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Sample records for superconducting fault-current limiter

  1. 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)

  2. 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.

  3. 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.

  4. 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

  5. Computer modelling of superconductive fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Weller, R.A.; Campbell, A.M.; Coombs, T.A.; Cardwell, D.A.; Storey, R.J. [Cambridge Univ. (United Kingdom). Interdisciplinary Research Centre in Superconductivity (IRC); Hancox, J. [Rolls Royce, Applied Science Division, Derby (United Kingdom)

    1998-05-01

    Investigations are being carried out on the use of superconductors for fault current limiting applications. A number of computer programs are being developed to predict the behavior of different `resistive` fault current limiter designs under a variety of fault conditions. The programs achieve solution by iterative methods based around real measured data rather than theoretical models in order to achieve accuracy at high current densities. (orig.) 5 refs.

  6. 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.

  7. 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

  8. 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)

  9. 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.

  10. Transmission Level High Temperature Superconducting Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Gary [SuperPower, Inc., Schenectady, NY (United States)

    2016-10-05

    The primary objective of this project was to demonstrate the feasibility and reliability of utilizing high-temperature superconducting (HTS) materials in a Transmission Level Superconducting Fault Current Limiter (SFCL) application. During the project, the type of high-temperature superconducting material used evolved from 1st generation (1G) BSCCO-2212 melt cast bulk high-temperature superconductors to 2nd generation (2G) YBCO-based high-temperature superconducting tape. The SFCL employed SuperPower's “Matrix” technology, that offers modular features to enable scale up to transmission voltage levels. The SFCL consists of individual modules that contain elements and parallel inductors that assist in carrying the current during the fault. A number of these modules are arranged in an m x n array to form the current-limiting matrix.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. A hybrid superconducting fault current limiter for enhancing transient stability in Korean power systems

    Science.gov (United States)

    Seo, Sangsoo; Kim, Seog-Joo; Moon, Young-Hwan; Lee, Byongjun

    2013-11-01

    Additional power generation sites have been limited in Korea, despite the fact load demands are gradually increasing. In order to meet these increasing demands, Korea’s power system company has begun constructing new generators at existing sites. Thus, multi-unit plants can create problems in terms of transient stability when a large disturbance occurs. This paper proposes a hybrid superconducting fault current limiter (SFCL) application to enhance the transient stability of multi-unit power plants. SFCLs reduce fault currents, and limitation currents decrease the imbalance of the mechanical and electrical torque of the generators, resulting in an improvement in transient stability.

  18. Adaptation of superconducting fault current limiter to high-speed reclosing

    International Nuclear Information System (INIS)

    Koyama, T.; Yanabu, S.

    2009-01-01

    Using a high temperature superconductor, we constructed and tested a model superconducting fault current limiter (SFCL). The superconductor might break in some cases because of its excessive generation of heat. Therefore, it is desirable to interrupt early the current that flows to superconductor. So, we proposed the SFCL using an electromagnetic repulsion switch which is composed of a superconductor, a vacuum interrupter and a by-pass coil, and its structure is simple. Duration that the current flow in the superconductor can be easily minimized to the level of less than 0.5 cycle using this equipment. On the other hand, the fault current is also easily limited by large reactance of the parallel coil. There is duty of high-speed reclosing after interrupting fault current in the electric power system. After the fault current is interrupted, the back-up breaker is re-closed within 350 ms. So, the electromagnetic repulsion switch should return to former state and the superconductor should be recovered to superconducting state before high-speed reclosing. Then, we proposed the SFCL using an electromagnetic repulsion switch which employs our new reclosing function. We also studied recovery time of the superconductor, because superconductor should be recovered to superconducting state within 350 ms. In this paper, the recovery time characteristics of the superconducting wire were investigated. Also, we combined the superconductor with the electromagnetic repulsion switch, and we did performance test. As a result, a high-speed reclosing within 350 ms was proven to be possible.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. Power flow analysis and optimal locations of resistive type superconducting fault current limiters.

    Science.gov (United States)

    Zhang, Xiuchang; Ruiz, Harold S; Geng, Jianzhao; Shen, Boyang; Fu, Lin; Zhang, Heng; Coombs, Tim A

    2016-01-01

    Based on conventional approaches for the integration of resistive-type superconducting fault current limiters (SFCLs) on electric distribution networks, SFCL models largely rely on the insertion of a step or exponential resistance that is determined by a predefined quenching time. In this paper, we expand the scope of the aforementioned models by considering the actual behaviour of an SFCL in terms of the temperature dynamic power-law dependence between the electrical field and the current density, characteristic of high temperature superconductors. Our results are compared to the step-resistance models for the sake of discussion and clarity of the conclusions. Both SFCL models were integrated into a power system model built based on the UK power standard, to study the impact of these protection strategies on the performance of the overall electricity network. As a representative renewable energy source, a 90 MVA wind farm was considered for the simulations. Three fault conditions were simulated, and the figures for the fault current reduction predicted by both fault current limiting models have been compared in terms of multiple current measuring points and allocation strategies. Consequently, we have shown that the incorporation of the E - J characteristics and thermal properties of the superconductor at the simulation level of electric power systems, is crucial for estimations of reliability and determining the optimal locations of resistive type SFCLs in distributed power networks. Our results may help decision making by distribution network operators regarding investment and promotion of SFCL technologies, as it is possible to determine the maximum number of SFCLs necessary to protect against different fault conditions at multiple locations.

  13. Mitigation of commutation failures in LCC–HVDC systems based on superconducting fault current limiters

    International Nuclear Information System (INIS)

    Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook

    2016-01-01

    Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC–HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC–HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC–HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC–HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

  14. Mitigation of commutation failures in LCC–HVDC systems based on superconducting fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2016-11-15

    Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC–HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC–HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC–HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC–HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

  15. Mitigation of commutation failures in LCC-HVDC systems based on superconducting fault current limiters

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook

    2016-11-01

    Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC-HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC-HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC-HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC-HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

  16. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2014-09-15

    Highlights: • The role of SFCLs in VSC-HVDC systems was evaluated. • Simulation model based on Korea Jeju-Haenam HVDC power system was designed. • An effect and the feasible locations of resistive SFCLs were evaluated. • DC line-to-line, DC line-to-ground and 3 phase AC faults were imposed and analyzed. - Abstract: Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

  17. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    International Nuclear Information System (INIS)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook

    2014-01-01

    Highlights: • The role of SFCLs in VSC-HVDC systems was evaluated. • Simulation model based on Korea Jeju-Haenam HVDC power system was designed. • An effect and the feasible locations of resistive SFCLs were evaluated. • DC line-to-line, DC line-to-ground and 3 phase AC faults were imposed and analyzed. - Abstract: Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results

  18. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook

    2014-09-01

    Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

  19. 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

  20. 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.

  1. Fault current limiter

    Science.gov (United States)

    Darmann, Francis Anthony

    2013-10-08

    A fault current limiter (FCL) includes a series of high permeability posts for collectively define a core for the FCL. A DC coil, for the purposes of saturating a portion of the high permeability posts, surrounds the complete structure outside of an enclosure in the form of a vessel. The vessel contains a dielectric insulation medium. AC coils, for transporting AC current, are wound on insulating formers and electrically interconnected to each other in a manner such that the senses of the magnetic field produced by each AC coil in the corresponding high permeability core are opposing. There are insulation barriers between phases to improve dielectric withstand properties of the dielectric medium.

  2. Superconducting fault current limiter. Fifth quarterly technical progress report, August 8, 1978-November 7, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    Progress in the development of fault current limiters for superconducting power transmission systems is reported. The analysis and design of a magnetically switched resistive device and the experimental program were emphasized and reported. A transient heat transfer model was developed which indicates the parameters which are important in determining the thermal heating and recovery of the superconduting film. Designs for the switching coil and the S/C element were also carried out and are reported. A four-pole magnetic coil is recommended; this generates a magnetic field which is nearly perpendicular to spiral or helical S/C film geometrics. A spirally-designed, 3000 ohm limiter is shown to be able to fit within a .5 to 1m inner radius, .05 to .03 m wide, 1.3 to 3.9 m long annualr region. The experimental program has included work on materials development and on prepartion of the switching and thermal recovery experimental facility. The material development program has uncovered several serious short-comings of NbN as the S/C film material. Macroscopic holes and surface debris, and microscopic imperfections reduce the critical current density below the expected value and, in addition, cause nonuniform switching. Reasons for these effects are postulated, and a continuing, vigorous materials program is suggested in hopes of alleviating these problems. Virtually all of the experimental equipment had been installed, and so the magnetic switching and thermal recovery experiments can begin and progress during the next quarter. (LCL)

  3. Application of fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, A.

    2007-11-30

    This report presents the results of a study commissioned by the Department for Business, Enterprise and Industry (BERR; formerly the Department of Trade and Industry) into the application of fault current limiters in the UK. The study reviewed the current state of fault current limiter (FCL) technology and regulatory position in relation to all types of current limiters. It identified significant research and development work with respect to medium voltage FCLs and a move to high voltage. Appropriate FCL technologies being developed include: solid state breakers; superconducting FCLs (including superconducting transformers); magnetic FCLs; and active network controllers. Commercialisation of these products depends on successful field tests and experience, plus material development in the case of high temperature superconducting FCL technologies. The report describes FCL techniques, the current state of FCL technologies, practical applications and future outlook for FCL technologies, distribution fault level analysis and an outline methodology for assessing the materiality of the fault level problem. A roadmap is presented that provides an 'action agenda' to advance the fault level issues associated with low carbon networks.

  4. Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook

    2015-11-01

    High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

  5. Application of the (Hg,Re)-1223 ceramic on superconducting fault current limiter

    International Nuclear Information System (INIS)

    Passos, C.A.C.; Passamai, J.L.; Orlando, M.T.D.; Medeiros, E.F.; Sampaio, R.V.; Oliveira, F.D.C.; Fardin, J.F.; Simonetti, D.S.L.

    2007-01-01

    We have investigated a small resistive SFCL device based on Hg 0.8 Re 0.2 Ba 2 Ca 2 Cu 3 O 8+δ , (Hg,Re)-1223, ceramic in order to obtain in the future a SFCL prototype for protecting a low impedance and high current system. Our initial study has shown that a fault current of 1.55 x 10 2 A peak /cm 2 at 60 Hz was reduced to 0.82 x 10 2 A peak /cm 2 , that is, the device limited the current at 59% without any damage on the (Hg,Re)-1223 superconductor in this range of current. It was observed that the device immediately recovered the initial conditions after that the fault current event is finished without any damage

  6. Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2015-11-15

    Highlights: • The role of SFCL in types of HVDC system was evaluated. • A simulation model based on Korea Jeju–Haenam HVDC power system was designed in Matlab/Simulink. • Utilizing the designed both HVDC power system models, the efficiency of DC-SFCL was relatively low, compared to AC-SFCL. • It was deduced that the AC-SFCL was more effective in LCC-HVDC system than VSC-HVDC system. - Abstract: High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

  7. Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

    International Nuclear Information System (INIS)

    Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook

    2015-01-01

    Highlights: • The role of SFCL in types of HVDC system was evaluated. • A simulation model based on Korea Jeju–Haenam HVDC power system was designed in Matlab/Simulink. • Utilizing the designed both HVDC power system models, the efficiency of DC-SFCL was relatively low, compared to AC-SFCL. • It was deduced that the AC-SFCL was more effective in LCC-HVDC system than VSC-HVDC system. - Abstract: High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

  8. 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

  9. A novel method of flat YBCO rings development for shield-type superconducting fault current limiters fabrication

    International Nuclear Information System (INIS)

    Hekmati, Arsalan; Hosseini, Mehdi; Vakilian, Mehdi; Fardmanesh, Mehdi

    2012-01-01

    A method has been proposed for flat YBCO ring Fabrication. A prototype SFCL with proposed design has been fabricated using the rings. J c characteristics of the rings are measured using an innovative method. The application of flat superconductor rings has been investigated in the structure of inductive shield-type high temperature superconducting fault current limiters, HT c -SFCL. A laboratory scale inductive shield-type HT c -SFCL has been designed and fabricated using flat superconductor rings. The fabrication process has been fully presented. YBCO powder has been used for the fabrication of superconductor rings. This fabrication process, being quite innovative, is introduced completely. The method of the trapped field measurement has been used for the critical current density measurement of the fabricated superconductor rings. The device with nominal current of 2 A was tested in a 30 V circuit. The SFCL successfully limited the fault currents of up to 10 times the nominal current to an approximately fixed value of 3 A. The voltage-current characteristic of the fabricated prototype has also been obtained and has shown compatibility with the fault current limitation results.

  10. Experimental testing and modelling of a resistive type superconducting fault current limiter using MgB2 wire

    International Nuclear Information System (INIS)

    Smith, A C; Pei, X; Oliver, A; Husband, M; Rindfleisch, M

    2012-01-01

    A prototype resistive superconducting fault current limiter (SFCL) was developed using single-strand round magnesium diboride (MgB 2 ) wire. The MgB 2 wire was wound with an interleaved arrangement to minimize coil inductance and provide adequate inter-turn voltage withstand capability. The temperature profile from 30 to 40 K and frequency profile from 10 to 100 Hz at 25 K were tested and reported. The quench properties of the prototype coil were tested using a high current test circuit. The fault current was limited by the prototype coil within the first quarter-cycle. The prototype coil demonstrated reliable and repeatable current limiting properties and was able to withstand a potential peak current of 372 A for one second without any degradation of performance. A three-strand SFCL coil was investigated and demonstrated scaled-up current capacity. An analytical model to predict the behaviour of the prototype single-strand SFCL coil was developed using an adiabatic boundary condition on the outer surface of the wire. The predicted fault current using the analytical model showed very good correlation with the experimental test results. The analytical model and a finite element thermal model were used to predict the temperature rise of the wire during a fault. (paper)

  11. High aspect ratio problem in simulation of a fault current limiter based on superconducting tapes

    International Nuclear Information System (INIS)

    Velichko, A V; Coombs, T A

    2006-01-01

    We are offering a solution for the high-aspect-ratio problem relevant to the numerical simulation of AC loss in superconductors and metals with high aspect (width-to-thickness) ratio. This is particularly relevant to simulation of fault current limiters (FCLs) based on second generation YBCO tapes on RABiTS. By assuming a linear scaling of the electric and thermal properties with the size of the structure, we can replace the real sample with an effective sample of a reduced aspect ratio by introducing size multipliers into the equations that govern the physics of the system. The simulation is performed using both a proprietary equivalent circuit software and a commercial FEM software. The correctness of the procedure is verified by simulating temperature and current distributions for samples with all three dimensions varying within 10 -3 -10 3 of the original size. Qualitatively the distributions for the original and scaled samples are indistinguishable, whereas quantitative differences in the worst case do not exceed 10%

  12. High aspect ratio problem in simulation of a fault current limiter based on superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Velichko, A V; Coombs, T A [Electrical Engineering Division, University of Cambridge (United Kingdom)

    2006-06-15

    We are offering a solution for the high-aspect-ratio problem relevant to the numerical simulation of AC loss in superconductors and metals with high aspect (width-to-thickness) ratio. This is particularly relevant to simulation of fault current limiters (FCLs) based on second generation YBCO tapes on RABiTS. By assuming a linear scaling of the electric and thermal properties with the size of the structure, we can replace the real sample with an effective sample of a reduced aspect ratio by introducing size multipliers into the equations that govern the physics of the system. The simulation is performed using both a proprietary equivalent circuit software and a commercial FEM software. The correctness of the procedure is verified by simulating temperature and current distributions for samples with all three dimensions varying within 10{sup -3}-10{sup 3} of the original size. Qualitatively the distributions for the original and scaled samples are indistinguishable, whereas quantitative differences in the worst case do not exceed 10%.

  13. Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lei, E-mail: stclchen1982@163.com [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zhu, Lin [Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville 37996 (United States); Guo, Fang [Department of Substation, Guang Dong Electric Power Design Institute, Guangzhou 510663 (China)

    2015-11-15

    Highlights: • A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid. • The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability. • The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. • The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability. - Abstract: Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

  14. Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

    International Nuclear Information System (INIS)

    Chen, Lei; Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui; Zhu, Lin; Guo, Fang

    2015-01-01

    Highlights: • A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid. • The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability. • The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. • The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability. - Abstract: Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

  15. Experimental studies of the quench behaviour of MgB{sub 2} superconducting wires for fault current limiter applications

    Energy Technology Data Exchange (ETDEWEB)

    Ye Lin [Interdisciplinary Research Center (IRC) in Superconductivity, Cavendish Laboratory/Department of Engineering, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Majoros, M [Laboratories for Applied Superconductivity and Magnetism, Ohio State University, Columbus, OH 43210 (United States); Campbell, A M [Interdisciplinary Research Center (IRC) in Superconductivity, Cavendish Laboratory/Department of Engineering, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Coombs, T [Interdisciplinary Research Center (IRC) in Superconductivity, Cavendish Laboratory/Department of Engineering, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Astill, D [Interdisciplinary Research Center (IRC) in Superconductivity, Cavendish Laboratory/Department of Engineering, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Harrison, S [Scientific Magnetics, Culham Science Centre, Culham, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Husband, M [Strategic Research Center (SRC)-Electrical Engineering, Rolls-Royce plc, Derby DE24 8BJ (United Kingdom); Rindfleisch, M [Hyper Tech Research Inc., Columbus, OH 43212 (United States); Tomsic, M [Hyper Tech Research Inc., Columbus, OH 43212 (United States)

    2007-07-15

    Various MgB{sub 2} wires with different sheath materials provided by Hyper Tech Research Inc., have been tested in the superconducting fault current limiter (SFCL) desktop tester at 24-26 K in a self-field. Samples 1 and 2 are similarly fabricated monofilamentary MgB{sub 2} wires with a sheath of CuNi, except that sample 2 is doped with SiC and Mg addition. Sample 3 is a CuNi sheathed multifilamentary wire with Cu stabilization and Mg addition. All the samples with Nb barriers have the same diameter of 0.83 mm and superconducting fractions ranging from 15% to 27% of the total cross section. They were heat-treated at temperatures of 700 deg. C for a hold time of 20-40 min. Current limiting properties of MgB{sub 2} wires subjected to pulse overcurrents have been experimentally investigated in an AC environment in the self-field at 50 Hz. The quench currents extracted from the pulse measurements were in a range of 200-328 A for different samples, corresponding to an average engineering critical current density (J{sub e}) of around 4.8 x 10{sup 4} A cm{sup -2} at 25 K in the self-field, based on the 1 {mu}V cm{sup -1} criterion. This work is intended to compare the quench behaviour in the Nb-barrier monofilamentary and multifilamentary MgB{sub 2} wires with CuNi and Cu/CuNi sheaths. The experimental results can be applied to the design of fault current limiter applications based on MgB{sub 2} wires.

  16. Study of recovery characteristics of 2nd generation HTS tapes with different stabilizers for resistive type superconducting fault current limiters

    International Nuclear Information System (INIS)

    Sheng, Jie; Zeng, Weina; Ma, Jun; Yao, Zhihao; Li, Zhuyong; Jin, Zhijian; Hong, Zhiyong

    2016-01-01

    Highlights: • Three methods of measuring the recovery time of HTS tapes are compared. • Four tapes with different stabilizers were tested to compare their recovery characteristics. • The HTS tapes with thinner stabilizers have better recovery characteristics. • Encapsulation makes the recovery characteristics of HTS tapes worse. • The results can be reference of the re-reclosed operation time interval. - Abstract: The resistive type superconducting fault current limiter (SFCL) is one of the most important superconducting power applications nowadays. As known, this type of SFCL is settled directly in the power transmission line. When a short fault happens, the temperature of the superconductors in the SFCL will increase sharply due to the huge generated heat. This means the superconductors need time to recover the superconducting properties and be ready for the next short fault. So the recovery characteristics become one of the most crucial features of the resistive type SFCL. In this paper, several different kinds of measuring methods are presented to calculate the recovery time of the HTS tapes, and comparison of these methods is also carried out by a standard test. On basis of this, samples with different kinds of stabilizers are used to explore the influence of stabilizer on their recovery characteristics. In addition, the influence of the encapsulation technology is also discussed in this paper.

  17. Application of a combined superconducting fault current limiter and STATCOM to enhancement of power system transient stability

    Energy Technology Data Exchange (ETDEWEB)

    Mahdad, Belkacem, E-mail: bemahdad@mselab.org; Srairi, K.

    2013-12-15

    Highlights: •A simple interactive model SFCL–STATCOM Controller is proposed to enhance the transient stability. •The STATCOM controller is integrated in coordination with the SFCL to support the excessive reactive power during fault. •Voltage stability index based continuation power flow is used to locate the STATCOM and the SFCL. •The clearing time improved compared to other cases (with only SFCL, with only STATCOM). •The choice of the STATCOM parameters is very important to exploit efficiently the integration of STATCOM Controller. -- Abstract: Stable and reliable operation of the power system network is dependent on the dynamic equilibrium between energy production and power demand under large disturbance such as short circuit or important line tripping. This paper investigates the use of combined model based superconducting fault current limiter (SFCL) and shunt FACTS Controller (STATCOM) for assessing the transient stability of a power system considering the automatic voltage regulator. The combined model located at a specified branch based on voltage stability index using continuation power flow. The main role of the proposed combined model is to achieve simultaneously a flexible control of reactive power using STATCOM Controller and to reduce fault current using superconducting technology based SFCL. The proposed combined model has been successfully adapted within the transient stability program and applied to enhance the transient power system stability of the WSCC9-Bus system. Critical clearing time (CCT) has been used as an index to evaluate and validate the contribution of the proposed coordinated Controller. Simulation results confirm the effectiveness and perspective of this combined Controller to enhance the dynamic power system performances.

  18. Development of 6.6 kV/600 A superconducting fault current limiter using coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Yazawa, T., E-mail: takashi.yazawa@toshiba.co.j [Toshiba Corporation, Power Systems Company (Japan); Koyanagi, K.; Takahashi, M.; Toba, K.; Takigami, H.; Urata, M. [Toshiba Corporation, Power Systems Company (Japan); Iijima, Y.; Saitoh, T. [Fujikura Ltd. (Japan); Amemiya, N. [Superconductivity Research Laboratory, ISTEC (Japan); Shiohara, Y. [Department of Electrical Engineering, Kyoto University (Japan); Ito, T. [Tokyo Gas Co., Ltd. (Japan)

    2009-10-15

    As one of the programs in the Ministry of Economy, Trade and Industry (METI) project regarding R and D on superconducting coated conductor, three-phase superconducting fault current limiter (SFCL) for 6.6 kV application was developed and successfully tested. The developed SFCL was mainly comprised three-phase set of current limiting coils installed in a sub-cooled nitrogen cryostat with a GM cryocooler, circuit breakers and a sequence circuit. The whole system was installed in a cubicle. Two tapes of coated conductor were wound in parallel in each coil to obtain the rated current of 72 A rms. After developing the whole SFCL system, short circuit experiments were implemented with a short circuit generator. In a three-line ground fault test, the SFCL successfully restricted the prospected short circuit current over 1.6 kA to about 800 A by the applied voltage of 6.6 kV. The SFCL was installed in a user field and connected with a gas engine generator, followed by a consecutive operation. In this program, 600 A class FCL coil, with which four coated conductor tapes were wound, was also developed. The coil showed sufficiently low AC loss at the rated current. With these results, the program attained the planned target of the fundamentals for the 6.6 kV/600 A SFCL.

  19. 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.

  20. Characteristics of transformer-type superconducting fault current limiter depending on reclosing in changing the number of turns of secondary winding

    International Nuclear Information System (INIS)

    Choi, S.G.; Choi, H.S.; Cho, Y.S.; Park, H.M.; Jung, B.I.; Ha, K.H.

    2011-01-01

    The amount of consumed power is increasing with industrial development and rapidly increasing population. In accidents due to increased power consumption, the fault current sharply increases. Superconducting fault current limiters (SFCL) are studied widely to limit such fault currents. In this study, the characteristics of a transformer-type SFCL are analyzed depending on reclosing in changing the number of secondary winding turns. For experiment conditions, the turn ratio of the primary and secondary windings of a transformer-type SFCL was set to 4:2 and 4:4. The voltage was incremented by 80 V from 120 V for the experiment. The circuit breaker was operated with two open times of CO-0.17 s -CO-0.17 s -CO seconds (C; closed, O; open), respectively. Comparing the result for the experiment conditions with the case of the turn ratios of the primary and secondary windings at 4:4 and 4:2, the fault current was limited effectively in 4:2 than in 4:4 for the fault current limit ratios. With respect to the result of recovery characteristics, it was examined that the superconducting unit recovered faster when the turn ratio of the primary and secondary windings was 4:2 than 4:4. Comparing the amount of consumed power related to the recovery characteristics of the superconducting element, it was examined that the recovery time was faster in less power consumption for the superconducting unit. As such, since a transformer-type SFCL depending on reclosing in changing the number of turns of the secondary winding controls the turn ratio of the secondary winding to control fault current limiting and recovery characteristics, it can normally operate.

  1. Parameter design and performance simulation of a 10 kV voltage compensation type active superconducting fault current limiter

    International Nuclear Information System (INIS)

    Chen, L.; Tang, Y.J.; Song, M.; Shi, J.; Ren, L.

    2013-01-01

    Highlights: •For a practical 10 kV system, the 10 kV active SFCL’s basic parameters are designed. •Under different fault conditions, the 10 kV active SFCL’s performances are simulated. •The designed 10 kV active SFCL’s engineering feasibility is discussed preliminarily. -- Abstract: Since the introduction of superconducting fault current limiter (SFCL) into electrical distribution system may be a good choice with economy and practicability, the parameter design and current-limiting characteristics of a 10 kV voltage compensation type active SFCL are studied in this paper. Firstly, the SFCL’s circuit structure and operation principle are presented. Then, taking a practical 10 kV distribution system as its application object, the SFCL’s basic parameters are designed to meet the system requirements. Further, using MATLAB, the detailed current-limiting performances of the 10 kV active SFCL are simulated under different fault conditions. The simulation results show that the active SFCL can deal well with the faults, and the parameter design’s suitability can be testified. At the end, in view of the engineering feasibility of the 10 kV active SFCL, some preliminary discussions are carried out

  2. The first Italian superconducting fault current limiter: Results of the field testing experience after one year operation

    International Nuclear Information System (INIS)

    Martini, L; Bocchi, M; Ascade, M; Valzasina, A; Rossi, V; Angeli, G; Ravetta, C

    2014-01-01

    Ricerca sul Sistema Energetico S.p.A. (RSE) has been gaining a relevant experience in the simulation, design and installation of resistive-type Superconducting Fault Current Limiter (SFCL) devices for more than five years in the framework of a R and D national project funded by the Ricerca di Sistema (RdS). The most recent outcome of this research activity is the installation of a resistive-type BSCCO-based 9 kV / 3.4 MVA SFCL device in a single feeder branch of the Medium Voltage (MV) distribution network managed by A2A Reti Elettriche S.p.A (A2A) in the Milano area. This installation represents the first SFCL successfully installed in Italy. In this paper, we report on the main outcomes after a more than 1-year long steady-state field testing activity. The design of an upgraded device to be installed in the same substation has already been initiated: the new SFCL will allow to protect four different feeders, therefore implying a device upgrade up to 15.6 MVA.

  3. The impedance of inductive superconducting fault current limiters operating with stacks of thin film Y123/Au washers or bulk Bi2223 rings as secondaries

    International Nuclear Information System (INIS)

    Fernandez, J A Lorenzo; Osorio, M R; Toimil, P; Ferro, G; Blanch, M; Veira, J A; Vidal, F

    2006-01-01

    Inductive fault current limiters operating with stacks of various small superconducting elements acting as secondaries were studied. The stacks consist of Y 1 Ba 2 Cu 3 O 7-δ thin film washers or Bi 1.8 Pb 0.26 Sr 2 Ca 2 Cu 3 O 10+x bulk rings. A central result of our work is an experimental demonstration that the limiting capability of the device is strongly reduced when several bulk rings are stacked, whereas it remains almost unchanged for thin film washers. The use of thin films should therefore allow us to build more efficient high power inductive limiters based on stacks of small washers

  4. Construction of testing facilities and verifying tests of a 22.9 kV/630 A class superconducting fault current limiter

    Science.gov (United States)

    Yim, S.-W.; Yu, S.-D.; Kim, H.-R.; Kim, M.-J.; Park, C.-R.; Yang, S.-E.; Kim, W.-S.; Hyun, O.-B.; Sim, J.; Park, K.-B.; Oh, I.-S.

    2010-11-01

    We have constructed and completed the preparation for a long-term operation test of a superconducting fault current limiter (SFCL) in a Korea Electric Power Corporation (KEPCO) test grid. The SFCL with rating of 22.9 kV/630 A, 3-phases, has been connected to the 22.9 kV test grid equipped with reclosers and other protection devices in Gochang Power Testing Center of KEPCO. The main goals of the test are the verification of SFCL performance and protection coordination studies. A line-commutation type SFCL was fabricated and installed for this project, and the superconducting components were cooled by a cryo-cooler to 77 K in the sub-cooled liquid nitrogen pressurized by 3 bar of helium gas. The verification test includes un-manned - long-term operation with and without loads and fault tests. Since the test site is 170 km away from the laboratory, we will adopt the un-manned operation with real-time remote monitoring and controlling using high speed internet. For the fault tests, we will apply fault currents up to around 8 kArms to the SFCL using an artificial fault generator. The fault tests may allow us not only to confirm the current limiting capability of the SFCL, but also to adjust the SFCL - recloser coordination such as resetting over-current relay parameters. This paper describes the construction of the testing facilities and discusses the plans for the verification tests.

  5. Construction of testing facilities and verifying tests of a 22.9 kV/630 A class superconducting fault current limiter

    International Nuclear Information System (INIS)

    Yim, S.-W.; Yu, S.-D.; Kim, H.-R.; Kim, M.-J.; Park, C.-R.; Yang, S.-E.; Kim, W.-S.; Hyun, O.-B.; Sim, J.; Park, K.-B.; Oh, I.-S.

    2010-01-01

    We have constructed and completed the preparation for a long-term operation test of a superconducting fault current limiter (SFCL) in a Korea Electric Power Corporation (KEPCO) test grid. The SFCL with rating of 22.9 kV/630 A, 3-phases, has been connected to the 22.9 kV test grid equipped with reclosers and other protection devices in Gochang Power Testing Center of KEPCO. The main goals of the test are the verification of SFCL performance and protection coordination studies. A line-commutation type SFCL was fabricated and installed for this project, and the superconducting components were cooled by a cryo-cooler to 77 K in the sub-cooled liquid nitrogen pressurized by 3 bar of helium gas. The verification test includes un-manned - long-term operation with and without loads and fault tests. Since the test site is 170 km away from the laboratory, we will adopt the un-manned operation with real-time remote monitoring and controlling using high speed internet. For the fault tests, we will apply fault currents up to around 8 kA rms to the SFCL using an artificial fault generator. The fault tests may allow us not only to confirm the current limiting capability of the SFCL, but also to adjust the SFCL - recloser coordination such as resetting over-current relay parameters. This paper describes the construction of the testing facilities and discusses the plans for the verification tests.

  6. Passive fault current limiting device

    Science.gov (United States)

    Evans, Daniel J.; Cha, Yung S.

    1999-01-01

    A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment.

  7. Super conducting fault current limiter and inductor design

    International Nuclear Information System (INIS)

    Rogers, J.; Boenig, H.; Chowdhuri, P.; Schermer, R.; Weldon, D.; Wollan, J.

    1983-01-01

    A superconducting fault current limiter (SFCL) that uses a biased superconducting inductor in a diode or thyristor bridge circuit was analyzed for transmission systems in 69, 138, and 230 rms kV utility transmission systems. The limiter was evaluated for costs with all components--superconducting coil, diode and/or SCR power electronics, high voltage insulation, high voltage bushings and vapor cooled leads, dewar, and refrigerator--included. A design was undertaken for the superconducting cable and coils for both diode and SCR 69 kV limiter circuits

  8. Technical Evaluation of Superconducting Fault Current Limiters Used in a Micro-Grid by Considering the Fault Characteristics of Distributed Generation, Energy Storage and Power Loads

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2016-09-01

    Full Text Available Concerning the development of a micro-grid integrated with multiple intermittent renewable energy resources, one of the main issues is related to the improvement of its robustness against short-circuit faults. In a sense, the superconducting fault current limiter (SFCL can be regarded as a feasible approach to enhance the transient performance of a micro-grid under fault conditions. In this paper, the fault transient analysis of a micro-grid, including distributed generation, energy storage and power loads, is conducted, and regarding the application of one or more flux-coupling-type SFCLs in the micro-grid, an integrated technical evaluation method considering current-limiting performance, bus voltage stability and device cost is proposed. In order to assess the performance of the SFCLs and verify the effectiveness of the evaluation method, different fault cases of a 10-kV micro-grid with photovoltaic (PV, wind generator and energy storage are simulated in the MATLAB software. The results show that, the efficient use of the SFCLs for the micro-grid can contribute to reducing the fault current, improving the voltage sags and suppressing the frequency fluctuations. Moreover, there will be a compromise design to fully take advantage of the SFCL parameters, and thus, the transient performance of the micro-grid can be guaranteed.

  9. Reverse engineering of inductive fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Pina, J M; Neves, M Ventim; Rodrigues, A L [Centre of Technology and Systems Faculdade de Ciencias e Tecnologia, Nova University of Lisbon Monte de Caparica, 2829-516 Caparica (Portugal); Suarez, P; Alvarez, A, E-mail: jmmp@fct.unl.p [' Benito Mahedero' Group of Electrical Applications of Superconductors Escuela de IngenierIas Industrials, University of Extremadura Avenida de Elvas s/n, 06006 Badajoz (Spain)

    2010-06-01

    The inductive fault current limiter is less compact and harder to scale to high voltage networks than the resistive one. Nevertheless, its simple construction and mechanical robustness make it attractive in low voltage grids. Thus, it might be an enabling technology for the advent of microgrids, low voltage networks with dispersed generation, controllable loads and energy storage. A new methodology for reverse engineering of inductive fault current limiters based on the independent analysis of iron cores and HTS cylinders is presented in this paper. Their electromagnetic characteristics are used to predict the devices' hysteresis loops and consequently their dynamic behavior. Previous models based on the separate analysis of the limiters' components were already derived, e.g. in transformer like equivalent models. Nevertheless, the assumptions usually made may limit these models' application, as shown in the paper. The proposed methodology obviates these limitations. Results are validated through simulations.

  10. Reverse engineering of inductive fault current limiters

    International Nuclear Information System (INIS)

    Pina, J M; Neves, M Ventim; Rodrigues, A L; Suarez, P; Alvarez, A

    2010-01-01

    The inductive fault current limiter is less compact and harder to scale to high voltage networks than the resistive one. Nevertheless, its simple construction and mechanical robustness make it attractive in low voltage grids. Thus, it might be an enabling technology for the advent of microgrids, low voltage networks with dispersed generation, controllable loads and energy storage. A new methodology for reverse engineering of inductive fault current limiters based on the independent analysis of iron cores and HTS cylinders is presented in this paper. Their electromagnetic characteristics are used to predict the devices' hysteresis loops and consequently their dynamic behavior. Previous models based on the separate analysis of the limiters' components were already derived, e.g. in transformer like equivalent models. Nevertheless, the assumptions usually made may limit these models' application, as shown in the paper. The proposed methodology obviates these limitations. Results are validated through simulations.

  11. MgB2-based superconductors for fault current limiters

    Science.gov (United States)

    Sokolovsky, V.; Prikhna, T.; Meerovich, V.; Eisterer, M.; Goldacker, W.; Kozyrev, A.; Weber, H. W.; Shapovalov, A.; Sverdun, V.; Moshchil, V.

    2017-02-01

    A promising solution of the fault current problem in power systems is the application of fast-operating nonlinear superconducting fault current limiters (SFCLs) with the capability of rapidly increasing their impedance, and thus limiting high fault currents. We report the results of experiments with models of inductive (transformer type) SFCLs based on the ring-shaped bulk MgB2 prepared under high quasihydrostatic pressure (2 GPa) and by hot pressing technique (30 MPa). It was shown that the SFCLs meet the main requirements to fault current limiters: they possess low impedance in the nominal regime of the protected circuit and can fast increase their impedance limiting both the transient and the steady-state fault currents. The study of quenching currents of MgB2 rings (SFCL activation current) and AC losses in the rings shows that the quenching current density and critical current density determined from AC losses can be 10-20 times less than the critical current determined from the magnetization experiments.

  12. Resistive Fault Current Limiter Prototypes: Mechanical and Electrical Analyses

    International Nuclear Information System (INIS)

    Martini, L; Arcos, I; Bocchi, M; Brambilla, R; Dalessandro, R; Frigerio, A; Rossi, V

    2006-01-01

    The problem of excessive short-circuit currents has become an important issue for power systems operators and there are clear indications for a growing interest in superconducting fault current limiter devices for MV and HV grids. In this work, we report on both simulation and electrical testing on single-phase SFCL prototypes developed in the framework of an Italian RTD project to be completed with a 3-phase SFCL unit by the end of 2005

  13. 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

  14. 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)

  15. Adjustable direct current and pulsed circuit fault current limiter

    Science.gov (United States)

    Boenig, Heinrich J.; Schillig, Josef B.

    2003-09-23

    A fault current limiting system for direct current circuits and for pulsed power circuit. In the circuits, a current source biases a diode that is in series with the circuits' transmission line. If fault current in a circuit exceeds current from the current source biasing the diode open, the diode will cease conducting and route the fault current through the current source and an inductor. This limits the rate of rise and the peak value of the fault current.

  16. Quench propagation in coated conductors for fault current limiters

    International Nuclear Information System (INIS)

    Roy, F.; Perez, S.; Therasse, M.; Dutoit, B.; Sirois, F.; Decroux, M.; Antognazza, L.

    2009-01-01

    A fundamental understanding of the quench phenomenon is crucial in the future design and operation of high temperature superconductors based fault current limiters. The key parameter that quantifies the quenching process in superconductors is the normal zone propagation (NZP) velocity, which is defined as the speed at which the normal zone expands into the superconducting volume. In the present paper, we used numerical models developed in our group recently to investigate the quench propagation in coated conductors. With our models, we have shown that the NZP in these tapes depends strongly on the substrate properties.

  17. Fault current limiter with shield and adjacent cores

    Science.gov (United States)

    Darmann, Francis Anthony; Moriconi, Franco; Hodge, Eoin Patrick

    2013-10-22

    In a fault current limiter (FCL) of a saturated core type having at least one coil wound around a high permeability material, a method of suppressing the time derivative of the fault current at the zero current point includes the following step: utilizing an electromagnetic screen or shield around the AC coil to suppress the time derivative current levels during zero current conditions.

