (Japan)

2011-05-15

This paper deals with modal bifurcation of a multi-degree-of-freedom high-T{sub c} superconducting levitation system. As modeling of large-scale high-T{sub c} superconducting levitation applications, where plural superconducting bulks are often used, it can be helpful to consider a system constituting of multiple oscillators magnetically coupled with each other. This paper investigates nonlinear dynamics of two permanent magnets levitated above high-T{sub c} superconducting bulks and placed between two fixed permanent magnets without contact. First, the nonlinear equations of motion of the levitated magnets were derived. Then the method of averaging was applied to them. It can be found from the obtained solutions that this nonlinear two degree-of-freedom system can have two asymmetric modes, in addition to a symmetric mode and an antisymmetric mode both of which also exist in the linearized system. One of the backbone curves in the frequency response shows a modal bifurcation where the two stable asymmetric modes mentioned above appear with destabilization of the antisymmetric mode, thus leading to modal localization. These analytical predictions have been confirmed in our numerical analysis and experiments of free vibration and forced vibration. These results, never predicted by linear analysis, can be important for application of high-T{sub c} superconducting levitation systems.

Superconductivity at high pressures

Energy Technology Data Exchange (ETDEWEB)

Brandt, N B; Ginzburg, N I

1969-07-01

Work published during the last 3 or 4 yrs concerning the effect of pressure on superconductivity is reviewed. Superconducting modifications of Si, Ge, Sb, Te, Se, P and Ce. Change of Fermi surface under pressure for nontransition metals. First experiments on the influence of pressure on the tunneling effect in superconductors provide new information on the nature of the change in phonon and electron energy spectra of metals under hydrostatic compression. 78 references.

Theory of superconductivity

International Nuclear Information System (INIS)

Crisan, M.

1988-01-01

This book discusses the most important aspects of the theory. The phenomenological model is followed by the microscopic theory of superconductivity, in which modern formalism of the many-body theory is used to treat most important problems such as superconducting alloys, coexistence of superconductivity with the magnetic order, and superconductivity in quasi-one-dimensional systems. It concludes with a discussion on models for exotic and high temperature superconductivity. Its main aim is to review, as complete as possible, the theory of superconductivity from classical models and methods up to the 1987 results on high temperature superconductivity. Contents: Phenomenological Theory of Superconductivity; Microscopic Theory of Superconductivity; Theory of Superconducting Alloys; Superconductors in a Magnetic Field; Superconductivity and Magnetic Order; Superconductivity in Quasi-One-Dimensional Systems; and Non-Conventional Superconductivity

Development of superconducting equipment for fusion device

International Nuclear Information System (INIS)

Konno, Masayuki; Ueda, Toshio; Hiue, Hisaaki; Ohgushi, Kouzou

1993-01-01

At Fuji Electric Co., Ltd., the development of superconductivity was started from 1960, and superconducting equipment for fusion device has been developed for ten years. The superconducting equipment, which is developed for fusion by Fuji Electric Co., Ltd., are able to be grouped in three categories which are current lead, superconducting coil and superconducting bus-line. The current lead is an electrical feeder between a superconducting coil and an electrical power supply. The rated current of developed current lead is 30kA at continuous use and 100kA at short time use respectively. The advanced disk type coil is developed for the toroidal field coil and some coils are developed for critical current measurement. Superconductor is applied to the superconducting bus-line between the superconducting coils and the current leads, and the bus-line is being developed for the Large Helical Device. This report describes an abstract of these equipment. (author)

Development of superconducting ship propulsion system

International Nuclear Information System (INIS)

Sakuraba, Junji; Mori, Hiroyuki; Hata, Fumiaki; Sotooka, Koukichi

1991-01-01

When we plan displacement-type monohull high speed vessels, it is difficult to get the hull form with the wave-making resistance minimum, because the stern shape is restricted by arrangement of propulsive machines and shafts. A small-sized and light-weight propulsive machines will reduce the limit to full form design. Superconducting technology will have capability of realizing the small-sized and light-weight propulsion motor. The superconducting electric propulsion system which is composed of superconducting propulsion motors and generators, seems to be an ideal propulsion system for future vehicles. We have constructed a 480 kW superconducting DC homopolar laboratory test motor for developing this propulsion system. The characteristic of this motor is that it has a superconducting field winding and a segmented armature drum. The superconducting field winding which operates in the persistent current mode, is cooled by a condensation heat exchanger and helium refigerating system built into the cryostat of the superconducting field winding. The operating parameters of this motor agreed well with the design parameters. Using the design concepts of this motor, we have conceptually designed a 150,000-200,000 PS superconducting electric propulsive system for a displacement-type monohull high speed ship. (author)

Testing of full size high current superconductors in SULTAN III

Science.gov (United States)

Blau, B.; Rohleder, I.; Vecsey, G.; Pasotti, G.; Ricci, M. V.; Sacchetti, N.; Bruzzone, P.; Katheder, H.; Mitchell, N.; Bessette, D.

1994-07-01

The high field test facility SULTAN III in operation at PSI/Switzerland tests full size industrial prototype superconductors for fusion applications such as ITER. The facility provides a background field of up to 11 T over a length of 58 cm. A 50 kA superconducting transformer works as a very low noise current source which allows a criterion of 0.1 mu V/cm to determine the superconducting to normal transition. Three 3.6 m long cable-in-conduit conductors based on both NbTi and Nb3Sn, developed by different manufacturers, suitable for the central solenoid and toroidal field coils of ITER, have been tested so far. This paper presents the results of extensive measurements of critical current and current sharing temperature of the Nb3Sn conductors in the 8 - 11 T range for temperatures between 4.5 K and 11 K. Voltage versus current curves have been analyzed with respect to the n value. The manufacturing of a high quality joint between two Nb3Sn conductors after heat treatment is reported, together with some measurements of the joint resistance.

Testing of full size high current superconductors in SULTAN III

International Nuclear Information System (INIS)

Blau, B.; Rohleder, I.; Vecsey, G.

1994-01-01

The high field test facility SULTAN III in operation at PSI/Switzerland tests full size industrial prototype superconductors for fusion applications such as ITER. The facility provides a background field of up to 11 T over a length of 58 cm. A 50 kA superconducting transformer works as a very low noise current source which allows a criterion of 0.1 μV/cm to determine the superconducting to normal transition. Three 3.6 m long cable-in-conduit conductors based on both NbTi and Nb 3 Sn, developed by different manufacturers, suitable for the central solenoid and toroidal field coils of ITER, have been tested so far. This paper presents the results of extensive measurements of critical current and current sharing temperature of the Nb 3 Sn conductors in the 8--11 T range for temperatures between 4.5 K and 11 K Voltage versus current curves have been analyzed with respect to the n value. The manufacturing of a high quality joint between two Nb 3 Sn conductors after heat treatment is reported, together with some measurements of the joint resistance

Development of high purity niobium material for superconducting cavities

International Nuclear Information System (INIS)

Umezawa, Hiroaki; Takeuchi, Koichi; Sakita, Kohei; Suzuki, Takafusa; Saito, Kenji; Noguchi, Shuichi.