  18. Design Aspects and Test of an Inductive Fault Current Limiter

    Directory of Open Access Journals (Sweden)

    Arsénio Pedro

    2014-05-01

    Full Text Available Magnetic shielding inductive fault current limiters with high temperature superconducting tapes are considered as emerging devices that provide technology for the advent of modern power grids. The development of such limiters requires magnetic iron cores and leads to several design challenges regarding the constitutive parts of the limiter, namely the primary and secondary windings. Preliminary tests in a laboratory scale prototype have been carried out considering an assembly designed for simplicity in which the optimization of the magnetic coupling between the primary and secondary was not the main focus. This work addresses the design configuration of an inductive current limiter prototype regarding the assembly of the primary and secondary windings in the core. The prototype is based on a closed magnetic core wound by a primary, built from a normal electric conductor, and a short-circuited secondary, built from first generation superconducting tape. Four different design configurations are considered. Through experimental tests, the performance of such prototype is discussed and compared, in terms of normal and fault operation regimes. The results show that all the configurations assure effective magnetic shielding at normal operation regime, however, at fault operation regime, there are differences among configurations.

  19. A study on DC hybrid three-phase fault current limiting interrupter for a power distribution system

    International Nuclear Information System (INIS)

    Shao, Hongtian; Satoh, Tomoyuki; Yamaguchi, Mitsugi; Fukui, Satoshi; Ogawa, Jun; Satoh, Takao; Ishikawa, Hiroyuki

    2005-01-01

    For the purpose of protecting electric power system, many researches and developments of fault current limiters are being performed. The authors studied a dc hybrid three-phase fault current limiting interrupter (FCLI) composed of a superconducting reactor and an S/N transition element, connected in series each other. The dc hybrid type fault current limiting interrupter can limit a fault current by means of the inductance of high temperature superconducting (HTS) coil together with the normal transition of HTS bulk material (HTSB). In the case of an accident, the normal transition of the bulk material can be accelerated by the magnetic field of the HTS coil. In this paper, the dc hybrid type fault current limiting interrupter for 5.5 km long 6.6 kV-600 A power distribution system is analyzed, and performances of fault current limitation and interruption are confirmed. Moreover, a reclosing operation is discussed for this power distribution system

  20. 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)

  1. Fault current limiter using bulk oxides superconductors

    International Nuclear Information System (INIS)

    Belmont, O.; Ferracci, P.; Porcar, L.; Barbut, J.M.; Tixador, P.; Noudem, J.G.; Bourgault, D.; Tournier, R.

    1998-01-01

    We study the limitation possibilities of bulk Bi high T c materials. For this we test these materials with AC or DC currents above their critical currents. We study particularly the evolution of the voltage with time or with current. The material, the value of the current and the time duration play important parts. For sintered Bi samples the voltage depends only on the current even for values much larger than the critical current. With textured samples the V(I) curves shows an hysteretic behaviour due to a warming up. The textured materials are more interesting than sintered ones in terms of required volume for the current limitation. In both cases the superconductors are in a dissipative state but not in the normal state. This state is nevertheless reached if the dissipated energy inside the sample is sufficient. We have tried to apply a magnetic field on the samples in order to trigger a more effective limitation. The voltage increases but with a limited effect for currents much higher (3-4 times) than the critical zero field current. We think that the dissipative state is due mainly to the grain boundaries which become resistive above the critical current. (orig.)

  2. High voltage fault current limiter having immersed phase coils

    Science.gov (United States)

    Darmann, Francis Anthony

    2014-04-22

    A fault current limiter including: a ferromagnetic circuit formed from a ferromagnetic material and including at least a first limb, and a second limb; a saturation mechanism surrounding a limb for magnetically saturating the ferromagnetic material; a phase coil wound around a second limb; a dielectric fluid surrounding the phase coil; a gaseous atmosphere surrounding the saturation mechanism.

  3. Performance inspection of smart superconducting fault current controller in radial distribution substation through PSCAD/EMTDC simulation

    Energy Technology Data Exchange (ETDEWEB)

    MassoudiFarid, Mehrdad; Shin, Jae Woong; Lee, Ji Ho; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of)

    2013-12-15

    In power grid, in order to level out the generation with demand, up-gradation of the system is occasionally required. This will lead to more fault current levels. However, upgrading all the protection instruments of the system is both costly and extravagant. This issue could be dominated by using Smart Fault Current Controller (SFCC). While the impact of Fault current Limiters (FCL) in various locations has been studied in different situations for years, the performance of SFCC has not been investigated extensively. In this research, SFCC which has adopted the characteristics of a full bridge thyristor rectifier with a superconducting coil is applied to three main locations such as load feeder, Bus-tie position and main feeder location and its behavior is investigated through simulation in presence and absence of small Distributed Generation unit (DG). The results show a huge difference in limiting the fault current when using SFCC.

  4. Analysis on fault current limiting and recovery characteristics of a flux-lock type SFCL with an isolated transformer

    International Nuclear Information System (INIS)

    Ko, Seckcheol; Lim, Sung-Hun; Han, Tae-Hee

    2013-01-01

    Highlights: ► Countermeasure to reduce the power burden of HTSC element consisting of the flux-lock type SFCL was studied. ► The power burden of HTSC element could be decreased by using the isolated transformer. ► The SFCL designed with the additive polarity winding could be confirmed to cause less power burden of the HTSC element. -- Abstract: The flux-lock type superconducting fault current limiter (SFCL) can quickly limit the fault current shortly after the short circuit occurs and recover the superconducting state after the fault removes. However, the superconducting element comprising the flux-lock type SFCL can be destructed when the high fault current passes through the SFCL. Therefore, the countermeasure to control the fault current and protect the superconducting element is required. In this paper, the flux-lock type SFCL with an isolated transformer, which consists of two parallel connected coils on an iron core and the isolated transformer connected in series with one of two coils, was proposed and the short-circuit experimental device to analyze the fault current limiting and the recovery characteristics of the flux-lock type SFCL with the isolated transformer were constructed. Through the short-circuit tests, the flux-lock type SFCL with the isolated transformer was confirmed to perform more effective fault current limiting and recovery operation compared to the flux-lock type SFCL without the isolated transformer from the viewpoint of the quench occurrence and the recovery time of the SFCL

  5. Test results of fault current limiter using YBCO tapes with shunt protection

    Energy Technology Data Exchange (ETDEWEB)

    Baldan, Carlos A; Lamas, Jerika S; Shigue, Carlos Y [Escola de Engenharia de Lorena, EEL USP, Lorena - SP (Brazil); Filho, Ernesto Ruppert, E-mail: cabaldan@gmail.co [Faculdade de Engenharia Eletrica, FEEC Unicamp, Campinas - SP (Brazil)

    2010-06-01

    A Fault Current Limiter (FCL) based on high temperature superconducting elements with four tapes in parallel were designed and tested in 220 V line for a fault current peak between 1 kA to 4 kA. The elements employed second generation (2G) HTS tapes of YBCO coated conductor with stainless steel reinforcement. The tapes were electrically connected in parallel with effective length of 0.4 m per element (16 elements connected in series) constituting a single-phase unit. The FCL performance was evaluated through over-current tests and its recovery characteristics under load current were analyzed using optimized value of the shunt protection. The projected limiting ratio achieved a factor higher than 4 during fault of 5 cycles without degradation. Construction details and further test results will be shown in the paper.

  6. Status of high temperature superconductor cable and fault current limiter projects at American Superconductor

    International Nuclear Information System (INIS)

    Maguire, J.F.; Yuan, J.

    2009-01-01

    This paper will describe the status of three key programs currently underway at American Superconductor Corp. The first program is the LIPA project which is a transmission voltage high temperature superconducting cable program, with funding support from the US Department of Energy. The 600 m cable, capable of carrying 574 MVA, was successfully installed and commissioned in LIPA grid on April 22, 2008. An overview of the project, system level design details and operational data will be provided. In addition, the status of the newly awarded LIPA II project will be described. The second program is Project Hydra, with funding support from the US Department of Homeland Security, to design, develop and demonstrate an HTS cable with fault current limiting functionality. The cable is 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The cable will be permanently installed and energized in Manhattan, New York in 2010. The initial status of Project Hydra will be presented. The final program to be discussed is a transmission voltage, high temperature superconducting fault current limiter funded by the US DOE. The project encompasses the design, construction and test of a 115 kV FCL for power transmission within a time frame of 4-5 years. Installation and testing are planned for a Southern California Edison substation. A project overview and progress under the first phase will be reported.

  7. Status of high temperature superconductor cable and fault current limiter projects at American Superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Maguire, J.F., E-mail: jmaguire@amsc.co [American Superconductor Co., 64 Jackson Road, Devens, MA 01434 (United States); Yuan, J. [American Superconductor Co., 64 Jackson Road, Devens, MA 01434 (United States)

    2009-10-15

    This paper will describe the status of three key programs currently underway at American Superconductor Corp. The first program is the LIPA project which is a transmission voltage high temperature superconducting cable program, with funding support from the US Department of Energy. The 600 m cable, capable of carrying 574 MVA, was successfully installed and commissioned in LIPA grid on April 22, 2008. An overview of the project, system level design details and operational data will be provided. In addition, the status of the newly awarded LIPA II project will be described. The second program is Project Hydra, with funding support from the US Department of Homeland Security, to design, develop and demonstrate an HTS cable with fault current limiting functionality. The cable is 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The cable will be permanently installed and energized in Manhattan, New York in 2010. The initial status of Project Hydra will be presented. The final program to be discussed is a transmission voltage, high temperature superconducting fault current limiter funded by the US DOE. The project encompasses the design, construction and test of a 115 kV FCL for power transmission within a time frame of 4-5 years. Installation and testing are planned for a Southern California Edison substation. A project overview and progress under the first phase will be reported.

  8. Optimum design of matrix fault current limiters using the series resistance connected with shunt coil

    Science.gov (United States)

    Chung, D. C.; Choi, H. S.; Lee, N. Y.; Nam, G. Y.; Cho, Y. S.; Sung, T. H.; Han, Y. H.; Kim, B. S.; Lim, S. H.

    2007-10-01

    In this paper we described the improved design for the matrix fault current limiters (MFCL). To do this, we used thin film-type superconducting elements. therefore it means that we can make the MFCL with minimized size and high switching speed because of the high current density and the high indexing value of superconducting thin film. Also we could minimize the bulky shunt coil using the connection of a series resistance with a shunt coil. Also we could effectively block up a leakage current in shunt coils under no-fault condition and simply control total impedances of a current-limiting part using this method. After we designed an appropriated 1 × 2 basic MFCL module with an applied voltage of 160 V, we enlarged it to a 2 × 2 MFCL module and a 3 × 2 MFCL module where applied voltages were 320 V and 480 V, respectively. Experimental results for our MFCL were reported in terms of various fault currents, variation of series resistance and so on. We think that these methods will be useful in the optimum design of an m × n MFCL.

  9. Optimum design of matrix fault current limiters using the series resistance connected with shunt coil

    International Nuclear Information System (INIS)

    Chung, D.C.; Choi, H.S.; Lee, N.Y.; Nam, G.Y.; Cho, Y.S.; Sung, T.H.; Han, Y.H.; Kim, B.S.; Lim, S.H.

    2007-01-01

    In this paper we described the improved design for the matrix fault current limiters (MFCL). To do this, we used thin film-type superconducting elements. therefore it means that we can make the MFCL with minimized size and high switching speed because of the high current density and the high indexing value of superconducting thin film. Also we could minimize the bulky shunt coil using the connection of a series resistance with a shunt coil. Also we could effectively block up a leakage current in shunt coils under no-fault condition and simply control total impedances of a current-limiting part using this method. After we designed an appropriated 1 x 2 basic MFCL module with an applied voltage of 160 V, we enlarged it to a 2 x 2 MFCL module and a 3 x 2 MFCL module where applied voltages were 320 V and 480 V, respectively. Experimental results for our MFCL were reported in terms of various fault currents, variation of series resistance and so on. We think that these methods will be useful in the optimum design of an m x n MFCL

  10. Status of high temperature superconductor cable and fault current limiter projects at American Superconductor

    Science.gov (United States)

    Maguire, J. F.; Yuan, J.

    2009-10-01

    This paper will describe the status of three key programs currently underway at American Superconductor Corp. The first program is the LIPA project which is a transmission voltage high temperature superconducting cable program, with funding support from the US Department of Energy. The 600 m cable, capable of carrying 574 MVA, was successfully installed and commissioned in LIPA grid on April 22, 2008. An overview of the project, system level design details and operational data will be provided. In addition, the status of the newly awarded LIPA II project will be described. The second program is Project Hydra, with funding support from the US Department of Homeland Security, to design, develop and demonstrate an HTS cable with fault current limiting functionality. The cable is 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The cable will be permanently installed and energized in Manhattan, New York in 2010. The initial status of Project Hydra will be presented. The final program to be discussed is a transmission voltage, high temperature superconducting fault current limiter funded by the US DOE. The project encompasses the design, construction and test of a 115 kV FCL for power transmission within a time frame of 4-5 years. Installation and testing are planned for a Southern California Edison substation. A project overview and progress under the first phase will be reported.

  11. A novel concept of fault current limiter based on saturable core in high voltage DC transmission system

    Science.gov (United States)

    Yuan, Jiaxin; Zhou, Hang; Gan, Pengcheng; Zhong, Yongheng; Gao, Yanhui; Muramatsu, Kazuhiro; Du, Zhiye; Chen, Baichao

    2018-05-01

    To develop mechanical circuit breaker in high voltage direct current (HVDC) system, a fault current limiter is required. Traditional method to limit DC fault current is to use superconducting technology or power electronic devices, which is quite difficult to be brought to practical use under high voltage circumstances. In this paper, a novel concept of high voltage DC transmission system fault current limiter (DCSFCL) based on saturable core was proposed. In the DCSFCL, the permanent magnets (PM) are added on both up and down side of the core to generate reverse magnetic flux that offset the magnetic flux generated by DC current and make the DC winding present a variable inductance to the DC system. In normal state, DCSFCL works as a smoothing reactor and its inductance is within the scope of the design requirements. When a fault occurs, the inductance of DCSFCL rises immediately and limits the steepness of the fault current. Magnetic field simulations were carried out, showing that compared with conventional smoothing reactor, DCSFCL can decrease the high steepness of DC fault current by 17% in less than 10ms, which verifies the feasibility and effectiveness of this method.

  12. 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)

  13. Comparison of the quench and fault current limiting characteristics of the flux-coupling type SFCL with single and three-phase transformer

    Science.gov (United States)

    Jung, Byung Ik; Cho, Yong Sun; Park, Hyoung Min; Chung, Dong Chul; Choi, Hyo Sang

    2013-01-01

    The South Korean power grid has a network structure for the flexible operation of the system. The continuously increasing power demand necessitated the increase of power facilities, which decreased the impedance in the power system. As a result, the size of the fault current in the event of a system fault increased. As this increased fault current size is threatening the breaking capacity of the circuit breaker, the main protective device, a solution to this problem is needed. The superconducting fault current limiter (SFCL) has been designed to address this problem. SFCL supports the stable operation of the circuit breaker through its excellent fault-current-limiting operation [1-5]. In this paper, the quench and fault current limiting characteristics of the flux-coupling-type SFCL with one three-phase transformer were compared with those of the same SFCL type but with three single-phase transformers. In the case of the three-phase transformers, both the superconducting elements of the fault and sound phases were quenched, whereas in the case of the single-phase transformer, only that of the fault phase was quenched. For the fault current limiting rate, both cases showed similar rates for the single line-to-ground fault, but for the three-wire earth fault, the fault current limiting rate of the single-phase transformer was over 90% whereas that of the three-phase transformer was about 60%. It appears that when the three-phase transformer was used, the limiting rate decreased because the fluxes by the fault current of each phase were linked in one core. When the power loads of the superconducting elements were compared by fault type, the initial (half-cycle) load was great when the single-phase transformer was applied, whereas for the three-phase transformer, its power load was slightly lower at the initial stage but became greater after the half fault cycle.

  14. Comparison of the quench and fault current limiting characteristics of the flux-coupling type SFCL with single and three-phase transformer

    International Nuclear Information System (INIS)

    Jung, Byung Ik; Cho, Yong Sun; Park, Hyoung Min; Chung, Dong Chul; Choi, Hyo Sang

    2013-01-01

    Highlight: ► Comparison of quench and fault-current-limiting behavior of SFCLs by Tr type. -- Abstract: The South Korean power grid has a network structure for the flexible operation of the system. The continuously increasing power demand necessitated the increase of power facilities, which decreased the impedance in the power system. As a result, the size of the fault current in the event of a system fault increased. As this increased fault current size is threatening the breaking capacity of the circuit breaker, the main protective device, a solution to this problem is needed. The superconducting fault current limiter (SFCL) has been designed to address this problem. SFCL supports the stable operation of the circuit breaker through its excellent fault-current-limiting operation [1–5]. In this paper, the quench and fault current limiting characteristics of the flux-coupling-type SFCL with one three-phase transformer were compared with those of the same SFCL type but with three single-phase transformers. In the case of the three-phase transformers, both the superconducting elements of the fault and sound phases were quenched, whereas in the case of the single-phase transformer, only that of the fault phase was quenched. For the fault current limiting rate, both cases showed similar rates for the single line-to-ground fault, but for the three-wire earth fault, the fault current limiting rate of the single-phase transformer was over 90% whereas that of the three-phase transformer was about 60%. It appears that when the three-phase transformer was used, the limiting rate decreased because the fluxes by the fault current of each phase were linked in one core. When the power loads of the superconducting elements were compared by fault type, the initial (half-cycle) load was great when the single-phase transformer was applied, whereas for the three-phase transformer, its power load was slightly lower at the initial stage but became greater after the half fault cycle

  15. A novel and smart design of superconducting fault current controller : implementation and verification for various fault condition

    NARCIS (Netherlands)

    Babar, M.; Al-Ammar, E.A.

    2013-01-01

    By the advent of the Smart Grid and integration of distributed generators, electrical networks are facing uncountable challenges. The existing protection schemes that simply limit the fault current to the predetermined set values may not perform optimally, and even the existing protection

  16. Fault current limitation with HTc superconductors; Limitation de courant a partir de materiaux supraconducteurs HTc

    Energy Technology Data Exchange (ETDEWEB)

    Buzon, D.

    2002-09-15

    This report deals with the possibility of using high critical temperature (HTc) superconductors for current limitation. The transition from a superconductive to a high dissipative state could be used to limit inrush currents. This application of superconductivity is very attractive because it's an innovative device for electrical networks without any conventional equivalence at high voltage. This device would allow to improve the density of connections and the continuity of the electrical distribution. This study can be divided into two fields. The aim of the first one is to analyse the behaviour of different HTc superconductors for current limitation. We carried out experimental measurements to characterise those conductors during a nominal AC rating (measurements of losses) and during a fault setting. Particularly, a description of the transition in bulk textured YBCO samples near Tc was made of inhomogeneous transition of the device and to estimate its losses. Finally, a 1 kV / 100 A demonstrator made of 43 meanders of textured YBCO was tested at 90,5 K. Thermal gradients seem to be responsible of the altering of some of the samples. The other part of this study concerns the dynamic of the transition. Near Tc, our experiments showed that the transition is more homogeneous. Experimental measurements also showed the influence of thermal exchanges with the cryogenic surrounding on the transition. This point can be justified if the dissipated energy is locally concentrated. (author)

  17. Fault current limitation with HTc superconductors; Limitation de courant a partir de materiaux supraconducteurs HTc

    Energy Technology Data Exchange (ETDEWEB)

    Buzon, D

    2002-09-15

    This report deals with the possibility of using high critical temperature (HTc) superconductors for current limitation. The transition from a superconductive to a high dissipative state could be used to limit inrush currents. This application of superconductivity is very attractive because it's an innovative device for electrical networks without any conventional equivalence at high voltage. This device would allow to improve the density of connections and the continuity of the electrical distribution. This study can be divided into two fields. The aim of the first one is to analyse the behaviour of different HTc superconductors for current limitation. We carried out experimental measurements to characterise those conductors during a nominal AC rating (measurements of losses) and during a fault setting. Particularly, a description of the transition in bulk textured YBCO samples near Tc was made of inhomogeneous transition of the device and to estimate its losses. Finally, a 1 kV / 100 A demonstrator made of 43 meanders of textured YBCO was tested at 90,5 K. Thermal gradients seem to be responsible of the altering of some of the samples. The other part of this study concerns the dynamic of the transition. Near Tc, our experiments showed that the transition is more homogeneous. Experimental measurements also showed the influence of thermal exchanges with the cryogenic surrounding on the transition. This point can be justified if the dissipated energy is locally concentrated. (author)

  18. Improvement of Protection Coordination for a Distribution System Connected to a Microgrid using Unidirectional Fault Current Limiter

    Directory of Open Access Journals (Sweden)

    Mazen Abdel-Salam

    2017-09-01

    Full Text Available The presence of distributed generation (DG units in distribution systems increases the fault current level, which disrupts the existing coordination time interval of the protective overcurrent relays. One of the ways for decreasing DG effects on the coordination of protective devices is re-coordination of the relays by installing unidirectional fault current limiter (UFCL between the main grid (upstream network and the microgrid (downstream network. The UFCL does not limit fault current contribution of the upstream network when fault occurs in downstream but limits fault current contribution of the downstream network when fault occurs in the upstream. Moreover, it preserves the coordination between all of the relays. Several case studies are carried out for illustrating the performance of the UFCL in maintaining the relay coordination.

  19. A dulal-functional medium voltage level DVR to limit downstream fault currents

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Li, Yun Wei; Vilathgamuwa, D. Mahinda

    2007-01-01

    on the other parallel feeders connected to PCC. Furthermore, if not controlled properly, the DVR might also contribute to this PCC voltage sag in the process of compensating the missing voltage, thus further worsening the fault situation. To limit the flow of large line currents, and therefore restore the PCC...... situations. Controlling the DVR as a virtual inductor would also ensure zero real power absorption during the DVR compensation and thus minimize the stress in the dc link. Finally, the proposed fault current limiting algorithm has been tested in Matlab/Simulink simulation and experimentally on a medium......The dynamic voltage restorer (DVR) is a modern custom power device used in power distribution networks to protect consumers from sudden sags (and swells) in grid voltage. Implemented at medium voltage level, the DVR can be used to protect a group of medium voltage or low voltage consumers. However...

  20. Progress in American Superconductor’s HTS wire and optimization for fault current limiting systems

    Energy Technology Data Exchange (ETDEWEB)

    Malozemoff, Alexis P., E-mail: amalozemoff@amsc.com

    2016-11-15

    Highlights: • AMSC HTS wire critical current needed for rotating machinery is doubled by 16 MeV Au irradiation. • Nonuniformity of HTS wires in power devices causes hot spot formation during power system faults. • Lower normal-state resistivity and critical current lower HTS wire hot spot heating during faults. • HTS wire hot spot heating in HTS cables during faults must stay below lN{sub 2} bubble nucleation point. • HTS wire can be designed to meet hot spot heating limits in fault current limiting cables. - Abstract: American Superconductor has developed composite coated conductor tape-shaped wires using high temperature superconductor (HTS) on a flexible substrate with laminated metal stabilizer. Such wires enable many applications, each requiring specific optimization. For example, coils for HTS rotating machinery require increased current density J at 25–50 K. A collaboration with Argonne, Brookhaven and Los Alamos National Laboratories and several universities has increased J using an optimized combination of precipitates and ion irradiation defects in the HTS. Major commercial opportunities also exist to enhance electric power grid resiliency by linking substations with distribution-voltage HTS power cables [10]. Such links provide alternative power sources if one substation's transmission-voltage power is compromised. But they must also limit fault currents which would otherwise be increased by such distribution-level links. This can be done in an HTS cable, exploiting the superconductor-to-resistive transition when current exceeds the wires’ critical J. A key insight is that such transitions are usually nonuniform; so the wire must be designed to prevent localized hot spots from damaging the wire or even generating gas bubbles in the cable causing dielectric breakdown. Analysis shows that local heating can be minimized by increasing the composite tape's total thickness, decreasing its total resistance in the normal state and

  1. AC over-current test results of YBCO conductor for YBCO power transformer with fault current limiting function

    International Nuclear Information System (INIS)

    Tomioka, A.; Otonari, T.; Ogata, T.; Iwakuma, M.; Okamoto, H.; Hayashi, H.; Iijima, Y.; Saito, T.; Gosho, Y.; Tanabe, K.; Izumi, T.; Shiohara, Y.

    2011-01-01

    The single-layer coils with a diameter of 250 mm and 12 turns were manufactured with YBCO tapes with a CuNi- or Cu-Tape. The AC over-current tests were carried out in subcooled liquid nitrogen at 66 K and 74 K to develop power transformers with current limiting function. The AC over-current was two to seven times larger than the I c of conductor and it was reduced to the same level of I c . The I c of model coils did not degrade. The test results showed the possibility of YBCO superconducting transformers with current limiting function. We are developing elemental technology for 66 kV/6.9 kV 20 MVA-class YBCO power transformer. The YBCO transformer is considered to have a possibility to stabilize the power system by improving function of fault current limiting. Current limiting behavior functions over critical current flows. There is a possibility that superconducting characteristic may be damaged due to increase in temperature of YBCO tapes. Therefore, we have taken a measure to combine YBCO tape with CuNi tape or Cu Tape. We manufactured model coils using these conductors and conducted the AC over-current tests. The test current was two to seven times larger than the I c of conductor and it was damped with time from its maximum value according to the generation of conductor resistance. We verified the effectiveness of current limiting characteristics. In these tests, the I c of model coil did not degrade. We consider this conductor to be able to withstand AC over-current with the function of current limiting.

  2. Development and Testing of a Transmission Voltage SuperLimiter™ Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Romanosky, Walter [American Superconductor Corporation, Devens, MA (United States)

    2012-09-01

    This report summarizes work by American Superconductor (AMSC), Los Alamos National Laboratory (LANL), Nexans, Siemens and Southern California Edison on a 138kV resistive type high temperature superconductor (HTS) fault current limiter (FCL) under a cooperative agreement with the U.S. Department of Energy (DOE). Phase 1A encompassed core technology development and system design and was previously reported (see summary that follows in Section 1.1 of the Introduction). This report primarily discusses work performed during Phase 1B, and addresses the fabrication and test of a single-phase prototype FCL. The results are presented along with a discussion of requirements/specifications and lessons learned to aid future development and product commercialization.

  3. Analysis of a flux-coupling type superconductor fault current limiter with pancake coils

    Science.gov (United States)

    Liu, Shizhuo; Xia, Dong; Zhang, Zhifeng; Qiu, Qingquan; Zhang, Guomin

    2017-10-01

    The characteristics of a flux-coupling type superconductor fault current limiter (SFCL) with pancake coils are investigated in this paper. The conventional double-wound non-inductive pancake coil used in AC power systems has an inevitable defect in Voltage Sourced Converter Based High Voltage DC (VSC-HVDC) power systems. Due to its special structure, flashover would occur easily during the fault in high voltage environment. Considering the shortcomings of conventional resistive SFCLs with non-inductive coils, a novel flux-coupling type SFCL with pancake coils is carried out. The module connections of pancake coils are performed. The electromagnetic field and force analysis of the module are contrasted under different parameters. To ensure proper operation of the module, the impedance of the module under representative operating conditions is calculated. Finally, the feasibility of the flux-coupling type SFCL in VSC-HVDC power systems is discussed.

  4. Reliability analysis of component-level redundant topologies for solid-state fault current limiter

    Science.gov (United States)

    Farhadi, Masoud; Abapour, Mehdi; Mohammadi-Ivatloo, Behnam

    2018-04-01

    Experience shows that semiconductor switches in power electronics systems are the most vulnerable components. One of the most common ways to solve this reliability challenge is component-level redundant design. There are four possible configurations for the redundant design in component level. This article presents a comparative reliability analysis between different component-level redundant designs for solid-state fault current limiter. The aim of the proposed analysis is to determine the more reliable component-level redundant configuration. The mean time to failure (MTTF) is used as the reliability parameter. Considering both fault types (open circuit and short circuit), the MTTFs of different configurations are calculated. It is demonstrated that more reliable configuration depends on the junction temperature of the semiconductor switches in the steady state. That junction temperature is a function of (i) ambient temperature, (ii) power loss of the semiconductor switch and (iii) thermal resistance of heat sink. Also, results' sensitivity to each parameter is investigated. The results show that in different conditions, various configurations have higher reliability. The experimental results are presented to clarify the theory and feasibility of the proposed approaches. At last, levelised costs of different configurations are analysed for a fair comparison.

  5. A Secondary-Control Based Fault Current Limiter for Four-Wire Three Phase Inverter-Interfaced DGs

    DEFF Research Database (Denmark)

    Beheshtaein, Siavash; Savaghebi, Mehdi; Guerrero, Josep M.

    2017-01-01

    Fault current limiters (FCLs) are one class of solutions to cope with the upcoming challenges in microgrid protection. Considering high penetration of distributed generations (DGs) in microgrids, the necessity of designing cheap and effective FCL is getting higher. This paper attempts to fill thi...

  6. Development of a prototype solid state fault current limiting and interrupting device for low voltage distribution networks.

    OpenAIRE

    Ahmed, M.; Putrus, G. A.; Ran, L.; Penlington, R.

    2006-01-01

    This paper describes the development of a solid-state Fault Current Limiting and Interrupting Device (FCLID) suitable for low voltage distribution networks. The main components of the FCLID are a bidirectional semiconductor switch that can disrupt the short-circuit current, and a voltage clamping element that helps in controlling the current and absorbing the inductive energy stored in the network during current interruption. Using a hysteresis type control algorithm, the short-circuit curren...

  7. Fault Ride Through Capability Enhancement of a Large-Scale PMSG Wind System with Bridge Type Fault Current Limiters

    Directory of Open Access Journals (Sweden)

    ALAM, M. S.

    2018-02-01

    Full Text Available In this paper, bridge type fault current limiter (BFCL is proposed as a potential solution to the fault problems of permanent magnet synchronous generator (PMSG based large-scale wind energy system. As PMSG wind system is more vulnerable to disturbances, it is essential to guarantee the stability during severe disturbances by enhancing the fault ride through capability. BFCL controller has been designed to insert resistance and inductance during the inception of system disturbances in order to limit fault current. Constant capacitor voltage has been maintained by the grid voltage source converter (GVSC controller while current extraction or injection has been achieved by machine VSC (MVSC controller. Symmetrical and unsymmetrical faults have been applied in the system to show the effectiveness of the proposed BFCL solution. PMSG wind system, BFCL and their controllers have been implemented by real time hardware in loop (RTHIL setup with real time digital simulator (RTDS and dSPACE. Another significant feature of this work is that the performance of the proposed BFCL is compared with that of series dynamic braking resistor (SDBR. Comparative RTHIL implementation results show that the proposed BFCL is very efficient in improving system fault ride through capability by limiting the fault current and outperforms SDBR.

  8. Fault ride-through enhancement of fixed speed wind turbine using bridge-type fault current limiter

    Directory of Open Access Journals (Sweden)

    Mostafa I. Marei

    2016-05-01

    Full Text Available The interaction between wind energy turbines and the grid results in two main problems, increasing the short-circuit level and reducing the Fault Ride-Through (FRT capability during faults. The objective of this paper is to solve these problems, for fixed speed Wind Energy Systems (WECS, utilizing the bridge-type Fault Current Limiter (FCL with a discharging resistor. A simple cascaded control system is proposed for the FCL to regulate the terminal voltage of the generator and limit the current. The system is simulated on PSCAD/EMTDC software to evaluate the dynamic performance of the proposed WECS compensated by FCL. The simulation results show the potentials of the FCL as a simple and effective method for solving grid interconnection problems of WECS.

  9. A study on the short-circuit test by fault angle control and the recovery characteristics of the fault current limiter using coated conductor

    International Nuclear Information System (INIS)

    Park, D.K.; Kim, Y.J.; Ahn, M.C.; Yang, S.E.; Seok, B.-Y.; Ko, T.K.

    2007-01-01

    Superconducting fault current limiters (SFCLs) have been developed in many countries, and they are expected to be used in the recent electric power systems, because of their great efficiency for operating these power system stably. It is necessary for resistive FCLs to generate resistance immediately and to have a fast recovery characteristic after the fault clearance, because of re-closing operation. Short-circuit tests are performed to obtained current limiting operational and recovery characteristics of the FCL by a fault controller using a power switching device. The power switching device consists of anti-parallel connected thyristors. The fault occurs at the desired angle by controlling the firing angle of thyristors. Resistive SFCLs have different current limiting characteristics with respect to the fault angle in the first swing during the fault. This study deals with the short-circuit characteristic of FCL coils using two different YBCO coated conductors (CCs), 344 and 344s, by controlling the fault angle and experimental studies on the recovery characteristic by a small current flowing through the SFCL after the fault clearance. Tests are performed at various voltages applied to the SFCL in a saturated liquid nitrogen cooling system

  10. The short-circuit test results of 6.9 kV/2.3 kV 400 kVA-class YBCO model transformer with fault current limiting function

    International Nuclear Information System (INIS)

    Tomioka, A.; Bohno, T.; Kakami, S.; Isozaki, M.; Watanabe, K.; Toyama, K.; Sugiyama, S.; Konno, M.; Gosho, Y.; Okamoto, H.; Hayashi, H.; Tsutsumi, T.; Iwakuma, M.; Saito, T.; Tanabe, K.; Shiohara, Y.

    2013-01-01

    Highlights: ► We manufactured the 400 kV A-class YBCO model transformer with FCL function. ► Short-circuit test was performed by applying 6.9 kV on primary side. ► The short-circuit current was limited to 174 A for a prospective current of 559 A. ► It agreed with the design and we also confirmed the I c did not degrade. ► The results suggest the possibility to design YBCO transformers with FCL function. -- Abstract: We are developing an elemental technology for 66/6.9 kV 20 MVA-class superconducting power transformer with fault current limiting function. In order to obtain the characteristics of YBCO conductor when the AC over current supplied to the conductor, the model coils were manufactured with YBCO tapes and tested. Based on these results, we manufactured the 6.9 kV/2.3 kV 400 kVA-class YBCO model transformer with fault current limiting function and performed short-circuit test. At the 0.25 s after short-circuit, the short-circuit current of primary winding was limited to about 174 A for a prospective current of 559 A. It was consistent with the design. The I–V characteristics of the winding did not change before and after the test. We consider the model transformer to be able to withstand AC over-current with the function of current limiting. The results suggest the possibility to design YBCO superconducting transformers with fault current limiting function for practical power grid

  11. Optimal Placement and Sizing of Fault Current Limiters in Distributed Generation Systems Using a Hybrid Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    N. Bayati

    2017-02-01

    Full Text Available Distributed Generation (DG connection in a power system tends to increase the short circuit level in the entire system which, in turn, could eliminate the protection coordination between the existing relays. Fault Current Limiters (FCLs are often used to reduce the short-circuit level of the network to a desirable level, provided that they are dully placed and appropriately sized. In this paper, a method is proposed for optimal placement of FCLs and optimal determination of their impedance values by which the relay operation time, the number and size of the FCL are minimized while maintaining the relay coordination before and after DG connection. The proposed method adopts the removal of low-impact FCLs and uses a hybrid Genetic Algorithm (GA optimization scheme to determine the optimal placement of FCLs and the values of their impedances. The suitability of the proposed method is demonstrated by examining the results of relay coordination in a typical DG network before and after DG connection.

  12. Development of Bulk Bi2+xSr3-yCa yCu 2O8+delta Superconductors by Partial-Melting Route for Fault Current Limiters Application

    Directory of Open Access Journals (Sweden)

    Bojan A. Marinkovic

    2002-06-01

    Full Text Available The production of bulk Bi2+xSr3-yCa yCu 2O8+delta (Bi-2212 superconductors for fault current limiter application was developed via a partial-melting route. Aiming high Ic (critical current, which is the essential superconducting characteristic for application of this material in the construction of Fault Current Limiters (FCL, the produced blocks have predominance of Bi-2212 phase (83 wt%, which characterizes with high values of zero and onset transport critical temperature of 92K and 97.5K, respectively. A relatively low transition width, deltaT, from the superconducting to the normal state of 5.5K, revealed a good intergrain connectivity. Consequently, current measurements on the blocks of Bi-2212 show promising Ic values of 230A and 850A for direct and alternate current, respectively. It is expected that further increases in the Ic values will depend on the elimination of an observed amorphous phase and further reduction of amount and grain sizes of secondary phases, still present in the blocks obtained by the proposed partial-melting route. This may be achieved by a further optimization of the partial-melting processing parameters.

  13. 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

  14. Fault Ride-through Capability Enhancement of Voltage Source Converter-High Voltage Direct Current Systems with Bridge Type Fault Current Limiters

    Directory of Open Access Journals (Sweden)

    Md Shafiul Alam

    2017-11-01

    Full Text Available This paper proposes the use of bridge type fault current limiters (BFCLs as a potential solution to reduce the impact of fault disturbance on voltage source converter-based high voltage DC (VSC-HVDC systems. Since VSC-HVDC systems are vulnerable to faults, it is essential to enhance the fault ride-through (FRT capability with auxiliary control devices like BFCLs. BFCL controllers have been developed to limit the fault current during the inception of system disturbances. Real and reactive power controllers for the VSC-HVDC have been developed based on current control mode. DC link voltage control has been achieved by a feedback mechanism such that net power exchange with DC link capacitor is zero. A grid-connected VSC-HVDC system and a wind farm integrated VSC-HVDC system along with the proposed BFCL and associated controllers have been implemented in a real time digital simulator (RTDS. Symmetrical three phase as well as different types of unsymmetrical faults have been applied in the systems in order to show the effectiveness of the proposed BFCL solution. DC link voltage fluctuation, machine speed and active power oscillation have been greatly suppressed with the proposed BFCL. Another significant feature of this work is that the performance of the proposed BFCL in VSC-HVDC systems is compared to that of series dynamic braking resistor (SDBR. Comparative results show that the proposed BFCL is superior over SDBR in limiting fault current as well as improving system fault ride through (FRT capability.

  15. An improved low-voltage ride-through performance of DFIG based wind plant using stator dynamic composite fault current limiter.

    Science.gov (United States)

    Gayen, P K; Chatterjee, D; Goswami, S K

    2016-05-01

    In this paper, an enhanced low-voltage ride-through (LVRT) performance of a grid connected doubly fed induction generator (DFIG) has been presented with the usage of stator dynamic composite fault current limiter (SDCFCL). This protection circuit comprises of a suitable series resistor-inductor combination and parallel bidirectional semiconductor switch. The SDCFCL facilitates double benefits such as reduction of rotor induced open circuit voltage due to increased value of stator total inductance and concurrent increase of rotor impedance. Both effects will limit rotor circuit over current and over voltage situation more secured way in comparison to the conventional scheme like the dynamic rotor current limiter (RCL) during any type of fault situation. The proposed concept is validated through the simulation study of the grid integrated 2.0MW DFIG. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Study on Application of New Approach of Fault Current Limiters in Fault Ride through Capability Improvement of DFIG Based Wind Turbine

    DEFF Research Database (Denmark)

    Naderi, Seyed Behzad; Davari, Pooya; Zhou, Dao

    2018-01-01

    Due to salient advantages, Doubly-Fed Induction Generator (DFIG) has more application in power network compared to Fixed Speed Wind Turbine. Because of employing back-to-back converters, one of the important studies regarding new grid code requirements is Fault Ride-Through (FRT) capability....... The proposed FCL can insert a controllable resistance in fault current pass to not only restrict fault current level and compensate voltage sag in the stator but also consume pre-fault output active power of the DFIG regarding wind speed variation. Simulation results and analytics are presented to prove...

  17. 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.)

  18. 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

  19. Fullerides - Superconductivity at the limit

    NARCIS (Netherlands)

    Palstra, Thomas T. M.

    The successful synthesis of highly crystalline Cs3C60, exhibiting superconductivity up to a record temperature for fullerides of 38 K, demonstrates a powerful synthetic route for investigating the origin of superconductivity in this class of materials.

  20. Superconducting magnetic energy storage, possibilities and limitations

    International Nuclear Information System (INIS)

    Bace, M.; Knapp, V.

    1981-01-01

    Energy storage is of great importance for the exploitation of new energy sources as well as for the better utilisation of conventional ones. Several proposals in recent years have suggested that superconducting magnets could be used as energy storage in large electricity networks. It is a purpose of this note to point out that the requirements which have to be met by energy storage in a large electricity network place serious limitation on the possible use of superconducting energy storage. (author)

  1. 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.

  2. 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.

  3. Developments of engineering applications of superconductivity at IRD

    International Nuclear Information System (INIS)

    Appleton, A.D.

    1982-01-01

    The current status of research and development in the fields of superconducting dc motors, ac generators and fault current limiters at International Research and Development Co Ltd is described. (U.K.)

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Analysis of performance limitations for superconducting cavities

    International Nuclear Information System (INIS)

    J. R. Delayen; L. R. Doolittle; C. E. Reece

    1998-01-01

    The performance of superconducting cavities in accelerators can be limited by several factors, such as: field emission, quenches, arcing, rf power; and the maximum gradient at which a cavity can operate will be determined by the lowest of these limitations for that particular cavity. The CEBAF accelerator operates with over 300 cavities and, for each of them, the authors have determined the maximum operating gradient and its limiting factor. They have developed a model that allows them to determine the distribution of gradients that could be achieved for each of these limitations independently of the others. The result of this analysis can guide an R and D program to achieve the best overall performance improvement. The same model can be used to relate the performance of single-cell and multi-cell cavities

  9. Pressure support for limiting strain in a superconducting winding

    International Nuclear Information System (INIS)

    Marston, P.G.; Nolan, J.J.

    1978-01-01

    A pressure support unit is described for limiting strain in a superconducting winding including a restraining member surrounding the superconducting winding; and a pressure compartment, having at least one segment for receiving pressurized fluid, disposed between the superconducting winding and the restraining member; and a pressure support system comprising a plurality of such pressure support units

  10. Study on current limiting characteristics of SFCL with two trigger current levels

    International Nuclear Information System (INIS)

    Lim, S.H.

    2010-01-01

    In this paper, the superconducting fault current limiter (SFCL) with two trigger current levels was suggested and its effectiveness through the analysis on the current limiting characteristics was described. The proposed SFCL, which consists of the triggering and the limiting components, can limit the fault current by generating the limiting impedance through two steps according to the amplitude of the initial fault current. In case that the fault happens, the lower initial fault current causes the only superconducting element of the triggering component to be quenched. On the other hand, the higher initial fault current makes both the superconducting elements comprising the triggering and the limiting components of the SFCL to be quenched, which contributes to the higher impedance of the SFCL. Therefore, the effective fault current limiting operation of the SFCL can be performed by generating the SFCL's impedance in proportion to the amplitude of the initial fault current. To confirm the current limiting operation of the proposed SFCL, the short-circuit tests of the SFCL according to the fault angle were carried out and its effective fault current limiting operations could be discussed.

  11. 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.

  12. Vacuum physics analysis of HT-7 superconducting tokamak pump limiter

    International Nuclear Information System (INIS)

    Hu Jiansheng; Li Chengfu; He Yexi

    1998-10-01

    The pump limiter is analysed with HT-7 superconducting tokamak parameter and the pump limiter construction. The particle exhaust of the pump limiter can be to achieve about 7.7%. So the pump limiter can be applied in the HT-7 device and will make good affection in plasma discharge

  13. FCL: A solution to fault current problems in DC networks

    International Nuclear Information System (INIS)

    Cointe, Y; Tixador, P; Villard, C

    2008-01-01

    Within the context of the electric power market liberalization, DC networks have many interests compared to AC ones. New energy landscapes open the way of a diversified production. Innovative interconnection diagrams, in particular using DC buses, are under development. In this case it is not possible to defer the fault current interruption in the AC side. DC fault current cutting remains a difficult problem. FCLs (Fault Current Limiters) enable to limit the current to a preset value, lower than the theoretical short-circuit current. For this application Coated Conductors (CC) offer an excellent opportunity. Due to these promising characteristics we build a test bench and work on the implementation of these materials. The test bench is composed by 10 power amplifiers, to reach 4 kVA in many configurations of current and voltage. We carried out limiting experiments on DyBaCuO CC from EHTS, samples are about five centimeters long and many potential measuring points are pasted on the shunt to estimate the quench homogeneity. Thermal phenomena in FCLs are essential, numerical models are important to calculate the maximum temperatures. To validate these models we measure the CC temperature by depositing thermal sensors (Cu resistance) above the shunt layer and the substrate. An electrical insulation with a low thermal resistivity between the CC and the sensors is necessary. We use a thin layer of Parylene because of its good mechanical and electrical insulation properties at low temperature. The better quench behaviour of CC for temperatures close to the critical temperature has been confirmed. The measurements are in good agreement with simulations, this validates the thermal models

  14. Numerical analysis of the stability of HTS power cable under fault current considering the gaps in the cable

    International Nuclear Information System (INIS)

    Fang, J.; Li, H.F.; Zhu, J.H.; Zhou, Z.N.; Li, Y.X.; Shen, Z.; Dong, D.L.; Yu, T.; Li, Z.M.; Qiu, M.

    2013-01-01

    Highlights: •The equivalent circuit equations and the heat balance equations were established. •The current distributions of the HTS cable under fault current were obtained. •The temperature curves of conductor layers under fault current were obtained. •The effect of the gap liquid nitrogen on the thermal characteristics was studied. -- Abstract: During the operation of a high temperature superconducting power cable in a real grid, the power cable can be impacted inevitably by large fault current. The study on current distribution and thermal characteristics in the cable under fault current is the foundation to analyze its stability. To analyze the operation situation of 110 kV/3 kA class superconducting cable under the fault current of 25 kA rms for 3 s, the equivalent circuit equations and heat balance equations were established. The current distribution curves and the temperature distribution curves were obtained. The liquid nitrogen which exists in the gaps of HTS cable was taken into consideration, the influence of gap liquid nitrogen on the thermal characteristics was investigated. The analysis results can be used to estimate the security and stability of the superconducting cable

  15. Numerical analysis of the stability of HTS power cable under fault current considering the gaps in the cable

    Energy Technology Data Exchange (ETDEWEB)

    Fang, J., E-mail: fangseer@sina.com [School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China); Li, H.F. [School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhu, J.H.; Zhou, Z.N. [China Electric Power Research Institute, Beijing 100192 (China); Li, Y.X.; Shen, Z.; Dong, D.L.; Yu, T. [School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China); Li, Z.M.; Qiu, M. [China Electric Power Research Institute, Beijing 100192 (China)

    2013-11-15

    Highlights: •The equivalent circuit equations and the heat balance equations were established. •The current distributions of the HTS cable under fault current were obtained. •The temperature curves of conductor layers under fault current were obtained. •The effect of the gap liquid nitrogen on the thermal characteristics was studied. -- Abstract: During the operation of a high temperature superconducting power cable in a real grid, the power cable can be impacted inevitably by large fault current. The study on current distribution and thermal characteristics in the cable under fault current is the foundation to analyze its stability. To analyze the operation situation of 110 kV/3 kA class superconducting cable under the fault current of 25 kA{sub rms} for 3 s, the equivalent circuit equations and heat balance equations were established. The current distribution curves and the temperature distribution curves were obtained. The liquid nitrogen which exists in the gaps of HTS cable was taken into consideration, the influence of gap liquid nitrogen on the thermal characteristics was investigated. The analysis results can be used to estimate the security and stability of the superconducting cable.

  16. Applied superconductivity. Handbook on devices and applications. Vol. 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Paul (ed.) [Jena Univ. (Germany). Inst. fuer Festkoerperphysik, AG Tieftemperaturphysik

    2015-07-01

    The both volumes contain the following 12 chapters: 1. Fundamentals; 2. Superconducting Materials; 3. Technology, Preparation, and Characterization (bulk materials, thin films, multilayers, wires, tapes; cooling); 4, Superconducting Magnets; 5. Power Applications (superconducting cables, superconducting current leads, fault current limiters, transformers, SMES and flywheels; rotating machines; SmartGrids); 6. Superconductive Passive Devices (superconducting microwave components; cavities for accelerators; superconducting pickup coils; magnetic shields); 7. Applications in Quantum Metrology (superconducting hot electron bolometers; transition edge sensors; SIS Mixers; superconducting photon detectors; applications at Terahertz frequency; detector readout); 8. Superconducting Radiation and Particle Detectors; 9. Superconducting Quantum Interference (SQUIDs); 10. Superconductor Digital Electronics; 11. Other Applications (Josephson arrays as radiation sources. Tunable microwave devices) and 12. Summary and Outlook (of the superconducting devices).

  17. Applied superconductivity. Handbook on devices and applications. Vol. 1 and 2

    International Nuclear Information System (INIS)

    Seidel, Paul

    2015-01-01

    The both volumes contain the following 12 chapters: 1. Fundamentals; 2. Superconducting Materials; 3. Technology, Preparation, and Characterization (bulk materials, thin films, multilayers, wires, tapes; cooling); 4, Superconducting Magnets; 5. Power Applications (superconducting cables, superconducting current leads, fault current limiters, transformers, SMES and flywheels; rotating machines; SmartGrids); 6. Superconductive Passive Devices (superconducting microwave components; cavities for accelerators; superconducting pickup coils; magnetic shields); 7. Applications in Quantum Metrology (superconducting hot electron bolometers; transition edge sensors; SIS Mixers; superconducting photon detectors; applications at Terahertz frequency; detector readout); 8. Superconducting Radiation and Particle Detectors; 9. Superconducting Quantum Interference (SQUIDs); 10. Superconductor Digital Electronics; 11. Other Applications (Josephson arrays as radiation sources. Tunable microwave devices) and 12. Summary and Outlook (of the superconducting devices).

  18. Radiation-effects limits on copper in superconducting magnets

    Energy Technology Data Exchange (ETDEWEB)

    Guinan, M.W.

    1983-05-25

    The determination of the response of copper stabilizers to neutron irradiation in fusion-reactor superconducting magnets requires information in four areas: (1) neutron flux and spectrum determination, (2) resistivity changes at zero field, (3) resistivity changes at field, and (4) the cyclic irradiation and annealing. Applications of our current understanding of the limits of copper stabilizers in fusion-reactor designs are explored in two examples. Recommendations for future additions to the data base are discussed.

  19. Radiation-effects limits on copper in superconducting magnets

    International Nuclear Information System (INIS)

    Guinan, M.W.

    1983-01-01

    The determination of the response of copper stabilizers to neutron irradiation in fusion-reactor superconducting magnets requires information in four areas: (1) neutron flux and spectrum determination, (2) resistivity changes at zero field, (3) resistivity changes at field, and (4) the cyclic irradiation and annealing. Applications of our current understanding of the limits of copper stabilizers in fusion-reactor designs are explored in two examples. Recommendations for future additions to the data base are discussed

  20. Superconduction in limiting-power synchronous generators. State, lines of development, problems

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzen, H W; Sergl, J

    1976-01-01

    The limiting power of conventional 2-pole rotary current synchronous generators is estimated. The limiting power may be raised by using superconducting materials for the field winding. After a short description of superconductive materials, the construction of a synchronous generator with a superconducting field winding is described. Finally, some problems in calculating the magnetic field and the transient behavior are discussed.

  1. Development of new-concept superconducting power equipment; Shinkino chodendo denryoku kiki no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Hamajima, T.; Tsurunaga, K.; Urata, M. [Toshiba Corp., Tokyo (Japan)

    1998-01-01

    The superconducting magnet energy storage (SMES) system has a function by which magnetic energy is stored in a superconducting coil without loss and discharged very rapidly into the power line when needed. The fault current limiter has a function by which transport current is passed without impedance and excessive fault current is restricted by generating large impedance in an emergency. These are the functions of new power equipment, which can not be realized by the conventional equipment. In the small-scale SMES project, Toshiba has fabricated 100 kWh-class element coils and 1 kWh/1 MW modules as the first step of practical application for power system control. For the superconducting fault current limiter, Toshiba has developed a 6.6 kV-1 kA class fault current limiter without supplying cooling medium such as helium, and limiting tests of fault current have been successfully conducted. Through the long-term tests of element coils for SMES and the system interconnection tests of module-type SMES, it is expected that the technological development for practical application is accelerated. 4 refs., 7 figs., 3 tabs.

  2. Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sung Hun [Dept. of Electrical Engineering, Soongsil University, Seoul (Korea, Republic of); Han, Tae Hee [Dept. of Aero Materials Engineering, Jungwon University, Goesan (Korea, Republic of)

    2017-06-15

    In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

  3. Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

    International Nuclear Information System (INIS)

    Lim, Sung Hun; Han, Tae Hee

    2017-01-01

    In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding

  4. Apparent destruction of superconductivity in the disordered one-dimensional limit

    International Nuclear Information System (INIS)

    Graybeal, J.M.; Mankiewich, P.M.; Dynes, R.C.; Beasley, M.R.

    1987-01-01

    We present the results of a model-system study of the competition between superconductivity and disorder in narrow superconducting wires. As one moves from the two-dimensional regime toward the one-dimensional limit, large and systematic reductions in the superconducting transition temperature are obtained. The observed behavior extrapolates to the total destruction of superconductivity in the disordered one-dimensional limit. Our findings are in clear disagreement with a recent theoretical treatment. In addition, the superconducting fluctuations appear to be modified by disorder for the narrowest samples

  5. Superconductivity

    International Nuclear Information System (INIS)

    Taylor, A.W.B.; Noakes, G.R.

    1981-01-01

    This book is an elementray introduction into superconductivity. The topics are the superconducting state, the magnetic properties of superconductors, type I superconductors, type II superconductors and a chapter on the superconductivity theory. (WL)

  6. Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

    International Nuclear Information System (INIS)

    Khan, Umer Amir; Lee, Jong-Geon; Seo, In-Jin; Amir, Faisal; Lee, Bang-Wook

    2015-01-01

    Highlights: • A novel hybrid-type superconducting circuit breaker (SDCCB) is proposed. • SDCCB has SFCL located in the main current path to limit the fault current until the final trip signal. • SFCL in SDCCB suppressed the fast rising DC fault current for a predefined time. • SFCL significantly reduced the DC current breaking stress on SDCCB components. • SDCCB isolated the HVDC faulty line in three, four, and five converter stations MTDC. - Abstract: Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

  7. Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Umer Amir [Hanyang University, Sa-3dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of); National University of Sciences and Technology, PNEC Campus, Habib Rehmatullah Road, Karachi (Pakistan); Lee, Jong-Geon; Seo, In-Jin [Hanyang University, Sa-3dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of); Amir, Faisal [National University of Sciences and Technology, PNEC Campus, Habib Rehmatullah Road, Karachi (Pakistan); Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr [Hanyang University, Sa-3dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of)

    2015-11-15

    Highlights: • A novel hybrid-type superconducting circuit breaker (SDCCB) is proposed. • SDCCB has SFCL located in the main current path to limit the fault current until the final trip signal. • SFCL in SDCCB suppressed the fast rising DC fault current for a predefined time. • SFCL significantly reduced the DC current breaking stress on SDCCB components. • SDCCB isolated the HVDC faulty line in three, four, and five converter stations MTDC. - Abstract: Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

  8. Superconducting magnetic energy storage (SMES) program, January 1-December 31, 1981

    International Nuclear Information System (INIS)

    Rogers, J.D.

    1982-02-01

    Work reported is on the development of a 30 MJ superconducting magnetic energy storage (SMES) unit for use by the Bonneville Power Administration (BPA) to stabilize power oscillations on their Pacific AC Intertie. The 30 MJ superconducting coil manufacture was completed. Design of the seismic mounting of the coil to the nonconducting dewar lid and a concrete foundation is complete. The superconducting application VAR (SAVAR) control study indicated a low economic advantage and the SAVAR program was terminated. An economic and technological evaluation of superconducting fault current limiter (SFCL) was completed and the results are reported

  9. 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

  10. Radiation effects limits on copper in superconducting magnets

    International Nuclear Information System (INIS)

    Guinan, M.W.

    1984-01-01

    The determination of the response of copper stabilizers to neutron irradiation in fusion reactor superconducting magnets requires information in four areas. (1) Neutron flux and spectrum determination are a major factor in the accuracy with which stabilizer response can be predicted. Since magnet stability depends on the weakest link, calculations must be made in sufficient detail to fully account for steep flux gradients and local pertubations from penetrations. (2) Resistivity changes at zero field in magnet spectra are generally calculated from the damage energy cross-section or the equivalent displacement (dpa) rate. (3) Resistivity changes at field for conceptual designs are generally determined from the changes predicted at zero field by the use of a Kohler plot. The cyclic irradiation and annealing, expected to be characteristic of fusion reactor magnet operation, is presently the largest source of uncertainty in determining the limits of neutron exposure for copper stabilizers. Applications of our current understanding of the limits of copper stabilizers in fusion reactor designs are explored in two examples. Recommendations for future additions to the data base are discussed

  11. Superconductivity

    International Nuclear Information System (INIS)

    Langone, J.

    1989-01-01

    This book explains the theoretical background of superconductivity. Includes discussion of electricity, material fabrication, maglev trains, the superconducting supercollider, and Japanese-US competition. The authors reports the latest discoveries

  12. 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

  13. Determining the Impact of Steady-State PV Fault Current Injections on Distribution Protection

    Energy Technology Data Exchange (ETDEWEB)

    Seuss, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grijalva, Santiago [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    This report investigates the fault current contribution from a single large PV system and the impact it has on existing distribution overcurrent protection devices. Assumptions are made about the modeling of the PV system under fault to perform exhaustive steady - state fault analyses throughout distribution feeder models. Each PV interconnection location is tested to determine how the size of the PV system affects the fault current measured by each protection device. This data is then searched for logical conditions that indicate whether a protection device has operated in a manner that will cause more customer outages due to the addition of the PV system. This is referred to as a protection issue , and there are four unique types of issues that have been identified in the study. The PV system size at which any issues occur are recorded to determine the feeder's PV hosting capacity limitations due to interference with protection settings. The analysis is carried out on six feeder models. The report concludes with a discussion of the prevalence and cause of each protection issue caused by PV system fault current.

  14. 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

  15. 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

  16. 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).

  17. Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

    Science.gov (United States)

    Khan, Umer Amir; Lee, Jong-Geon; Seo, In-Jin; Amir, Faisal; Lee, Bang-Wook

    2015-11-01

    Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

  18. Advanced superconducting power cable for MV urban power supply

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Frank [Nexans Deutschland GmbH, Hannover (Germany); Merschel, Frank [RWE Deutschland AG, Essen (Germany); Noe, Mathias [Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2015-07-01

    In recent years the technology of superconducting power cable systems has progressed such that the technical hurdles preparing for commercial applications have been mastered. Several field tests of large scale prototypes for the applications of superconducting cables as well as superconducting fault current limiters have been successfully accomplished and the technology of such systems is ready for commercialization. The presentation will give a detailed overview of the German AmpaCity project. An overview will be given on the development, manufacturing and installation of the 10 kV, 40 MVA HTS system consisting of a fault current limiter and of a 1 km cable in the city of Essen. Since it is the first time that a one kilometer HTS cable system is installed together with an HTS fault current limiter in a real grid application between two substations within a city center area, AmpaCity serves as a lighthouse project. In addition it is worldwide the longest installed HTS cable system so far. It is expected that relatively large technical advances will be made in the future of the comparatively new HTS technology, which in turn will bring associated cost reductions. For this reason, the AmpaCity pilot project in the downtown area of Essen in Germany will be an important step on the way to achieving more widespread application of HTS technology.

  19. Superconductivity

    International Nuclear Information System (INIS)

    Kakani, S.L.; Kakani, Shubhra

    2007-01-01

    The monograph provides readable introduction to the basics of superconductivity for beginners and experimentalists. For theorists, the monograph provides nice and brief description of the broad spectrum of experimental properties, theoretical concepts with all details, which theorists should learn, and provides a sound basis for students interested in studying superconducting theory at the microscopic level. Special chapter on the theory of high-temperature superconductivity in cuprates is devoted

  20. Fault Current Characteristics of the DFIG under Asymmetrical Fault Conditions

    Directory of Open Access Journals (Sweden)

    Fan Xiao

    2015-09-01

    Full Text Available During non-severe fault conditions, crowbar protection is not activated and the rotor windings of a doubly-fed induction generator (DFIG are excited by the AC/DC/AC converter. Meanwhile, under asymmetrical fault conditions, the electrical variables oscillate at twice the grid frequency in synchronous dq frame. In the engineering practice, notch filters are usually used to extract the positive and negative sequence components. In these cases, the dynamic response of a rotor-side converter (RSC and the notch filters have a large influence on the fault current characteristics of the DFIG. In this paper, the influence of the notch filters on the proportional integral (PI parameters is discussed and the simplified calculation models of the rotor current are established. Then, the dynamic performance of the stator flux linkage under asymmetrical fault conditions is also analyzed. Based on this, the fault characteristics of the stator current under asymmetrical fault conditions are studied and the corresponding analytical expressions of the stator fault current are obtained. Finally, digital simulation results validate the analytical results. The research results are helpful to meet the requirements of a practical short-circuit calculation and the construction of a relaying protection system for the power grid with penetration of DFIGs.

  1. Superconductivity

    International Nuclear Information System (INIS)

    Caruana, C.M.

    1988-01-01

    Despite reports of new, high-temperature superconductive materials almost every day, participants at the First Congress on Superconductivity do not anticipate commercial applications with these materials soon. What many do envision is the discovery of superconducting materials that can function at much warmer, perhaps even room temperatures. Others hope superconductivity will usher in a new age of technology as semiconductors and transistors did. This article reviews what the speakers had to say at the four-day congress held in Houston last February. Several speakers voiced concern that the Reagan administration's apparent lack of interest in funding superconductivity research while other countries, notably Japan, continue to pour money into research and development could hamper America's international competitiveness

  2. Superconductivity

    CERN Document Server

    Ketterson, John B

    2008-01-01

    Conceived as the definitive reference in a classic and important field of modern physics, this extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in the field of superconductivity. Leading researchers, including Nobel laureates, describe the state-of-the-art in conventional and unconventional superconductors at a particularly opportune time, as new experimental techniques and field-theoretical methods have emerged. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued intense research into electron-phone based superconductivity. Considerable attention is devoted to high-Tc superconductivity, novel superconductivity, including triplet pairing in the ruthenates, novel superconductors, such as heavy-Fermion metals and organic materials, and also granular superconductors. What’s more, several contributions address superconductors with impurities and nanostructured superconductors. Important new results on...

  3. Current limiting behavior in three-phase transformer-type SFCLs using an iron core according to variety of fault

    Science.gov (United States)

    Cho, Yong-Sun; Jung, Byung-Ik; Ha, Kyoung-Hun; Choi, Soo-Geun; Park, Hyoung-Min; Choi, Hyo-Sang

    To apply the superconducting fault current limiter (SFCL) to the power system, the reliability of the fault-current-limiting operation must be ensured in diverse fault conditions. The SFCL must also be linked to the operation of the high-speed recloser in the power system. In this study, a three-phase transformer-type SFCL, which has a neutral line to improve the simultaneous quench characteristics of superconducting elements, was manufactured to analyze the fault-current-limiting characteristic according to the single, double, and triple line-to-ground faults. The transformer-type SFCL, wherein three-phase windings are connected to one iron core, reduced the burden on the superconducting element as the superconducting element on the sound phase was also quenched in the case of the single line-to-ground fault. In the case of double or triple line-to-ground faults, the flux from the faulted phase winding was interlinked with other faulted or sound phase windings, and the fault-current-limiting rate decreased because the windings of three phases were inductively connected by one iron core.

  4. Superconductivity

    CERN Document Server

    Poole, Charles P; Creswick, Richard J; Prozorov, Ruslan

    2014-01-01

    Superconductivity, Third Edition is an encyclopedic treatment of all aspects of the subject, from classic materials to fullerenes. Emphasis is on balanced coverage, with a comprehensive reference list and significant graphics from all areas of the published literature. Widely used theoretical approaches are explained in detail. Topics of special interest include high temperature superconductors, spectroscopy, critical states, transport properties, and tunneling. This book covers the whole field of superconductivity from both the theoretical and the experimental point of view. This third edition features extensive revisions throughout, and new chapters on second critical field and iron based superconductors.

  5. The elastic limit of vortex movement in superconducting thin films

    International Nuclear Information System (INIS)

    Doyle, R.A.; Kumar, D.; Pullan, P.; Gross, R.; Campbell, A.M.; Blamire, M.G.; Somekh, R.E.; Evetts, J.E.

    1993-01-01

    Here we report four point ac transport FD measurements on epitaxial YBCO films and also polycrystalline NbTa films. Considerable efforts have recently been put into investigating low T c systems (11) in order to model high Tc materials in which the pinning and other properties are less easily controlled by microstructural modification and in which the parameter values are less well known. Moreover no reports exist of the FD behaviour of low T c thin film systems. In the case of the YBCO films, the results will be seen to be able to be reconciled with IP effects due to the superconducting CuO layers. In the case of the NbTa films, the results are in agreement with extrinsic pinning expected from the columnar defects (grain boundaries) observed in microstructural (SEM) studies (11). The data on all samples suggests core pinning in both (high Κ) systems. Features in the FD curves of the YBCO system when the field is carefully applied parallel to the planes occur at distances corresponding to the interlayer spacing providing direct evidence for IP. The technique also offers the possibility of investigating the frequency dependence of the effect as well as looking for curvature in the FD response below the onset of dissipation in the resistive component. The former study should be able to separate resistive from hysteretic (Bean) type losses whereas the latter might expose information about the shape of the pinning wells in addition to their sizes. These are discussed briefly here but will form the basis of further more detailed study. It will be argued that the FD technique is a powerful approach for investigation of the mixed state, allowing information to be extracted which is unavailable from other techniques. (orig.)

  6. Ultimate Gradient Limitation in Niobium Superconducting Accelerating Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Checchin, Mattia [Illinois Inst. of Technology, Chicago, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Grassellino, Anna [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Martinello, Martina [Illinois Inst. of Technology, Chicago, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Posen, Sam [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Romanenko, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zasadzinski, John [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-06-01

    The present study is addressed to the theoretical description of the ultimate gradient limitation in SRF cavities. Our intent is to exploit experimental data to confirm models which provide feed-backs on how to improve the current state-of-art. New theoretical insight on the cavities limiting factor can be suitable to improve the quench field of N-doped cavities, and therefore to take advantage of high Q0 at high gradients.

  7. Superconductivity

    International Nuclear Information System (INIS)

    Narlikar, A.V.

    1993-01-01

    Amongst the numerous scientific discoveries that the 20th century has to its credit, superconductivity stands out as an exceptional example of having retained its original dynamism and excitement even for more than 80 years after its discovery. It has proved itself to be a rich field by continually offering frontal challenges in both research and applications. Indeed, one finds that a majority of internationally renowned condensed matter theorists, at some point of their career, have found excitement in working in this important area. Superconductivity presents a unique example of having fetched Nobel awards as many as four times to date, and yet, interestingly enough, the field still remains open for new insights and discoveries which could undeniably be of immense technological value. 1 fig

  8. Kinetics-Driven Superconducting Gap in Underdoped Cuprate Superconductors Within the Strong-Coupling Limit

    Directory of Open Access Journals (Sweden)

    Yucel Yildirim

    2011-09-01

    Full Text Available A generic theory of the quasiparticle superconducting gap in underdoped cuprates is derived in the strong-coupling limit, and found to describe the experimental “second gap” in absolute scale. In drastic contrast to the standard pairing gap associated with Bogoliubov quasiparticle excitations, the quasiparticle gap is shown to originate from anomalous kinetic (scattering processes, with a size unrelated to the pairing strength. Consequently, the k dependence of the gap deviates significantly from the pure d_{x^{2}-y^{2}} wave of the order parameter. Our study reveals a new paradigm for the nature of the superconducting gap, and is expected to reconcile numerous apparent contradictions among existing experiments and point toward a more coherent understanding of high-temperature superconductivity.

  9. Superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    This book profiles the research activity of 42 companies in the superconductivity field, worldwide. It forms a unique and comprehensive directory to this emerging technology. For each research site, it details the various projects in progress, analyzes the level of activity, pinpoints applications and R and D areas, reviews strategies and provides complete contact information. It lists key individuals, offers international comparisons of government funding, reviews market forecasts and development timetables and features a bibliography of selected articles on the subject

  10. Superconductivity

    International Nuclear Information System (INIS)

    Buller, L.; Carrillo, F.; Dietert, R.; Kotziapashis, A.

    1989-01-01

    Superconductors are materials which combine the property of zero electric resistance with the capability to exclude any adjacent magnetic field. This leads to many large scale applications such as the much publicized levitating train, generation of magnetic fields in MHD electric generators, and special medical diagnostic equipment. On a smaller-scale, superconductive materials could replace existing resistive connectors and decrease signal delays by reducing the RLC time constants. Thus, a computer could operate at much higher speeds, and consequently at lower power levels which would reduce the need for heat removal and allow closer spacing of circuitry. Although technical advances and proposed applications are constantly being published, it should be recognized that superconductivity is a slowly developing technology. It has taken scientists almost eighty years to learn what they now know about this material and its function. The present paper provides an overview of the historical development of superconductivity and describes some of the potential applications for this new technology as it pertains to the electronics industry

  11. Simulating the effect of SFCL on limiting the internal fault of synchronous machine

    International Nuclear Information System (INIS)

    Kheirizad, I; Varahram, M H; Jahed-Motlagh, M R; Rahnema, M; Mohammadi, A

    2008-01-01

    In this paper, we have modelled a synchronous generator with internal one phase to ground fault and then the performance of this machine with internal one phase to ground fault have been analyzed. The results show that if the faults occur in vicinity of machine's terminal, then we would have serious damages. To protect the machine from this kind of faults we have suggested integrating a SFCL (superconducting fault current limiter) into the machine's model. The results show that the fault currents in this case will reduce considerably without influencing the normal operation of the machine

  12. Microscopic Investigation of Materials Limitations of Superconducting RF Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Anlage, Steven [Univ. of Maryland, College Park, MD (United States)

    2017-08-04

    Our overall goal is to contribute to the understanding of defects that limit the high accelerating gradient performance of Nb SRF cavities. Our approach is to develop a microscopic connection between materials defects and SRF performance. We developed a near-field microwave microscope to establish this connection. The microscope is based on magnetic hard drive write heads, which are designed to create very strong rf magnetic fields in very small volumes on a surface.

  13. Superconducting magnet radiation limit considerations for fusion reactors

    International Nuclear Information System (INIS)

    Sawan, M.E.; Walstrom, P.L.

    1986-01-01

    The radiation limits for fusion reactor magnets have a direct impact on the cost of electricity. For example, reducing the inboard shield by 1 cm saves up to $3 million in the Tokamak Fusion Core Experiment cost. The magnet components most sensitive to radiation damage are the superconductor, stabilizer, and insulators. Nuclear heating in the magnet affects the design and also impacts the economic performance of the reactor through increased refrigeration costs. The radiation effects in the different components of the magnet are related, as all of them are determined by the flux level in the magnet. Hence, in efforts to push radiation limits, these effects should be considered simultaneously. Furthermore, the levels of radiation effects that correspond to the optimum nuclear heating determined from economic trade-off analysis will be useful in specifying the fluence, dose, and stabilization limit goals for the magnet development program. In this paper, we review the available irradiation data and assess the need for achieving higher irradiation levels

  14. Superconductivity

    International Nuclear Information System (INIS)

    2007-01-01

    During 2007, a large amount of the work was centred on the ITER project and related tasks. The activities based on low-temperature superconducting (LTS) materials included the manufacture and qualification of ITER full-size conductors under relevant operating conditions, the design of conductors and magnets for the JT-60SA tokamak and the manufacture of the conductors for the European dipole facility. A preliminary study was also performed to develop a new test facility at ENEA in order to test long-length ITER or DEMO full-size conductors. Several studies on different superconducting materials were also started to create a more complete database of superconductor properties, and also for use in magnet design. In this context, an extensive measurement campaign on transport and magnetic properties was carried out on commercially available NbTi strands. Work was started on characterising MgB 2 wire and bulk samples to optimise their performance. In addition, an intense experimental study was started to clarify the effect of mechanical loads on the transport properties of multi-filamentary Nb 3 Sn strands with twisted or untwisted superconducting filaments. The experimental activity on high-temperature superconducting (HTS) materials was mainly focussed on the development and characterisation of YBa 2 Cu 3 O 7-X (YBCO) based coated conductors. Several characteristics regarding YBCO deposition, current transport performance and tape manufacture were investigated. In the framework of chemical approaches for YBCO film growth, a new method, developed in collaboration with the Technical University of Cluj-Napoca (TUCN), Romania, was studied to obtain YBCO film via chemical solution deposition, which modifies the well-assessed metallic organic deposition trifluoroacetate (MOD-TFA) approach. The results are promising in terms of critical current and film thickness values. YBCO properties in films with artificially added pinning sites were characterised in collaboration with

  15. Analysis on current limiting characteristics of a transformer type SFCL with two triggering current levels

    International Nuclear Information System (INIS)

    Lim, Sung-Hun; Ko, Seckcheol; Han, Tae-Hee

    2013-01-01

    Highlights: ► We suggested the transformer type SFCL with two triggering current levels. ► The short-circuit tests for the suggested SFCL was executed. ► The fault angle as the fault conditions to verify its operation was selected. ► The usefulness of the suggested SFCL was confirmed through the short-circuit test. -- Abstract: In this paper, the transformer type superconducting fault current limiter (SFCL) with two triggering current levels was suggested and its current limiting characteristics were analyzed. The structure of the suggested transformer type SFCL with two triggering current levels largely consists of two parts. One is the transformer with two magnetically coupled coils, which correspond to the primary winding and the secondary one connected with one high-T C superconducting (HTSC) element. The other is third coil, or, another secondary winding with one HTSC element, which is wound on the same iron core together with two coils. This suggested transformer type SFCL can limit the fault current by generating its limiting impedance with two different amplitudes, which are dependent on the initial amplitude of the fault current in case of the fault occurrence. To confirm the usefulness of the proposed SFCL, the current limiting tests of the SFCL according to the fault angle, one of the effective fault conditions to affect the amplitude of the initial fault current, were carried out and its effective limiting operations were discussed

  16. Investigations of current limiting properties of the MgB{sub 2} wires subjected to pulse overcurrents in the benchtop tester

    Energy Technology Data Exchange (ETDEWEB)

    Ye Lin [Interdisciplinary Research Center (IRC) in Superconductivity, Department of Engineering, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Majoros, M [Laboratories for Applied Superconductivity and Magnetism, Ohio State University, Columbus, OH 43210 (United States); Campbell, A M [Interdisciplinary Research Center (IRC) in Superconductivity, Department of Engineering, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Coombs, T [Interdisciplinary Research Center (IRC) in Superconductivity, Department of Engineering, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Harrison, S [Scientific Magnetics, Culham Science Centre, Culham, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Sargent, P [Diboride Conductors Ltd, Cambridge CB1 3QJ (United Kingdom); Haslett, M [Diboride Conductors Ltd, Cambridge CB1 3QJ (United Kingdom); Husband, M [Strategic Research Center (SRC)-Electrical Engineering, Rolls-Royce Plc., Derby DE24 8BJ (United Kingdom)

    2007-04-15

    A laboratory scale desktop test system including a cryogenic system, an AC pulse generation system and a real time data acquisition program in LabView/DAQmx, has been developed to evaluate the quench properties of MgB{sub 2} wires as an element in a superconducting fault current limiter under pulse overcurrents at 25 K in self-field conditions. The MgB{sub 2} samples started from a superconducting state and demonstrated good current limiting properties characterized by a fast transition to the normal state during the first half of the cycle and a continuously limiting effect in the subsequent cycles without burnouts. The experimental and numerical simulation results on the quench behaviour indicate the feasibility of using MgB{sub 2} for future superconducting fault current limiter (SFCL) applications.

  17. Upper critical field of complex superconducting networks in the continuum limit

    International Nuclear Information System (INIS)

    Santhanam, P.; Chi, C.C.

    1988-01-01

    We propose a simple method for calculating the superconducting upper critical field of complex periodic two-dimensional networks in the continuum limit. Two specific lattices with space groups P4gm and C2mm are used to demonstrate this approach. We obtain the result that the ratio of the critical field of these networks to that of a uniform film is close to but larger than 2

  18. Overview of Superconductivity and Challenges in Applications

    CERN Document Server

    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...

  19. Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Batistoni, Paola; De Marco, Francesco; Pieroni, Leonardo [ed.