1993-01-01

For the superconducting niobium cavities, issues of thermal quench and field emission have to be solved to achieve a high field gradient (>25MV/m) for TESLA (TeV Energy Superconducting Linear Accelerator). In order to overcome the quench, upgrading of thermal conductivity of niobium material at the low temperature is very important. On the reduction of the field emission not only dust particles but also defect, impurity and inhomogeneity should be considered. Therefore development of high purity niobium material is very important to solve these issues. This paper describes the our latest R and D for high purity niobium material. (author)

Microstructural and superconducting properties of high current metal-organic chemical vapor deposition YBa2Cu3O7-δ coated conductor wires

International Nuclear Information System (INIS)

Holesinger, T G; Maiorov, B; Ugurlu, O; Civale, L; Chen, Y; Xiong, X; Xie, Y; Selvamanickam, V

2009-01-01

Metal-organic chemical vapor deposition (MOCVD) on flexible, ion beam assisted deposition MgO templates has been used to produce high critical current density (J c ) (Y,Sm) 1 Ba 2 Cu 3 O y (REBCO) films suitable for use in producing practical high temperature superconducting (HTS) coated conductor wires. Thick films on tape were produced with sequential additions of 0.7 μm of REBCO via a reel-to-reel progression through a custom-designed MOCVD reactor. Multi-pass processing for thick film deposition is critically dependent upon minimizing surface secondary phase formation. Critical currents (I c s) of up to 600 A/cm width (t = 2.8 μm, J c = 2.6 MA cm -2 , 77 K, self-field) were obtained in short lengths of HTS wires. These high performance MOCVD films are characterized by closely spaced (Y,Sm) 2 O 3 nanoparticle layers that may be tilted relative to the film normal and REBCO orientation. Small shifts in the angular dependence of J c in low and intermediate applied magnetic fields can be associated with the tilted nanoparticle layers. Also present in these films were YCuO 2 nanoplates aligned with the YBCO matrix (short dimension perpendicular to the film normal), threading dislocations, and oriented composite defects (OCDs). The latter structures consist of single or multiple a-axis oriented grains coated on each side with insulating (Y,Sm) 2 O 3 or CuO. The OCDs formed a connected network of insulating phases by the end of the fourth pass. Subsequent attempts at adding additional layers did not increase I c . There is an inconsistency between the measured J c and the observed microstructural degradation that occurs with each additional layer, suggesting that previously deposited layers are improving with each repeated reactor pass. These dynamic changes suggest a role for post-processing to optimize superconducting properties of as-deposited films, addressing issues associated with reproducibility and manufacturing yield.

A high-power magnetically switched superconducting rectifier operating at 5 Hz

NARCIS (Netherlands)

Mulder, G.B.J.; Krooshoop, Hendrikus J.G.; Nijhuis, Arend; ten Kate, Herman H.J.; van de Klundert, L.J.M.

1987-01-01

Above a certain current level, the use of a superconducting rectifier as a cryogenic current source offers advantages compared to the use of a power supply at room temperature which requires large current feed-throughs into the cryostat. In some cases, the power of such a rectifier is immaterial,

Implementation of superconducting fault current limiter for flexible operation in the power substation

Energy Technology Data Exchange (ETDEWEB)

Song, Chong Suk, E-mail: chong_suk@korea.ac.kr [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of); Lee, Hansang [School of Railway and Electrical Engineering, Kyungil University, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-701 (Korea, Republic of); Cho, Yoon-sung [Department of Electric and Energy Engineering, Catholic University of Daegu, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-702 (Korea, Republic of); Suh, Jaewan [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of); Jang, Gilsoo, E-mail: gjang@korea.ac.kr [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of)

2014-09-15

Highlights: • The power load concentrated in load centers results in high levels of fault current. • This paper introduces a fault current reduction scheme using SFCLs in substations. • The SFCL is connected in parallel to the bus tie between the two busbars. • The fault current mitigation using SFCLs is verified through PSS/e simulations. - Abstract: The concentration of large-scale power loads located in the metropolitan areas have resulted in high fault current levels during a fault thereby requiring the substation to operate in the double busbar configuration mode. However, the double busbar configuration mode results in deterioration of power system reliability and unbalanced power flow in the adjacent transmission lines which may result in issues such as overloading of lines. This paper proposes the implementation of the superconducting fault current limiter (SFCL) to be installed between the two substation busbars for a more efficient and flexible operation of the substation enabling both single and double busbar configurations depending on the system conditions for guaranteeing power system reliability as well as fault current limitations. Case studies are being performed for the effectiveness of the SFCL installation and results are compared for the cases where the substation is operating in single and double busbar mode and with and without the installation of the SFCL for fault current mitigation.

Special features of the current-voltage characteristics of short superconducting bridges

International Nuclear Information System (INIS)

Zhilinskii, S.; Latyshev, Y.; Nad', F.

1981-01-01

A study was made of variable-thickness superconducting bridges made of tin and indium. The current-voltage characteristics were determined for these bridges as a function of their length and width. The characteristics exhibited a linear region as well as an inflection. The temperature of the appearance of such an inflection depended on the length of the bridge but was independent of the bridge material

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

International Nuclear Information System (INIS)

Cabovich, Alexander M.; Voitenko, Alexander I.

2016-01-01

The state of the art concerning tunnel measurements of energy gaps in cuprate oxides has been analyzed. A detailed review of the relevant literature is made, and original results calculated for the quasiparticle tunnel current J(V) between a metallic tip and a disordered d-wave superconductor partially gapped by charge density waves (CDWs) are reported, because it is this model of high-temperature superconductors that becomes popular owing to recent experiments in which CDWs were observed directly. The current was calculated suggesting the scatter of both the superconducting and CDW order parameters due to the samples intrinsic inhomogeneity. It was shown that peculiarities in the current-voltage characteristics inherent to the case of homogeneous super-conducting material are severely smeared, and the CDW-related features transform into experimentally observed peak-dip-hump structures. Theoretical results were used to fit data measured for YBa_2Cu_3O_7_-_d_e_l_t_a and Bi_2Sr_2CaCu_2O_8_+_d_e_l_t_a. The fitting demonstrated a good qualitative agreement between the experiment and model calculations. The analysis of the energy gaps in high-Tc superconductors is important both per se and as a tool to uncover the nature of superconductivity in cuprates not elucidated so far despite of much theoretical effort and experimental progress.

Anisotrophic currents and flux jumps in high-Tc superconducting films with self-organized arrays of planar defects

International Nuclear Information System (INIS)

Yurchenko, V.V.; Qviller, A.J.; Mozhaev, P.B.; Mozhaeva, J.E.; Hansen, J.B.; Jacobsen, C.S.; Kotelyanskii, I.M.; Pan, A.V.; Johansen, T.H.

2010-01-01

Regular arrays of planar defects with a period of a few nanometers can be introduced in superconducting YBa 2 Cu 3 O 7-δ (YBCO) thin films by depositing them on vicinal (also called miscut or tilted) substrates. This results in the anisotropy of critical currents flowing in the plane of the film. We present results of real-time magneto-optical imaging (MOI) of magnetic flux distribution and dynamics in a series of YBCO thin films deposited on NdGaO 3 substrates with different miscut angles θ. MOI allows reconstructing the current flow profiles. From the angle formed between domains with different directions of the current flow we determine the anisotropy parameter of the in-plane current, as well as its field and temperature dependences. The artificially introduced defects also have a dramatic effect on the dynamics of the flux propagation: for 10 o o the magnetic flux propagates along the easy channels intermittently, i.e. in a form of flux jumps. This behavior is indicative of thermo-magnetic instability in superconductors, but we argue that this effect can be of a different nature.

Are we getting to the point of understanding high-temperature superconductivity?

International Nuclear Information System (INIS)

Huebener, R.P.; Tsuei, C.C.; Newns, D.M.