    2005-07-01

    Research on superconductivity at ENEA is mainly devoted to projects related to the ITER magnet system. In this framework, ENEA has been strongly involved in the design, manufacturing and test campaigns of the ITER toroidal field model coil (TFMC), which reached a world record in operating current (up to 80 kA). Further to this result, the activities in 2004 were devoted to optimising the ITER conductor performance. ENEA participated in the tasks launched by EFDA to define and produce industrial-scale advanced Nb3Sn strand to be used in manufacturing the ITER high-field central solenoid (CS) and toroidal field (TF) magnets. As well as contributing to the design of the new strand and the final conductor layout, ENEA will also perform characterisation tests, addressing in particular the influence of mechanical stress on the Nb3Sn performance. As a member of the international ITER-magnet testing group, ENEA plays a central role in the measurement campaigns and data analyses for each ITER-related conductor and coil. The next phase in the R and D of the ITER magnets will be their mechanical characterisation in order to define the fabrication route of the coils and structures. During 2004 the cryogenic measurement campaign on the Large Hadron Collider (LHC) by-pass diode stacks was completed. As the diode-test activity was the only LHC contract to be finished on schedule, the 'Centre Europeenne pour la Recherche Nucleaire' (CERN) asked ENEA to participate in an international tender for the cold check of the current leads for the LHC magnets. The contract was obtained, and during 2004, the experimental setup was designed and realised and the data acquisition system was developed. The measurement campaign was successfully started at the end of 2004 and will be completed in 2006.

  20. 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.

  1. Proc. of the workshop on pushing the limits of RF superconductivity.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K-J., Eyberger, C., editors

    2005-04-13

    For three days in late September last year, some sixty experts in RF superconductivity from around the world came together at Argonne to discuss how to push the limits of RF superconductivity for particle accelerators. It was an intense workshop with in-depth presentations and ample discussions. There was added excitement due to the fact that, a few days before the workshop, the International Technology Recommendation Panel had decided in favor of superconducting technology for the International Linear Collider (ILC), the next major high-energy physics accelerator project. Superconducting RF technology is also important for other large accelerator projects that are either imminent or under active discussion at this time, such as the Rare Isotope Accelerator (RIA) for nuclear physics, energy recovery linacs (ERLs), and x-ray free-electron lasers. For these accelerators, the capability in maximum accelerating gradient and/or the Q value is essential to limit the length and/or operating cost of the accelerators. The technological progress of superconducting accelerators during the past two decades has been truly remarkable, both in low-frequency structures for acceleration of protons and ions as well as in high-frequency structures for electrons. The requirements of future accelerators demand an even higher level of performance. The topics of this workshop are therefore highly relevant and timely. The presentations given at the workshop contained authoritative reviews of the current state of the art as well as some original materials that previously had not been widely circulated. We therefore felt strongly that these materials should be put together in the form of a workshop proceeding. The outcome is this report, which consists of two parts: first, a collection of the scholarly papers prepared by some of the participants and second, copies of the viewgraphs of all presentations. The presentation viewgraphs, in full color, are also available from the Workshop

  2. Method and apparatus to trigger superconductors in current limiting devices

    Science.gov (United States)

    Yuan, Xing; Hazelton, Drew Willard; Walker, Michael Stephen

    2004-10-26

    A method and apparatus for magnetically triggering a superconductor in a superconducting fault current limiter to transition from a superconducting state to a resistive state. The triggering is achieved by employing current-carrying trigger coil or foil on either or both the inner diameter and outer diameter of a superconductor. The current-carrying coil or foil generates a magnetic field with sufficient strength and the superconductor is disposed within essentially uniform magnetic field region. For superconductor in a tubular-configured form, an additional magnetic field can be generated by placing current-carrying wire or foil inside the tube and along the center axial line.

  3. Comparative study on current limiting characteristics of flux-lock type SFCL with series or parallel connection of two coils

    International Nuclear Information System (INIS)

    Lim, S.H.

    2008-01-01

    We investigated the current limiting characteristics of the flux-lock type superconducting fault current limiter (SFCL) with series or parallel connection of two coils. These two flux-lock type SFCLs with magnetically coupled two coils have the same operational principle that the fault current can be limited by the magnetic flux generated between two coils of the SFCL when a fault happens. In addition, the inductance ratio and the winding direction of two coils in both the SFCLs are the major design parameters that affect the fault current limiting characteristics of the SFCL. On the other hand, the operational current and the limiting impedance of both the SFCLs under the same design condition have the different tendency, which results from the different winding methods of two coils on an iron core. Therefore, the comparative study for both the SFCLs from the current limiting performance of the SFCL point of view is needed. To compare the current limiting characteristics of both the SFCLs, the operational current and the limiting impedance of the SFCL, which describes the performance of the SFCL, were derived from each SFCL's electrical equivalent circuit. Through the analysis for the fault current limiting experiments of both the SFCLs, the different current limiting characteristics of both the SFCLs were discussed

  4. Improving sensitivity of residual current transformers to high frequency earth fault currents

    Directory of Open Access Journals (Sweden)

    Czapp Stanislaw

    2017-09-01

    Full Text Available For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.

  5. Development of superconducting power devices in Europe

    International Nuclear Information System (INIS)

    Tixador, Pascal

    2010-01-01

    Europe celebrated last year (2008) the 100-year anniversary of the first liquefaction of helium by H. Kammerling Onnes in Leiden. It led to the discovery of superconductivity in 1911. Europe is still active in the development of superconducting (SC) devices. The discovery of high critical temperature materials in 1986, again in Europe, has opened a lot of opportunities for SC devices by broking the 4 K cryogenic bottleneck. Electric networks experience deep changes due to the emergence of dispersed generation (renewable among other) and to the advances in ICT (Information Communication Technologies). The networks of the future will be 'smart grids'. Superconductivity will offer 'smart' devices for these grids like FCL (Fault Current Limiter) or VLI (Very Low Inductance) cable and would certainly play an important part. Superconductivity also will participate to the required sustainable development by lowering the losses and enhancing the mass specific powers. Different SC projects in Europe will be presented (Cable, FCL, SMES, Flywheel and Electrical Machine) but the description is not exhaustive. Nexans has commercialized the first two FCLs without public funds in the European grid (UK and Germany). The Amsterdam HTS cable is an exciting challenge in term of losses for long SC cables. European companies (Nexans, Air Liquide, Siemens, Converteam, ...) are also very active for projects outside Europe (LIPA, DOE FCL, ...).

  6. Study of field-limiting defects in superconducting RF cavities for electron-accelerators

    International Nuclear Information System (INIS)

    Aderhold, Sebastian

    2015-02-01

    Superconducting radio-frequency resonators made from niobium are an integral part of many accelerator projects. Their main advantage are the low ohmic losses resulting in the possibility for a long pulse structure and high duty cycles up to continous wave (cw) operation. The European X-Ray Free-Electron Laser (XFEL) and the International Linear Collider (ILC) are based on this technology. In some cases the resonators reach accelerating electric fields close to the theoretical limit of bulk niobium. Yet most resonators are limited at lower fields and mass production for large scale accelerator projects suffers from the spread in the achievable gradient per resonator. The main limitations are field emission and the breakdown of superconductivity (quench). While field emission is mostly attributed to the overall surface cleanliness of the resonator, quench is usually associated with local defects. Optical inspection of the inner surface of the resonators with unprecedented resolution, accuracy and a special illumination has been established at DESY and used to study such local surface defects. More than 30 resonators have been inspected. Distinctive features from these inspections have been catalogued and assessed for their potential risk for the performance of the resonator. Several confirmed quenching defects could be extracted for further analysis and could be traced back to likely origins in the production process. A new, automated set-up for optical inspection of large series of resonators, named OBACHT, has been developed and successfully commissioned. Its design includes the minimal need for operator interference, reproducibility, robustness and versatility, in order to fit the requirements for application both in a laboratory and in a production environment. To facilitate the comparison of the results obtained during the global R and D effort on resonators for the ILC, the ILC global yield database has been established. The yield and selection rules for the

  7. Enhancing LVRT of DFIG by Using a Superconducting Current Limiter on Rotor Circuit

    Directory of Open Access Journals (Sweden)

    Flávio Oliveira

    2015-12-01

    Full Text Available This paper have studied the dynamic of a 2.0 MW Doubly Fed Induction Generator (DFIG during a severe voltage sag. Using the dynamic model of a DFIG, it was possible to determine the current, Electromagnetic Force and flux behavior during three-phase symmetrical voltage dip. Among the technologies of wind turbines the DFIG is widely employed; however, this machine is extremely susceptible to disturbances from the grid. In order to improve DFIG Low Voltage Ride-Through (LVRT, it is proposed a novel solution, using Superconducting Current Limiter (SCL in two arrangements: one, the SCL is placed between the machine rotor and the rotor side converter (RSC, and another placed in the RSC DC-link. The proposal is validated through simulation using PSCAD™/EMTDC™ and according to requirements of specific regulations. The analysis ensure that both SCL arrangements behave likewise, and are effective in decrement the rotor currents during the disturbance.

  8. Field limit and nano-scale surface topography of superconducting radio-frequency cavity made of extreme type II superconductor

    OpenAIRE

    Kubo, Takayuki

    2014-01-01

    The field limit of superconducting radio-frequency cavity made of type II superconductor with a large Ginzburg-Landau parameter is studied with taking effects of nano-scale surface topography into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the pro...

  9. Exchange and spin-fluctuation superconducting pairing in the strong correlation limit of the Hubbard model

    International Nuclear Information System (INIS)

    Plakida, N. M.; Anton, L.; Adam, S. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO); Adam, Gh. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO)

    2001-01-01

    A microscopical theory of superconductivity in the two-band singlet-hole Hubbard model, in the strong coupling limit in a paramagnetic state, is developed. The model Hamiltonian is obtained by projecting the p-d model to an asymmetric Hubbard model with the lower Hubbard subband occupied by one-hole Cu d-like states and the upper Hubbard subband occupied by two-hole p-d singlet states. The model requires two microscopical parameters only, the p-d hybridization parameter t and the charge-transfer gap Δ. It was previously shown to secure an appropriate description of the normal state properties of the high -T c cuprates. To treat rigorously the strong correlations, the Hubbard operator technique within the projection method for the Green function is used. The Dyson equation is derived. In the molecular field approximation, d-wave superconducting pairing of conventional hole (electron) pairs in one Hubbard subband is found, which is mediated by the exchange interaction given by the interband hopping, J ij = 4 (t ij ) 2 / Δ. The normal and anomalous components of the self-energy matrix are calculated in the self-consistent Born approximation for the electron-spin-fluctuation scattering mediated by kinematic interaction of the second order of the intraband hopping. The derived numerical and analytical solutions predict the occurrence of singlet d x 2 -y 2 -wave pairing both in the d-hole and singlet Hubbard subbands. The gap functions and T c are calculated for different hole concentrations. The exchange interaction is shown to be the most important pairing interaction in the Hubbard model in the strong correlation limit, while the spin-fluctuation coupling results only in a moderate enhancement of T c . The smaller weight of the latter comes from two specific features: its vanishing inside the Brillouin zone (BZ) along the lines, |k x | + |k y |=π pointing towards the hot spots and the existence of a small energy shell within which the pairing is effective. By

  10. 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.

  11. Fault current limiter-predominantly resistive behavior of a BSCCO shielded-core reactor

    International Nuclear Information System (INIS)

    Ennis, M. G.; Tobin, T. J.; Cha, Y. S.; Hull, J. R.

    2000-01-01

    Tests were conducted to determine the electrical and magnetic characteristics of a superconductor shielded core reactor (SSCR). The results show that a closed-core SSCR is predominantly a resistive device and an open-core SSCR is a hybrid resistive/inductive device. The open-core SSCR appears to dissipate less than the closed-core SSCR. However, the impedance of the open-core SSCR is less than that of the closed-core SSCR. Magnetic and thermal diffusion are believed to be the mechanism that facilitates the penetration of the superconductor tube under fault conditions

  12. Market potential of superconductor current limiters; Marktpotential von supraleitenden Strombegrenzern

    Energy Technology Data Exchange (ETDEWEB)

    Lakner, M.; Braun, D. [ABB Schweiz AG, Corporate Research, Baden-Daettwil (Switzerland); Schnyder, G.; Mauchle, P. [Schnyder Ingenieure AG, Huenenberg (Switzerland)

    2003-07-01

    This final report for the Swiss Federal Office of Energy describes the two concepts - 'resistive' and 'inductive' - used for Superconducting Fault Current Limiters (SCFCL) that utilise the transition from zero to finite resistance to limit short-circuit currents. The main advantages of SCFCL are compared to other current-limiting technologies: They can limit any type of prospective fault current, operate fail-safe, be self-triggered and self-restoring. Their main disadvantage - the cooling effort necessary - is also discussed. The application possibilities of SCFCL were investigated by simulating the impact on utility and industrial grids. Applications of SCFCL such as the coupling of medium-voltage grids and their use in series with a circuit-breaker on the secondary side of a substation transformer are discussed. It is also shown that, by using fault current limiters, considerable cost savings can be made, especially in connection with new installations or the extension of existing plants.

  13. The intrinsic crossing point of the magnetization vs. temperature curves in superconducting cuprates in the high-magnetic-field limit

    International Nuclear Information System (INIS)

    Mosqueira, J.; Torron, C.; Veira, J.A.; Vidal, F.

    1998-01-01

    The crossing point of the magnetization vs. temperature curves that appears below T c in highly anisotropic superconducting cuprates was measured in different compounds, with a different number, N, of superconducting CuO 2 layers per periodicity length, s, and also with different values of s. By correcting the measurements from different extrinsic inhomogeneity effects through the Meissner fraction, it is demonstrated experimentally for the first time that in the high-magnetic-field limit the intrinsic crossing point may be explained at a quantitative level in terms of the Tesanovic and coworkers approach based on thermal fluctuations of quasi-2D vortices (pancakes), with an effective periodicity length equal to s, independently of N. (orig.)

  14. Probing the fundamental limit of niobium in high radiofrequency fields by dual mode excitation in superconducting radiofrequency cavities

    International Nuclear Information System (INIS)

    Eremeev, Grigory; Geng, Rongli; Palczewski, Ari

    2011-01-01

    We have studied thermal breakdown in several multicell superconducting radiofrequency cavity by simultaneous excitation of two TM 010 passband modes. Unlike measurements done in the past, which indicated a clear thermal nature of the breakdown, our measurements present a more complex picture with interplay of both thermal and magnetic effects. JLab LG-1 that we studied was limited at 40.5 MV/m, corresponding to B peak = 173 mT, in 89 mode. Dual mode measurements on this quench indicate that this quench is not purely magnetic, and so we conclude that this field is not the fundamental limit in SRF cavities

  15. 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

  16. Radiation effects limits on superconducting magnets: Data base for copper stabilizers

    Energy Technology Data Exchange (ETDEWEB)

    Guinan, M.W.

    1986-02-24

    A simple model has been developed which can predict the magnetoresistance of copper as a function of initial purity, the extent of cold work and the presence of both irradiation produced point defects and the extended defects produced by annealing. The remaining area of uncertainty in a complete description of the response of superconducting magnets to irradiation-anneal cycles is the dependence of annealing on dose impurity concentration and cold-work.

  17. Radiation effects limits on superconducting magnets: Data base for copper stabilizers

    International Nuclear Information System (INIS)

    Guinan, M.W.

    1986-01-01

    A simple model has been developed which can predict the magnetoresistance of copper as a function of initial purity, the extent of cold work and the presence of both irradiation produced point defects and the extended defects produced by annealing. The remaining area of uncertainty in a complete description of the response of superconducting magnets to irradiation-anneal cycles is the dependence of annealing on dose impurity concentration and cold-work

  18. Physics of Limiting Phenomena in Superconducting Microwave Resonators: Vortex Dissipation, Ultimate Quench and Quality Factor Degradation Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Checchin, Mattia [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-12-01

    Superconducting niobium accelerating cavities are devices operating in radio-frequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associate d to the

  19. Physics of limiting phenomena in superconducting microwave resonators: Vortex dissipation, ultimate quench and quality factor degradation mechanisms

    Science.gov (United States)

    Checchin, Mattia

    Superconducting niobium accelerating cavities are devices operating in radiofrequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associated to the superheating

  20. Study of quality and field limitation of superconducting 1.3 GHz 9-Cell RF-cavities at DESY

    International Nuclear Information System (INIS)

    Schlander, Felix

    2013-01-01

    The European XFEL and the International Linear Collider are based on superconducting rf cavities made of niobium. Their advantages are low ohmic losses which allow high duty cycles and the possibility to use a large beam aperture which is substantial to prevent wake fields at high current accelerators. To reach the theoretical limits of superconducting cavities, it is required to understand the present performance limitations. These are field emission, thermal breakdown (quench) and the ohmic losses dependent on the accelerating field, which are expressed in the quality factor. As the limiting mechanisms themselves are understood in general, the origin of the quench is often unclear. To determine the quench locations, a localisation tool for thermal breakdown using the second sound in superfluid helium has been installed at the cavity test facility at DESY and the results for a sample of about 30 cavities have been examined. The features of the distribution of the quench locations have been analysed and it has been found that the quench locations are in the area of the highest surface magnetic field and not necessarily at the equator of the cells. The data sample has been extended in an attempt to characterise the average behaviour of the quality factor related to the accelerating field. An analysis of the surface resistance of individual cavities shows that a recently developed model for the surface resistance of niobium is not able to describe the measurement in all detail, but the application of an additional mechanism showed promising results.

  1. Study of quality and field limitation of superconducting 1.3 GHz 9-Cell RF-cavities at DESY

    Energy Technology Data Exchange (ETDEWEB)

    Schlander, Felix

    2013-01-15

    The European XFEL and the International Linear Collider are based on superconducting rf cavities made of niobium. Their advantages are low ohmic losses which allow high duty cycles and the possibility to use a large beam aperture which is substantial to prevent wake fields at high current accelerators. To reach the theoretical limits of superconducting cavities, it is required to understand the present performance limitations. These are field emission, thermal breakdown (quench) and the ohmic losses dependent on the accelerating field, which are expressed in the quality factor. As the limiting mechanisms themselves are understood in general, the origin of the quench is often unclear. To determine the quench locations, a localisation tool for thermal breakdown using the second sound in superfluid helium has been installed at the cavity test facility at DESY and the results for a sample of about 30 cavities have been examined. The features of the distribution of the quench locations have been analysed and it has been found that the quench locations are in the area of the highest surface magnetic field and not necessarily at the equator of the cells. The data sample has been extended in an attempt to characterise the average behaviour of the quality factor related to the accelerating field. An analysis of the surface resistance of individual cavities shows that a recently developed model for the surface resistance of niobium is not able to describe the measurement in all detail, but the application of an additional mechanism showed promising results.

  2. Towards a phase-locked superconducting integrated receiver: prospects and limitations

    DEFF Research Database (Denmark)

    Koshelets, V.P.; Shitov, S.V.; Dmitriev, P.N.

    2002-01-01

    Presently a Josephson flux flow oscillator (FFO) appears to be the most developed superconducting on-chip local oscillator for integrated submillimeter-wave SIS receivers. The feasibility of phase locking the FFO to an external reference oscillator at all frequencies of interest has to be proven...... compared to theory in order to optimize the FFO design. The influence of FFO parameters on radiation linewidth, particularly the effect of the differential resistances associated both with the bias current and the applied magnetic field, has been studied. Two integrated receiver concepts with phase...

  3. 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.

  4. 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.

  5. Superconducting states in strongly correlated systems with nonstandard quasiparticles and real space pairing: an unconventional Fermi-liquid limit

    Directory of Open Access Journals (Sweden)

    J. Spałek

    2010-01-01

    Full Text Available We use the concept of generalized (almost localized Fermi Liquid composed of nonstandard quasiparticles with spin-dependence effective masses and the effective field induced by electron correlations. This Fermi liquid is obtained within the so-called statistically-consistent Gutzwiller approximation (SGA proposed recently [cf. J. Jędrak et al., arXiv: 1008.0021] and describes electronic states of the correlated quantum liquid. Particular emphasis is put on real space pairing driven by the electronic correlations, the Fulde-Ferrell state of the heavy-fermion liquid, and the d-wave superconducting state of high temperature curate superconductors in the overdoped limit. The appropriate phase diagrams are discussed showing in particular the limits of stability of the Bardeen-Cooper-Schrieffer (BCS type of state.

  6. Superconductivity program for electric systems, Superconductivity Technology Center, Los Alamos National Laboratory, annual progress report for fiscal year 1997

    Energy Technology Data Exchange (ETDEWEB)

    Willis, J.O.; Newnam, B.E. [eds.; Peterson, D.E.

    1999-03-01

    Development of high-temperature superconductors (HTS) has undergone tremendous progress during the past year. Kilometer tape lengths and associated magnets based on BSCCO materials are now commercially available from several industrial partners. Superconducting properties in the exciting YBCO coated conductors continue to be improved over longer lengths. The Superconducting Partnership Initiative (SPI) projects to develop HTS fault current limiters and transmission cables have demonstrated that HTS prototype applications can be produced successfully with properties appropriate for commercial applications. Research and development activities at LANL related to the HTS program for Fiscal Year 1997 are collected in this report. LANL continues to support further development of Bi2223 and Bi2212 tapes in collaboration with American Superconductor Corporation (ASC) and Oxford Superconductivity Technology, Inc. (OSTI), respectively. The tape processing studies involving novel thermal treatments and microstructural characterization have assisted these companies in commercializing these materials. The research on second-generation YBCO-coated conductors produced by pulsed-laser deposition (PLD) over buffer template layers produced by ion beam-assisted deposition (IBAD) continues to lead the world. The applied physics studies of magnetic flux pinning by proton and heavy ion bombardment of BSCCO and YBCO tapes have provided many insights into improving the behavior of these materials in magnetic fields. Sections 4 to 7 of this report contain a list of 29 referred publications and 15 conference abstracts, a list of patent and license activities, and a comprehensive list of collaborative agreements in progress and completed.

  7. Radiation effects limits on superconducting magnets: data base for copper stabilizers

    International Nuclear Information System (INIS)

    Guinan, M.W.

    1986-01-01

    The objective of this work is to quantify the changes which occur in the magnetoresistivity of coppers (having various purities and pretreatments) at fields up to 12T during the course of sequential neutron irradiations at 4K and anneals to room temperature. In conjunction with work by Klabunde and Coltman at ORNL, the results should lead to engineering design data for the stabilizers of superconducting magnets in fusion reactors. These magnets are expected to be irradiated during reactor operation and warmed to room temperature periodically during maintenance. Two of eight differently prepared copper stabilizer samples, previously irradiated in the RTNS-II at LLNL, the IPNS-1 at ANL, and the BSR at ONRL, have been irradiated to a fluence of 1.33 x 10 22 n/m 2 at RNTS-II. During the course of the irradiation the samples were periodically removed (without warming) for measurements of the transverse magnetoresistance and returned for continued irradiation. This experiment extends the range of neutron irradiation induced resistivity by a factor of five over the previous experiments. A simple model is developed which reproduces the magnetoresistance results of all the experiments to an accuracy of 2.5%

  8. Field limit and nano-scale surface topography of superconducting radio-frequency cavity made of extreme type II superconductor

    Science.gov (United States)

    Kubo, Takayuki

    2015-06-01

    The field limit of a superconducting radio-frequency cavity made of a type II superconductor with a large Ginzburg-Landau parameter is studied, taking the effects of nano-scale surface topography into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the product of the superheating field for an ideal flat surface and a suppression factor that contains the effects of nano-defects. A nano-defect is modeled by a triangular groove with a depth smaller than the penetration depth. An analytical formula for the suppression factor of bulk and multilayer superconductors is derived in the framework of the London theory. As an immediate application, the suppression factor of the dirty Nb processed by electropolishing is evaluated by using results of surface topographic study. The estimated field limit is consistent with the present record field of nitrogen-doped Nb cavities. Suppression factors of surfaces of other bulk and multilayer superconductors, and those after various surface processing technologies, can also be evaluated by using the formula.

  9. The progresses of superconducting technology for power grid last decade in China

    International Nuclear Information System (INIS)

    Xiao, Liye; Gu, Hong Wei

    2015-01-01

    With the increasing development of renewable energy, it is expected that large-scale renewable power would be transported from the west and north area of China to the east and south area. For this reason, it will be necessary to develop a wide-area power grid in which the renewable energy would be the dominant power source, and the power grid will be faced by some critical challenges such as long-distance large-capacity power transmission, the stability of the wide-area power grid and the land use problem for the power grid. The superconducting technology for power (STP) would be a possible alternative for the development of China’s future power grid. In last decade, STP has been extensively developed in China. In this paper, we present an overview of the R and D of STP last decade in China including: 1) the development of high temperature superconducting (HTS) materials, 2) DC power cables, 3) superconducting power substations, 4) fault current limiters and 5) superconducting magnetic energy storage (SMES)

  10. The progresses of superconducting technology for power grid last decade in China

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Liye; Gu, Hong Wei [Applied Superconductivity Laboratory, Chinese Academy of Sciences, Beijing (China)

    2015-03-15

    With the increasing development of renewable energy, it is expected that large-scale renewable power would be transported from the west and north area of China to the east and south area. For this reason, it will be necessary to develop a wide-area power grid in which the renewable energy would be the dominant power source, and the power grid will be faced by some critical challenges such as long-distance large-capacity power transmission, the stability of the wide-area power grid and the land use problem for the power grid. The superconducting technology for power (STP) would be a possible alternative for the development of China’s future power grid. In last decade, STP has been extensively developed in China. In this paper, we present an overview of the R and D of STP last decade in China including: 1) the development of high temperature superconducting (HTS) materials, 2) DC power cables, 3) superconducting power substations, 4) fault current limiters and 5) superconducting magnetic energy storage (SMES)

  11. Lower hybrid current drive experiments with graphite limiters in the HT-7 superconducting tokamak

    International Nuclear Information System (INIS)

    Liu, J.; Gao, X.; Hu, L.Q.; Asif, M.; Chen, Z.Y.; Ding, B.J.; Zhou, Q.; Liu, H.Q.; Jie, Y.X.; Kong, W.; Lin, S.Y.; Ding, Y.H.; Gao, L.; Xu, Q.

    2006-01-01

    Recent progress of lower hybrid (LH) experiments with new graphite limiters configuration in the HT-7 tokamak is presented. The lower hybrid current drive (LHCD) efficiency can be determined by fitting based on experimental data. Improved particle confinement was observed via LHCD (P LHW >300 kW) characterized by the particle confinement time τ p increased about 1.56 times. It is found that runaways are suppressed during loop voltage is decreasing at the flat-top phase of LH discharges. The main limitations of pulse length are presented in long-pulse experiments with new limiter configuration

  12. Discrimination of Inrush from Fault Currents in Power Transformers Based on Equivalent Instantaneous Inductance Technique Coupled with Finite Element Method

    Directory of Open Access Journals (Sweden)

    M. Jamali

    2011-09-01

    Full Text Available The phenomenon of magnetizing inrush is a transient condition, which occurs primarily when a transformer is energized. The magnitude of inrush current may be as high as ten times or more times of transformer rated current that causes malfunction of protection system. So, for safe running of a transformer, it is necessary to distinguish inrush current from fault currents. In this paper, an equivalent instantaneous inductance (EII technique is used to discriminate inrush current from fault currents. For this purpose, a three-phase power transformer has been simulated in Maxwell software that is based on finite elements. This three-phase power transformer has been used to simulate different conditions. Then, the results have been used as inputs in MATLAB program to implement the equivalent instantaneous inductance technique. The results show that in the case of inrush current, the equivalent instantaneous inductance has a drastic variation, while it is almost constant in the cases of fault conditions.

  13. Superconducting transformer

    International Nuclear Information System (INIS)

    Murphy, J.H.

    1982-01-01

    A superconducting transformer having a winding arrangement that provides for current limitation when subjected to a current transient as well as more efficient utilization of radial spacing and winding insulation. Structural innovations disclosed include compressed conical shaped winding layers and a resistive matrix to promote rapid switching of current between parallel windings

  14. Insulation design of cryogenic bushing for superconducting electric power applications

    Energy Technology Data Exchange (ETDEWEB)

    Koo, J.Y., E-mail: koojy@hanyang.ac.kr [Department of Electronics, Electrical, Control and Instrumentation Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Lee, Y.J.; Shin, W.J.; Kim, Y.H. [Department of Electronics, Electrical, Control and Instrumentation Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Kim, J.T. [Department of Electrical Engineering, Daejin University, Pocheon 487-711 (Korea, Republic of); Lee, B.W. [Department of Electronics, Electrical, Control and Instrumentation Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Lee, S.H., E-mail: k720lsh@kins.re.kr [Expert Group Electric and Control Department, Korea Institute of Nuclear Safety, Daejeon 305-600 (Korea, Republic of)

    2013-01-15

    Highlights: ► In this paper, design factors of cryogenic bushings were discussed and test results of specimen were introduced in detail. ► We focused on the comparative study of breakdown characteristics of different electrode materials. ► Puncture and creepage breakdown characteristics were analyzed based on the withstand voltage. ► We obtained the basic design factors of extra high voltage condenser bushing. ► We obtained the basic design factors of extra high voltage condenser bushing, which could be used in cryogenic environment. -- Abstract: Recently, the superconductivity projects to develop commercial superconducting devices for extra high voltage transmission lines have been undergoing in many countries. One of the critical components to be developed for high voltage superconducting devices, including superconducting transformers, cables, and fault current limiters, is a high voltage bushing, to supply high current to devices without insulating difficulties, that is designed for cryogenic environments. Unfortunately, suitable bushings for HTS equipment were not fully developed for some cryogenic insulation issues. Such high voltage bushings would need to provide electrical insulation capabilities from room temperature to cryogenic temperatures. In this paper, design factors of cryogenic bushings were discussed and test results of specimen were introduced in detail. First, the dielectric strength of three kinds of metals has been measured with uniform and non-uniform electrodes by withstand voltage of impulse and AC breakdown test in LN{sub 2}. Second, puncture breakdown voltage of glass fiber reinforced plastics (GFRPs) plates has been analyzed with non-uniform electrodes. Finally, creepage discharge voltages were measured according to the configuration of non-uniform and uniform electrode on the FRP plate. From the test results, we obtained the basic design factors of extra high voltage condenser bushing, which could be used in cryogenic

  15. Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

    Science.gov (United States)

    Fasano, Y.; Szabó, P.; Kačmarčík, J.; Pribulová, Z.; Pedrazzini, P.; Samuely, P.; Correa, V. F.

    2018-05-01

    We present scanning tunneling spectroscopy measurements of the local quasiparticles' excitation spectra of the heavy fermion CeCoIn5 between 440 mK and 3 K in samples with a bulk Tc = 2.25 K . The spectral shape of our low-temperature tunneling data, quite textbook nodal- Δ conductance, allow us to confidently fit the spectra with a d-wave density of states considering also a shortening of quasiparticles' lifetime term Γ. The Δ (0) value obtained from the fits yields a BCS ratio 2 Δ /kTc = 7.73 suggesting that CeCoIn5 is an unconventional superconductor in the strong coupling limit. The fits also reveal that the height of coherence peaks in CeCoIn5 is reduced with respect to a pure BCS spectra and therefore the coupling of quasiparticles with spin excitations should play a relevant role. The tunneling conductance shows a depletion at energies smaller than Δ for temperatures larger than the bulk Tc, giving further support to the existence of a pseudogap phase that in our samples span up to T* ∼ 1.2Tc . The phenomenological scaling of the pseudogap temperature observed in various families of cuprates, 2 Δ /kT* ∼ 4.3 , is not fulfilled in our measurements. This suggests that in CeCoIn5 the strong magnetic fluctuations might conspire to close the local superconducting gap at a smaller pesudogap temperature-scale than in cuprates.

  16. Quantum-limited detection of millimeter waves using superconducting tunnel junctions

    International Nuclear Information System (INIS)

    Mears, C.A.

    1991-09-01

    The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit by studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 ± 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker's theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs

  17. Resistive current limiter with high-temperature superconductors. Final report

    International Nuclear Information System (INIS)

    Schubert, M.

    1995-12-01

    Fundamental results of the possibility of using high temperature superconductors (HTSC) in resistive fault current limiters are discussed. Measurement of the homogeneity of BSCCO-powder-in-tube materials were made. In addition, investigations of the transition from superconducting to normalconducting state under AC-current conditions were carried out. Based on these results, simulations of HTSC-materials on ceramic substrate were made and recent results are presented. Important results of the investigations are: 1. Current-limiting without external trigger only possible when the critical current density of HTSC exceeds 10 4 A/cm 2 . 2. Inhomogeneities sometimes cause problems with local destruction. This can be solved by parallel-elements or external trigger. 3. Fast current-limiting causes overvoltages which can be reduced by using parallel-elements. (orig.) [de

  18. Fabrication And Characterization of YBa2Cu3O7-x Ring For The Laboratory Scale Fault Current Limiter

    International Nuclear Information System (INIS)

    Adi, Wisnu Ari; Sukirman, Engkir; Winatapura, Didin S.; Handayani, Ari

    2004-01-01

    Two rings of YBa 2 Cu 3 O 7-x superconductor have been made by using the pressing method, that has been modified. The inner diameter, outer diameter, and thickness of ring 1 are 23.46 mm, 40.66 mm, and 6.84 mm, while for ring 2 are 23.65 mm, 40.73 mm, and 8.28 mm, respectively. The XRD data show that both samples have the same 123-phase. The critical temperature, Tc of both samples is 91 K. The estimate values of induction magnetic field at the center of ring 1 and ring 2 are 1.27 x 10 -4 T (I c = 3.48 A) and 1.65 x 10 -4 T (I c = 3.52 A), respectively

  19. 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

  20. 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

  1. Limitation of short-circuit power due to distributed generation

    NARCIS (Netherlands)

    Morren, J.; Reckers, T.J.M.; Berende, M.J.C.; Slootweg, J.G.

    2012-01-01

    Introduction of DG units in the network will result in increasing fault current levels. In this contribution several solutions are described to limit the fault currents in the network, in order to avoid overloading and destruction of components in the networks. The main focus of the paper is on the

  2. Superconducting rotating machines

    International Nuclear Information System (INIS)

    Smith, J.L. Jr.; Kirtley, J.L. Jr.; Thullen, P.

    1975-01-01

    The opportunities and limitations of the applications of superconductors in rotating electric machines are given. The relevant properties of superconductors and the fundamental requirements for rotating electric machines are discussed. The current state-of-the-art of superconducting machines is reviewed. Key problems, future developments and the long range potential of superconducting machines are assessed

  3. 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

  4. High-gradient near-quench-limit operation of superconducting Tesla-type cavities in scope of the International Linear Collider

    Directory of Open Access Journals (Sweden)

    Mathieu Omet

    2014-07-01

    Full Text Available We report the successful demonstration of an ILC-like high-gradient near-quench-limit operation at the Superconducting RF Test Facility at the High Energy Accelerator Research Organization (KEK in Japan. Preparation procedures necessary for the accelerator operation were conducted, such as rf phase calibration, beam-based gradient calibration, and automated beam compensation. Test runs were performed successfully for nominal operation, high-loaded Q (Q_{L} operation, and automated P_{k}Q_{L} operation. The results are described in terms of the achieved precision and stabilities of gradients and phases.

  5. Superconducting Nonlinear Kinetic Inductance Devices

    Data.gov (United States)

    National Aeronautics and Space Administration — Superconducting quantum interference devices, or SQUIDs, are by far the most sensitive magnetometers available, but two issues limit their commercial potential:...

  6. Frequency-domain cascading microwave superconducting quantum interference device multiplexers; beyond limitations originating from room-temperature electronics

    Science.gov (United States)

    Kohjiro, Satoshi; Hirayama, Fuminori

    2018-07-01

    A novel approach, frequency-domain cascading microwave multiplexers (MW-Mux), has been proposed and its basic operation has been demonstrated to increase the number of pixels multiplexed in a readout line U of MW-Mux for superconducting detector arrays. This method is an alternative to the challenging development of wideband, large power, and spurious-free room-temperature (300 K) electronics. The readout system for U pixels consists of four main parts: (1) multiplexer chips connected in series those contain U superconducting resonators in total. (2) A cryogenic high-electron-mobility transistor amplifier (HEMT). (3) A 300 K microwave frequency comb generator based on N(≡U/M) parallel units of digital-to-analog converters (DAC). (4) N parallel units of 300 K analog-to-digital converters (ADC). Here, M is the number of tones each DAC produces and each ADC handles. The output signal of U detectors multiplexed at the cryogenic stage is transmitted through a cable to the room temperature and divided into N processors where each handles M pixels. Due to the reduction factor of 1/N, U is not anymore dominated by the 300 K electronics but can be increased up to the potential value determined by either the bandwidth or the spurious-free power of the HEMT. Based on experimental results on the prototype system with N = 2 and M = 3, neither excess inter-pixel crosstalk nor excess noise has been observed in comparison with conventional MW-Mux. This indicates that the frequency-domain cascading MW-Mux provides the full (100%) usage of the HEMT band by assigning N 300 K bands on the frequency axis without inter-band gaps.

  7. Superconductivity - applications

    International Nuclear Information System (INIS)

    The paper deals with the following subjects: 1) Electronics and high-frequency technology, 2) Superconductors for energy technology, 3) Superconducting magnets and their applications, 4) Electric machinery, 5) Superconducting cables. (WBU) [de

  8. Superconductivity: A critical analysis

    International Nuclear Information System (INIS)

    Sacchetti, Nicola

    1997-01-01

    It is some forty years now that superconductivity has entered into the field of applied Physics. Countless applications have been proposed some of which have been successfully tested in the form of prototypes and relatively few have become widely used products. This article offers an objective examination of what applied superconductivity represents in the area of modern technology highlighting its exclusive advantages and its inevitable limitations

  9. Fluctuations on the magnetic response of superconducting thin films of Nb and MgB2 - Percolation limit of vortex mobility

    International Nuclear Information System (INIS)

    Colauto, F.; Orgiani, P.; Xi, X.X.; Kang, W.N.; Choi, E.M.; Kim, H.J.; Lee, S.I.; Patino, E.; Blamire, M.G.; Ortiz, W.A.

    2007-01-01

    Application of a magnetic field of sufficient intensity orthogonal to superconducting thin films may produce dendritic patterns, where penetrated and Meissner regions coexist. The dendritic mode can be detected by AC-susceptibility measurements, since fingers penetrated by the magnetic field act as intergranular material. Measurements of the AC-susceptibility have the conventional shape for smaller values of magnitude and frequency of the excitation field. However, for frequencies in the vicinity of 1 kHz and AC-fields around 3 Oe and above, the curve deviates from its canonical behavior and fluctuates, the excursion becoming wider as the amplitude is increased. In this contribution we present results of a systematic study conducted to determine the threshold between smooth and fluctuating regimes of the magnetic response of the film, which is interpreted as the percolation limit of vortex mobility throughout the sample

  10. Fluctuations on the magnetic response of superconducting thin films of Nb and MgB{sub 2} - Percolation limit of vortex mobility

    Energy Technology Data Exchange (ETDEWEB)

    Colauto, F. [Depto. de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil); Orgiani, P.; Xi, X.X. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Kang, W.N.; Choi, E.M.; Kim, H.J.; Lee, S.I. [Pohang University of Science and Technology, Department of Physics, Pohang (Korea, Republic of); Patino, E.; Blamire, M.G. [University of Cambridge, Department of Metallurgy and Materials Sciences, Cambridge (United Kingdom); Ortiz, W.A. [Depto. de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)], E-mail: wortiz@df.ufscar.br

    2007-09-01

    Application of a magnetic field of sufficient intensity orthogonal to superconducting thin films may produce dendritic patterns, where penetrated and Meissner regions coexist. The dendritic mode can be detected by AC-susceptibility measurements, since fingers penetrated by the magnetic field act as intergranular material. Measurements of the AC-susceptibility have the conventional shape for smaller values of magnitude and frequency of the excitation field. However, for frequencies in the vicinity of 1 kHz and AC-fields around 3 Oe and above, the curve deviates from its canonical behavior and fluctuates, the excursion becoming wider as the amplitude is increased. In this contribution we present results of a systematic study conducted to determine the threshold between smooth and fluctuating regimes of the magnetic response of the film, which is interpreted as the percolation limit of vortex mobility throughout the sample.

  11. A statistical rationale for establishing process quality control limits using fixed sample size, for critical current verification of SSC superconducting wire

    International Nuclear Information System (INIS)

    Pollock, D.A.; Brown, G.; Capone, D.W. II; Christopherson, D.; Seuntjens, J.M.; Woltz, J.

    1992-03-01

    The purpose of this paper is to demonstrate a statistical method for verifying superconducting wire process stability as represented by I c . The paper does not propose changing the I c testing frequency for wire during Phase 1 of the present Vendor Qualification Program. The actual statistical limits demonstrated for one supplier's data are not expected to be suitable for all suppliers. However, the method used to develop the limits and the potential for improved process through their use, may be applied equally. Implementing the demonstrated method implies that the current practice of testing all pieces of wire from each billet, for the purpose of detecting manufacturing process errors (i.e. missing a heat-treatment cycle for a part of the billet, etc.) can be replaced by other less costly process control measures. As used in this paper process control limits for critical current are quantitative indicators of the source manufacturing process uniformity. The limits serve as alarms indicating the need for manufacturing process investigation

  12. Superconductivity in borides and carbides

    International Nuclear Information System (INIS)

    Muranaka, Takahiro

    2007-01-01

    It was thought that intermetallic superconductors do not exhibit superconductivity at temperatures over 30 K because of the Bardeen-Cooper-Schrieffer (BCS) limit; therefore, researchers have been interested in high-T c cuprates. Our group discovered high-T c superconductivity in MgB 2 at 39 K in 2001. This discovery has initiated a substantial interest in the potential of high-T c superconductivity in intermetallic compounds that include 'light' elements (borides, carbides, etc.). (author)

  13. 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.)

  14. Basic Research Needs for Superconductivity. Report of the Basic Energy Sciences Workshop on Superconductivity, May 8-11, 2006

    International Nuclear Information System (INIS)

    Sarrao, J.; Kwok, W-K; Bozovic, I.; Mazin, I.; Seamus, J. C.; Civale, L.; Christen, D.; Horwitz, J.; Kellogg, G.; Finnemore, D.; Crabtree, G.; Welp, U.; Ashton, C.; Herndon, B.; Shapard, L.; Nault, R. M.

    2006-01-01

    codes. Unlike traditional grid technology, superconducting fault current limiters are smart. They increase their resistance abruptly in response to overcurrents from faults in the system, thus limiting the overcurrents and protecting the grid from damage. They react fast in both triggering and automatically resetting after the overload is cleared, providing a new, self-healing feature that enhances grid reliability. Superconducting reactive power regulators further enhance reliability by instantaneously adjusting reactive power for maximum efficiency and stability in a compact and economic package that is easily sited in urban grids. Not only do superconducting motors and generators cut losses, weight, and volume by a factor of two, but they are also much more tolerant of voltage sag, frequency instabilities, and reactive power fluctuations than their conventional counterparts. The challenge facing the electricity grid to provide abundant, reliable power will soon grow to crisis proportions. Continuing urbanization remains the dominant historic demographic trend in the United States and in the world. By 2030, nearly 90% of the U.S. population will reside in cities and suburbs, where increasingly strict permitting requirements preclude bringing in additional overhead access lines, underground cables are saturated, and growth in power demand is highest. The power grid has never faced a challenge so great or so critical to our future productivity, economic growth, and quality of life. Incremental advances in existing grid technology are not capable of solving the urban power bottleneck. Revolutionary new solutions are needed ? the kind that come only from superconductivity

  15. Basic Research Needs for Superconductivity. Report of the Basic Energy Sciences Workshop on Superconductivity, May 8-11, 2006

    Energy Technology Data Exchange (ETDEWEB)

    Sarrao, J.; Kwok, W-K; Bozovic, I.; Mazin, I.; Seamus, J. C.; Civale, L.; Christen, D.; Horwitz, J.; Kellogg, G.; Finnemore, D.; Crabtree, G.; Welp, U.; Ashton, C.; Herndon, B.; Shapard, L.; Nault, R. M.

    2006-05-11

    codes. Unlike traditional grid technology, superconducting fault current limiters are smart. They increase their resistance abruptly in response to overcurrents from faults in the system, thus limiting the overcurrents and protecting the grid from damage. They react fast in both triggering and automatically resetting after the overload is cleared, providing a new, self-healing feature that enhances grid reliability. Superconducting reactive power regulators further enhance reliability by instantaneously adjusting reactive power for maximum efficiency and stability in a compact and economic package that is easily sited in urban grids. Not only do superconducting motors and generators cut losses, weight, and volume by a factor of two, but they are also much more tolerant of voltage sag, frequency instabilities, and reactive power fluctuations than their conventional counterparts. The challenge facing the electricity grid to provide abundant, reliable power will soon grow to crisis proportions. Continuing urbanization remains the dominant historic demographic trend in the United States and in the world. By 2030, nearly 90% of the U.S. population will reside in cities and suburbs, where increasingly strict permitting requirements preclude bringing in additional overhead access lines, underground cables are saturated, and growth in power demand is highest. The power grid has never faced a challenge so great or so critical to our future productivity, economic growth, and quality of life. Incremental advances in existing grid technology are not capable of solving the urban power bottleneck. Revolutionary new solutions are needed ? the kind that come only from superconductivity.

  16. the tj model and superconductivity

    African Journals Online (AJOL)

    DJFLEX

    Perhaps that in the reason why their explanations of the superconductivity have had limited scope . A proper theory and mechanism of superconductivity in the ceramic cuprates should take account of magnetism inherent in the compounds. For the (214) compound experiment have revealed strong antiferromagnetic (AF).

  17. Superconducting cermets

    International Nuclear Information System (INIS)

    Goyal, A.; Funkenbusch, P.D.; Chang, G.C.S.; Burns, S.J.

    1988-01-01

    Two distant classes of superconducting cermets can be distinguished, depending on whether or not a fully superconducting skeleton is established. Both types of cermets have been successfully fabricated using non-noble metals, with as high as 60wt% of the metal phase. The electrical, magnetic and mechanical behavior of these composites is discussed

  18. 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

  19. Superconducting technology

    International Nuclear Information System (INIS)

    2010-01-01

    Superconductivity has a long history of about 100 years. Over the past 50 years, progress in superconducting materials has been mainly in metallic superconductors, such as Nb, Nb-Ti and Nb 3 Sn, resulting in the creation of various application fields based on the superconducting technologies. High-T c superconductors, the first of which was discovered in 1986, have been changing the future vision of superconducting technology through the development of new application fields such as power cables. On basis of these trends, future prospects of superconductor technology up to 2040 are discussed. In this article from the viewpoints of material development and the applications of superconducting wires and electronic devices. (author)

  20. Interface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gariglio, S., E-mail: stefano.gariglio@unige.ch [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland); Gabay, M. [Laboratoire de Physique des Solides, Bat 510, Université Paris-Sud 11, Centre d’Orsay, 91405 Orsay Cedex (France); Mannhart, J. [Max Planck Institute for Solid State Research, 70569 Stuttgart (Germany); Triscone, J.-M. [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland)

    2015-07-15

    Highlights: • We discuss interfacial superconductivity, a field boosted by the discovery of the superconducting interface between LaAlO. • This system allows the electric field control and the on/off switching of the superconducting state. • We compare superconductivity at the interface and in bulk doped SrTiO. • We discuss the role of the interfacially induced Rashba type spin–orbit. • We briefly discuss superconductivity in cuprates, in electrical double layer transistor field effect experiments. • Recent observations of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3} are presented. - Abstract: Low dimensional superconducting systems have been the subject of numerous studies for many years. In this article, we focus our attention on interfacial superconductivity, a field that has been boosted by the discovery of superconductivity at the interface between the two band insulators LaAlO{sub 3} and SrTiO{sub 3}. We explore the properties of this amazing system that allows the electric field control and on/off switching of superconductivity. We discuss the similarities and differences between bulk doped SrTiO{sub 3} and the interface system and the possible role of the interfacially induced Rashba type spin–orbit. We also, more briefly, discuss interface superconductivity in cuprates, in electrical double layer transistor field effect experiments, and the recent observation of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3}.

  1. Organic superconductivity

    International Nuclear Information System (INIS)

    Jerome, D.

    1980-01-01

    We present the experimental evidences for the existence of a superconducting state in the Quasi One Dimensional organic conductor (TMTSF) 2 PF 6 . Superconductivity occuring at 1 K under 12 kbar is characterized by a zero resistance diamagnetic state. The anistropy of the upper critical field of this type II superconductor is consistent with the band structure anistropy. We present evidences for the existence of large superconducting precursor effects giving rise to a dominant paraconductive contribution below 40 K. We also discuss the anomalously large pressure dependence of T sb(s), which drops to 0.19 K under 24 kbar in terms of the current theories. (author)

  2. 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

  3. Superconducting linac

    International Nuclear Information System (INIS)

    Bollinger, L.M.; Shepard, K.W.; Wangler, T.P.

    1978-01-01

    This project has two goals: to design, build, and test a small superconducting linac to serve as an energy booster for heavy ions from an FN tandem electrostatic accelerator, and to investigate various aspects of superconducting rf technology. The main design features of the booster are described, a status report on various components (resonators, rf control system, linac control system, cryostats, buncher) is given, and plans for the near future are outlined. Investigations of superconducting-linac technology concern studies on materials and fabrication techniques, resonator diagnostic techniques, rf-phase control, beam dynamics computer programs, asymmetry in accelerating field, and surface-treatment techniques. The overall layout of the to-be-proposed ATLAS, the Argonne Tandem-Linac Accelerator System, is shown; the ATLAS would use superconducting technology to produce beams of 5 to 25 MeV/A. 6 figures

  4. Superconducting materials

    International Nuclear Information System (INIS)

    Kormann, R.; Loiseau, R.; Marcilhac, B.

    1989-01-01

    The invention concerns superconducting ceramics containing essentially barium, calcium and copper fluorinated oxides with close offset and onset temperatures around 97 K and 100 K and containing neither Y nor rare earth [fr

  5. Hole superconductivity

    International Nuclear Information System (INIS)

    Hirsch, J.E.; Marsiglio, F.

    1989-01-01

    The authors review recent work on a mechanism proposed to explain high T c superconductivity in oxides as well as superconductivity of conventional materials. It is based on pairing of hole carriers through their direct Coulomb interaction, and gives rise to superconductivity because of the momentum dependence of the repulsive interaction in the solid state environment. In the regime of parameters appropriate for high T c oxides this mechanism leads to characteristic signatures that should be experimentally verifiable. In the regime of conventional superconductors most of these signatures become unobservable, but the characteristic dependence of T c on band filling survives. New features discussed her include the demonstration that superconductivity can result from repulsive interactions even if the gap function does not change sign and the inclusion of a self-energy correction to the hole propagator that reduces the range of band filling where T c is not zero

  6. Superconducted tour

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1988-09-15

    Superconductivity - the dramatic drop in electrical resistance in certain materials at very low temperatures - has grown rapidly in importance over the past two or three decades to become a key technology for high energy particle accelerators. It was in this setting that a hundred students and 15 lecturers met in Hamburg in June for a week's course on superconductivity in particle accelerators, organized by the CERN Accelerator School and the nearby DESY Laboratory.

  7. Superconductivity: Phenomenology

    International Nuclear Information System (INIS)

    Falicov, L.M.

    1988-08-01

    This document discusses first the following topics: (a) The superconducting transition temperature; (b) Zero resistivity; (c) The Meissner effect; (d) The isotope effect; (e) Microwave and optical properties; and (f) The superconducting energy gap. Part II of this document investigates the Ginzburg-Landau equations by discussing: (a) The coherence length; (b) The penetration depth; (c) Flux quantization; (d) Magnetic-field dependence of the energy gap; (e) Quantum interference phenomena; and (f) The Josephson effect

  8. Connectivity and superconductivity

    CERN Document Server

    Rubinstein, Jacob

    2000-01-01

    The motto of connectivity and superconductivity is that the solutions of the Ginzburg--Landau equations are qualitatively influenced by the topology of the boundaries, as in multiply-connected samples. Special attention is paid to the "zero set", the set of the positions (also known as "quantum vortices") where the order parameter vanishes. The effects considered here usually become important in the regime where the coherence length is of the order of the dimensions of the sample. It takes the intuition of physicists and the awareness of mathematicians to find these new effects. In connectivity and superconductivity, theoretical and experimental physicists are brought together with pure and applied mathematicians to review these surprising results. This volume is intended to serve as a reference book for graduate students and researchers in physics or mathematics interested in superconductivity, or in the Schrödinger equation as a limiting case of the Ginzburg--Landau equations.

  9. Superconducting cyclotrons

    International Nuclear Information System (INIS)

    Blosser, H.G.; Johnson, D.A.; Burleigh, R.J.

    1976-01-01

    Superconducting cyclotrons are particularly appropriate for acceleration of heavy ions. A review is given of design features of a superconducting cyclotron with energy 440 (Q 2 /A) MeV. A strong magnetic field (4.6 tesla average) leads to small physical size (extraction radius 65 cm) and low construction costs. Operating costs are also low. The design is based on established technology (from present cyclotrons and from large bubble chambers). Two laboratories (in Chalk River, Canada and in East Lansing, Michigan) are proceeding with construction of full-scale prototype components for such cyclotrons

  10. Superconductivity, energy storage and switching

    International Nuclear Information System (INIS)

    Laquer, H.L.

    1974-01-01

    The phenomenon of superconductivity can contribute to the technology of energy storage and switching in two distinct ways. On one hand the zero resistivity of the superconductor can produce essentially infinite time constants so that an inductive storage system can be charged from very low power sources. On the other hand, the recovery of finite resistivity in a normal-going superconducting switch can take place in extremely short times, so that a system can be made to deliver energy at a very high power level. Topics reviewed include: physics of superconductivity, limits to switching speed of superconductors, physical and engineering properties of superconducting materials and assemblies, switching methods, load impedance considerations, refrigeration economics, limitations imposed by present day and near term technology, performance of existing and planned energy storage systems, and a comparison with some alternative methods of storing and switching energy. (U.S.)

  11. 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.

  12. Improved protection system for phase faults on marine vessels based on ratio between negative sequence and positive sequence of the fault current

    DEFF Research Database (Denmark)

    Ciontea, Catalin-Iosif; Hong, Qiteng; Booth, Campbell

    2018-01-01

    algorithm is implemented in a programmable digital relay embedded in a hardware-in-the-loop (HIL) test set-up that emulates a typical maritime feeder using a real-time digital simulator. The HIL set-up allows testing of the new protection method under a wide range of faults and network conditions......This study presents a new method to protect the radial feeders on marine vessels. The proposed protection method is effective against phase–phase (PP) faults and is based on evaluation of the ratio between the negative sequence and positive sequence of the fault currents. It is shown...... that the magnitude of the introduced ratio increases significantly during the PP fault, hence indicating the fault presence in an electric network. Here, the theoretical background of the new method of protection is firstly discussed, based on which the new protection algorithm is described afterwards. The proposed...

  13. Superconducting materials

    International Nuclear Information System (INIS)

    Ruvalds, J.

    1990-01-01

    This report discusses the following topics: Fermi liquid nesting in high temperature superconductors; optical properties of high temperature superconductors; Hall effect in superconducting La 2-x Sr x CuO 4 ; source of high transition temperatures; and prospects for new superconductors

  14. Superconducting magnets

    International Nuclear Information System (INIS)

    1994-08-01

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-T c superconductor at low temperature

  15. Superconducting magnets

    International Nuclear Information System (INIS)

    Willen, E.

    1996-01-01

    Superconducting dipole magnets for high energy colliders are discussed. As an example, the magnets recently built for the Relativistic Heavy Ion Collider at Brookhaven are reviewed. Their technical performance and the cost for the industry-built production dipoles are given. The cost data is generalized in order to extrapolate the cost of magnets for a new machine

  16. Bipolar superconductivity

    International Nuclear Information System (INIS)

    Pankratov, S.G.

    1987-01-01

    A model of bipolaron superconductivity suggested by Soviet scientist Alexandrov A.S. and French scientist Ranninger is presentes in a popular way. It is noted that the bipolaron theory gives a good explanation of certain properties of new superconductors, high critical temperature, in particular

  17. Superconducting transistor

    International Nuclear Information System (INIS)

    Gray, K.E.

    1978-01-01

    A three film superconducting tunneling device, analogous to a semiconductor transistor, is presented, including a theoretical description and experimental results showing a current gain of four. Much larger current gains are shown to be feasible. Such a development is particularly interesting because of its novelty and the striking analogies with the semiconductor junction transistor

  18. Meissner effect in superconducting microtraps

    International Nuclear Information System (INIS)

    Cano, Daniel

    2009-01-01

    This thesis investigates the impact of the Meissner effect on magnetic microtraps for ultracold atoms near superconducting microstructures. This task has been accomplished both theoretically and experimentally. The Meissner effect distorts the magnetic fields near superconducting surfaces, thus altering the parameters of magnetic microtraps. Both computer simulations and experimental measurements demonstrate that the Meissner effect shortens the distance between the magnetic microtrap and the superconducting surface, reduces the magnetic-field gradients and dramatically lowers the trap depth. A novel numerical method for calculating magnetic fields in atom chips with superconducting microstructures has been developed. This numerical method overcomes the geometrical limitations of other calculation techniques and can solve superconducting microstructures of arbitrary geometry. The numerical method has been used to calculate the parameters of magnetic microtraps in computer-simulated chips containing thin-film wires. Simulations were carried out for both the superconducting and the normal-conducting state, and the differences between the two cases were analyzed. Computer simulations have been contrasted with experimental measurements. The experimental apparatus generates a magnetic microtrap for ultracold Rubidium atoms near a superconducting Niobium wire of circular cross section. The design and construction of the apparatus has met the challenge of integrating the techniques for producing atomic quantum gases with the techniques for cooling solid bodies to cryogenic temperatures. By monitoring the position of the atom cloud, one can observe how the Meissner effect influences the magnetic microtrap. (orig.)

  19. Meissner effect in superconducting microtraps

    Energy Technology Data Exchange (ETDEWEB)

    Cano, Daniel

    2009-04-30

    This thesis investigates the impact of the Meissner effect on magnetic microtraps for ultracold atoms near superconducting microstructures. This task has been accomplished both theoretically and experimentally. The Meissner effect distorts the magnetic fields near superconducting surfaces, thus altering the parameters of magnetic microtraps. Both computer simulations and experimental measurements demonstrate that the Meissner effect shortens the distance between the magnetic microtrap and the superconducting surface, reduces the magnetic-field gradients and dramatically lowers the trap depth. A novel numerical method for calculating magnetic fields in atom chips with superconducting microstructures has been developed. This numerical method overcomes the geometrical limitations of other calculation techniques and can solve superconducting microstructures of arbitrary geometry. The numerical method has been used to calculate the parameters of magnetic microtraps in computer-simulated chips containing thin-film wires. Simulations were carried out for both the superconducting and the normal-conducting state, and the differences between the two cases were analyzed. Computer simulations have been contrasted with experimental measurements. The experimental apparatus generates a magnetic microtrap for ultracold Rubidium atoms near a superconducting Niobium wire of circular cross section. The design and construction of the apparatus has met the challenge of integrating the techniques for producing atomic quantum gases with the techniques for cooling solid bodies to cryogenic temperatures. By monitoring the position of the atom cloud, one can observe how the Meissner effect influences the magnetic microtrap. (orig.)

  20. 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

  1. Fundamental of cryogenics (for superconducting RF technology)

    CERN Document Server

    Pierini, Paolo

    2013-01-01

    This review briefly illustrates a few fundamental concepts of cryogenic engineering, the technological practice that allows reaching and maintaining the low-temperature operating conditions of the superconducting devices needed in particle accelerators. To limit the scope of the task, and not to duplicate coverage of cryogenic engineering concepts particularly relevant to superconducting magnets that can be found in previous CAS editions, the overview presented in this course focuses on superconducting radio-frequency cavities.

  2. Color superconductivity

    International Nuclear Information System (INIS)

    Wilczek, F.

    1997-01-01

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken

  3. Color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Wilczek, F. [Institute for Advanced Study, Princeton, NJ (United States)

    1997-09-22

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken.

  4. Superconducting magnet

    Science.gov (United States)

    1985-01-01

    Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

  5. Melt formed superconducting joint between superconducting tapes

    International Nuclear Information System (INIS)

    Benz, M.G.; Knudsen, B.A.; Rumaner, L.E.; Zaabala, R.J.

    1992-01-01

    This patent describes a superconducting joint between contiguous superconducting tapes having an inner laminate comprised of a parent-metal layer selected from the group niobium, tantalum, technetium, and vanadium, a superconductive intermetallic compound layer on the parent-metal layer, a reactive-metal layer that is capable of combining with the parent-metal and forming the superconductive intermetallic compound, the joint comprising: a continuous precipitate of the superconductive intermetallic compound fused to the tapes forming a continuous superconducting path between the tapes

  6. Superconducting energy store

    International Nuclear Information System (INIS)

    Elsel, W.

    1986-01-01

    The advantages obtained by the energy store device according to the invention with a superconducting solenoid system consist of the fact that only relatively short superconducting forward and return leads are required, which are collected into cables as far as possible. This limits the coolant losses of the cables. Only one relatively expensive connecting part with a transition of its conductors from room temperature to a low temperature is required, which, like the normal conducting current switch, is easily accessible. As the continuation has to be cooled independently of the upper part solenoid, cooling of this continuation part can prevent the introduction of large quantities of heat into the connected part solenoid. Due to the cooling of the forward and return conductors of the connecting cable with the coolant of the lower part solenoid, there are relatively few separations between the coolant spaces of the part solenoids. (orig./MM) [de

  7. Quasiparticle dynamics in aluminium superconducting microwave resonators

    NARCIS (Netherlands)

    De Visser, P.J.

    2014-01-01

    This thesis describes the intrinsic limits of superconducting microresonator detectors. In a superconductor at low temperature, most of the electrons are paired into so called Cooper pairs, which cause the well-known electrical conduction without resistance. Superconducting microwave resonators have

  8. Superconducting plasmas

    International Nuclear Information System (INIS)

    Ohnuma, Toshiro; Ohno, J.

    1994-01-01

    Superconducting (SC) plasmas are proposed and investigated. The SC plasmas are not yet familiar and have not yet been studied. However, the existence and the importance of SC plasmas are stressed in this report. The existence of SC plasmas are found as follows. There is a fundamental property of Meissner effect in superconductors, which shows a repulsive effect of magnetic fields. Even in that case, in a microscopic view, there is a region of magnetic penetration. The penetration length λ is well-known as London's penetration depth, which is expressed as δ = (m s /μ 0 n s q s 2 ) 1/2 where m s , n s , q s and μ o show the mass, the density, the charge of SC electron and the permeability in free space, respectively. Because this expression is very simple, no one had tried it into more simple and meaningful form. Recently, one of the authors (T.O.) has found that the length can be expressed into more simple and understandable fundamental form as λ = c/ω ps where c = (ε 0 μ 0 ) -1/2 and ω ps = (n s q s 2 /m s ε 0 ) 1/2 are the light velocity and the superconducting plasma frequency. From this simple expression, the penetration depth of the magnetic field to SC is found as a SC plasma skin depth, that is, the fundamental property of SC can be expressed by the SC plasmas. This discovery indicates an importance of the studies of superconducting plasmas. From these points, several properties (propagating modes et al) of SC plasmas, which consist of SC electrons, normal electrons and lattice ions, are investigated in this report. Observations of SC plasma frequency is also reported with a use of Terahertz electromagnet-optical waves

  9. The state of superconductivity

    International Nuclear Information System (INIS)

    Clark, T.D.

    1981-01-01

    The present status of applications based on the phenomena of superconductivity are reviewed. Superconducting materials, large scale applications, the Josephson effect and its applications, and superconductivity in instrumentation, are considered. The influence that superconductivity has had on modern theories of elementary particles, such as gauge symmetry breaking, is discussed. (U.K.)

  10. Anisotropic two-gap superconductivity and the absence of a Pauli paramagnetic limit in single-crystalline LaO0.5F0.5BiS2

    Science.gov (United States)

    Chan, Y. C.; Yip, K. Y.; Cheung, Y. W.; Chan, Y. T.; Niu, Q.; Kajitani, J.; Higashinaka, R.; Matsuda, T. D.; Yanase, Y.; Aoki, Y.; Lai, K. T.; Goh, Swee K.

    2018-03-01

    Ambient-pressure-grown LaO0.5F0.5BiS2 with a superconducting transition temperature Tc˜3 K possesses a highly anisotropic normal state. By a series of electrical resistivity measurements with a magnetic-field direction varying between the crystalline c axis and the a b plane, we present datasets displaying the temperature dependence of the out-of-plane upper critical field Hc2 ⊥(T ) , the in-plane upper critical field Hc2 ∥(T ) , as well as the angular dependence of Hc 2 at fixed temperatures for ambient-pressure-grown LaO0.5F0.5BiS2 single crystals. The anisotropy of the superconductivity, Hc2 ∥/Hc2 ⊥ , reaches ˜16 on approaching 0 K, but it decreases significantly near Tc. A pronounced upward curvature of Hc2 ∥(T ) is observed near Tc, which we analyze using a two-gap model. Moreover, Hc2 ∥(0 ) is found to exceed the Pauli paramagnetic limit, which can be understood by considering the strong spin-orbit coupling associated with Bi as well as the breaking of the local inversion symmetry at the electronically active BiS2 bilayers. Hence, LaO0.5F0.5BiS2 with a centrosymmetric lattice structure is a unique platform to explore the physics associated with local parity violation in the bulk crystal.

  11. 100 years of superconductivity

    CERN Document Server

    Rogalla, Horst

    2011-01-01

    Even a hundred years after its discovery, superconductivity continues to bring us new surprises, from superconducting magnets used in MRI to quantum detectors in electronics. 100 Years of Superconductivity presents a comprehensive collection of topics on nearly all the subdisciplines of superconductivity. Tracing the historical developments in superconductivity, the book includes contributions from many pioneers who are responsible for important steps forward in the field.The text first discusses interesting stories of the discovery and gradual progress of theory and experimentation. Emphasizi

  12. 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

  13. Superconducting accelerator technology

    International Nuclear Information System (INIS)

    Grunder, H.A.; Hartline, B.K.

    1986-01-01

    Modern and future accelerators for high energy and nuclear physics rely increasingly on superconducting components to achieve the required magnetic fields and accelerating fields. This paper presents a practical overview of the phenomenon of superconductivity, and describes the design issues and solutions associated with superconducting magnets and superconducting rf acceleration structures. Further development and application of superconducting components promises increased accelerator performance at reduced electric power cost

  14. Superconducting microphone for photoacoustic spectroscopy

    International Nuclear Information System (INIS)

    Ribeiro, P.C.; Labrunie, M.; Weid, J.P. von der; Symko, O.G.

    1982-07-01

    A superconducting microphone has been developed for photoacoustic spectroscopy at low temperatures. The microphone consists of a thin mylar membrane coated with a film of lead whose motion is detected by a SQUID magnetometer. For the simple set-up presented here, the limiting pressure sensitivity is 7.5x10 -14 atmospheres/√Hz. (Author) [pt

  15. Modern technologies in rf superconductivity

    International Nuclear Information System (INIS)

    Lengeler, H.

    1994-01-01

    The development and application of superconducting rf cavities in particle accelerators is a fine example of advanced technology and of close cooperation with industry. This contribution examines the theoretical and present-day practical limitations of sc cavities and describes some advanced technologies needed for their large scale applications. (orig.)

  16. Many-polaron theory for superconductivity and charge-density waves in a strongly coupled electron-phonon system with quasi-two-dimensionality: An interpolation between the adiabatic limit and the inverse-adiabatic limit

    International Nuclear Information System (INIS)

    Nasu, K.

    1987-01-01

    The phase diagram of a two-dimensional N-site N-electron system (N>>1) with site-diagonal electron-phonon (e-ph) coupling is studied in the context of polaron theory, so as to clarify the competition between the superconducting (SC) state and the charge-density wave (CDW) state. The Fermi surface of noninteracting electrons is assumed to be a complete circle with no nesting-type instability in the case of weak e-ph coupling, so as to focus on such a strong coupling that even the standard ''strong-coupling theory'' for superconductivity breaks down. Phonon clouds moving with electrons as well as a frozen phonon are taken into account by a variational method, combined with a mean-field theory. It covers the whole region of three basic parameters characterizing the system: the intersite transfer energy of electron T, the e-ph coupling energy S, and the phonon energy ω. The resultant phase diagram is given in a triangular coordinate space spanned by T, S, and ω. In the adiabatic region ω >(T,S) near the ω vertex of the triangle, on the other hand, each electron becomes a small polaron, and the SC state is always more stable than the CDW state, because the retardation effect is absent

  17. Large superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Magnusson, Niklas; Jensen, Bogi Bech

    2012-01-01

    and the rotation speed is lowered in order to limit the tip speed of the blades. The ability of superconducting materials to carry high current densities with very small losses might facilitate a new class of generators operating with an air gap flux density considerably higher than conventional generators...... and thereby having a smaller size and weight [1, 2]. A 5 MW superconducting wind turbine generator forms the basics for the feasibility considerations, particularly for the YBCO and MgB2 superconductors entering the commercial market. Initial results indicate that a 5 MW generator with an active weight of 34...

  18. Understanding and application of superconducting materials

    International Nuclear Information System (INIS)

    Moon, Byeong Mu; Lee, Chun Heung

    1997-02-01

    This book deals with superconducting materials, which contains from basic theory to application of superconducting materials. The contents of this book are mystery of superconducting materials, properties of superconducting materials, thermodynamics of superconducting materials, theoretical background of superconducting materials, tunnelling and quantum interference, classification and properties of superconducting materials, high temperature superconducting materials, production and analysis of superconducting materials and application of superconducting materials.

  19. 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)

  20. ac superconducting articles

    International Nuclear Information System (INIS)

    Meyerhoff, R.W.

    1977-01-01

    A noval ac superconducting cable is described. It consists of a composite structure having a superconducting surface along with a high thermally conductive material wherein the superconducting surface has the desired physical properties, geometrical shape and surface finish produced by the steps of depositing a superconducting layer upon a substrate having a predetermined surface finish and shape which conforms to that of the desired superconducting article, depositing a supporting layer of material on the superconducting layer and removing the substrate, the surface of the superconductor being a replica of the substrate surface

  1. 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)

  2. Application of superconductivity in cyclotron construction

    International Nuclear Information System (INIS)

    Blosser, H.G.

    1982-01-01

    This paper reviews major concepts and design features of the new class of cyclotrons which use superconducting coils to provide main magnet excitation. The discussion begins with a brief historical review tracing the evolution of these ''superconducting'' cyclotrons and the impact of this application of superconductivity in pushing back traditional cyclotron construction limits. This is followed by a review of the principal phenomena which come into play to set new limits on the operating regime, and the nature of these limits, some of which arise from orbit properties and some of which result from construction intricacies in the coil and in the rf system. Conclusions anticipate a future widely encompassing role in the application of superconductivity to cyclotron

  3. Additive Manufactured Superconducting Cavities

    Science.gov (United States)

    Holland, Eric; Rosen, Yaniv; Woolleet, Nathan; Materise, Nicholas; Voisin, Thomas; Wang, Morris; Mireles, Jorge; Carosi, Gianpaolo; Dubois, Jonathan

    Superconducting radio frequency cavities provide an ultra-low dissipative environment, which has enabled fundamental investigations in quantum mechanics, materials properties, and the search for new particles in and beyond the standard model. However, resonator designs are constrained by limitations in conventional machining techniques. For example, current through a seam is a limiting factor in performance for many waveguide cavities. Development of highly reproducible methods for metallic parts through additive manufacturing, referred to colloquially as 3D printing\\x9D, opens the possibility for novel cavity designs which cannot be implemented through conventional methods. We present preliminary investigations of superconducting cavities made through a selective laser melting process, which compacts a granular powder via a high-power laser according to a digitally defined geometry. Initial work suggests that assuming a loss model and numerically optimizing a geometry to minimize dissipation results in modest improvements in device performance. Furthermore, a subset of titanium alloys, particularly, a titanium, aluminum, vanadium alloy (Ti - 6Al - 4V) exhibits properties indicative of a high kinetic inductance material. This work is supported by LDRD 16-SI-004.

  4. Magnetic interaction between spatially extended superconducting tunnel junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    2002-01-01

    A general description of magnetic interactions between superconducting tunnel junctions is given. The description covers a wide range of possible experimental systems, and we explicitly explore two experimentally relevant limits of coupled junctions. One is the limit of junctions with tunneling...... been considered through arrays of superconducting weak links based on semiconductor quantum wells with superconducting electrodes. We use the model to make direct interpretations of the published experiments and thereby propose that long-range magnetic interactions are responsible for the reported...

  5. WORKSHOPS: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    In the continual push towards higher energy particle beams, superconducting radiofrequency techniques now play a vital role, highlighted in the fifth workshop on radiofrequency superconductivity, held at DESY from 19 - 24 August 1991

  6. WORKSHOPS: Radiofrequency superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1992-01-15

    In the continual push towards higher energy particle beams, superconducting radiofrequency techniques now play a vital role, highlighted in the fifth workshop on radiofrequency superconductivity, held at DESY from 19 - 24 August 1991.

  7. 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

  8. 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.)

  9. Superconducting Magnets for Accelerators

    Science.gov (United States)

    Brianti, G.; Tortschanoff, T.

    1993-03-01

    This chapter describes the main features of superconducting magnets for high energy synchrotrons and colliders. It refers to magnets presently used and under development for the most advanced accelerators projects, both recently constructed or in the preparatory phase. These magnets, using the technology mainly based on the NbTi conductor, are described from the aspect of design, materials, construction and performance. The trend toward higher performance can be gauged from the doubling of design field in less than a decade from about 4 T for the Tevatron to 10 T for the LHC. Special properties of the superconducting accelerator magnets, such as their general layout and the need of extensive computational treatment, the limits of performance inherent to the available conductors, the requirements on the structural design are described. The contribution is completed by elaborating on persistent current effects, quench protection and the cryostat design. As examples the main magnets for HERA and SSC, as well as the twin-aperture magnets for LHC, are presented.

  10. Enhanced superconductivity of fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Washington, II, Aaron L.; Teprovich, Joseph A.; Zidan, Ragaiy

    2017-06-20

    Methods for enhancing characteristics of superconductive fullerenes and devices incorporating the fullerenes are disclosed. Enhancements can include increase in the critical transition temperature at a constant magnetic field; the existence of a superconducting hysteresis over a changing magnetic field; a decrease in the stabilizing magnetic field required for the onset of superconductivity; and/or an increase in the stability of superconductivity over a large magnetic field. The enhancements can be brought about by transmitting electromagnetic radiation to the superconductive fullerene such that the electromagnetic radiation impinges on the fullerene with an energy that is greater than the band gap of the fullerene.

  11. Superconductivity in Medicine

    Science.gov (United States)

    Alonso, Jose R.; Antaya, Timothy A.

    2012-01-01

    Superconductivity is playing an increasingly important role in advanced medical technologies. Compact superconducting cyclotrons are emerging as powerful tools for external beam therapy with protons and carbon ions, and offer advantages of cost and size reduction in isotope production as well. Superconducting magnets in isocentric gantries reduce their size and weight to practical proportions. In diagnostic imaging, superconducting magnets have been crucial for the successful clinical implementation of magnetic resonance imaging. This article introduces each of those areas and describes the role which superconductivity is playing in them.

  12. Superconductivity in mixed boson-fermion systems

    International Nuclear Information System (INIS)

    Ioffe, L.; Larkin, A.I.; Ovchinnikov, Yu.N.; Yu, L.

    1989-12-01

    The superconductivity of mixed boson-fermion systems is studied using a simple boson-fermion transformation model. The critical temperature of the superconducting transition is calculated over a wide range of the narrow boson band position relative to the Fermi level. The BCS scenario and boson condensation picture are recovered in two limiting cases of high and low positions of boson band, respectively, with modifications due to boson-fermion interaction. (author). 11 refs

  13. Superconductivity in transition metals.

    Science.gov (United States)

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  14. Demonstration of superconducting micromachined cavities

    Energy Technology Data Exchange (ETDEWEB)

    Brecht, T., E-mail: teresa.brecht@yale.edu; Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J. [Department of Applied Physics, Yale University, New Haven, Connecticut 06511 (United States)

    2015-11-09

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing.

  15. 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

  16. The present role of superconductivity in fusion

    International Nuclear Information System (INIS)

    Shimamoto, S.

    1986-01-01

    After completion of large fusion devices in the world, such as JT-60, JET and TFTR, high temperature plasma is proceeding to critical condition for fusion. The devices up to now use mainly conventional magnet. However, for the next generation machine which demonstrates fusion reaction, deuterium-tritium burning, superconducting magnet system is indispensable from view point of both net energy extraction and capacity limitation of power supply. In order to realize such a large and complicated system, a lot of development works is being carried out. This paper describes required parameters of superconducting magnet and helium refrigerator, the state of plasma condition and superconducting magnet. It is shown that the present technology of superconducting magnet is not so far from realization of fusion experimental reactor

  17. A statistical rationale for establishing process quality control limits using fixed sample size, for critical current verification of SSC superconducting wire

    International Nuclear Information System (INIS)

    Pollock, D.A.; Brown, G.; Capone, D.W. II; Christopherson, D.; Seuntjens, J.M.; Woltz, J.