1994-01-01

The model elaborated by van Hove allows a coherent explanation of various anomalies observed with the phenomenon of high-T c superconductivity, including the cause of T c reaching such a high value, or the materials behaving like marginal Fermi liquids. However, there remain other enigma to be solved before it will be possible to fully explain and understand high-T c superconductivity. (DG) [de

Determination of the inter- and intra-granular critical currents in superconducting YBa2Cu3O7 welds

International Nuclear Information System (INIS)

Bozzo, B; Iliescu, S; Bartolome, E; Palau, A; Granados, X; Puig, T; Obradors, X; Amoros, J; Carrera, M

2005-01-01

A method for determining simultaneously the inter- and intra-grain critical currents has been developed in welded YBa 2 Cu 3 O 7 (YBCO) ceramics by solving the Inverse Problem for local maps of the magnetic field in the remanent state. From that current distribution, the current density flowing through the superconducting weld as well as the current density circulating inside the grains can be deduced. The method is discussed and it is applied to several examples of YBCO/Ag/YBCO welds. The results obtained show that it is possible to obtain superconducting joints with a quality at the same level as that of the starting material

Forecasting of superconducting compounds

International Nuclear Information System (INIS)

Savitskii, E.M.; Gribulya, V.G.; Kiseleva, N.N.

1981-01-01

In forecasting new superconducting intermetallic compounds of the A15 and Mo 3 Se types most promising from the viewpoint of high critical temperature Tsub(c), high critical magnetic fields Hsub(c), and high critical currents and in estimating their transition temperature it is proposed to apply cybernetic methods of computer learning

Possibility of a high-T{sub c} superconducting bulk magnet for maglev trains in the future; Koonchodendo baruku jishaku no jikifujoshiki tetudo heno oyo kanosei

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, H. [Railway Technical Research Institute, Fundamental Research Division, Tokyo (Japan)

1999-11-25

Superconducting magnets made of high-T{sub c} superconductors are promising for industrial applications. It is well known that REBa{sub 2}Cu{sub 3}O{sub 7-x} superconductors prepared by melt processes have a high critical current density, J{sub c}, at 77K and high magnetic fields. The materials are very prospective for high magnetic field application as a superconducting permanent/bulk magnet with liquid-nitrogen refrigeration. LREBaCuO bulks, compared with REBaCuO bulks, exhibit a larger, J{sub c} in high magnetic fields and a much improved irreversibility field, H{sub irr}, at 77K. In this study, we discuss the possibility and trapped field properties of a superconducting bulk magnet, as well as the melt processing for bulk superconductors and their characteristic superconducting and mechanical properties. One of the applications is a superconducting bulk magnet for future magnetically levitated (Maglev) trains. (author)

Superconductivity

CERN Document Server

Poole, Charles P; Farach, Horacio A

1995-01-01

Superconductivity covers the nature of the phenomenon of superconductivity. The book discusses the fundamental principles of superconductivity; the essential features of the superconducting state-the phenomena of zero resistance and perfect diamagnetism; and the properties of the various classes of superconductors, including the organics, the buckministerfullerenes, and the precursors to the cuprates. The text also describes superconductivity from the viewpoint of thermodynamics and provides expressions for the free energy; the Ginzburg-Landau and BCS theories; and the structures of the high

Electron mean free path dependence of the critical currents and the pair-breaking limit in superconducting films

International Nuclear Information System (INIS)

Fedorov, N.; Rinderer, L.

1977-01-01

We have studied the current-induced breakdown of superconductivity in wide (100--980 μm) and thin (0.25--0.98 μm) films of tin. It is shown that the current at which the resistance of the sample begins to rise rapidly in the process of the destruction of superconductivity by a current can be fairly well associated with the theoretical value of the pair-breaking current in the Ginzburg-Landau phenomenological approach (I/sub c//sup G L/). This effect is observed over a rather wide temperature region (up to ΔTapprox.0.7 K), depending on the electron mean free path in the films. The values of the critical currents outside the above-mentioned region correlate qualitatively with those determined by inhomogeneities of the films as proposed by Larkin and Ovchinnikov

Pulse measurement of the hot spot current in a NbTiN superconducting filament

Science.gov (United States)

Harrabi, K.; Mekki, A.; Kunwar, S.; Maneval, J. P.

2018-02-01

We have studied the voltage response of superconducting NbTiN filaments to a step-pulse of over-critical current I > Ic. The current induces the destruction of the Cooper pairs and initiates different mechanisms of dissipation depending on the bath temperature T. For the sample investigated, and for T above a certain T*, not far from Tc, the resistance manifests itself in the form of a phase-slip center, which turns into a normal hot spot (HS) as the step-pulse is given larger amplitudes. However, at all temperatures below T*, the destruction of superconductivity still occurs at Ic(T), but leads directly to an ever-growing HS. By lowering the current amplitude during the pulse, one can produce a steady HS and thus define a threshold HS current Ih(T). That is achieved by combining two levels of current, the first and larger one to initiate an HS, the second one to search for constant voltage response. The double diagram of the functions Ic(T) and Ih(T) was plotted in the T-range Tc/2 < T < Tc, and their crossing found at T* = (8.07 ± 0.07) K.

Unresolved problems in superconductivity of CaC6

NARCIS (Netherlands)

Mazin, I.I.; Boen, L.; Dolgov, O.V.; Golubov, Alexandre Avraamovitch; Bachelet, G.B.; Giantomassi, M.; Andersen, O.K.

2007-01-01

We discuss the current status of the theory of the “high-temperature” superconductivity in intercalated graphites YbC6 and CaC6. We emphasize that while the general picture of conventional, phonon-driven superconductivity has already emerged and is generally accepted, there are still interesting

Simulation of an HTS Synchronous Superconducting Generator

DEFF Research Database (Denmark)

In this work we present a simulation of a synchronous generator with superconducting rotor windings. As many other electrical rotating machines, superconducting generators are exposed to ripple fields that could be produced from a wide variety of sources: short circuit, load change, etc. Unlike...... of heating losses a cumbersome task. Furthermore, the high aspect ratio of the superconducting materials involved adds a penalty in the time required to perform simulations. The chosen strategy for simulation is as follows: A mechanical torque signal together with an electric load is used to drive the finite...... element model of a synchronous generator where the current distribution in the rotor windings is assumed uniform. Then, a second finite element model for the superconducting material is linked to calculate the actual current distribution in the windings of the rotor. Finally, heating losses are computed...

Superconductivity

International Nuclear Information System (INIS)

Onnes, H.K.

1988-01-01

The author traces the development of superconductivity from 1911 to 1986. Some of the areas he explores are the Meissner Effect, theoretical developments, experimental developments, engineering achievements, research in superconducting magnets, and research in superconducting electronics. The article also mentions applications shown to be technically feasible, but not yet commercialized. High-temperature superconductivity may provide enough leverage to bring these applications to the marketplace

Quench propagation in High Temperature Superconducting materials integrated in high current leads

CERN Document Server

Milani, D

2001-01-01

High temperature superconductors (HTS) have been integrated in the high current leads for the Large Hadron Collider (LHC), under construction at CERN, in order to reduce the heat leak into the liquid helium bath due to the joule effect. The use of the HTS technology in the lower part of the current leads allowed to significantly reduce the heat charge on the cryogenic system. Hybrid current leads have been designed to fulfill the LHC requirements with respect to thermal load; several tests have been performed to study the lead behavior especially during a quench transient. Quench experiments have been performed at CERN on 13 kA prototypes to determine the adequate design and protection. In all the tests it is possible to know the temperature profile of the HTS only with the help of quench simulations that model the thermo-hydraulic processes during quench. The development of a theoretical model for the simulation allows reducing the number of test to perform and to scale the experimental result to other curre...

Spontaneous and persistent currents in superconductive and mesoscopic structures (Review Article)

International Nuclear Information System (INIS)

Kulik, I.O.