    1992-01-01

    This work has demonstrated the statistical concepts behind the XBAR R method for determining sample limits to verify billet I c performance and process uniformity. Using a preliminary population estimate for μ and σ from a stable production lot of only 5 billets, we have shown that reasonable sensitivity to systematic process drift and random within billet variation may be achieved, by using per billet subgroup sizes of moderate proportions. The effects of subgroup size (n) and sampling risk (α and β) on the calculated control limits have been shown to be important factors that need to be carefully considered when selecting an actual number of measurements to be used per billet, for each supplier process. Given the present method of testing in which individual wire samples are ramped to I c only once, with measurement uncertainty due to repeatability and reproducibility (typically > 1.4%), large subgroups (i.e. >30 per billet) appear to be unnecessary, except as an inspection tool to confirm wire process history for each spool. The introduction of the XBAR R method or a similar Statistical Quality Control procedure is recommend for use in the superconducing wire production program, particularly when the program transitions from requiring tests for all pieces of wire to sampling each production unit

  18. Laser activated superconducting switch

    International Nuclear Information System (INIS)

    Wolf, A.A.

    1976-01-01

    A superconducting switch or bistable device is described consisting of a superconductor in a cryogen maintaining a temperature just below the transition temperature, having a window of the proper optical frequency band for passing a laser beam which may impinge on the superconductor when desired. The frequency of the laser is equal to or greater than the optical absorption frequency of the superconducting material and is consistent with the ratio of the gap energy of the switch material to Planck's constant, to cause depairing of electrons, and thereby normalize the superconductor. Some embodiments comprise first and second superconducting metals. Other embodiments feature the two superconducting metals separated by a thin film insulator through which the superconducting electrons tunnel during superconductivity

  19. Superconducting Magnets

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    Starting from the beam requirements for accelerator magnets, we will outline the main issues and the physical limitations for producing strong and pure magnetic fields with superconductors. The seminar will mainly focus on the magnets for the accelerator, and give some hints on the magnets for the experiments. Prerequisite knowledge: Basic knowledge of Maxwell equations, and linear optics for particle accelerators (FODO cell, beta functions).

  20. Frontiers in Superconducting Materials

    CERN Document Server

    Narlikar, Anant V

    2005-01-01

    Frontiers in Superconducting Materials gives a state-of-the-art report of the most important topics of the current research in superconductive materials and related phenomena. It comprises 30 chapters written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students. It also addresses electronic and electrical engineers. Even non-specialists interested in superconductivity might find some useful answers.

  1. Superconductivity and their applications

    OpenAIRE

    Roque, António; Sousa, Duarte M.; Fernão Pires, Vítor; Margato, Elmano

    2017-01-01

    Trabalho apresentado em International Conference on Renewable Energies and Power Quality (ICREPQ’17), 4 a 6 de Abril de 2017, Málaga, Espanha The research in the field of superconductivity has led to the synthesis of superconducting materials with features that allow you to expand the applicability of this kind of materials. Among the superconducting materials characteristics, the critical temperature of the superconductor is framing the range and type of industrial applications that can b...

  2. Superconducting machines. Chapter 4

    International Nuclear Information System (INIS)

    Appleton, A.D.

    1977-01-01

    A brief account is given of the principles of superconductivity and superconductors. The properties of Nb-Ti superconductors and the method of flux stabilization are described. The basic features of superconducting d.c. machines are illustrated by the use of these machines for ship propulsion, steel-mill drives, industrial drives, aluminium production, and other d.c. power supplies. Superconducting a.c. generators and their design parameters are discussed. (U.K.)

  3. Superconductivity in the actinides

    International Nuclear Information System (INIS)

    Smith, J.L.; Lawson, A.C.

    1985-01-01

    The trends in the occurrence of superconductivity in actinide materials are discussed. Most of them seem to show simple transition metal behavior. However, the superconductivity of americium proves that the f electrons are localized in that element and that ''actinides'' is the correct name for this row of elements. Recently the superconductivity of UBe 13 and UPt 3 has been shown to be extremely unusual, and these compounds fall in the new class of compounds now known as heavy fermion materials

  4. WORKSHOP: Radiofrequency superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1984-10-15

    The Second Workshop on Radiofrequency Superconductivity was held at CERN from 23-27 July, four years after the first, organized at Karlsruhe. 35 invited talks were presented to the about 80 participants from Australia, Brazil, Europe, Japan and the United States. For the first time, ten Laboratories operating or planning superconducting accelerators for heavy ions participated and shared their experience with the community proposing the use of superconducting accelerating sections for electron accelerators.

  5. WORKSHOP: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    The Second Workshop on Radiofrequency Superconductivity was held at CERN from 23-27 July, four years after the first, organized at Karlsruhe. 35 invited talks were presented to the about 80 participants from Australia, Brazil, Europe, Japan and the United States. For the first time, ten Laboratories operating or planning superconducting accelerators for heavy ions participated and shared their experience with the community proposing the use of superconducting accelerating sections for electron accelerators

  6. 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

  7. Superconductivity and its application

    International Nuclear Information System (INIS)

    Spadoni, M.

    1988-01-01

    This paper, after a short introduction to superconductivity and to multifilamentary superconducting composites is aiming to review the state of the art and the future perspective of some of the applications of the superconducting materials. The main interest is focussed to large scale applications like, for istance, magnets for accelerators or fusion reactors, superconducting system for NMR thomography, etc. A short paragraph is dedicated to applications for high sensitivity instrumentation. The paper is then concluded by some considerations about the potentialities of the newly discovered high critical temperature materials

  8. Superconducting quantum electronics

    International Nuclear Information System (INIS)

    Kose, V.

    1989-01-01

    This book reviews recent accomplishments, presents new results and discusses possible future developments of superconducting quantum electronics and high T c superconductivity. The three main parts of the book deal with fundamentals, sensitive detectors, and precision metrology. New results reported include: correct equivalent circuits modelling superconducting electronic devices; exact solution of the Mattis-Bardeen equations describing various experiments for thin films; complete theoretical description and experimental results for a new broad band spectrum analyzer; a new Josephson junction potentiometer allowing tracing of unknown voltage ratios back to well-known frequency ratios; and fast superconducting SQUID shift registers enabling the production of calculable noise power spectra in the microwave region

  9. Superconducting linear accelerator cryostat

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Elkonin, B.V.; Sokolowski, J.S.

    1984-01-01

    A large vertical cryostat for a superconducting linear accelerator using quarter wave resonators has been developed. The essential technical details, operational experience and performance are described. (author)

  10. 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 ...

  11. Limits to the critical transport current in superconducting (Bi,Pb)2Sr2Ca2Cu3O10 silver-sheathed tapes: The railway-switch model

    International Nuclear Information System (INIS)

    Hensel, B.; Grasso, G.; Fluekiger, R.

    1995-01-01

    We have proposed the ''railway-switch'' model to describe the superconducting transport current in (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 silver-sheathed tapes. The model assumes that in the textured polycrystalline filament the frequent small-angle c-axis tilt grain boundaries (''railway switches'') constitute strong links for the supercurrent. With the objective to identify the mechanisms that limit the critical-current density in the tapes we present measurements of the transport critical current normal to the tape plane and of the current-transfer length along the tape axis. From I-V curves we obtain the longitudinal critical-current distribution and compare it to the thickness variation of the filament. The experiments have been performed on monofilamentary powder-in-tube samples prepared in long lengths by rolling as the only tape-forming process. For all investigated samples the critical-current density at T=77 K in self-field was in the range j c =20--30 kA/cm 2 . We conclude that the dominant limitation for the transport critical current in the tapes is imposed by the low intragrain critical-current density j c c along the c axis (as compared to the in-plane critical-current density j c ab ) and by the even lower critical-current density j c t across twist boundaries or intergrowths. Possibilities for an improvement of the performance of the (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 silver-sheathed tapes are discussed

  12. Research on superconducting generator and materials in Japan

    International Nuclear Information System (INIS)

    Uyeda, K.; Maki, N.; Kurihara, S.; Ueda, A.; Hirose, S.; Itoh, K.

    1988-01-01

    As a first step of application of superconducting technology to electric power equipment, the practical use of superconducting generator is sucessfully developed, enhanced generation efficiency, reduced construction cost, improved stability limit. For the development, it is required to integrated such technical assets as new generator design technology based on detailed analysis of techniques and high strength material for with standing intensive electro-magnetic force. This paper describes history and results of research and development of superconducting generator for experimental machines, the results of feasibility study of pilot generator, and master plan for research and development of superconducting technology for applications to generator and the other power apparatus

  13. Characterization of a superconducting Pb photocathode in a superconducting rf photoinjector cavity

    CERN Document Server

    Barday, R; Jankowiak, A; Kamps, T; Knobloch, J; Kugeler, O; Matveenko, A; Neumann, A; Schmeißer, M; Volker, J; Kneisel, P; Nietubyc, R; Schubert S; Smedley J; Sekutowicz, J; Will, I

    2014-01-01

    Photocathodes are a limiting factor for the next generation of ultrahigh brightness photoinjectors. We studied the behavior of a superconducting Pb cathode in the cryogenic environment of a superconducting rf gun cavity to measure the quantum efficiency, its spatial distribution, and the work function. We will also discuss how the cathode surface contaminants modify the performance of the photocathode as well as the gun cavity and we discuss the possibilities to remove these contaminants.

  14. Field-Induced Superconductivity in Electric Double Layer Transistors

    NARCIS (Netherlands)

    Ueno, Kazunori; Shimotani, Hidekazu; Yuan, Hongtao; Ye, Jianting; Kawasaki, Masashi; Iwasa, Yoshihiro

    Electric field tuning of superconductivity has been a long-standing issue in solid state physics since the invention of the field-effect transistor (FET) in 1960. Owing to limited available carrier density in conventional FET devices, electric-field-induced superconductivity was believed to be

  15. Radiation effects on superconductivity

    International Nuclear Information System (INIS)

    Brown, B.S.

    1975-01-01

    The effect of radiation on the superconducting transition temperature (T/sub c/), upper critical field (H/sub c2/), and volume-pinning-force density (F/sub p/) were discussed for the three kinds of superconducting material (elements, alloys, and compounds). 11 figures, 3 tables, 86 references

  16. Superconducting elliptical cavities

    CERN Document Server

    Sekutowicz, J K

    2011-01-01

    We give a brief overview of the history, state of the art, and future for elliptical superconducting cavities. Principles of the cell shape optimization, criteria for multi-cell structures design, HOM damping schemes and other features are discussed along with examples of superconducting structures for various applications.

  17. Superconductivity in technology

    International Nuclear Information System (INIS)

    Komarek, P.

    1976-01-01

    Physics, especially high energy physics and solid state physics was the first area in which superconducting magnets were used but in the long run, the most extensive application of superconductivity will probably be in energy technology. Superconducting power transmission cables, magnets for energy conversion in superconducting electrical machines, MHD-generators and fusion reactors and magnets for energy storage are being investigated. Magnets for fusion reactors will have particularly large physical dimensions, which means that much development effort is still needed, for there is no economic alternative. Superconducting surfaces in radio frequency cavities can give Q-values up to a factor of 10 6 higher than those of conventional resonators. Particle accelerators are the important application. And for telecommunication, simple coaxial superconducting radio frequency cables seem promising. The tunnel effect in superconducting junctions is now being developed commercially for sensitive magnetometers and may soon possibly feature in the memory cells of computer devices. Hence superconductivity can play an important role in the technological world, solving physical and technological problems and showing economic advantages as compared with possible conventional techniques, bearing also in mind the importance of reliability and safety. (author)

  18. Academic training: Applied superconductivity

    CERN Multimedia

    2007-01-01

    LECTURE SERIES 17, 18, 19 January from 11.00 to 12.00 hrs Council Room, Bldg 503 Applied Superconductivity : Theory, superconducting Materials and applications E. PALMIERI/INFN, Padova, Italy When hearing about persistent currents recirculating for several years in a superconducting loop without any appreciable decay, one realizes that we are dealing with a phenomenon which in nature is the closest known to the perpetual motion. Zero resistivity and perfect diamagnetism in Mercury at 4.2 K, the breakthrough during 75 years of several hundreds of superconducting materials, the revolution of the "liquid Nitrogen superconductivity"; the discovery of still a binary compound becoming superconducting at 40 K and the subsequent re-exploration of the already known superconducting materials: Nature discloses drop by drop its intimate secrets and nobody can exclude that the last final surprise must still come. After an overview of phenomenology and basic theory of superconductivity, the lectures for this a...

  19. Superconductivity in bad metals

    International Nuclear Information System (INIS)

    Emery, V.J.; Kivelson, S.A.

    1995-01-01

    It is argued that many synthetic metals, including high temperature superconductors are ''bad metals'' with such a poor conductivity that the usual mean-field theory of superconductivity breaks down because of anomalously large classical and quantum fluctuations of the phase of the superconducting order parameter. Some consequences for high temperature superconductors are described

  20. Nano-fabricated superconducting radio-frequency composites, method for producing nano-fabricated superconducting rf composites

    Science.gov (United States)

    Norem, James H.; Pellin, Michael J.

    2013-06-11

    Superconducting rf is limited by a wide range of failure mechanisms inherent in the typical manufacture methods. This invention provides a method for fabricating superconducting rf structures comprising coating the structures with single atomic-layer thick films of alternating chemical composition. Also provided is a cavity defining the invented laminate structure.

  1. Acoustic wave spread in superconducting-normal-superconducting sandwich

    International Nuclear Information System (INIS)

    Urushadze, G.I.

    2004-01-01

    The acoustic wave spread, perpendicular to the boundaries between superconducting and normal metals in superconducting-normal-superconducting (SNS) sandwich has been considered. The alternate current flow sound induced by the Green function method has been found and the coefficient of the acoustic wave transmission through the junction γ=(S 1 -S 2 )/S 1 , (where S 1 and S 2 are average energy flows formed on the first and second boundaries) as a function of the phase difference between superconductors has been investigated. It is shown that while the SNS sandwich is almost transparent for acoustic waves (γ 0 /τ), n=0,1,2, ... (where τ 0 /τ is the ratio of the broadening of the quasiparticle energy levels in impurity normal metal as a result of scattering of the carriers by impurities 1/τ to the spacing between energy levels 1/τ 0 ), γ=2, (S 2 =-S 1 ), which corresponds to the full reflection of the acoustic wave from SNS sandwich. This result is valid for the limit of a pure normal metal but in the main impurity case there are two amplification and reflection regions for acoustic waves. The result obtained shows promise for the SNS sandwich as an ideal mirror for acoustic wave reflection

  2. Submicron superconducting structures

    International Nuclear Information System (INIS)

    Golovashkin, A.I.; Lykov, A.N.

    1986-01-01

    An overview of works concerning superconducting structures of submicron dimensions and a system of such structures is given. It is noted that usage of the above structures in superconducting microelectronics permits, first, to increase the element packing density, to decrease the signal transmission time, capacity, power dissipated in high-frequency applications. Secondly, negligible coherence length in transition metals, their alloys and high-temperature compounds also restrict the dimensions of superconducting weak couplings when the 'classical' Josephson effect is displayed. The most effective methods for production of submicron superconducting structures are the following: lithography, double scribering. Recently the systems of superconducting submicron elements are extensively studied. It is shown that such systems can be phased by magnetic field

  3. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Mijatovic, Nenad; Seiler, Eugen

    2010-01-01

    , the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10......We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future...... offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However...

  4. Superconducting Wind Turbine Generators

    Directory of Open Access Journals (Sweden)

    Yunying Pan

    2016-08-01

    Full Text Available Wind energy is well known as a renewable energy because its clean and less polluted characteristic, which is the foundation of development modern wind electricity. To find more efficient wind turbine is the focus of scientists around the world. Compared from conventional wind turbines, superconducting wind turbine generators have advantages at zero resistance, smaller size and lighter weight. Superconducting wind turbine will inevitably become the main trends in this area. This paper intends to introduce the basic concept and principle of superconductivity, and compare form traditional wind turbine to obtain superiority, then to summary three proposed machine concept.While superconductivity have difficulty  in modern technology and we also have proposed some challenges in achieving superconducting wind turbine finally.

  5. Superconducting microtraps for ultracold atoms

    International Nuclear Information System (INIS)

    Hufnagel, C.

    2011-01-01

    Atom chips are integrated devices in which atoms and atomic clouds are stored and manipulated in miniaturized magnetic traps. State of the art fabrication technologies allow for a flexible design of the trapping potentials and consequently provide extraordinary control over atomic samples, which leads to a promising role of atom chips in the engineering and investigation of quantum mechanical systems. Naturally, for quantum mechanical applications, the atomic coherence has to be preserved. Using room temperature circuits, the coherence time of atoms close to the surface was found to be drastically limited by thermal current fluctuations in the conductors. Superconductors offer an elegant way to circumvent thermal noise and therefore present a promising option for the coherent manipulation of atomic quantum states. In this thesis trapping and manipulation of ultracold Rubidium atoms in superconducting microtraps is demonstrated. In this connection the unique properties of superconductors are used to build traps based on persistent currents, the Meissner effect and remanent magnetization. In experiment it is shown, that in superconducting atom chips, thermal magnetic field noise is significantly reduced. Furthermore it is demonstrated, that atomic samples can be employed to probe the properties of superconducting materials. (author) [de

  6. Superconductivity and electron microscopy

    International Nuclear Information System (INIS)

    Hawkes, P.W.; Valdre, U.

    1977-01-01

    In this review article, two aspects of the role of superconductivity in electron microscopy are examined: (i) the development of superconducting devices (mainly lenses) and their incorporation in electron microscopes; (ii) the development of electron microscope techniques for studying fundamental and technological problems associated with superconductivity. The first part opens with a brief account of the relevant properties of conventional lenses, after which the various types of superconducting lenses are described and their properties compared. The relative merits and inconveniences of superconducting and conventional lenses are examined, particular attention being paid to the spherical and chromatic aberration coefficients at accelerating voltages above a megavolt. This part closes with a survey of the various microscope designs that have been built or proposed, incorporating superconducting components. In the second part, some methods that have been or might be used in the study of superconductivity in the electron microscope are described. A brief account of the types of application for which they are suitable is given. (author)

  7. Superconducting materials and magnets

    International Nuclear Information System (INIS)

    1991-04-01

    The Technical Committee Meeting on Superconducting Materials and Magnets was convened by the IAEA and held by invitation of the Japanese government on September 4-6, 1989 in Tokyo. The meeting was hosted by the National Research Institute for Metals. Topics of the conference related to superconducting magnets and technology with particular application to fusion and the superconducting supercollider. Technology using both high and low-temperature superconductors was discussed. This document is a compendium of the papers presented at the meeting. Refs, figs and tabs

  8. 'Speedy' superconducting circuits

    International Nuclear Information System (INIS)

    Holst, T.

    1994-01-01

    The most promising concept for realizing ultra-fast superconducting digital circuits is the Rapid Single Flux Quantum (RSFQ) logic. The basic physical principle behind RSFQ logic, which include the storage and transfer of individual magnetic flux quanta in Superconducting Quantum Interference Devices (SQUIDs), is explained. A Set-Reset flip-flop is used as an example of the implementation of an RSFQ based circuit. Finally, the outlook for high-temperature superconducting materials in connection with RSFQ circuits is discussed in some details. (au)

  9. ESCAR superconducting magnet system

    International Nuclear Information System (INIS)

    Gilbert, W.S.; Meuser, R.B.; Pope, W.L.; Green, M.A.

    1975-01-01

    Twenty-four superconducting dipoles, each about 1 meter long, provide the guide field for the Experimental Superconducting Accelerator Ring proton accelerator--storage ring. Injection of 50 MeV protons corresponds to a 3 kG central dipole field, and a peak proton energy of 4.2 GeV corresponds to a 46 kG central field. Thirty-two quadrupoles provide focusing. The 56 superconducting magnets are contained in 40 cryostats that are cryogenically connected in a novel series ''weir'' arrangement. A single 1500 W refrigeration plant is required. Design and testing of the magnet and cryostat system are described. (U.S.)

  10. Superconducting tin core fiber

    International Nuclear Information System (INIS)

    Homa, Daniel; Liang, Yongxuan; Hill, Cary; Kaur, Gurbinder; Pickrell, Gary

    2015-01-01

    In this study, we demonstrated superconductivity in a fiber with a tin core and fused silica cladding. The fibers were fabricated via a modified melt-draw technique and maintained core diameters ranging from 50-300 microns and overall diameters of 125-800 microns. Superconductivity of this fiber design was validated via the traditional four-probe test method in a bath of liquid helium at temperatures on the order of 3.8 K. The synthesis route and fiber design are perquisites to ongoing research dedicated all-fiber optoelectronics and the relationships between superconductivity and the material structures, as well as corresponding fabrication techniques. (orig.)

  11. Superconductivity in doped insulators

    International Nuclear Information System (INIS)

    Emery, V.J.; Kivelson, S.A.

    1995-01-01

    It is shown that many synthetic metals, including high temperature superconductors are ''bad metals'', with such a poor conductivity that the usual meanfield theory of superconductivity breaks down because of anomalously large classical and quantum fluctuations of the phase of the superconducting order parameter. It is argued that the supression of a first order phase transition (phase separation) by the long-range Coulomb interaction leads to high temperature superconductivity accompanied by static or dynamical charge inhomogeneIty. Evidence in support of this picture for high temperature superconductors is described

  12. Superconducting active impedance converter

    International Nuclear Information System (INIS)

    Ginley, D.S.; Hietala, V.M.; Martens, J.S.

    1993-01-01

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures

  13. Introduction to superconductivity

    CERN Document Server

    Darriulat, Pierre

    1998-01-01

    The lecture series will address physicists, such as particle and nuclear physicists, familiar with non-relativistic quantum mechanics but not with solid state physics. The aim of this introduction to low temperature superconductivity is to give sufficient bases to the student for him/her to be able to access the scientific literature on this field. The five lectures will cover the following topics : 1. Normal metals, free electron gas, chambers equation. 2. Cooper pairs, the BCS ground state, quasi particle excitations. 3. DC superconductivity, Meissner state, dirty superconductors.4. Self consistent approach, Ginsburg Landau equations, Abrikosov fluxon lattice. 5. Josephson effects, high temperature superconductivity.

  14. Superconducting permanent magnets

    International Nuclear Information System (INIS)

    Wipf, S.L.; Laquer, H.L.

    1989-01-01

    The concept of superconducting permanent magnets with fields trapped in shells or cylinders of Type II superconductors is an old one. Unfortunately, the low values of 0.5 to 1T for the first flux jump field, which is independent of the actual current density, have frustrated its implementation with classical Type II superconductors. The fact that the flux jump fields for high temperature superconductors should be an order of magnitude larger at liquid nitrogen temperatures allows us to reconsider these options. Analysis of the hysteresis patterns, based on the critical state model, shows that, if the dimensions are chosen so that the sample is penetrated at a field B/sub p/, which is equal to or just less than the first flux jump field, B/sub fj/, a temporarily applied field of 2B/sub fj/ will trap 0.5 B/sub fj/. Thus for a 90 K superconductor with a B/sub fj/ of 6T, a permanent field of 3 T should be trapped, with an energy product of 1.8 MJ/m/sup 3/ (225 MG . Oe). This is five times as large as for the best permanent magnet materials. The authors discuss means to verify the analysis and the limitations imposed by the low critical current densities in presently available high temperature superconductors

  15. Superconductivity of small particles

    International Nuclear Information System (INIS)

    Leavens, C.R.; Fenton, E.W.

    1981-01-01

    The Eliashberg gap equations are used to investigate the contribution of surface-phonon softening to the size dependence of the superconducting transition temperature (T/sub c/) of small metallic particles. Because of our limited quantitative knowledge of phonon spectra and electron-phonon coupling in the surface region, the effect cannot be calculated with certainty. Previous calculations which agree with experiment depend on a fortuitous choice of input parameters which cannot be justified at present. For this reason the absence of any observable size effect for T/sub c/ in Pb is especially important. This null effect is obtained in Pb if the electron-phonon coupling strength is the same in the surface region as in the bulk. This assumption can be tested experimentally because it means that the energy gap of Pb should not be independent of particle size but rather should increase significantly with decreasing radius. Hence, measurement of the size dependence of the energy gap for well-characterized small particles of Pb could provide information regarding the importance of the phonon-softening mechanism, at least for Pb

  16. Observation of a new turbulence-driven limit-cycle state in H-modes with lower hybrid current drive and lithium-wall conditioning in the EAST superconducting tokamak

    DEFF Research Database (Denmark)

    Wang, H.Q.; Xu, G.S.; Guo, H.Y.

    2012-01-01

    The first high confinement H-mode plasma has been obtained in the Experimental Advanced Superconducting Tokamak (EAST) with about 1 MW lower hybrid current drive after wall conditioning by lithium evaporation and real-time injection of Li powder. Following the L–H transition, a small-amplitude, low...

  17. Magnetic Design of Superconducting Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Todesco, E [European Organization for Nuclear Research, Geneva (Switzerland)

    2014-07-01

    In this paper we discuss the main principles of magnetic design for superconducting magnets (dipoles and quadrupoles) for particle accelerators. We give approximated equations that govern the relation between the field/gradient, the current density, the type of superconductor (Nb−Ti or Nb3Sn), the thickness of the coil, and the fraction of stabilizer. We also state the main principle controlling the field quality optimization, and discuss the role of iron. A few examples are given to show the application of the equations and their validity limits.

  18. Magnetic and superconducting nanowires

    DEFF Research Database (Denmark)

    Piraux, L.; Encinas, A.; Vila, L.

    2005-01-01

    magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also...

  19. 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

  20. Superconducting Technology Assessment

    National Research Council Canada - National Science Library

    2005-01-01

    This Superconducting Technology Assessment (STA) has been conducted by the National Security Agency to address the fundamental question of a potential replacement for silicon complementary metal oxide semiconductor (CMOS...

  1. Superconductivity and its devices

    International Nuclear Information System (INIS)

    Forbes, D.S.

    1981-01-01

    Among the more important developments that are discussed are cryotrons, superconducting motors and generators, and high-field magnets. Cryotrons will create faster and more economical computer systems. Superconducting motors and generators will cost much less to build than conventional electric generators and cut fuel consumption. Moreover, high-field magnets are being used to confine plasma in connection with nuclear fusion. Superconductors have a vital role to play in all of these developments. Most importantly, though, are the magnetic properties of superconductivity. Superconducting magnets are an integral part of nuclear fusion. In addition, high-field magnets are necessary in the use of accelerators, which are needed to study the interactions between elementary particles

  2. Superconductivity: Heike's heritage

    NARCIS (Netherlands)

    van der Marel, D.; Golden, M.

    2011-01-01

    A century ago, Heike Kamerlingh Onnes discovered superconductivity. And yet, despite the conventional superconductors being understood, the list of unconventional superconductors is growing — for which unconventional theories may be required.

  3. Superconducting Detectors for Superlight Dark Matter.

    Science.gov (United States)

    Hochberg, Yonit; Zhao, Yue; Zurek, Kathryn M

    2016-01-08

    We propose and study a new class of superconducting detectors that are sensitive to O(meV) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark-matter limit, m(X)≳1  keV. We compute the rate of dark-matter scattering off of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological or astrophysical constraints could be detected by such detectors with a moderate size exposure.

  4. 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

  5. A superconducting RFQ for an ECR injector

    International Nuclear Information System (INIS)

    Ben-Zvi, I.

    1988-01-01

    The beam dynamics and resonator properties of a superconducting radio-frequency quadrupole (RFQ) for heavy ions are discussed. The motivation is its use as a very low velocity section following an electron cyclotron resonance (ECR) source for injection into a superconducting heavy-ion linac. The constraints on the design and performance of this accelerating structure are presented. Expressions for a limiting stable phase angle and longitudinal and transverse acceptance are derived. A numerical example is given, using the SUNYLAC linac at Sony Stony Brook. Beam-dynamics calculations with PARMTEQ are reported, verifying the theoretical beam-dynamics calculations. (author) 12 refs., 1 tab

  6. RADIOFREQUENCY SUPERCONDUCTIVITY: Workshop

    International Nuclear Information System (INIS)

    Lengeler, Herbert

    1989-01-01

    Superconducting radiofrequency is already playing an important role in the beam acceleration system for the TRISTAN electron-positron collider at the Japanese KEK Laboratory and new such systems are being prepared for other major machines. Thus the fourth Workshop on Radiofrequency Superconductivity, organized by KEK under the chairmanship of local specialist Yuzo Kojima and held just before the International Conference on High Energy Accelerators, had much progress to review and even more to look forward to

  7. Stacked magnet superconducting bearing

    International Nuclear Information System (INIS)

    Rigney, T.K. II; Saville, M.P.

    1993-01-01

    A superconducting bearing is described, comprising: a plurality of permanent magnets magnetized end-to-end and stacked side-by-side in alternating polarity, such that flux lines flow between ends of adjacent magnets; isolating means, disposed between said adjacent magnets, for reducing flux leakage between opposing sides of said adjacent magnets; and a member made of superconducting material having at least one surface in communication with said flux lines

  8. 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.

  9. Generalized Superconductivity. Generalized Levitation

    International Nuclear Information System (INIS)

    Ciobanu, B.; Agop, M.

    2004-01-01

    In the recent papers, the gravitational superconductivity is described. We introduce the concept of generalized superconductivity observing that any nongeodesic motion and, in particular, the motion in an electromagnetic field, can be transformed in a geodesic motion by a suitable choice of the connection. In the present paper, the gravitoelectromagnetic London equations have been obtained from the generalized Helmholtz vortex theorem using the generalized local equivalence principle. In this context, the gravitoelectromagnetic Meissner effect and, implicitly, the gravitoelectromagnetic levitation are given. (authors)

  10. Superconducting magnets for accelerators

    International Nuclear Information System (INIS)

    Denisov, Yu.N.

    1979-01-01

    Expediency of usage and possibilities arising in application of superconducting devices in magnetic systems of accelerators and experimental nuclear-physical devices are studied. Parameters of specific devices are given. It is emphasized that at the existing level of technological possibilities, construction and usage of superconducting magnetic systems in experimental nuclear physics should be thought of as possible, from the engineering, and expedient, from the economical viewpoints [ru

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

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Liu, Dong; Polinder, Henk

    2016-01-01

    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 generator terminals. In this paper, a finite element model that couples magnetic fields and the generator’s equivalent circuits is developed to simulate short circuit faults. Afterwards, the model is used to study the transient performance of a 10 MW HTS wind turbine generator under four different short...... that the short circuits pose great challenges to the generator, and careful consideration should be given to protect the generator. The results presented in this paper would be beneficial to the design, operation and protection of an HTS wind turbine generator....

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

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Liu, Dong; Polinder, Henk

    2017-01-01

    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 take...... place at generator terminals. In this paper, a finite element model that couples magnetic fields and the generator's equivalent circuits is developed to simulate short-circuit faults. Afterward, the model is used to study the transient performance of a 10-MW HTS wind turbine generator under four...... show that the short circuits pose great challenges to the generator, and careful consideration should be given to protect the generator. The findings presented in this paper would be beneficial to the design, operation and protection of an HTS wind turbine generator....

  13. Emergent Higgsless Superconductivity

    Directory of Open Access Journals (Sweden)

    Cristina Diamantini M.

    2017-01-01

    Full Text Available We present a new Higgsless model of superconductivity, inspired from anyon superconductivity but P- and T-invariant and generalizable to any dimension. While the original anyon superconductivity mechanism was based on incompressible quantum Hall fluids as average field states, our mechanism involves topological insulators as average field states. In D space dimensions it involves a (D-1-form fictitious pseudovector gauge field which originates from the condensation of topological defects in compact lowenergy effective BF theories. There is no massive Higgs scalar as there is no local order parameter. When electromagnetism is switched on, the photon acquires mass by the topological BF mechanism. Although the charge of the gapless mode (2 and the topological order (4 are the same as those of the standard Higgs model, the two models of superconductivity are clearly different since the origins of the gap, reflected in the high-energy sectors are totally different. In 2D thi! s type of superconductivity is explicitly realized as global superconductivity in Josephson junction arrays. In 3D this model predicts a possible phase transition from topological insulators to Higgsless superconductors.

  14. Superconducting Fullerene Nanowhiskers

    Directory of Open Access Journals (Sweden)

    Yoshihiko Takano

    2012-04-01

    Full Text Available We synthesized superconducting fullerene nanowhiskers (C60NWs by potassium (K intercalation. They showed large superconducting volume fractions, as high as 80%. The superconducting transition temperature at 17 K was independent of the K content (x in the range between 1.6 and 6.0 in K-doped C60 nanowhiskers (KxC60NWs, while the superconducting volume fractions changed with x. The highest shielding fraction of a full shielding volume was observed in the material of K3.3C60NW by heating at 200 °C. On the other hand, that of a K-doped fullerene (K-C60 crystal was less than 1%. We report the superconducting behaviors of our newly synthesized KxC60NWs in comparison to those of KxC60 crystals, which show superconductivity at 19 K in K3C60. The lattice structures are also discussed, based on the x-ray diffraction (XRD analyses.

  15. 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.)

  16. Acoustic detection in superconducting magnets for performance characterization and diagnostics

    OpenAIRE

    Marchevsky, M.; Wang, X.; Sabbi, G.; Prestemon, S.

    2014-01-01

    Quench diagnostics in superconducting accelerator magnets is essential for understanding performance limitations and improving magnet design. Applicability of the conventional quench diagnostics methods such as voltage taps or quench antennas is limited for long magnets or complex winding geometries, and alternative approaches are desirable. Here, we discuss acoustic sensing technique for detecting mechanical vibrations in superconducting magnets. Using LARP high-field Nb3Sn quadrupole HQ01 [...

  17. NATO Advanced Study Institute on Superconducting Electronics

    CERN Document Server

    Nisenhoff, Martin; Superconducting Electronics

    1989-01-01

    The genesis of the NATO Advanced Study Institute (ASI) upon which this volume is based, occurred during the summer of 1986 when we came to the realization that there had been significant progress during the early 1980's in the field of superconducting electronics and in applications of this technology. Despite this progress, there was a perception among many engineers and scientists that, with the possible exception of a limited number of esoteric fundamental studies and applications (e.g., the Josephson voltage standard or the SQUID magnetometer), there was no significant future for electronic systems incorporating superconducting elements. One of the major reasons for this perception was the aversion to handling liquid helium or including a closed-cycle helium liquefier. In addition, many critics felt that IBM's cancellation of its superconducting computer project in 1983 was "proof" that superconductors could not possibly compete with semiconductors in high-speed signal processing. From our persp...

  18. Superconducting transformers, rectifiers, and switches. (Review paper)

    International Nuclear Information System (INIS)

    Ignatov, V.E.; Koval'kov, G.A.; Moskvitin, A.I.

    Cryogenic rectifiers using power cryotrons have been fabricated by many foreign firms since 1960. Present-day flux pumps require a low voltage power supply (several tens of millivolts) and a high current (kiloamperes). Increasing the power supply voltage will quadratically increase the flux pump losses and, given the limitations of existing materials, are not economically profitable. Present-day, cryotron-type flux pumps can best be used in power systems as a power supply for superconducting magnets, solenoids, storage devices, and superconducting exciting coils for turbogenerators. To increase the voltage of the next generation of transformers for superconducting dc power transmission, a research program must be set up to improve the cryotrons and to develop systems based on a different principle of operation, for example, semiconductor devices based on the principle of the volume effect in the intermediate environment

  19. High-current applications of superconductivity

    International Nuclear Information System (INIS)

    Komarek, P.

    1995-01-01

    The following topics were dealt with: superconducting materials, design principles of superconducting magnets, magnets for research and engineering, superconductivity for power engineering, superconductivity in nuclear fusion technology, economical considerations

  20. Safety concerns for superconducting magnets of upcoming fusion experiments

    International Nuclear Information System (INIS)

    Turner, L.R.

    1983-01-01

    -Several fusion experiments being constructed (Tore Supra) or contemplated (DCT 8, Alcator DCT) feature superconducting coils. These coils introduce the following safety concerns: 1. Internally Cooled Conductor (ICC). ICC's are found to be highly stable against short heat pulses, even when the coolant is stagnant or moving at low steady-state velocity. However, a large heat pulse is certain to quench the conductor. Thus, determining the stability limits is vital. 2. Helium II Cooling. Helium II has both unique advantages as a coolant and unique safety problems. 3. Shorted Turns. In magnets with shorts from operational accidents, the current can switch back and forth between the short and the shorted turns, as those alternatively go normal and superconducting. 4. Hybrid Superconducting-Normal Conducting Coil System. The possibility of unequal currents in the different magnets and thus of unexpected forces on the superconducting magnets is much greater than for an all-superconducting system. Analysis of these problems are presented

  1. Quantum suppression of superconductivity in nanowires

    International Nuclear Information System (INIS)

    Bezryadin, Alexey

    2008-01-01

    It is of fundamental importance to establish whether there is a limit to how thin a superconducting wire can be, while retaining its superconducting character-and if there is such limit, to understand what determines it. This issue may be of practical importance in defining the limit to miniaturization of superconducting electronic circuits. Recently, a new fabrication method, called molecular templating, was developed and used to answer such questions. In this approach, a suspended carbon nanotube is coated with a thin superconducting metal film, thus forming a superconducting nanowire. The wire obtained is automatically attached to the two leads formed by the sides of the trench. The usual material for such wires is the amorphous alloy of MoGe (Graybeal 1985 PhD Thesis Stanford University; Graybeal and Beasley 1984 Phys. Rev. B 29 4167; Yazdani and Kapitulnik 1995 Phys. Rev. Lett. 74 3037; Turneaure et al 2000 Phys. Rev. Lett. 84 987). Such wires typically exhibit a high degree of homogeneity and can be made very small: as thin as ∼5 nm in diameter and as short as ∼40 nm in length. The results of transport measurements on such homogeneous wires can be summarized as follows. Short wires, shorter than some empirical length, ∼200 nm for MoGe, exhibit a clear dichotomy. They show either a superconducting behavior, with the resistance controlled by thermal fluctuations, or a weakly insulating behavior, with the resistance controlled by the weak Coulomb blockade. Thus a quantum superconductor-insulator transition (SIT) is indicated. Longer wires exhibit a gradual crossover behavior, from almost perfectly superconducting to normal or weakly insulating behavior, as their diameter is reduced. Measurements of wires, which are made inhomogeneous (granular) on purpose, show that such wires, even if they are short in the sense stated above, do not show a clear dichotomy, which could be identified as an SIT (Bollinger et al 2004 Phys. Rev. B 69 180503(R)). Thus

  2. Test equipment for a flywheel energy storage system using a magnetic bearing composed of superconducting coils and superconducting bulks

    International Nuclear Information System (INIS)

    Ogata, M; Matsue, H; Yamashita, T; Hasegawa, H; Nagashima, K; Maeda, T; Matsuoka, T; Mukoyama, S; Shimizu, H; Horiuchi, S

    2016-01-01

    Energy storage systems are necessary for renewable energy sources such as solar power in order to stabilize their output power, which fluctuates widely depending on the weather. Since ‘flywheel energy storage systems’ (FWSSs) do not use chemical reactions, they do not deteriorate due to charge or discharge. This is an advantage of FWSSs in applications for renewable energy plants. A conventional FWSS has capacity limitation because of the mechanical bearings used to support the flywheel. Therefore, we have designed a superconducting magnetic bearing composed of a superconducting coil stator and a superconducting bulk rotor in order to solve this problem, and have experimentally manufactured a large scale FWSS with a capacity of 100 kWh and an output power of 300 kW. The superconducting magnetic bearing can levitate 4 tons and enables the flywheel to rotate smoothly. A performance confirmation test will be started soon. An overview of the superconducting FWSS is presented in this paper. (paper)

  3. Conceptual study of superconducting urban area power systems

    International Nuclear Information System (INIS)

    Noe, Mathias; Gold-acker, Wilfried; Bach, Robert; Prusseit, Werner; Willen, Dag; Poelchau, Juri; Linke, Christian

    2010-01-01

    Efficient transmission, distribution and usage of electricity are fundamental requirements for providing citizens, societies and economies with essential energy resources. It will be a major future challenge to integrate more sustainable generation resources, to meet growing electricity demand and to renew electricity networks. Research and development on superconducting equipment and components have an important role to play in addressing these challenges. Up to now, most studies on superconducting applications in power systems have been concentrated on the application of specific devices like for example cables and current limiters. In contrast to this, the main focus of our study is to show the consequence of a large scale integration of superconducting power equipment in distribution level urban power systems. Specific objectives are to summarize the state-of-the-art of superconducting power equipment including cooling systems and to compare the superconducting power system with respect to energy and economic efficiency with conventional solutions. Several scenarios were considered starting from the replacement of an existing distribution level sub-grid up to a full superconducting urban area distribution level power system. One major result is that a full superconducting urban area distribution level power system could be cost competitive with existing solutions in the future. In addition to that, superconducting power systems offer higher energy efficiency as well as a number of technical advantages like lower voltage drops and improved stability.

  4. Superconducting wind turbine generators

    International Nuclear Information System (INIS)

    Abrahamsen, A B; Seiler, E; Zirngibl, T; Andersen, N H; Mijatovic, N; Traeholt, C; Pedersen, N F; Oestergaard, J; Noergaard, P B

    2010-01-01

    We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10 MW is suggested to secure the accumulation of reliability experience. Finally, the quantities of high temperature superconducting tape needed for a 10 kW and an extreme high field 10 MW generator are found to be 7.5 km and 1500 km, respectively. A more realistic estimate is 200-300 km of tape per 10 MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train.

  5. Superconductivity and macroscopic quantum phenomena

    International Nuclear Information System (INIS)

    Rogovin, D.; Scully, M.

    1976-01-01

    It is often asserted that superconducting systems are manifestations of quantum mechanics on a macroscopic scale. In this review article it is demonstrated that this quantum assertion is true within the framework of the microscopic theory of superconductivity. (Auth.)

  6. Superconducting state mechanisms and properties

    CERN Document Server

    Kresin, Vladimir Z; Wolf, Stuart A

    2014-01-01

    'Superconducting State' provides a very detailed theoretical treatment of the key mechanisms of superconductivity, including the current state of the art (phonons, magnons, and plasmons). A very complete description is given of the electron-phonon mechanism responsible for superconductivity in the majority of superconducting systems, and the history of its development, as well as a detailed description of the key experimental techniques used to study the superconducting state and determine the mechanisms. In addition, there are chapters describing the discovery and properties of the key superconducting compounds that are of the most interest for science, and applications including a special chapter on the cuprate superconductors. It provides detailed treatments of some very novel aspects of superconductivity, including multiple bands (gaps), the "pseudogap" state, novel isotope effects beyond BCS, and induced superconductivity.

  7. Rf superconducting devices

    International Nuclear Information System (INIS)

    Hartwig, W.H.; Passow, C.

    1975-01-01

    Topics discussed include (1) the theory of superconductors in high-frequency fields (London surface impedance, anomalous normal surface resistance, pippard nonlocal theory, quantum mechanical model, superconductor parameters, quantum mechanical calculation techniques for the surface, impedance, and experimental verification of surface impedance theories); (2) residual resistance (separation of losses, magnetic field effects, surface resistance of imperfect and impure conductors, residual loss due to acoustic coupling, losses from nonideal surfaces, high magnetic field losses, field emission, and nonlinear effects); (3) design and performance of superconducting devices (design considerations, materials and fabrication techniques, measurement of performance, and frequency stability); (4) devices for particle acceleration and deflection (advantages and problems of using superconductors, accelerators for fast particles, accelerators for particles with slow velocities, beam optical devices separators, and applications and projects under way); (5) applications of low-power superconducting resonators (superconducting filters and tuners, oscillators and detectors, mixers and amplifiers, antennas and output tanks, superconducting resonators for materials research, and radiation detection with loaded superconducting resonators); and (6) transmission and delay lines

  8. Superconducting Ferromagnetic Nanodiamond.

    Science.gov (United States)

    Zhang, Gufei; Samuely, Tomas; Xu, Zheng; Jochum, Johanna K; Volodin, Alexander; Zhou, Shengqiang; May, Paul W; Onufriienko, Oleksandr; Kačmarčík, Jozef; Steele, Julian A; Li, Jun; Vanacken, Johan; Vacík, Jiri; Szabó, Pavol; Yuan, Haifeng; Roeffaers, Maarten B J; Cerbu, Dorin; Samuely, Peter; Hofkens, Johan; Moshchalkov, Victor V

    2017-06-27

    Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these two competing orderings sheds light not only on the cause of various quantum phenomena in strongly correlated systems but also on the general mechanism of superconductivity. Here we report on the observation of the electronic entanglement between superconducting and ferromagnetic states in hydrogenated boron-doped nanodiamond films, which have a superconducting transition temperature T c ∼ 3 K and a Curie temperature T Curie > 400 K. In spite of the high T Curie , our nanodiamond films demonstrate a decrease in the temperature dependence of magnetization below 100 K, in correspondence to an increase in the temperature dependence of resistivity. These anomalous magnetic and electrical transport properties reveal the presence of an intriguing precursor phase, in which spin fluctuations intervene as a result of the interplay between the two antagonistic states. Furthermore, the observations of high-temperature ferromagnetism, giant positive magnetoresistance, and anomalous Hall effect bring attention to the potential applications of our superconducting ferromagnetic nanodiamond films in magnetoelectronics, spintronics, and magnetic field sensing.

  9. Superconductive analogue of spin glasses

    International Nuclear Information System (INIS)

    Feigel'man, M.; Ioffe, L.; Vinokur, V.; Larkin, A.

    1987-07-01

    The properties of granular superconductors in magnetic fields, namely the existence of a new superconductive state analogue of the low-temperature superconductive state in spin glasses are discussed in the frame of the infinite-range model and the finite-range models. Experiments for elucidation of spin-glass superconductive state in real systems are suggested. 30 refs

  10. 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

  11. On anyon superconductivity--

    International Nuclear Information System (INIS)

    Chen, Y.-H.; Wilczek, F.; Witten, E.; Halperin, B.I.

    1989-01-01

    We investigate the statistical mechanics of a gas of fractional statistics particles in 2 + 1 dimensions. In the case of statistics very close to Fermi statistics (statistical parameter θ = π(1 - 1/n), for large n), the effect of the statistics is a weak attraction. Building upon earlier RPA calculation for the case n = 2, the authors argue that for large n perturbation theory is reliable and exhibits superfluidity (or superconductivity after coupling to electromagnetism). They describe the order parameter for this superconductng phase in terms of spontaneous breaking of commutativity of translations as opposed to the usual pairing order parameters. The vortices of the superconducting anyon gas are charged, and superconducting order parameters of the usual type vanish. They investigate the characteristic P and T violating phenomenology

  12. Superconducting linac booster

    International Nuclear Information System (INIS)

    Srinivasan, B.; Betigeri, M.G.; Pandey, M.K.; Pillay, R.G.; Kurup, M.B.

    1997-01-01

    The report on superconducting LINAC booster, which is a joint project of Bhabha Atomic Research Centre (BARC) and Tata Institute of Fundamental Research (TIFR), brings out the work accomplished so far towards the development of the technology of superconducting LINAC to boost the energy of ions from the 14UD Pelletron. The LINAC is modular in construction with each module comprising of a helium cryostat housing four lead-plated quarter wave resonators. The resonators are superconducting for temperatures below 7.19K. An energy boost of 2 MeV/q per module is expected to be achieved. The first module and the post-tandem superbuncher have been fabricated and tested on the LINAC beam line. This report gives a summary of the technological achievements and also brings out the difficulties encountered during the R and D phase. (author)

  13. Superconducting accelerator magnet design

    International Nuclear Information System (INIS)

    Wolff, S.

    1994-01-01

    Superconducting dipoles, quadrupoles and correction magnets are necessary to achieve the high magnetic fields required for big accelerators presently in construction or in the design phase. Different designs of superconducting accelerator magnets are described and the designs chosen at the big accelerator laboratories are presented. The most frequently used cosθ coil configuration is discussed in detail. Approaches for calculating the magnetic field quality including coil end fields are presented. Design details of the cables, coils, mechanical structures, yokes, helium vessels and cryostats including thermal radiation shields and support structures used in superconducting magnets are given. Necessary material properties are mentioned. Finally, the main results of magnetic field measurements and quench statistics are presented. (orig.)

  14. Large Superconducting Magnet Systems

    CERN Document Server

    Védrine, P.

    2014-07-17

    The increase of energy in accelerators over the past decades has led to the design of superconducting magnets for both accelerators and the associated detectors. The use of Nb−Ti superconducting materials allows an increase in the dipole field by up to 10 T compared with the maximum field of 2 T in a conventional magnet. The field bending of the particles in the detectors and generated by the magnets can also be increased. New materials, such as Nb$_{3}$Sn and high temperature superconductor (HTS) conductors, can open the way to higher fields, in the range 13–20 T. The latest generations of fusion machines producing hot plasma also use large superconducting magnet systems.

  15. Superconducting super collider

    International Nuclear Information System (INIS)

    Limon, P.J.

    1987-01-01

    The Superconducting Super Collider is to be a 20 TeV per beam proton-proton accelerator and collider. Physically the SCC will be 52 miles in circumference and slightly oval in shape. The use of superconducting magnets instead of conventional cuts the circumference from 180 miles to the 52 miles. The operating cost of the SCC per year is estimated to be about $200-250 million. A detailed cost estimate of the project is roughly $3 billion in 1986 dollars. For the big collider ring, the technical cost are dominated by the magnet system. That is why one must focus on the cost and design of the magnets. Presently, the process of site selection is underway. The major R and D efforts concern superconducting dipoles. The magnets use niobium-titanium as a conductor stabilized in a copper matrix. 10 figures

  16. Crystalline color superconductivity

    International Nuclear Information System (INIS)

    Alford, Mark; Bowers, Jeffrey A.; Rajagopal, Krishna

    2001-01-01

    In any context in which color superconductivity arises in nature, it is likely to involve pairing between species of quarks with differing chemical potentials. For suitable values of the differences between chemical potentials, Cooper pairs with nonzero total momentum are favored, as was first realized by Larkin, Ovchinnikov, Fulde, and Ferrell (LOFF). Condensates of this sort spontaneously break translational and rotational invariance, leading to gaps which vary periodically in a crystalline pattern. Unlike the original LOFF state, these crystalline quark matter condensates include both spin-zero and spin-one Cooper pairs. We explore the range of parameters for which crystalline color superconductivity arises in the QCD phase diagram. If in some shell within the quark matter core of a neutron star (or within a strange quark star) the quark number densities are such that crystalline color superconductivity arises, rotational vortices may be pinned in this shell, making it a locus for glitch phenomena

  17. Large Superconducting Magnet Systems

    Energy Technology Data Exchange (ETDEWEB)

    Védrine, P [Saclay (France)

    2014-07-01

    The increase of energy in accelerators over the past decades has led to the design of superconducting magnets for both accelerators and the associated detectors. The use of Nb−Ti superconducting materials allows an increase in the dipole field by up to 10 T compared with the maximum field of 2 T in a conventional magnet. The field bending of the particles in the detectors and generated by the magnets can also be increased. New materials, such as Nb3Sn and high temperature superconductor (HTS) conductors, can open the way to higher fields, in the range 13–20 T. The latest generations of fusion machines producing hot plasma also use large superconducting magnet systems.

  18. Superconducting magnet technology for particle accelerators and detectors seminar

    CERN Multimedia

    CERN. Geneva

    2006-01-01

    This lecture is an introduction to superconducting magnets for particle accelerators and detectors, the aim being to explain the vocabulary and describe the basic technology of modern superconducting magnets, and to explore the limits of the technology. It will include the following: - Why we need superconducting magnets - Properties of superconductors, critical field, critical temperature - Why accelerators need fine filaments and cables; conductor manufacture - Temperature rise and temperature margin: the quench process, training - Quench protection schemes. Protection in the case of the LHC. - Magnets for detectors - The challenges of state-of-the-art magnets for High Energy Physics

  19. 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

  20. Materials for superconducting cavities

    International Nuclear Information System (INIS)

    Bonin, B.

    1996-01-01

    The ideal material for superconducting cavities should exhibit a high critical temperature, a high critical field, and, above all, a low surface resistance. Unfortunately, these requirements can be conflicting and a compromise has to be found. To date, most superconducting cavities for accelerators are made of niobium. The reasons for this choice are discussed. Thin films of other materials such as NbN, Nb 3 Sn, or even YBCO compounds can also be envisaged and are presently investigated in various laboratories. It is shown that their success will depend critically on the crystalline perfection of these films. (author)

  1. Today's markets for superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The worldwide market for superconductive products may exceed $1 billion in 1987. These products are expanding the frontiers of science, revolutionizing the art of medical diagnosis, and developing the energy technology of the future. In general, today's customers for superconductive equipment want the highest possible performance, almost regardless of cost. The products operate within a few degrees of absolute zero, and virtually all are fabricated from niobium or niobium alloys-so far the high-temperature superconductors discovered in 1986 and 1987 have had no impact on these markets. The industry shows potential and profound societal impact, even without the new materials

  2. Gambling with Superconducting Fluctuations

    Science.gov (United States)

    Foltyn, Marek; Zgirski, Maciej

    2015-08-01

    Josephson junctions and superconducting nanowires, when biased close to superconducting critical current, can switch to a nonzero voltage state by thermal or quantum fluctuations. The process is understood as an escape of a Brownian particle from a metastable state. Since this effect is fully stochastic, we propose to use it for generating random numbers. We present protocol for obtaining random numbers and test the experimentally harvested data for their fidelity. Our work is prerequisite for using the Josephson junction as a tool for stochastic (probabilistic) determination of physical parameters such as magnetic flux, temperature, and current.

  3. Superconducting cosmic strings

    International Nuclear Information System (INIS)

    Chudnovsky, E.M.; Field, G.B.; Spergel, D.N.; Vilenkin, A.

    1986-01-01

    Superconducting loops of string formed in the early Universe, if they are relatively light, can be an important source of relativistic particles in the Galaxy. They can be observed as sources of synchrotron radiation at centimeter wavelengths. We propose a string model for two recently discovered radio sources, the ''thread'' in the galactic center and the source G357.7-0.1, and predict that the filaments in these sources should move at relativistic speeds. We also consider superheavy superconducting strings, and the possibility that they be observed as extragalactic radio sources

  4. Superconducting Electronic Film Structures

    Science.gov (United States)

    1991-02-14

    Segmuller, A., Cooper, E.I., Chisholm, M.F., Gupta, A. Shinde, S., and Laibowitz, R.B. Lanthanum gallate substrates for epitaxial high-T superconducting thin...M. F. Chisholm, A. Gupta, S. Shinde, and R. B. Laibowitz, " Lanthanum Gallate Substrates for Epitaxial High-T c Superconducting Thin Films," Appl...G. Forrester and J. Talvacchio, " Lanthanum Copper Oxide Buffer Layers for Growth of High-T c Superconductor Films," Disclosure No. RDS 90-065, filed

  5. Superconductivity in doped semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bustarret, E., E-mail: Etienne.bustarret@neel.cnrs.fr

    2015-07-15

    A historical survey of the main normal and superconducting state properties of several semiconductors doped into superconductivity is proposed. This class of materials includes selenides, tellurides, oxides and column-IV semiconductors. Most of the experimental data point to a weak coupling pairing mechanism, probably phonon-mediated in the case of diamond, but probably not in the case of strontium titanate, these being the most intensively studied materials over the last decade. Despite promising theoretical predictions based on a conventional mechanism, the occurrence of critical temperatures significantly higher than 10 K has not been yet verified. However, the class provides an enticing playground for testing theories and devices alike.

  6. Technology of RF superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    This work has several parts, two of which are collaborative development projects with the majority of the work being performed at Argonne. The first is the development of a superconducting RFQ structure in collaboration with AccSys Technology Inc. of Pleasanton, California, funded as a Phase II SBIR grant. Another is a collaborative project with the Nuclear Science Centre, New Delhi, India (who are funding the work) to develop new superconducting ion accelerating structures. Other initiatives are developing various aspects of the technology required to utilize ATLAS as a secondary beam linac for radioactive beams

  7. Superconducting magnetic quadrupole

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.W.; Shepard, K.W.; Nolen, J.A.

    1995-08-01

    A design was developed for a 350 T/m, 2.6-cm clear aperture superconducting quadrupole focussing element for use in a very low q/m superconducting linac as discussed below. The quadrupole incorporates holmium pole tips, and a rectangular-section winding using standard commercially-available Nb-Ti wire. The magnet was modeled numerically using both 2D and 3D codes, as a basis for numerical ray tracing using the quadrupole as a linac element. Components for a prototype singlet are being procured during FY 1995.

  8. Characterization of superconducting multilayers samples

    CERN Document Server

    Antoine, C Z; Berry, S; Bouat, S; Jacquot, J F; Villegier, J C; Lamura, G; Gurevich, A

    2009-01-01

    Best RF bulk niobium accelerating cavities have nearly reached their ultimate limits at rf equatorial magnetic field H  200 mT close to the thermodynamic critical field Hc. In 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high values of Hc > HcNb for magnetic shielding of bulk niobium to increase the breakdown magnetic field inside SC RF cavities [1]. Depositing good quality layers inside a whole cavity is rather difficult but we have sputtered high quality samples by applying the technique used for the preparation of superconducting electronics circuits and characterized these samples by X-ray reflectivity, dc resistivity (PPMS) and dc magnetization (SQUID). Dc magnetization curves of a 250 nm thick Nb film have been measured, with and without a magnetron sputtered coating of a single or multiple stack of 15 nm MgO and 25 nm NbN layers. The Nb samples with/without the coating clearly exhibit different behaviors. Because SQUID measurements are influenced by edge an...

  9. 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

  10. Hall probe for measuring high currents in superconducting coils

    International Nuclear Information System (INIS)

    Ferendeci, A.M.

    1986-01-01

    Constructional details of a compact Hall probe for measuring high currents in superconducting coils are given. The Hall probe is easy to assemble and can be inserted or removed from the system without breaking the superconducting loop. Upper current limit of the probe can be increased by using larger magnetic core material. Shielding becomes necessary if the probe holder is to be placed near large current dependent magnetic fields

  11. Coherent defects in superconducting circuits

    International Nuclear Information System (INIS)

    Mueller, Clemens

    2011-01-01

    The interaction of superconducting circuits with additional quantum systems is a topic that has found extensive study in the recent past. In the limit where the added system are incoherent, this is the standard field of decoherence and the system dynamics can be described by a simple master equation. In the other limit however, when the additional parts are coherent, the resulting time-evolution can become more complicated. In this thesis we have investigated the interaction of superconducting circuits with coherent and incoherent two-level defects. We have shown theoretical calculations characterizing this interaction for all relevant parameter regimes. In the weak coupling limit, the interaction can be described in an effective bath picture, where the TLS act as parts of a large, decohering environment. For strong coupling, however, the coherent dynamics of the full coupled system has to be considered. We show the calculations of the coupled time-evolution and again characterize the interaction by an effective decoherence rate. We also used experimental data to characterize the microscopic origin of the defects and the details of their interaction with the circuits. The results obtained by analyzing spectroscopic data allow us to place strong constraint on several microscopic models for the observed TLS. However, these calculations are not yet fully conclusive as to the physical nature of the TLS. We propose additional experiments to fully characterize the interaction part of the Hamiltonian, thus providing the answer to the question of the physical origin of the coupling. Additionally we have developed a method to directly drive individual defect states via virtual excitation of the qubit. This method allows one to directly probe the properties of single TLS and possibly make use of their superior coherence times for quantum information purposes. The last part of this thesis provided a way for a possible implementation of geometric quantum computation in

  12. Inhomogeneous superconductivity in a ferromagnet

    International Nuclear Information System (INIS)

    Kontos, T.; Aprili, M.; Lesueur, J.; Genet, F.; Boursier, R.; Grison, X.

    2003-01-01

    We have studied a new superconducting state where the condensate wave function resulting from conventional pairing, is modified by an exchange field. Superconductivity is induced into a ferromagnetic thin film (F) by the proximity effect with a superconducting reservoir (S). We observed oscillations of the superconducting order parameter induced in F as a function of the distance from the S/F interface. They originate from the finite momentum transfer provided to Cooper pairs by the splitting of the spin up and down bands. We measured the superconducting density of states in F by tunneling spectroscopy and the Josephson critical current when F is coupled with a superconducting counter-electrode. Negative values of the superconducting order parameter are revealed by capsized tunneling spectra in F and a negative Josephson coupling (π-junction)

  13. Superconductivity and magnet technology

    International Nuclear Information System (INIS)

    Lubell, M.S.

    1975-01-01

    The background theory of superconducting behavior is reviewed. Three parameters that characterize superconducting materials with values of commercial materials as examples are discussed. More than 1000 compounds and alloy systems and 26 elements are known to exhibit superconducting properties under normal conditions at very low temperatures. A wide variety of crystal structures are represented among the known superconductors. The most important ones do seem to have cubic symmetry such as the body-centered cubic (NbZr and NbTi), face-centered cubic (NbN), and the A15 or β-tungsten structures (Nb 3 Sn), V 3 Ga, Nb 3 Ge, Nb 3 Al, and V 3 Si). Attempts to understand some of the particular phenomena associated with superconductors as a necessary prelude to constructing superconducting magnets are discussed by the author. The origin of degradation is briefly discussed and methods to stabilize magnets are illustrated. The results of Oak Ridge National Laboratory design studies of toroidal magnet systems for fusion reactors are described

  14. 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.

  15. ISR Superconducting Quadrupoles

    CERN Multimedia

    1977-01-01

    Michel Bouvier is preparing for curing the 6-pole superconducting windings inbedded in the cylindrical wall separating liquid helium from vacuum in the quadrupole aperture. The heat for curing the epoxy glue was provided by a ramp of infrared lamps which can be seen above the slowly rotating cylinder. See also 7703512X, 7702690X.

  16. 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

  17. Superconducting Super Collider project

    International Nuclear Information System (INIS)

    Perl, M.L.

    1986-04-01

    The scientific need for the Superconducting Super Collider (SSC) is outlined, along with the history of the development of the SSC concept. A brief technical description is given of each of the main points of the SSC conceptual design. The construction cost and construction schedule are discussed, followed by issues associated with the realization of the SSC. 8 refs., 3 figs., 3 tabs

  18. Checking BEBC superconducting magnet

    CERN Multimedia

    CERN PhotoLab

    1974-01-01

    The superconducting coils of the magnet for the 3.7 m Big European Bubble Chamber (BEBC) had to be checked, see Annual Report 1974, p. 60. The photo shows a dismantled pancake. By December 1974 the magnet reached again the field design value of 3.5 T.

  19. Niobium superconducting cavity

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  20. Superconducting magnets 1992

    International Nuclear Information System (INIS)

    1993-06-01

    This report discusses the following topics on Superconducting Magnets; SSC Magnet Industrialization; Collider Quadrupole Development; A Record-Setting Magnet; D20: The Push Beyond 10T; Nonaccelerator Applications; APC Materials Development; High-T c at Low Temperature; Cable and Cabling-Machine Development; and Analytical Magnet Design

  1. LHC superconducting strand

    CERN Multimedia

    Patrice Loiez

    1999-01-01

    This cross-section through a strand of superconducting matieral as used in the LHC shows the 8000 Niobium-Titanium filaments embedded like a honeycomb in copper. When cooled to 1.9 degrees above absolute zero in the LHC accelerator, these filaments will have zero resistance and so will carry a high electric current with no energy loss.

  2. Electrical Conduction and Superconductivity

    Indian Academy of Sciences (India)

    When an electric field is applied, this electron can be lifted to this higher energy ... By such a virtual process two electrons .... using superconducting coils has come to be a reality. ... nance imaging techniques used in medical diagnostics. Com ...

  3. Superconducting magnets for HERA

    International Nuclear Information System (INIS)

    Wolff, S.

    1987-01-01

    The Hadron-Electron-Ring Accelerator (HERA) presently under construction at DESY, Hamburg, consists of an electron storage ring of 30 GeV and a proton storage ring of 820 GeV. Superconducting magnets are used for the proton ring. There are 416 superconducting bending magnets of 4.698 T central field and 8.824 m magnetic length, 224 superconducting quadrupoles of 91.2 T/m central gradient and many superconducting correction dipoles, quadrupoles and sextupoles. The main dipoles and quadrupoles consist of two-layer coils of 75 mm inner diameter clammed with aluminium (for the dipoles) or stainless steel laminations (for the quadrupoles). The collared coils are surrounded by a laminated cold iron yoke and supported inside a low loss cryostat. The protection system uses cold diodes to bypass the current around a quenching magnet. The magnets are cooled with one phase helium supplied by a 3 block central refrigeration system of 20 kW refrigeration power at 4.3 K. Two helium is returned through the magnets in good thermal contact with the one phase helium in the dipoles for temperature control. This paper describes the magnet system and gives the results obtained for prototype magnets

  4. LEP superconducting cavity

    CERN Multimedia

    1995-01-01

    Engineers work in a clean room on one of the superconducting cavities for the upgrade to the LEP accelerator, known as LEP-2. The use of superconductors allow higher electric fields to be produced so that higher beam energies can be reached.

  5. Gossamer superconductivity, new paradigm?

    Energy Technology Data Exchange (ETDEWEB)

    Won, Hyekyung [Department of Physics, Hallym University, Chuncheon 200-702 (Korea); Haas, Stephan; Parker, David [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Maki, Kazumi [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Max-Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden (Germany); Dora, Balazs [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary); Virosztek, Attila [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary); Research Institute for Solid State Physics and Optics, P.O. Box 49, 1525 Budapest (Hungary)

    2006-01-01

    We review our recent works on d-wave density wave (dDW) and gossamer superconductivity (i.e. d-wave superconductivity in the presence of dDW) in high-T{sub c} cuprates and CeCoIn{sub 5}. a) We show that both the giant Nernst effect and the angle dependent magnetoresistance (ADMR) in the pseudogap phases of the cuprates and CeCoIn{sub 5} are manifestations of dDW. b) The phase diagram of high-T{sub c} cuprates is understood in terms of mean field theory, which includes two order parameters {delta}{sub 1} and {delta}{sub 2}, where one order paremeter is from dDW and the other from d-wave superconductivity. c) In the optimally to the overdoped region we find the spatially periodic dDW, an analogue of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, becomes more stable. d) In the underdoped region where {delta}{sub 2}/{delta}{sub 1}<<1 the Uemera relation is obtained within the present model. We speculate that the gossamer superconductivity is at the heart of high-T{sub c} cuprate superconductors, the heavy-fermion superconductor CeCoIn{sub 5} and the organic superconductors {kappa}-(ET){sub 2}Cu(NCS){sub 2} and (TMTSF){sub 2}PF{sub 6}. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Superconductivity : Controlling magnetism

    NARCIS (Netherlands)

    Golubov, Alexandre Avraamovitch; Kupriyanov, Mikhail Yu.

    Manipulation of the magnetic state in spin valve structures by superconductivity has now been achieved, opening a new route for the development of ultra-fast cryogenic memories. Spintronics is a rapidly developing field that allows insight into fundamental spin-dependent physical properties and the

  7. 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

  8. Magnetic levitation and superconductivity

    International Nuclear Information System (INIS)

    Albrecht, C.

    1989-01-01

    The paper explains the impressive advances made in the development of superconducting magnets, in cryogenic engineering, and in the development of drive and vehicle concepts in Japan in the period following termination of West German development work for the electrodynamical system (MLU 001, MLU 002). The potentials engineering due to the development of high-Tc superconductors are discussed. (orig./MM) [de

  9. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, G [Jefferson Lab (United States)

    2014-07-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  10. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  11. Coherence properties in superconducting flux qubits

    Energy Technology Data Exchange (ETDEWEB)

    Spilla, Samuele

    2015-02-16

    The research work discussed in this thesis deals with the study of superconducting Josephson qubits. Superconducting qubits are solid-state artificial atoms which are based on lithographically defined Josephson tunnel junctions properties. When sufficiently cooled, these superconducting devices exhibit quantized states of charge, flux or junction phase depending on their design parameters. This allows to observe coherent evolutions of their states. The results presented can be divided into two parts. In a first part we investigate operations of superconducting qubits based on the quantum coherence in superconducting quantum interference devices (SQUID). We explain experimental data which has been observed in a SQUID subjected to fast, large-amplitude modifications of its effective potential shape. The motivations for this work come from the fact that in the past few years there have been attempts to interpret the supposed quantum behavior of physical systems, such as Josephson devices, within a classical framework. Moreover, we analyze the possibility of generating GHZ states, namely maximally entangled states, in a quantum system made out of three Josephson qubits. In particular, we investigate the possible limitations of the GHZ state generation due to coupling to bosonic baths. In the second part of the thesis we address a particular cause of decoherence of flux qubits which has been disregarded until now: thermal gradients, which can arise due to accidental non equilibrium quasiparticle distributions. The reason for these detrimental effects is that heat currents flowing through Josephson tunnel junctions in response to a temperature gradient are periodic functions of the phase difference between the electrodes. The phase dependence of the heat current comes from Andreev reflection, namely an interplay between the quasiparticles which carry heat and the superconducting condensate which is sensitive to the superconducting phase difference. Generally speaking

  12. Superconducting niobium in high rf magnetic fields

    International Nuclear Information System (INIS)

    Mueller, G.

    1988-01-01

    The benefit of superconducting cavities for accelerator applications depends on the field and Q/sub 0/ levels which can be achieved reliably in mass producible multicell accelerating structures. The presently observed field and Q/sub 0/ limitations are caused by anomalous loss mechanisms which are not correlated with the intrinsic properties of the pure superconductor but rather due to defects or contaminants on the superconducting surface. The ultimate performance levels of clean superconducting cavities built from pure Nb will be given by the rf critical field and the surface resistance of the superconductor. In the first part of this paper a short survey is given of the maximum surface magnetic fields achieved in single-cell cavities. The results of model calculations for the thermal breakdown induced by very small defects and for the transition to the defect free case is discussed in part 2. In the last chapter, a discussion is given for the rf critical field of Nb on the basis of the Ginzburg-Landau Theory. It is shown that not only purity but also the homogeneity of the material should become important for the performance of superconducting Nb cavities at field levels beyond 100mT. Measurement results of the upper critical field for different grades of commercially available Nb sheet materials are given. 58 references, 20 figures, 1 table

  13. 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

  14. SUPERCONDUCTING SOLENOIDS FOR THE MUON COLLIDER

    Energy Technology Data Exchange (ETDEWEB)

    GREEN,M.A.; EYSSA,Y.; KENNY,S.; MILLER,J.R.; PRESTEMON,S.; WEGGEL,R.J.

    2000-06-12

    The muon collider is a new idea for lepton colliders. The ultimate energy of an electron ring is limited by synchrotron radiation. Muons, which have a rest mass that is 200 times that of an electron can be stored at much higher energies before synchrotron radiation limits ring performance. The problem with muons is their short life time (2.1 {micro}s at rest). In order to operate a muon storage ring large numbers of muon must be collected, cooled and accelerated before they decay to an electron and two neutrinos. As the authors see it now, high field superconducting solenoids are an integral part of a muon collider muon production and cooling systems. This report describes the design parameters for superconducting and hybrid solenoids that are used for pion production and collection, RF phase rotations of the pions as they decay into muons and the muon cooling (reduction of the muon emittance) before acceleration.

  15. Superconducting flux flow digital circuits

    International Nuclear Information System (INIS)

    Martens, J.S.; Zipperian, T.E.; Hietala, V.M.; Ginley, D.S.; Tigges, C.P.; Phillips, J.M.; Siegal, M.P.

    1993-01-01

    The authors have developed a family of digital logic circuits based on superconducting flux flow transistors that show high speed, reasonable signal levels, large fan-out, and large noise margins. The circuits are made from high-temperature superconductors (HTS) and have been shown to operate at over 90 K. NOR gates have been demonstrated with fan-outs of more than 5 and fully loaded switching times less than a fixture-limited 50 ps. Ring-oscillator data suggest inverter delay times of about 40ps when using a 3-μm linewidths. Simple flip-flops have also been demonstrated showing large noise margins, response times of less than 30 ps, and static power dissipation on the order of 30 nW. Among other uses, this logic family is appropriate as an interface between logic families such as single flux quantum and conventional semiconductor logic

  16. 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)

  17. Superconductivity: materials and applications; La supraconductivite: materiaux et apllications

    Energy Technology Data Exchange (ETDEWEB)

    Duchateau, J.L. [CEA Cadarache, 13 - Saint Paul lez Durance (France); Kircher, F. [CEA Saclay, 91 - Gif sur Yvette (France); Leveque, J. [Groupe de Recherche en Electrotechnique et Electronique de Nancy, GREEN - UHP, 54 - Vandoeuvre les Nancy (France); Tixador, P. [INP/Institut Neel, 38 - Grenoble (France)

    2008-07-01

    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.)

  18. 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

  19. 2017 Gordon Conference on Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Chubukov, Andrey [Univ. of Minnesota, Twin Cities, MN (United States)

    2017-11-14

    The DOE award was for a 2017 Gordon Research conference on Superconductivity (GRC). The objective of GRC is to interchange the information about the latest theoretical and experimental developments in the area of superconductivity and to select most perspective directions for future research in this area.The goal of the Gordon Conference on Superconductivity is to present and discuss the latest results in the field of modern superconductivity, discuss new ideas and new directions of research in the area. It is a long-standing tradition of the Gordon conference on Superconductivity that the vast majority of participants are junior scientists. Funding for the conference would primarily be used to support junior researchers, particularly from under-represented groups. We had more 10 female speakers, some of them junior researchers, and some funding was used to support these speakers. The conference was held together with Gordon Research Seminar on Superconductivity, where almost all speakers and participants were junior scientists.

  20. Vector superconductivity in cosmic strings

    International Nuclear Information System (INIS)

    Dvali, G.R.; Mahajan, S.M.

    1992-03-01

    We argue that in most realistic cases, the usual Witten-type bosonic superconductivity of the cosmic string is automatically (independent of the existence of superconducting currents) accompanied by the condensation of charged gauge vector bosons in the core giving rise to a new vector type superconductivity. The value of the charged vector condensate is related with the charged scalar expectation value, and vanishes only if the latter goes to zero. The mechanism for the proposed vector superconductivity, differing fundamentally from those in the literature, is delineated using the simplest realistic example of the two Higgs doublet standard model interacting with the extra cosmic string. It is shown that for a wide range of parameters, for which the string becomes scalarly superconducting, W boson condensates (the sources of vector superconductivity) are necessarily excited. (author). 14 refs

  1. Superconducting Accelerator Magnets

    CERN Document Server

    Mess, K H; Wolff, S

    1996-01-01

    The main topic of the book are the superconducting dipole and quadrupole magnets needed in high-energy accelerators and storage rings for protons, antiprotons or heavy ions. The basic principles of low-temperature superconductivity are outlined with special emphasis on the effects which are relevant for accelerator magnets. Properties and fabrication methods of practical superconductors are described. Analytical methods for field calculation and multipole expansion are presented for coils without and with iron yoke. The effect of yoke saturation and geometric distortions on field quality is studied. Persistent magnetization currents in the superconductor and eddy currents the copper part of the cable are analyzed in detail and their influence on field quality and magnet performance is investigated. Superconductor stability, quench origins and propagation and magnet protection are addressed. Some important concepts of accelerator physics are introduced which are needed to appreciate the demanding requirements ...

  2. Infrared Quenched Photoinduced Superconductivity

    Science.gov (United States)

    Federici, J. F.; Chew, D.; Guttierez-Solana, J.; Molina, G.; Savin, W.; Wilber, W.

    1996-03-01

    Persistant photoconductivity (PPC) and photoinduced superconductivity (PISC) in oxygen deficient YBa_2Cu_3O_6+x have received recent attention. It has been suggested that oxygen vacancy defects play an important role in the PISC/PPC mechanism.(J. F. Federici, D. Chew, B. Welker, W. Savin, J. Gutierrez-Solana, and T. Fink, Phys. Rev. B), December 1995 Supported by National Science Foundation In this model, defects trap photogenerated electrons so that electron-hole recombination can not occur thereby allowing photogenerated holes to contribute to the carrier density. Nominally, the photoinduced state is long-lived, persisting for days at low temperature. Experiment results will be presented demonstrating that the photoinduced superconductivity state can be quenched using infrared radiation. Implications for the validity of the PISC/PCC defect model will be discussed.

  3. Superconductivity an introduction

    CERN Document Server

    Kleiner, Reinhold

    2016-01-01

    The third edition of this proven text has been developed further in both scope and scale to reflect the potential for superconductivity in power engineering to increase efficiency in electricity transmission or engines. The landmark reference remains a comprehensive introduction to the field, covering every aspect from fundamentals to applications, and presenting the latest developments in organic superconductors, superconducting interfaces, quantum coherence, and applications in medicine and industry. Due to its precise language and numerous explanatory illustrations, it is suitable as an introductory textbook, with the level rising smoothly from chapter to chapter, such that readers can build on their newly acquired knowledge. The authors cover basic properties of superconductors and discuss stability and different material groups with reference to the latest and most promising applications, devoting the last third of the book to applications in power engineering, medicine, and low temperature physics. An e...

  4. Variable temperature superconducting microscope

    Science.gov (United States)

    Cheng, Bo; Yeh, W. J.