2004-01-01

We briefly review aspects of superconductive persistent currents in Josephson junctions of the S/I/S, S/O/S and S/N/S types, focusing on the origin of jumps in the current versus phase dependences, and discuss in more detail the persistent as well as 'spontaneous' currents in the Aharonov-Bohm mesoscopic and nanoscopic (macromolecular) structures. A fixed-number-of-electrons mesoscopic or macromolecular conducting ring is shown to be unstable against structural transformation removing spatial symmetry (in particular, azimuthal periodicity) of its electron- lattice Hamiltonian. In case when the transformation is blocked by strong coupling to an external azimuthally symmetric environment, the system becomes bistable in its electronic configuration at certain number of electrons. At such a condition, the persistent current has a nonzero value even at the (almost) zero applied Aharonov-Bohm flux, and results in very high magnetic susceptibility dM/dH at small nonzero fields, followed by an oscillatory dependence at larger fields. We tentatively assume that previously observed oscillatory magnetization in cyclic metallo-organic molecules by Gatteschi et al. can be attributed to persistent currents. If this proves correct, it may open an opportunity (and, more generally, macromolecular cyclic structures may suggest the possibility) of engineering quantum computational tools based on the Aharonov-Bohm effect in ballistic nanostructures and macromolecular cyclic aggregates

Raman scattering and luminescence of high-Tc superconducting oxides

International Nuclear Information System (INIS)

Eremenko, V.V.; Gnezdilov, V.P.; Fomin, V.I.; Fugol', I.Ya.; Samovarov, V.N.

1989-01-01

Raman and luminescence spectra of high-T c superconducting oxides are summarized, mainly YBa 2 Cu 3 O 7-σ and partly La 2-x Ba x CuO 4-σ . In raman spectra we succeeded to distinguish electron scattering to define the energy gap Δ in the superconducting state. The luminescence spectra are due to the emission of oxygen and interaction with conduction electrons. 70 refs.; 13 figs

Loss and Inductance Investigation in Superconducting Cable Conductors

DEFF Research Database (Denmark)

Olsen, Søren Krüger; Tønnesen, Ole; Træholt, Chresten

1999-01-01

An important parameter in the design and optimization of a superconducting cable conductor is the control of the current distribution among single tapes and layers. This distribution is to a large degree determined by inductances, since the resistances are low. The self and mutual inductances...... of transport current and current distribution.This presentation is based on a number of experiments performed on prototype superconducting cable conductors. The critical current (1uV/cm) of the conductor at 77K was 1590 A (cable #1) and 3240 A (cable #2) respectively.At an rms current of 2 kA (50 Hz) the AC......-loss was measured on cable #2 to 0.6W/mxphase. This is, to our knowledge, the lowest AC-loss (at 2kA and 77K) of a high temperature superconducting cable conductor reported so far....

An investigation into preparation of silver sheathed superconducting wires with a high critical temperature

International Nuclear Information System (INIS)

Chaffron, Laurent

1992-01-01

We have shown that the critical current density of YBaCuO superconducting wires prepared using 'powder in tube' method is limited by the following principal factors: - cracks and porosity arising from the shrinkage of the powder during sintering, - irregularities in the wire section, - presence of secondary phases in the phase diagram of the three oxides, - incomplete re-oxidation at the centre of the wire, - insufficient, or complete lack of, texture in the wire, - presence of amorphous, non superconducting phase across the grains that blocks grain boundary migration. We have reduced the deleterious effects due to the first four factors by modifying prior nature of the powder, by reinforcing the sheath and by modifying the thermal treatments. We also used creep sintering to produce a strong texture; however, our study shows that texture, though necessary, is not a sufficient condition for a high current. This is because the latter is limited by the presence of the amorphous phase at too many grain boundaries. Finally, we have obtained wires in which grain boundaries are clean and which have very high critical currents by melting the wire in a thermal gradient and by passing it through the gradient very slowly. Such a technique, however, is too slow for producing superconductors. (author) [fr

High field septum magnet using a superconducting shield for the Future Circular Collider

Directory of Open Access Journals (Sweden)

Dániel Barna

2017-04-01

Full Text Available A zero-field cooled superconducting shield is proposed to realize a high-field (3–4 T septum magnet for the Future Circular Collider hadron-hadron (FCC-hh ring. Three planned prototypes using different materials and technical solutions are presented, which will be used to evaluate the feasibility of this idea as a part of the FCC study. The numerical simulation methods are described to calculate the field patterns around such a shield. A specific excitation current configuration is presented that maintains a fairly homogeneous field outside of a rectangular shield in a wide range of field levels from 0 to 3 Tesla. It is shown that a massless septum configuration (with an opening in the shield is also possible and gives satisfactory field quality with realistic superconducting material properties.

High field septum magnet using a superconducting shield for the Future Circular Collider

CERN Document Server

AUTHOR|(CDS)2069375

2017-01-01

A zero-field cooled superconducting shield is proposed to realize a high-field (3–4 T) septum magnet for the Future Circular Collider hadron-hadron (FCC-hh) ring. Three planned prototypes using different materials and technical solutions are presented, which will be used to evaluate the feasibility of this idea as a part of the FCC study. The numerical simulation methods are described to calculate the field patterns around such a shield. A specific excitation current configuration is presented that maintains a fairly homogeneous field outside of a rectangular shield in a wide range of field levels from 0 to 3 Tesla. It is shown that a massless septum configuration (with an opening in the shield) is also possible and gives satisfactory field quality with realistic superconducting material properties.

FY 2000 research and development of fundamental technologies for AC superconducting power devices. R and D of fundamental technologies for superconducting power cables and faults current limiters, R and D of superconducting magnets for power applications, and study on the total systems and related subjects; 2000 nendo koryu chodendo denryoku kiki kiban gijutsu kenkyu kaihatsu seika hokokusho. Chodendo soden cable kiban gijutsu no kenkyu kaihatsu, chodendo genryuki kiban gijutsu no kenkyu kaihatsu, denryokuyo chodendo magnet no kenkyu kaihatsu, total system nado no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

The project for research and development of fundamental technologies for AC superconducting power devices has been started, and the FY 2000 results are reported. The R and D of fundamental technologies for superconducting power cables include grasping the mechanical characteristics associated with integration necessary for fabrication of large current capacity and long cables; development of barrier cable materials by various methods; and development of short insulated tubes as cooling technology for long superconducting cables, and grasping its thermal/mechanical characteristics. The R and D of faults current limiters include introduction of the unit for superconducting film fabrication, determination of the structures and layouts for large currents, and improvement of performance of each device for high voltages. R and D of superconducting magnets for power applications include grasping the fundamental characteristics of insulation at cryogenic temperature, completion of the insulation designs for high voltage/current lead bushing, and development of prototype sub-cooled nitrogen cooling unit for cooling each AC power device. Study on the total systems and related subjects include analysis for stabilization of the group model systems, to confirm improved voltage stability when the superconducting cable is in service. (NEDO)

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

Basic Study of Superconductive Actuator

OpenAIRE

涌井, 和也; 荻原, 宏康

2000-01-01

There are two kinds of electromagnetic propulsion ships : a superconductive electromagnetic propulsion ship and a superconductive electricity propulsion ship. A superconductive electromagnetic propulsion ship uses the electromagnetic force (Lorenz force) by the interaction between a magnetic field and a electric current. On the other hand, a superconductive electricity propulsion ship uses screws driven by a superconductive motor. A superconductive propulsion ship technique has the merits of ...

Superconducting Technology Program: Sandia 1993 annual report

International Nuclear Information System (INIS)

Roth, E.P.

1994-05-01

Sandia's STP program is a four-part high-temperature superconductor (HTS) research and development program consisting of efforts in powder synthesis and process development, thallium-based HTS film development, wire and tape fabrication, and HTS motor design. The objective of this work is to develop high-temperature superconducting conductors (wire and tape) capable of meeting requirements for high-power electrical devices of interest to industry. The four research efforts currently underway are: (1) process research on the material synthesis of high-temperature superconductors; (2) investigation of the synthesis and processing of thallium-based high-temperature superconducting thick films; (3) process development and characterization of high-temperature superconducting wire and tape, and (4) cryogenic design of a high-temperature superconducting motor. This report outlines the research that has been performed during FY93 in each of these four areas. A brief background of each project is included to provide historical context and perspective. Major areas of research are described, although no attempt has been made to exhaustively include all work performed in each of these areas

MICROSTRUCTURE OF SUPERCONDUCTING MGB(2).

Energy Technology Data Exchange (ETDEWEB)

ZHU,Y.; LI,Q.; WU,L.; VOLKOV,V.; GU,G.; MOODENBAUGH,A.R.

2001-07-12

Recently, Akimitsu and co-workers [1] discovered superconductivity at 39 K in the intermetallic compound MgB{sub 2}. This discovery provides a new perspective on the mechanism for superconductivity. More specifically, it opens up possibilities for investigation of structure/properties in a new class of materials. With the exceptions of the cuprate and C{sub 60} families of compounds, MgB{sub 2} possesses the highest superconducting transition temperature T{sub c}. Its superconductivity appears to follow the BCS theory, apparently being mediated by electron-phonon coupling. The coherence length of MgB{sub 2} is reported to be longer than that of the cuprates [2]. In contrast to the cuprates, grain boundaries are strongly coupled and current density is determined by flux pinning [2,3]. Presently, samples of MgB{sub 2} commonly display inhomogeneity and porosity on the nanoscale, and are untextured. In spite of these obstacles, magnetization and transport measurements show that polycrystalline samples may carry large current densities circulating across many grains [3,4]. Very high values of critical current densities and critical fields have been recently observed in thin films [5,6]. These attributes suggest possible large scale and electronic applications. The underlying microstructure can be intriguing, both in terms of basic science and in applied areas. Subsequent to the discovery, many papers were published [1-13], most dealing with synthesis, physical properties, and theory. There have yet been few studies of microstructure and structural defects [11, 14]. A thorough understanding of practical superconducting properties can only be developed after an understanding of microstructure is gained. In this work we review transmission electron microscopy (TEM) studies of sintered MgB{sub 2} pellets [14]. Structural defects, including second phase particles, dislocations, stacking faults, and grain boundaries, are analyzed using electron diffraction, electron

Low-velocity superconducting accelerating structures

International Nuclear Information System (INIS)

Delayen, J.R.

1990-01-01

The present paper reviews the status of RF superconductivity as applied to low-velocity accelerating properties. Heavy-ion accelerators must accelerate efficiently particles which travel at a velocity much smaller than that of light particles, whose velocity changes along accelerator, and also different particles which have different velocity profiles. Heavy-ion superconducting accelerators operate at frequencies which are lower than high-energy superconducting accelerators. The present paper first discusses the basic features of heavy-ion superconducting structures and linacs. Design choices are then addressed focusing on structure geometry, materials, frequency, phase control, and focusing. The report also gives an outline of the status of superconducting booster projects currently under way at the Argonne National Laboratory, SUNY Stony Brook, Weizmann Institute, University of Washington, Florida State, Saclay, Kansas State, Daresbury, Japanese Atomic Energy Research Institute, Legnaro, Bombay, Sao Paulo, ANU (Canberra), and Munich. Recent developments and future prospects are also described. (N.K.) 68 refs

Overview of Superconductivity and Challenges in Applications

Science.gov (United States)

Flükiger, Rene

2012-01-01

Considerable progress has been achieved during the last few decades in the various fields of applied superconductivity, while the related low temperature technology has reached a high level. Magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) are so far the most successful applications, with tens of thousands of units worldwide, but high potential can also be recognized in the energy sector, with high energy cables, transformers, motors, generators for wind turbines, fault current limiters and devices for magnetic energy storage. A large number of magnet and cable prototypes have been constructed, showing in all cases high reliability. Large projects involving the construction of magnets, solenoids as well as dipoles and quadrupoles are described in the present book. A very large project, the LHC, is currently in operation, demonstrating that superconductivity is a reliable technology, even in a device of unprecedented high complexity. A project of similar complexity is ITER, a fusion device that is presently under construction. This article starts with a brief historical introduction to superconductivity as a phenomenon, and some fundamental properties necessary for the understanding of the technical behavior of superconductors are described. The introduction of superconductivity in the industrial cycle faces many challenges, first for the properties of the base elements, e.g. the wires, tapes and thin films, then for the various applied devices, where a number of new difficulties had to be resolved. A variety of industrial applications in energy, medicine and communications are briefly presented, showing how superconductivity is now entering the market.

Structured Cable for High-Current Coils of Tokamaks

Science.gov (United States)

Benson, Christopher; McIntyre, Peter; Sattarov, Akhdiyor; Mann, Thomas

2011-10-01

The 45 kA superconducting cable for the ITER central solenoid coil has yielded questionable results in two recent tests. In both cases the cable Tc increased after cycling only a fraction of the design life, indicating degradation due to fatigue and fracture among the superconducting strands. The Accelerator Research Lab at Texas A&M University is developing a design for a Nb3Sn structured cable suitable for such tokamak coils. The superconductor is configured in 6 sub-cables, and each subcable is supported within a channel of a central support structure within a high-strength armor sheath. The structured cable addresses two issues that are thought to compromise opposition at high current. The strands are supported without cross-overs (which produce stress concentration); and armor sheath and core structure bypass stress through the coil and among subcables so that the stress within each subcable is only what is produced directly upon it. Details of the design and plans for development will be presented.

Superconducting versus normal conducting cavities

CERN Document Server

Podlech, Holger

2013-01-01

One of the most important issues of high-power hadron linacs is the choice of technology with respect to superconducting or room-temperature operation. The favour for a specific technology depends on several parameters such as the beam energy, beam current, beam power and duty factor. This contribution gives an overview of the comparison between superconducting and normal conducting cavities. This includes basic radiofrequency (RF) parameters, design criteria, limitations, required RF and plug power as well as case studies.

Anomalous anisotropic compression behavior of superconducting CrAs under high pressure

Science.gov (United States)

Yu, Zhenhai; Wu, Wei; Hu, Qingyang; Zhao, Jinggeng; Li, Chunyu; Yang, Ke; Cheng, Jinguang; Luo, Jianlin; Wang, Lin; Mao, Ho-kwang

2015-01-01

CrAs was observed to possess the bulk superconductivity under high-pressure conditions. To understand the superconducting mechanism and explore the correlation between the structure and superconductivity, the high-pressure structural evolution of CrAs was investigated using the angle-dispersive X-ray diffraction (XRD) method. The structure of CrAs remains stable up to 1.8 GPa, whereas the lattice parameters exhibit anomalous compression behaviors. With increasing pressure, the lattice parameters a and c both demonstrate a nonmonotonic change, and the lattice parameter b undergoes a rapid contraction at ∼0.18−0.35 GPa, which suggests that a pressure-induced isostructural phase transition occurs in CrAs. Above the phase transition pressure, the axial compressibilities of CrAs present remarkable anisotropy. A schematic band model was used to address the anomalous compression behavior of CrAs. The present results shed light on the structural and related electronic responses to high pressure, which play a key role toward understanding the superconductivity of CrAs. PMID:26627230

Applied superconductivity

CERN Document Server

Newhouse, Vernon L

1975-01-01

Applied Superconductivity, Volume II, is part of a two-volume series on applied superconductivity. The first volume dealt with electronic applications and radiation detection, and contains a chapter on liquid helium refrigeration. The present volume discusses magnets, electromechanical applications, accelerators, and microwave and rf devices. The book opens with a chapter on high-field superconducting magnets, covering applications and magnet design. Subsequent chapters discuss superconductive machinery such as superconductive bearings and motors; rf superconducting devices; and future prospec

Current voltage characteristics of composite superconductors with high contact resistance

International Nuclear Information System (INIS)

Akhmetov, A.A.; Baev, V.P.

1984-01-01

An experimental study has been made of current-voltage characteristics of composite superconductors with contact resistance between superconducting filaments and normal metal with high electrical conductivity. It is shown that stable resistive states exist in such conductors over a wide range of currents. The presence of resistive states is interpreted in terms of the resistive domain concept. The minimum and maximum currents of resistive states are found to be dependent on the electrical resistance of normal metal and magnetic field. (author)

Study on a Highly Stabilized Power Supply for Hybrid-Magnet Superconducting Outsert

International Nuclear Information System (INIS)

Wu Jinglin; Long Jiaojiao; Liu Xiaoning

2014-01-01

The superconducting outsert of the 40 T hybrid-magnet in High Magnetic Field Laboratory (HMFL) of Chinese Academy of Sciences (CAS) requires a highly stabilized power supply. In this paper, two kinds of power supply design are briefly presented and both advantages and disadvantages are analyzed. In order to overcome the drawbacks of switching power supply, a series regulated active filter is adopted and a new design is proposed which ensures cooperative relationship between the feedback control loops of the switching converter and the series regulated active filter. Besides, unlike the traditional switching power supply, which can generate positive voltage only, this new design can also generate negative voltage which is needed in the quench protection for the superconducting magnet. In order to demonstrate the effectiveness of the methodology, a low-power prototype has been accomplished. The simulation and experiment results show that the power supply achieves high precision under the combined action of two feedback control loops. The peak-to-peak amplitude of the output ripple voltage of the prototype is 0.063%, while the peak-to-peak amplitude of the output ripple current is 120 ppm. (fusion engineering)

Alternating current loss characteristics in (bismuth,lead)SCCO and yttrium barium copper oxide superconducting tapes

Science.gov (United States)

Nguyen, Doan Ngoc

Alternating current (AC) loss and current carrying capacity are two of the most crucial considerations in large-scale power applications of high temperature superconducting (HTS) conductors. AC losses result in an increased thermal load for cooling machines, and thus increased operating costs. Furthermore, AC losses can stimulate quenching phenomena or at least decrease the stability margin for superconducting devices. Thus, understanding AC losses is essential for the development of HTS AC applications. The main focus of this dissertation is to make reliable total AC loss measurements and interpret the experimental results in a theoretical framework. With a specially designed magnet, advanced total AC loss measurement system in liquid nitrogen (77 K) has been successfully built. Both calorimetric and electromagnetic methods were employed to confirm the validity of the measured results and to have a more thorough understanding of AC loss in HTS conductors. The measurement is capable of measuring total AC loss in HTS tapes over a wide range of frequency and amplitude of transport current and magnetic field. An accurate phase control technique allows measurement of total AC loss with any phase difference between the transport current and magnetic field by calorimetric method. In addition, a novel total AC loss measurement system with variable temperatures from 30 K to 100 K was successfully built and tested. Understanding the dependence of AC losses on temperature will enable optimization of the operating temperature and design of HTS devices. As a part of the dissertation, numerical calculations using Brandt's model were developed to study electrodynamics and total AC loss in HTS conductors. In the calculations, the superconducting electrical behavior is assumed to follow a power-law model. In general, the practical properties of conductors, including field-dependence of critical current density Jc, n-value and non-uniform distribution of Jc, can be accounted for in

A review of basic phenomena and techniques for sputter-deposition of high temperature superconducting films

Energy Technology Data Exchange (ETDEWEB)

Auciello, O. (Microelectronics Center of North Carolina, Research Triangle Park, NC (USA) North Carolina State Univ., Raleigh, NC (USA). Dept. of Materials Science and Engineering); Ameen, M.S.; Kingon, A.I.; Lichtenwalner, D.J. (North Carolina State Univ., Raleigh, NC (USA). Dept. of Materials Science and Engineering); Krauss, A.R. (Argonne National Lab., IL (USA))

1990-01-01

The processes involved in plasma and ion beam sputter-deposition of high temperature superconducting thin films are critically reviewed. Recent advances in the development of these techniques are discussed in relation to basic physical phenomena, specific to each technique, which must be understood before high quality films can be produced. Control of film composition is a major issue in sputter-deposition of multicomponent materials. Low temperature processing of films is a common goal for each technique, particularly in relation to integrating high temperature superconducting films with the current microelectronics technology. It has been understood for some time that for Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} deposition, the most intensely studied high-{Tc} compound, incorporation of sufficient oxygen into the film during deposition is necessary to produce as-deposited superconducting films at relatively substrate temperatures. Recent results have shown that with the use of suitable buffer layers, high quality Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} sputtered films can be obtained on Si substrates without the need for post-deposition anneal processing. This review is mainly focussed on issues related to sputter-deposition of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} thin films, although representative results concerning the bismuth and thallium based compounds are included. 143 refs., 11 figs.

The vortex structure and flux creep within superconducting permanent-magnet high aspect-ratio discs

International Nuclear Information System (INIS)

Watson, J.H.P.; Younas, I.

1997-01-01

Inhomogeneous type II superconducting discs magnetized by an applied field will retain some magnetization when field is switched off so the superconducting disc will behave as a permanent magnet after flux creep has reduced to a low value.This paper examines the superconducting vortex structure within superconducting permanent-magnet high aspect-ratio discs which is consistent with the calculated magnetic field distribution.The discs, with radius R, have the axis along the z-direction and the mid-plane of the disc corresponds to z = 0. These discs with large aspect ratios in the remnant state have a region between radius r l and R where the magnetic field is reversed. Surrounding the line r = r l and z = 0 there is a region where H cl which is in the Meissner state. Near r l the vortex lines are strongly curved. For radii r l vortex lines creep to larger values of r. For radii r > r l vortex lines creep to smaller values of r, meet at r l with vortex lines of opposite sign and form a continuous loop which decreases in size and is finally annihilated in the Meissner region. Flux creep induces lossless currents in the Meissner region. (author)

Magnet field design considerations for a high energy superconducting cyclotron

International Nuclear Information System (INIS)

Botman, J.I.M.; Craddock, M.K.; Kost, C.J.; Richardson, J.R.

1983-08-01

This paper reports the pole shape designs for a two stage superconducting isochronous cyclotron combination (CANUCK) to accelerate 100 μA proton beams to 15 GeV. The pole shape of the 15 sectors of the first stage 3.5 GeV proton cyclotron provides isochronism over the full energy range and a constant axial tune over all but the lowest energies. Progress on the pole design of the 42 sector 15 GeV second stage is also reported. The magnetic fields are computed from the current distribution of the superconducting coils and the infinitely thin current sheets simulating the fully saturated poles. A least squares method is used to minimize deviations from isochronism by adjusting the size of various elemental shim coils placed around the main coil. The method to obtain the desired axial tune is described

Analysis of the electrodynamics of subcable current distribution in the superconducting POLO coil cable

International Nuclear Information System (INIS)

Sihler, C.; Heller, R.; Maurer, W.; Ulbricht, A.; Wuechner, F.

1995-10-01

Unexpected ramp rate limitations (RRL) found in superconducting magnets during the development of magnet systems can be attributed to a current imbalance amongst the cabled strands which leads to a lower than expected quench current. In superconducting magnets the current distribution in the cable during ramping depends mainly on the electromagnetic properties of the system. A detailed analysis of principle causes for RRL phenomena was performed with a model for one half of the POLO coil considering the complete inductance matrix of the cable and the fact that all turns are mutually coupled. The main results of these calculations are that unequal contact resistances can not be responsible for RRL phenomena in coils with parameters comparable to those of the POLO coil and that already minor geometrical disturbances in the cable structure can lead to major and lasting imbalances in the current distribution of cables with insulated and non-insulated strands. During the POLO experiment the half-coil model was employed to get a better understanding of the measured compensated subcable voltages during quench. The good agreement of the calculated and measured results demonstrates the validity of the model for RRL analyses. (orig.)

Superconducting critical-current densities of commercial multifilamentary Nb3Sn(Ti) wires made by the bronze process

International Nuclear Information System (INIS)

Suenaga, M.; Tsuchiya, K.; Higuchi, N.; Tachikawa, K.

1985-01-01

Superconducting critical-current densities Jsub(c) in fields up to 24 T and at 4.2 and 1.8 K were measured for a number of commercial Nb 3 Sn wires which were alloyed with Ti. The best values of Jsub(c) at 20 T and at 4.2 and 1.8 K were 78 and 156 A mm -2 , respectively. In order to achieve these high current densities at H>20 T, it was shown that nonuniformity of the filaments had to be minimized. It was also shown that the grain size of Nb 3 Sn is not very important in determining Jsub(c) at these high magnetic fields, and that achieving high values of critical magnetic field Hsub(c2) is more important than small grain size. (author)

A new wire fabrication processing using high Ga content Cu-Ga compound in V3Ga compound superconducting wire

International Nuclear Information System (INIS)

Hishinuma, Yoshimitsu; Nishimura, Arata; Kikuchi, Akihiro; Iijima, Yasuo; Takeuchi, Takao

2007-01-01

A superconducting magnet system is also one of the important components in an advanced magnetic confinement fusion reactor. Then it is required to have a higher magnetic field property to confine and maintain steady-sate burning deuterium (D)-tritium (T) fusion plasma in the large interspace during the long term operation. Burning plasma is sure to generate 14 MeV fusion neutrons during deuterium-tritium reaction, and fusion neutrons will be streamed and penetrated to superconducting magnet through large ports with damping neutron energy. Therefore, it is necessary to consider carefully not only superconducting property but also neutron irradiation property in superconducting materials for use in a future fusion reactor, and a 'low activation and high field superconducting magnet' will be required to realize the fusion power plant beyond International Thermonuclear Experimental Reactor (ITER). V-based superconducting material has a much shorter decay time of induced radioactivity compared with the Nb-based materials. We thought that the V 3 Ga compound was one of the most promising materials for the 'low activation and higher field superconductors' for an advanced fusion reactor. However, the present critical current density (J c ) property of V 3 Ga compound wire is insufficient for apply to fusion magnet applications. We investigated a new route PIT process using a high Ga content Cu-Ga compound in order to improve the superconducting property of the V 3 Ga compound wire. (author)

Vitaly Ginzburg and high temperature superconductivity: Personal reminiscences

International Nuclear Information System (INIS)

Mazin, Igor I.

2008-01-01

This article is an attempt to give Western readers, as well as young researchers in Russia, a glance at the atmosphere in one of the leading physics institutions in the USSR from 1977-1988, through the eye of a graduate student and later a posdoc in the theory group led by Vitaly Ginzburg, arguably the most enthusiatic proponent of high-temperature superconductivity before the discovery of Bednorz and Muller. This is a very personal narration, wherein the events of my own life and career are inevitably intertwined with scientific events and with my reminiscences of great Russian physicists whom I had the pleasure to meet with while working in the 'High-Temperature Superconductivity Section' at the Lebedev Institute within the aforementioned 12 years

Critical current density, irreversibility line, and flux creep activation energy in silver-sheathed Bi2Sr2Ca2Cu3Ox superconducting tapes

International Nuclear Information System (INIS)

Shi, D.; Wang, Z.; Sengupta, S.; Smith, M.; Goodrich, L.F.; Dou, S.X.; Liu, H.K.; Guo, Y.C.

1992-08-01

Transport data, magnetic hysteresis and flux creep activation energy experimental results are presented for silver-sheathed high-T c Bi 2 Sr 2 Ca 2 Cu 3 O x superconducting tapes. The 110 K superconducting phase was formed by lead doping in a Bi-Sr-Ca-Cu-0 system. The transport critical current density was measured at 4.0 K to be 0.7 x 10 5 A/cm 2 (the corresponding critical current is 74 A) at zero field and 1.6 x 10 4 A/cm 2 at 12 T for H parallel ab. Excellent grain alignment in the a-b plane was achieved by a short-melting method, which considerably improved the critical current density and irreversibility line. Flux creep activation energy as a function of current is obtained based on the magnetic relaxation measurements

Superconductivity

International Nuclear Information System (INIS)

Andersen, N.H.; Mortensen, K.

1988-12-01

This report contains lecture notes of the basic lectures presented at the 1st Topsoee Summer School on Superconductivity held at Risoe National Laboratory, June 20-24, 1988. The following lecture notes are included: L.M. Falicov: 'Superconductivity: Phenomenology', A. Bohr and O. Ulfbeck: 'Quantal structure of superconductivity. Gauge angle', G. Aeppli: 'Muons, neutrons and superconductivity', N.F. Pedersen: 'The Josephson junction', C. Michel: 'Physicochemistry of high-T c superconductors', C. Laverick and J.K. Hulm: 'Manufacturing and application of superconducting wires', J. Clarke: 'SQUID concepts and systems'. (orig.) With 10 tabs., 128 figs., 219 refs

Second international Israeli conference on High Tc Superconductivity

International Nuclear Information System (INIS)

1993-01-01

The superconductivity fields covered in this conference are: theory, applications, devices, flux properties high frequencies, Josephson junctions, magnetism, material sciences and physical properties of superconductors, spectroscopy and resonances and thin films

The design of high-Tc superconductors - Room-temperature superconductivity?

International Nuclear Information System (INIS)

Tallon, J.L.; Storey, J.G.; Mallett, B.

2012-01-01

This year is the centennial of the discovery of superconductivity and the 25th anniversary of the discovery of high-T c superconductors (HTS). Though we still do not fully understand how HTS work, the basic rules of design can be determined from studying their systematics. We know what to do to increase T c and, more importantly, what to do to increase critical current density J c . This in turn lays down a challenge for the chemist. Can the ideal design be synthesized? More importantly, what are the limits? Can one make a room-temperature superconductor? In fact fluctuations place strict constraints on this objective and provide important guidelines for the design of the ideal superconductor.

Characteristics of the joint mini-model high temperature superconducting cable

International Nuclear Information System (INIS)

Kim, H.; Sim, K.; Cho, J.; Kim, S.; Kim, J.H.; Jung, H.Y.

2008-01-01

To obtain realistic data on the high temperature superconducting (HTS) power cable, 3-phase 100 m long, 22.9 kV class HTS power transmission cable system have been developed by Korea Electrotechnology Research Institute (KERI) and LS cable Ltd. that is one of 21st Century Frontier Project in Korea. This cable was installed at Go-chang testing site of Korea Electric Power Corporation (KEPCO). For the application of the HTS power cable joint is very important to ensure the performance. Therefore, this paper gives some investigation of AC loss, critical current and joint resistance in jointed HTS tape. We experimentally showed that the influence of joint resistance on AC loss by using several joint methods. Finally, we are measured critical current, AC loss and jointed resistance for the manufactured mini-model cable

Improved plasma confinement by modulated toroidal current on HT-7 superconducting tokamak

International Nuclear Information System (INIS)

Mao Jianshan; Zhao Junyu; Shen Biao; Luo Jiarong

2004-01-01

The improved confinement phase was observed during modulating toroidal current on the Hefei superconducting Tokamak-7 (HT-7). This improved plasma confinement phase is characterized by suppressing magnetohydrodynamic (MHD) instabilities effectively, thus increased the central line averaged electron density and the central electron temperature about 33%, out-put steeper density profiles, and reduced hydrogen radiation from the edge as well. The global energy confinement time was increased by 27%-45%; The impurity radiation was reduced by modulation of plasma toroidal current; particle confinement time was increased about two times; a stronger radial negative electric field formed inside the limiter. The radial electric field during modulating current was calculated and disscused. (authors)

Studies of the Superconducting Transition in the Mo/Au-Bilayer Thin Films

Science.gov (United States)

Sadleir, John; Smith, Stephen; Iyomoto, naoko; Bandler, Simon; Chervenak, Jay; Brown, Ari; Brekowsky, Regis; Kilbourne, Caroline; Robinson, Ian

2007-01-01

At NASA Goddard, microcalorimeter arrays using superconducting transition edge sensor thermometers (TESs) are under development for high energy resolution X-ray astrophysics applications. We report on our studies of the superconducting transition in our Mo/Au-bilayer TES films including: low current measurements of the superconducting bilayer's resistance transition versus temperature on pixels with different normal metal absorber attachment designs and measured temperature scaling of the critical current and critical magnetic field.

Superconducting ECR ion source system

International Nuclear Information System (INIS)

Sharma, S.C.; Gore, J.A.; Gupta, A.K.; Saxena, A.

2017-01-01

In order to cover the entire mass range of the elements across the periodic table, an ECR based heavy ion accelerator programme, consisting of a superconducting ECR (Electron Cyclotron Resonance) source and a room temperature RFQ (Radio Frequency Quadrupole) followed by low and high beta superconducting resonator cavities has been proposed. The 18 GHz superconducting ECR ion source system has already been commissioned and being operated periodically at FOTIA beam hall. This source is capable of delivering ion beams right from proton to uranium with high currents and high charge states over a wide mass range (1/7 ≤ q/m ≤ 1/2) across the periodic table, including U"3"4"+ (q/m∼1/7) with 100 pna yield. The normalized transverse beam emittance from ECR source is expected to be <1.0 pi mm mrad. ECR ion sources are quite robust, making them suitable for operating for weeks continuously without any interruption

Structural alloys for high field superconducting magnets

International Nuclear Information System (INIS)

Morris, J.W. Jr.

1985-08-01

Research toward structural alloys for use in high field superconducting magnets is international in scope, and has three principal objectives: the selection or development of suitable structural alloys for the magnet support structure, the identification of mechanical phenomena and failure modes that may influence service behavior, and the design of suitable testing procedures to provide engineering design data. This paper reviews recent progress toward the first two of these objectives. The structural alloy needs depend on the magnet design and superconductor type and differ between magnets that use monolithic and those that employ force-cooled or ICCS conductors. In the former case the central requirement is for high strength, high toughness, weldable alloys that are used in thick sections for the magnet case. In the latter case the need is for high strength, high toughness alloys that are used in thin welded sections for the conductor conduit. There is productive current research on both alloy types. The service behavior of these alloys is influenced by mechanical phenomena that are peculiar to the magnet environment, including cryogenic fatigue, magnetic effects, and cryogenic creep. The design of appropriate mechanical tests is complicated by the need for testing at 4 0 K and by rate effects associated with adiabatic heating during the tests. 46 refs

Critical current densities in superconducting materials

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

in them cannot be raised beyond a point (about 1000 amps/cm2), and they are ... a superconducting material, the zero resistance property of the ..... force as a function of field (h = H/HC2 is in reduced units) for CeRu2 samples (Roy et al. 1998) ...

AC Losses and Their Thermal Effect in High-Temperature Superconducting Machines

DEFF Research Database (Denmark)

Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan

2016-01-01

In transient operations or fault conditions, hightemperature superconducting (HTS) machines suffer ac losses, which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate ac losses and their thermal effect in HTS machines is presented....... The method consists of three submodels that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an ac loss model that has a homogeneous...

High-field superconducting nested coil magnet

Science.gov (United States)

Laverick, C.; Lobell, G. M.

1970-01-01

Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

LHC Report: superconducting circuit powering tests

CERN Multimedia

Mirko Pojer

2015-01-01

After the long maintenance and consolidation campaign carried out during LS1, the machine is getting ready to start operation with beam at 6.5 TeV… the physics community can’t wait! Prior to this, all hardware and software systems have to be tested to assess their correct and safe operation.   Most of the cold circuits (those with high current/stored energy) possess a sophisticated magnet protection system that is crucial to detect a transition of the coil from the superconducting to the normal state (a quench) and safely extract the energy stored in the circuits (about 1 GJ per dipole circuit at nominal current). LHC operation relies on 1232 superconducting dipoles with a field of up to 8.33 T operating in superfluid helium at 1.9 K, along with more than 500 superconducting quadrupoles operating at 4.2 or 1.9 K. Besides, many other superconducting and normal resistive magnets are used to guarantee the possibility of correcting all beam parameters, for a total of mo...

High critical temperature superconducting composite and fabrication process

International Nuclear Information System (INIS)

Dubots, P.; Legat, D.

1989-01-01

The core comprises a high temperature superconducting sintered oxide coated with alumina or barium oxide covered with a first sheath in aluminum, a second sheath in niobium and a third sheath in copper [fr

Improving superconducting properties of YBCO high temperature superconductor by Graphene Oxide doping

Energy Technology Data Exchange (ETDEWEB)

Dadras, S., E-mail: dadras@alzahra.ac.ir; Dehghani, S.; Davoudiniya, M.; Falahati, S.

2017-06-01

In this research, we report the synthesis and characterization of YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO) high temperature superconductor prepared by sol-gel method and doped with Graphene Oxide (GO) in different weight percentages, 0, 0.1, 0.7 and 1 % wt. The x-ray diffraction (XRD) analysis confirms the formation of orthorhombic phase of superconductivity for all the prepared samples. We found that GO doping reduces the crystalline size of the samples. We evaluated the effects of GO doping on the normal state resistivity (ρ), superconducting transition temperature (T{sub c}) and critical current density (J{sub c}). The results show that the GO doping has a positive effect on these properties. Also, the highest J{sub c} is obtained for the 0.7 %wt GO doped YBCO compound that its critical current density is about 15 times more than the J{sub c} of pure one in 0.4 T magnetic field. The scanning electron microscope (SEM) analysis shows that there are better connections between the grains of GO doped samples. - Highlights: • Graphene Oxide doping increased the YBCO critical current density. • Graphene Oxide creates a better connection between the YBCO grains. • The normal resistivity of samples were decreased by GO doping to YBCO compounds. • Graphene Oxide doping has a positive effect on the critical transition temperature.

A high field and cryogenic test facility for neutron irradiated superconducting wire

Science.gov (United States)

Nishimura, A.; Miyata, H.; Yoshida, M.; Iio, M.; Suzuki, K.; Nakamoto, T.; Yamazaki, M.; Toyama, T.

2017-12-01

A 15.5 T superconducting magnet and a variable temperature insert (VTI) system were installed at a radiation control area in Oarai center in Tohoku University to investigate the superconducting properties of activated superconducting materials by fast neutron. The superconductivity was measured at cryogenic temperature and high magnetic field. During these tests, some inconvenient problems were observed and the additional investigation was carried out. The variable temperature insert was designed and assembled to perform the superconducting property tests. without the liquid helium. To remove the heat induced by radiation and joule heating, high purity aluminum rod was used in VTI. The thermal contact was checked by FEM analysis and an additional support was added to confirm the decreasing the stress concentration and the good thermal contact. After the work for improvement, it was affirmed that the test system works well and all troubles were resolved. In this report, the improved technical solution is described and the first data set on the irradiation effect on Nb3Sn wire is presented.

Finite-element simulation of the performance of a superconducting meander structure shielding for a cryogenic current comparator