    2000-03-01

    We have developed and tested a promising type of superconducting quantum interference device (SQUID) microscope, which can be used to detect vortex motion and can operate in magnetic fields over a large temperature range. The system utilizes a single-loop coupling transformer, consisting of a patterned high Tc superconducting thin film. At one end of the transformer, a 20 μm diam detecting loop is placed close to the sample. At the other end, a large loop is coupled to a NbTi coil, which is connected to a low Tc SQUID sensor. Transformers in a variety of sizes have been tested and calibrated. The results show that the system is capable of detecting the motion of a single vortex. We have used the microscope to study the behavior of moving vortices at various positions in a YBa2Cu3O7 thin film bridge.

  5. Statistical mechanics of superconductivity

    CERN Document Server

    Kita, Takafumi

    2015-01-01

    This book provides a theoretical, step-by-step comprehensive explanation of superconductivity for undergraduate and graduate students who have completed elementary courses on thermodynamics and quantum mechanics. To this end, it adopts the unique approach of starting with the statistical mechanics of quantum ideal gases and successively adding and clarifying elements and techniques indispensible for understanding it. They include the spin-statistics theorem, second quantization, density matrices, the Bloch–De Dominicis theorem, the variational principle in statistical mechanics, attractive interaction, and bound states. Ample examples of their usage are also provided in terms of topics from advanced statistical mechanics such as two-particle correlations of quantum ideal gases, derivation of the Hartree–Fock equations, and Landau’s Fermi-liquid theory, among others. With these preliminaries, the fundamental mean-field equations of superconductivity are derived with maximum mathematical clarity based on ...

  6. Superconductivity in Chevrel phases

    International Nuclear Information System (INIS)

    Fischer, O.; Seeber, B.

    1979-01-01

    In the last years several ternary superconductors have been discovered, which possess unusual physical properties. Among them the molybdenum chalcogenides, which are often called Chevrel phases, have a special position. Some of these compounds have very high critical fields, which is of special interest for a technical application. In these substances the coexistence of magnetic ordering and superconductivity has been found for the first time, too. Recently it has become possible to prepare new compounds, which are interesting for superconductivity, by the appropriate coalescence of Mo 6 clusters. In the case of Tl 2 Mo 6 Se 6 (Tsub(c) = 3K) this development leads to a quasi-one-dimensional metallic system. (orig.)

  7. Metastable superconducting alloys

    International Nuclear Information System (INIS)

    Johnson, W.L.

    1978-07-01

    The study of metastable metals and alloys has become one of the principal activities of specialists working in the field of superconducting materials. Metastable crystalline superconductors such as the A15-type materials have been given much attention. Non-crystalline superconductors were first studied over twenty years ago by Buckel and Hilsch using the technique of thin film evaporation on a cryogenic substrate. More recently, melt-quenching, sputtering, and ion implantation techniques have been employed to produce a variety of amorphous superconductors. The present article presents a brief review of experimental results and a survey of current work on these materials. The systematics of superconductivity in non-crystalline metals and alloys are described along with an analysis of the microscopic parameters which underlie the observed trends. The unique properties of these superconductors which arise from the high degree of structural disorder in the amorphous state are emphasized

  8. Superconducting frustration bit

    International Nuclear Information System (INIS)

    Tanaka, Y.

    2014-01-01

    Highlights: • A frustration bit element is proposed for a conventional superconducting circuit. • It is composed of π-junctions. • It mimics the multiband superconductor. - Abstract: A basic design is proposed for a classical bit element of a superconducting circuit that mimics a frustrated multiband superconductor and is composed of an array of π-Josephson junctions (π-junction). The phase shift of π provides the lowest energy for one π-junction, but neither a π nor a zero phase shift gives the lowest energy for an assembly of π-junctions. There are two chiral states that can be used to store one bit information. The energy scale for reading and writing to memory is of the same order as the junction energy, and is thus in the same order of the driving energy of the circuit. In addition, random access is also possible

  9. Superconductivity and spin fluctuations

    International Nuclear Information System (INIS)

    Scalapino, D.J.

    1999-01-01

    The organizers of the Memorial Session for Herman Rietschel asked that the author review some of the history of the interplay of superconductivity and spin fluctuations. Initially, Berk and Schrieffer showed how paramagnon spin fluctuations could suppress superconductivity in nearly-ferromagnetic materials. Following this, Rietschel and various co-workers wrote a number of papers in which they investigated the role of spin fluctuations in reducing the Tc of various electron-phonon superconductors. Paramagnon spin fluctuations are also believed to provide the p-wave pairing mechanism responsible for the superfluid phases of 3 He. More recently, antiferromagnetic spin fluctuations have been proposed as the mechanism for d-wave pairing in the heavy-fermion superconductors and in some organic materials as well as possibly the high-Tc cuprates. Here the author will review some of this early history and discuss some of the things he has learned more recently from numerical simulations

  10. Stabilized superconducting materials and fabrication process

    International Nuclear Information System (INIS)

    Chevallier, B.; Dance, J.M.; Etourneau, J.; Lozano, L.; Tressaud, A.; Tournier, R.; Sulpice, A.; Chaussy, J.; Lejay, P.

    1989-01-01

    Superconducting ceramics are fluorinated at a temperature ≤ 120 0 C. Are also claimed new superconducting materials with a fluorine concentration gradient decreasing from the surface to the core. Superconductivity is stabilized and/or improved [fr

  11. Superconductivity in MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Muranaka, Takahiro; Akimitsu, Jun [Aoyama Gakuin Univ., Kanagawa (Japan). Dept. of Physics and Mathematics

    2011-07-01

    We review superconductivity in MgB{sub 2} in terms of crystal and electronic structure, electron-phonon coupling, two-gap superconductivity and application. Finally, we introduce the development of new superconducting materials in related compounds. (orig.)

  12. Topological confinement and superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Al-hassanieh, Dhaled A [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory

    2008-01-01

    We derive a Kondo Lattice model with a correlated conduction band from a two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence of a robust pairing mechanism in a model that only contains repulsive interactions. The mechanism is due to topological confinement and results from the interplay between antiferromagnetism and delocalization. By using Density-Matrix-Renormalization-Group (DMRG) we demonstrate that this mechanism leads to dominant superconducting correlations in aID-system.

  13. Unconventional superconductivity near inhomogeneities

    International Nuclear Information System (INIS)

    Poenicke, A.F.

    2008-01-01

    After the presentation of a quasi-classical theory the specific heat of Sr 2 RuO 4 is considered. Then tunneling spectroscopy on cuprate superconductors is discussed. Thereafter the subharmonic gap structure in d-wave superconductors is considered. Finally the application of the S-matrix in superconductivity is discussed with spin mixing, CrO 2 as example, and an interface model. (HSI)

  14. Unconventional superconductivity near inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Poenicke, A F

    2008-01-25

    After the presentation of a quasi-classical theory the specific heat of Sr{sub 2}RuO{sub 4} is considered. Then tunneling spectroscopy on cuprate superconductors is discussed. Thereafter the subharmonic gap structure in d-wave superconductors is considered. Finally the application of the S-matrix in superconductivity is discussed with spin mixing, CrO{sub 2} as example, and an interface model. (HSI)

  15. Superconduction at 77 K

    International Nuclear Information System (INIS)

    Mueller, H.G.

    1989-01-01

    This general paper deals with the advantages which may result from the use of ceramic high-temperature superconductors. The use of these new superconductors for generators and electric motors for ship propulsion is regarded as a promising potential defense application. Furthermore, SMES (Superconducting Magnetic Energy Storage) can be used as a 'power compressor' for future high-performance weapon systems such as electromagnetic cannons, high-energy lasers, and high power microwaves. (MM) [de

  16. Advanced superconducting materials

    International Nuclear Information System (INIS)

    Fluekiger, R.

    1983-11-01

    The superconducting properties of various materials are reviewed in view of their use in high field magnets. The critical current densities above 12 T of conductors based on NbN or PbMo 6 S 8 are compared to those of the most advanced practical conductors based on alloyed by Nb 3 Sn. Different aspects of the mechanical reinforcement of high field conductors, rendered necessary by the strong Lorentz forces (e.g. in fusion magnets), are discussed. (orig.) [de

  17. Superconducting magnet wire

    Science.gov (United States)

    Schuller, Ivan K.; Ketterson, John B.; Banerjee, Indrajit

    1986-01-01

    A superconducting tape or wire with an improved critical field is formed of alternating layers of a niobium-containing superconductor such as Nb, NbTi, Nb.sub.3 Sn or Nb.sub.3 Ge with a thickness in the range of about 0.5-1.5 times its coherence length, supported and separated by layers of copper with each copper layer having a thickness in the range of about 170-600 .ANG..

  18. Superconductivity in power engineering

    International Nuclear Information System (INIS)

    Chaddah, P.; Dande, Y.D.; Dasannacharya, B.A.; Malik, M.K.; Raghavan, R.V.

    1987-01-01

    The advantages of low power loss, high magnetic fields and compactness of size of superconducting magnets have generated world-wide interest in using them for MHD generators, Tokamak fusion reactors, energy storage systems etc. With a view to assess the feasibility of using the technology in power engineering in India, the status of the efforts in the country is reviewed and the areas of R and D required are indicated. 13 figures, 15 refs. (author)

  19. Superconducting linear colliders

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    The advantages of superconducting radiofrequency (SRF) for particle accelerators have been demonstrated by successful operation of systems in the TRISTAN and LEP electron-positron collider rings respectively at the Japanese KEK Laboratory and at CERN. If performance continues to improve and costs can be lowered, this would open an attractive option for a high luminosity TeV (1000 GeV) linear collider

  20. Superconducting Ferromagnetic Nanodiamond

    Czech Academy of Sciences Publication Activity Database

    Zhang, G.; Samuely, T.; Xu, Z.; Jochum, J. K.; Volodin, A.; Zhou, S. Q.; May, P. W.; Onufriienko, O.; Kacmarik, J.; Steele, J. A.; Li, J.; Vanacken, J.; Vacík, Jiří; Szabo, P.; Yuan, H. F.; Roeffaers, M. B. J.; Cerbu, D.; Samuely, P.; Hofkens, J.; Moshchalkov, V.V.

    2017-01-01

    Roč. 11, č. 6 (2017), s. 5358-5366 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : nanodiamond * superconductivity and ferromagnetism * spin fluctuations * giant positive magnetoresistance * anamalous Hall effect Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nano-materials (production and properties ) Impact factor: 13.942, year: 2016

  1. Superconducting cavities for HERA

    International Nuclear Information System (INIS)

    Dwersteg, B.; Ebeling, W.; Moeller, W.D.; Renken, D.; Proch, D.; Sekutowicz, J.; Susta, J.; Tong, D.

    1988-01-01

    Superconducting 500 MHz cavities are developed to demonstrate the feasibility of upgrading the e-beam energy of the HERA storage ring. A prototype module with 2 x 4 cell resonators and appropriate fundamental and higher mode couplers has been designed at DESY and is being built by industrial firms. The design and results of RF and cryogenic measurements are reported in detail. 17 references, 10 figures, 2 tables

  2. Superconductivity is pair work

    International Nuclear Information System (INIS)

    Wengenmayr, Roland

    2011-01-01

    Electric cables that routinely conduct electricity without loss - physicists have been motivated by this idea ever since superconductivity was discovered 100 years ago. Researchers working with Bernhard Keimer at the Max Planck Institute for Solid State Research in Stuttgart and Frank Steglich at the Max Planck Institute for Chemical Physics of Solids in Dresden want to gain a detailed understanding of how unconventional superconductors lose their resistivity. (orig.)

  3. Superconducting Panofsky quadrupoles

    International Nuclear Information System (INIS)

    Harwood, L.H.

    1981-01-01

    A design for a rectangular aperture quadrupole magnet without pole-tips was introduced by Hand and Panofsky in 1959. This design was quite radical but simple to construct. Few magnets of this design were ever built because of the large power needed. With the advent of superconducting coils there has been a renewed interest in them. The mathematical basis, field characteristics, and present and future construction of these magnets are described

  4. Cooldown of superconducting magnet strings

    International Nuclear Information System (INIS)

    Yuecel, A.; Carcagno, R.H.

    1995-01-01

    A numerical model for the cooldown of the superconducting magnet strings in the Accelerator System String Test (ASST) Facility at the Superconducting Super Collider (SSC) Laboratory is presented. Numerical results are compared with experimental data from the ASST test runs. Agreement between the numerical predictions and experiments is very good over the entire range from room temperature to liquid helium temperatures. The model can be readily adapted to predict the cooldown and warmup behavior of other superconducting magnets or cold masses

  5. Superconducting energy storage magnet

    International Nuclear Information System (INIS)

    Eyssa, Y.M.; Boom, R.W.; Young, W.C.; McIntosh, G.E.; Abdelsalam, M.K.

    1986-01-01

    A superconducting magnet is described comprising: (a) a first, outer coil of one layer of conductor including at least a superconducting composite material; (b) a second, inner coil of one layer of conductor including at least a superconducting composite material. The second coil disposed adjacent to the first coil with each turn of the second inner coil at substantially the same level as a turn on the first coil; (c) an inner support structure between the first and second coils and engaged to the conductors thereof, including support rails associated with each turn of conductor in each coil and in contact therewith along its length at positions on the inwardly facing periphery of the conductor. The rail associated with each conductor is electrically isolated from other rails in the inner support structure. The magnetic field produced by a current flowing in the same direction through the conductors of the first and second coils produces a force on the conductors that are directed inwardly toward the inner support structure

  6. Magnetically leviated superconducting bearing

    Science.gov (United States)

    Weinberger, Bernard R.; Lynds, Jr., Lahmer

    1993-01-01

    A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

  7. Lighting up superconducting stripes

    Science.gov (United States)

    Ergeçen, Emre; Gedik, Nuh

    2018-02-01

    Cuprate superconductors display a plethora of complex phases as a function of temperature and carrier concentration, the understanding of which could provide clues into the mechanism of superconductivity. For example, when about one-eighth of the conduction electrons are removed from the copper oxygen planes in cuprates such as La2‑xBaxCuO4 (LBCO), the doped holes (missing electrons) organize into one-dimensional stripes (1). The bulk superconducting transition temperature (Tc) is greatly reduced, and just above Tc, electrical transport perpendicular to the planes (along the c axis) becomes resistive, but parallel to the copper oxygen planes, resistivity remains zero for a range of temperatures (2). It was proposed a decade ago (3) that this anisotropic behavior is caused by pair density waves (PDWs); superconducting Cooper pairs exist along the stripes within the planes but cannot tunnel to the adjacent layers. On page 575 of this issue, Rajasekaran et al. (4) now report detection of this state in LBCO using nonlinear reflection of high-intensity terahertz (THz) light.

  8. Superconductivity in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert P. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Weller, Thomas E.; Howard, Christopher A. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Dean, Mark P.M. [Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Rahnejat, Kaveh C. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Saxena, Siddharth S. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Ellerby, Mark, E-mail: mark.ellerby@ucl.ac.uk [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom)

    2015-07-15

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC{sub 6} and YbC{sub 6} in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  9. Superconductivity in graphite intercalation compounds

    International Nuclear Information System (INIS)

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P.M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-01-01

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC 6 and YbC 6 in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition

  10. 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.

  11. 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)

  12. Superconducting magnet development in Japan

    International Nuclear Information System (INIS)

    Yasukochi, K.

    1983-01-01

    The present state of R and D works on the superconducting magnet and its applications in Japan are presented. On electrical rotating machines, 30 MVA superconducting synchronous rotary condenser (Mitsubishi and Fuji) and 50 MVA generator are under construction. Two ways of ship propulsion by superconducting magnets are developing. A superconducting magnetically levitated and linear motor propelled train ''MAGLEV'' was developed by the Japan National Railways (JNR). The superconducting magnet development for fusion is the most active field in Japan. The Cluster Test program has been demonstrated on a 10 T Nb 3 Sn coil and the first coil of Large Coil Task in IEA collaboration has been constructed and the domestic test was completed in JAERI. These works are for the development of toroidal coils of the next generation tokamak machine. R and D works on superconducting ohmic heating coil are in progress in JAERI and ETL. The latter group has constructed 3.8 MJ pulsed coil. A high ramp rate of changing field in pulsed magnet, 200 T/s, has been tested successfully. High Energy Physics Laboratory (KEK) are conducting active works. The superconducting μ meson channel and π meson channel have been constructed and are operating successfully. KEK has also a project of big accelerator named ''TRISTAN'', which is similar to ISABELLE project of BNL. Superconducting synchrotron magnets are developed for this project. The development of superconducting three thin wall solenoid has been started. One of them, CDF, is progressing under USA-Japan collaboration

  13. Unconventional superconductivity in honeycomb lattice

    Directory of Open Access Journals (Sweden)

    P Sahebsara

    2013-03-01

    Full Text Available   ‎ The possibility of symmetrical s-wave superconductivity in the honeycomb lattice is studied within a strongly correlated regime, using the Hubbard model. The superconducting order parameter is defined by introducing the Green function, which is obtained by calculating the density of the electrons ‎ . In this study showed that the superconducting order parameter appears in doping interval between 0 and 0.5, and x=0.25 is the optimum doping for the s-wave superconductivity in honeycomb lattice.

  14. Quasiparticle losses at the surface of superconducting tunnel junction detectors

    NARCIS (Netherlands)

    Panteleit, F.; Schroeder, T.; Martin, J.; Huebener, R.P.; Kiewiet, F.B.; Berg, van den M.L.; Korte, P.A.J.

    1999-01-01

    Superconducting tunnel junctions (STJs) are promising as high energy resolution x-ray detectors. However, the theoretical limit of the energy resolution of STJs has not yet been reached for several reasons. In many cases quasiparticle losses limit the energy resolution. We have investigated STJs

  15. Process for producing clad superconductive materials

    International Nuclear Information System (INIS)

    Cass, R.B.; Ott, K.C.; Peterson, D.E.

    1992-01-01

    This patent describes a process for fabricating superconducting composite wire. It comprises placing a superconductive precursor admixture capable of undergoing self propagating combustion in stoichiometric amounts sufficient to form a superconductive product within an oxygen-porous metal tube; sealing one end of the tube; igniting the superconductive precursor admixture whereby the superconductive precursor admixture endburns along the length of the admixture; and cross-section reducing the tube at a rate substantially equal to the rate of burning of the superconductive precursor admixture and at a point substantially planar with the burnfront of the superconductive precursor mixture, whereby a clad superconductive product is formed in situ

  16. Interface-Induced Zeeman-Protected Superconductivity in Ultrathin Crystalline Lead Films

    Directory of Open Access Journals (Sweden)

    Yi Liu

    2018-04-01

    Full Text Available Two-dimensional (2D superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity in 4-monolayer (ML to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111 substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.

  17. Interface-Induced Zeeman-Protected Superconductivity in Ultrathin Crystalline Lead Films

    Science.gov (United States)

    Liu, Yi; Wang, Ziqiao; Zhang, Xuefeng; Liu, Chaofei; Liu, Yongjie; Zhou, Zhimou; Wang, Junfeng; Wang, Qingyan; Liu, Yanzhao; Xi, Chuanying; Tian, Mingliang; Liu, Haiwen; Feng, Ji; Xie, X. C.; Wang, Jian

    2018-04-01

    Two-dimensional (2D) superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity) in 4-monolayer (ML) to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111) substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.

  18. Pulsed rf superconductivity program at SLAC

    International Nuclear Information System (INIS)

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

    1984-08-01

    Recent tests performed at SLAC on superconducting TM 010 caavities using short rf pulses (less than or equal to 2.5 μs) have established that at the cavity surface magnetic fields can be reached in the vicinity of the theoretical critical fields without an appreciable increase in average losses. Tests on niobium and lead cavities are reported. The pulse method seems to be best suited to study peak field properties of superconductors in the microwave band, without the limitations imposed by defects. The short pulses also seem to be more effective in decreasing the causes of field emission by rf processing. Applications of the pulsed rf superconductivity to high-gradient linear accelerators are also possible

  19. Phonon spectroscopy with superconducting tunnel junctions

    International Nuclear Information System (INIS)

    Grimshaw, J.M.

    1984-02-01

    Superconducting tunnel junctions can be used as generators and detectors of monochromatic phonons of frequency larger than 80 GHz, as was first devised by Eisenmenger and Dayem (1967) and Kinder (1972a, 1973). In this report, we intend to give a general outline of this type of spectroscopy and to present the results obtained so far. The basic physics underlying phonon generation and detection are described in chapter I, a wider approach being given in the references therein. In chapter II, the different types of junctions are considered with respect to their use. Chapter III deals with the evaporation technique for the superconducting junctions. The last part of this report is devoted to the results that we have obtained on γ-irradiated LiF, pure Si and Phosphorous implanted Si. In these chapters, the limitations of the spectrometer are brought out and suggestions for further work are given [fr

  20. ORPUS 1: a pulsed superconducting solenoid

    International Nuclear Information System (INIS)

    Schwall, R.E.

    1976-01-01

    A recent series of reference designs for Tokamak Experimental Power Reactors (EPR's) has indicated that superconducting poloidal field (PF) coils will be necessary for successful operation of these devices. It would also be desirable to use superconducting PF coils in earlier tokamak fusion devices if such coils could be developed quickly enough. The PF coil performance requirements are briefly reviewed and some implications for the coil design are developed. A small coil (stored energy 14 kJ) has been built using construction techniques similar to those which could be employed for PF coils. The coil has been charged at rates up to 2 T/sec. Both maximum field and charging rate were limited by available power supplies. Loss measurements were carried out during pulsed operation and data for hysteretic and eddy current loss are presented. The loss measurement system used allows considerable insight into the effects of conductor motion and training

  1. Safety and stability in superconducting magnets

    International Nuclear Information System (INIS)

    Herring, J.S.

    1989-01-01

    The increasing size and field of superconducting magnets required for new applications result in significant stored energy and magnetic forces. The use of superconducting magnets near humans has resulted in standards for limiting occupational exposures to magnetic field. While these standards are unofficial, they have been widely adopted. In addition, development of large magnet sets for the fusion program and for the MHD program has led to experiments on the behavior of shorted and arcing coils under transient conditions. In combination with various code development efforts, these experiments, in the US and Europe, are resulting in criteria for the design of stable coils which can safely discharge their stored energy. 22 refs., 6 tabs

  2. PREFACE: Focus section on superconducting power systems Focus section on superconducting power systems

    Science.gov (United States)

    Cardwell, D. A.; Amemiya, N.; Fair, R.

    2012-01-01

    This focus section of Superconductor Science and Technology looks at the properties, technology and applications of (RE)BCO and MgB2 based superconductors for power engineering systems. Both bulk and conductor forms of material are addressed, including elements of materials fabrication and processing, and the measurement of their applied properties for various levels of system application. The areas of research include ac losses in type II materials in power devices, cables and coated conductors, the development of high current dc cables and the application of superconductors in levitation devices, motors and fault current limiters. This focus section presents a broad cross-section of contemporary issues, that represent state-of-the-art for power applications of superconductors, and highlights the areas that require further development if commercial applications of these rapidly emerging materials are to be realised. It contains papers from some of the major groups in the field, including contributions from Europe, the USA and Japan, and describes devices that are relatively close to market.

  3. Instrumentation for localized superconducting cavity diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Conway, Z. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Physics Division; Ge, M. [Cornell Lab. for Accelerator-Based Sciences and Education, Ithaca, NY (United States); Iwashita, Y. [Kyoto Univ. (Japan)

    2017-01-12

    Superconducting accelerator cavities are now routinely operated at levels approaching the theoretical limit of niobium. To achieve these operating levels more information than is available from the RF excitation signal is required to characterize and determine fixes for the sources of performance limitations. This information is obtained using diagnostic techniques which complement the analysis of the RF signal. In this paper we describe the operation and select results from three of these diagnostic techniques: the use of large scale thermometer arrays, second sound wave defect location and high precision cavity imaging with the Kyoto camera.

  4. Electrotechnical prospects for superconducting applications

    Science.gov (United States)

    Brunet, Y.; Renard, M.

    After a review of the classical limitations, due to iron and copper losses, we give the necessary superconducting properties, needed to achieve significant progresses, either in the size, or in the efficiency of electrotechnical plants. The successive achievement in SC will be explained, in relation with the physics of usual SC, and the needed properties for technology. The problems encountered in electrotechnics by decreasing interest are : networks losses and stability, storage of energy production, transformation and protection. In each case, SC solutions may be found or at least imagined. We shall review the limitations estimated in each case, generally by extrapolation of small scale experiments, with 4 K SC, and try to see what are the modifications which may be obtained by the use of high Tc SC. Special attention will be paid to energy storage and electrical machinery and the interest of completely superconducting plants will be shown. Une fois précisées les limitations actuelles des matériels électriques imposées essentiellement par l'utilisation de matériaux comme le fer ou le cuivre, nous détaillons les caractéristiques des supraconducteurs susceptibles d'améliorer les performances des installations électrotechniques. Les progrès successifs des conducteurs supraconducteurs sont expliqués en tenant compte de leur impact technologique. Les problèmes rencontrés en électrotechnique sont : les pertes et la stabilité des réseaux, le stockage et la production de l'énergie. Dans chaque cas des solutions supraconductrices existent ou peuvent être imaginées. Nous examinons notamment pour les machines électriques et le stockage de l'énergie, les solutions qui existent ou sont en cours de développement avec des supraconducteurs à basse température (˜ 4 K) et quelles sont les modifications apportées par l'utilisation de supraconducteurs à haut Tc.

  5. Acoustic detection in superconducting magnets for performance characterization and diagnostics

    International Nuclear Information System (INIS)

    Marchevsky, M; Wang, X; Sabbi, G; Prestemon, S

    2013-01-01

    Quench diagnostics in superconducting accelerator magnets is essential for understanding performance limitations and improving magnet design. Applicability of the conventional quench diagnostics methods such as voltage taps or quench antennas is limited for long magnets or complex winding geometries, and alternative approaches are desirable. Here, we discuss acoustic sensing technique for detecting mechanical vibrations in superconducting magnets. Using LARP high-field Nb3Sn quadrupole HQ01, we show how acoustic data is connected with voltage instabilities measured simultaneously in the magnet windings during provoked extractions and current ramps to quench. Instrumentation and data analysis techniques for acoustic sensing are reviewed. (author)

  6. Acoustic detection in superconducting magnets for performance characterization and diagnostics

    CERN Document Server

    Marchevsky, M.; Sabbi, G.; Prestemon, S.

    2013-01-01

    Quench diagnostics in superconducting accelerator magnets is essential for understanding performance limitations and improving magnet design. Applicability of the conventional quench diagnostics methods such as voltage taps or quench antennas is limited for long magnets or complex winding geometries, and alternative approaches are desirable. Here, we discuss acoustic sensing technique for detecting mechanical vibrations in superconducting magnets. Using LARP high-field Nb$_{3}$Sn quadrupole HQ01 [1], we show how acoustic data is connected with voltage instabilities measured simultaneously in the magnet windings during provoked extractions and current ramps to quench. Instrumentation and data analysis techniques for acoustic sensing are reviewed.

  7. Heavy-ion superconducting linacs

    International Nuclear Information System (INIS)

    Delayen, J.R.

    1989-01-01

    This paper reviews the status of the superconducting heavy-ion accelerators. Most of them are linacs used as boosters for tandem electrostatic accelerators, although the technology is being extended to very low velocity to eliminate the need for an injector. The characteristics and features of the various superconducting heavy-ion accelerators are discussed. 45 refs

  8. Heavy-ion superconducting linacs

    Energy Technology Data Exchange (ETDEWEB)

    Delayen, J.R.

    1989-01-01

    This paper reviews the status of the superconducting heavy-ion accelerators. Most of them are linacs used as boosters for tandem electrostatic accelerators, although the technology is being extended to very low velocity to eliminate the need for an injector. The characteristics and features of the various superconducting heavy-ion accelerators are discussed. 45 refs.

  9. Meissner effect in superconducting microtraps

    OpenAIRE

    Cano, Daniel

    2009-01-01

    This thesis investigates the impact of the Meissner effect on magnetic microtraps for ultracold atoms near superconducting microstructures. This task has been accomplished both theoretically and experimentally. The Meissner effect distorts the magnetic fields near superconducting surfaces, thus altering the parameters of magnetic microtraps. Both computer simulations and experimental measurements demonstrate that the Meissner effect shortens the distance between the magnetic microtrap and the...

  10. Superconducting magnet for 'ML-100'

    Energy Technology Data Exchange (ETDEWEB)

    Saito, R; Fujinaga, T; Tada, N; Kimura, H

    1974-07-01

    A magneticaly levitated experimental vehicle (Ml-100) was designed and constructed in commemoration of the centenary of the Japanese National Railways. For magnetic levitation the vehicle is provided with two superconducting magnets. In the test operation of the vehicle, these superconducting magnets showed stable performance in levitating vehicle body.

  11. Superconducting bearings for flywheel applications

    Energy Technology Data Exchange (ETDEWEB)

    Abrahamsen, Asger Bech

    2001-05-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found on the applications of superconducting bearings in flywheels. (au)

  12. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  13. Superconducting Qubit Optical Transducer (SQOT)

    Science.gov (United States)

    2015-08-05

    parts on optical signals and any quasiparticle loss caused by optical photons on microwave signals. Using a superconducting 3D cavity as the microwave...plasmonic and quasiparticle losses. 3. The electro-optic material should be easily integrable with superconducting circuits. A fully integrated

  14. The Danish Superconducting Cable Project

    DEFF Research Database (Denmark)

    Tønnesen, Ole

    1997-01-01

    The design and construction of a superconducting cable is described. The cable has a room temperature dielectric design with the cryostat placed inside the electrical insulation.BSCCO 2223 superconducting tapes wound in helix form around a former are used as the cable conductor. Results from...

  15. Superconducting cavities for beauty factories

    International Nuclear Information System (INIS)

    Lengeler, H.

    1992-01-01

    The possibilities and merits of superconducting accelerating cavities for Beauty-factories are considered. There exist already large sc systems of size and frequency comparable to the ones needed for Beauty-factories. Their status and operation experience is discussed. A comparison of normal conducting and superconducting systems is done for two typical Beauty-factory rings

  16. A superconducting magnetic gear

    International Nuclear Information System (INIS)

    Campbell, A M

    2016-01-01

    A comparison is made between a magnetic gear using permanent magnets and superconductors. The objective is to see if there are any fundamental reasons why superconducting magnets should not provide higher power densities than permanent magnets. The gear is based on the variable permeability design of Attilah and Howe (2001 IEEE Trans. Magn. 37 2844–46) in which a ring of permanent magnets surrounding a ring of permeable pole pieces with a different spacing gives an internal field component at the beat frequency. Superconductors can provide much larger fields and forces but will saturate the pole pieces. However the gear mechanism still operates, but in a different way. The magnetisation of the pole pieces is now constant but rotates with angle at the beat frequency. The result is a cylindrical Halbach array which produces an internal field with the same symmetry as in the linear regime, but has an analytic solution. In this paper a typical gear system is analysed with finite elements using FlexPDE. It is shown that the gear can work well into the saturation regime and that the Halbach array gives a good approximation to the results. Replacing the permanent magnets with superconducting tapes can give large increases in torque density, and for something like a wind turbine a combined gear and generator is possible. However there are major practical problems. Perhaps the most fundamental is the large high frequency field which is inevitably present and which will cause AC losses. Also large magnetic fields are required, with all the practical problems of high field superconducting magnets in rotating machines. Nevertheless there are ways of mitigating these difficulties and it seems worthwhile to explore the possibilities of this technology further. (paper)

  17. Superconductivity at the industrial scale

    International Nuclear Information System (INIS)

    Tixador, P.; Lebrun, Ph.

    2011-01-01

    The discovery of superconductivity is 100 years old but theoretical works are still necessary: the BCS theory does not apply to the new families of high temperature superconducting materials discovered after 1986. In 2001 it was discovered that MgB 2 is superconducting at 39 K, this critical temperature is not the highest but MgB 2 is easy to produce and cheap. Today's highest critical temperature under atmospheric pressure is that of the HgTlBaCaCuO compound: 138 K. The complexity and the cost of cryogenic systems restrain the applications of superconductivity. The author reviews the applications of superconducting in medical imaging, particle detectors, and in the safety systems of power networks. (A.C.)

  18. 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)

  19. Three-terminal superconducting devices

    International Nuclear Information System (INIS)

    Gallagher, W.J.

    1985-01-01

    The transistor has a number of properties that make it so useful. The authors discuss these and the additional properties a transistor would need to have for high performance applications at temperatures where superconductivity could contribute advantages to system-level performance. These properties then serve as criteria by which to evaluate three-terminal devices that have been proposed for applications at superconducting temperatures. FETs can retain their transistor properties at low temperatures, but their power consumption is too large for high-speed, high-density cryogenic applications. They discuss in detail why demonstrated superconducting devices with three terminals -Josephson effect based devices, injection controlled weak links, and stacked tunnel junction devices such as the superconducting transistor proposed by K. Gray and the quiteron -- each fail to have true transistor-like properties. They conclude that the potentially very rewarding search for a transistor compatible with superconductivity in high performance applications must be in new directions

  20. Review of superconducting linacs

    International Nuclear Information System (INIS)

    Bollinger, L.M.

    1992-01-01

    This paper summarizes the status of the technology of superconducting (SC) linacs designed for the acceleration of ions. The emphasis is on the technical issues involved, with only brief descriptions of the numerous linacs now in operation or under construction. Recent developments of special interest are treated in more detail, and remaining technical challenges are outlined. The technology required for acceleration of ions with velocity β ∼ 1 is not discussed because it is almost the same as for relativistic electrons. That is, this paper is mainly about SC linacs for low-velocity heavy ions. (Author) 5 tabs., 6 figs., 29 refs

  1. A superconducting electron spectrometer

    International Nuclear Information System (INIS)

    Guttormsen, M.; Huebel, H.; Grumbkow, A. von

    1983-03-01

    The set-up and tests of an electron spectrometer for in-beam conversion electron measurements are described. A superconducting solenoid is used to transport the electrons from the target to cooled Si(Li) detectors. The solenoid is designed to produce either a homogeneous axially symmetric field of up to 2 Tesla or a variety of field profiles by powering the inner and outer set of coils of the solenoid separately. The electron trajectories resulting for various field profiles are discussed. In-beam electron spectra taken in coincidence with electrons, gammas and alpha-particles are shown. (Auth.)

  2. Superconducting ac cable

    Science.gov (United States)

    Schmidt, F.

    1980-11-01

    The components of a superconducting 110 kV ac cable for power ratings or = 2000 MVA were developed. The cable design is of the semiflexible type, with a rigid cryogenic envelope containing a flexible hollow coaxial cable core. The cable core consists of spirally wound Nb-A1 composite wires electrically insulated by high pressure polyethylene tape wrappings. A 35 m long single phase test cable with full load terminals rated at 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of this cable design.

  3. Superconductivity in nanostructured lead

    Science.gov (United States)

    Lungu, Anca; Bleiweiss, Michael; Amirzadeh, Jafar; Saygi, Salih; Dimofte, Andreea; Yin, Ming; Iqbal, Zafar; Datta, Timir

    2001-01-01

    Three-dimensional nanoscale structures of lead were fabricated by electrodeposition of pure lead into artificial porous opal. The size of the metallic regions was comparable to the superconducting coherence length of bulk lead. Tc as high as 7.36 K was observed, also d Tc/d H was 2.7 times smaller than in bulk lead. Many of the characteristics of these differ from bulk lead, a type I superconductor. Irreversibility line and magnetic relaxation rates ( S) were also studied. S( T) displayed two maxima, with a peak value about 10 times smaller than that of typical high- Tc superconductors.

  4. Remarks on superconductive networks

    International Nuclear Information System (INIS)

    Dominguez, D.; Lopez, A.R.N.; Simonin, J.M.

    1989-01-01

    Some remarks on the determination of the normal-superconductor phase boundary in random superconductive networks are made. A recently reported work by Soukoulis, Grest and Li which introduces weak links between nodes as these are removed in the site percolation problem is discussed. By the analysis of two simple geometries, it is shown that this procedure introduces spurious effects which mask the physical properties of the system. These affect in particular the field slope critical index and the sharpness of the normal-superconductor boundary. (Author)

  5. Superconducting magnet cooling system

    Science.gov (United States)

    Vander Arend, Peter C.; Fowler, William B.

    1977-01-01

    A device is provided for cooling a conductor to the superconducting state. The conductor is positioned within an inner conduit through which is flowing a supercooled liquid coolant in physical contact with the conductor. The inner conduit is positioned within an outer conduit so that an annular open space is formed therebetween. Through the annular space is flowing coolant in the boiling liquid state. Heat generated by the conductor is transferred by convection within the supercooled liquid coolant to the inner wall of the inner conduit and then is removed by the boiling liquid coolant, making the heat removal from the conductor relatively independent of conductor length.

  6. Introduction to superconductivity

    CERN Document Server

    Rose-Innes, A C

    1978-01-01

    Introduction to Superconductivity differs from the first edition chiefly in Chapter 11, which has been almost completely rewritten to give a more physically-based picture of the effects arising from the long-range coherence of the electron-waves in superconductors and the operation of quantum interference devices. In this revised second edition, some further modifications have been made to the text and an extra chapter dealing with """"high-temperature"""" superconductors has been added. A vast amount of research has been carried out on these since their discovery in 1986 but the results, both

  7. Ruthenates: simple superconducting qubits

    International Nuclear Information System (INIS)

    Gulian, Armen M.; Wood, Kent S.

    2004-01-01

    We propose triplet superconductors, such as ruthenates, as a prospective material for qubit construction. The vectorial nature of the order parameter in triplet superconductors makes it conceptually very easy to imagine the performance of the qubits. The Cooper condensate of pairs in triplet superconductors has all the attributes of the Bose-Einstein condensates and should facilitate long decoherence times of these qubits versus other 'vectorial' schemes for qubits, such as small ferromagnets. There are other benefits, which the superconducting state provides for a requirement like entanglement between qubits via the proximity effect

  8. Superconductivity in nanowires

    CERN Document Server

    Bezryadin, Alexey

    2012-01-01

    The importance and actuality of nanotechnology is unabated and will be for years to come. A main challenge is to understand the various properties of certain nanostructures, and how to generate structures with specific properties for use in actual applications in Electrical Engineering and Medicine.One of the most important structures are nanowires, in particular superconducting ones. They are highly promising for future electronics, transporting current without resistance and at scales of a few nanometers. To fabricate wires to certain defined standards however, is a major challenge, and so i

  9. Superconductivity at disordered interfaces

    International Nuclear Information System (INIS)

    Simanek, E.

    1979-01-01

    The increase of the superconducting transition temperature Tsub(c) due to the tunneling of conduction electrons into negative-u centers at a disordered metal-semiconductor interface is calculated. The strong dependence of the experimental increase of Tsub(c) on the Fermi energy of the metal is accounted for by the polaronic reduction of the tunneling matrix elements. The latter reduction is dynamically suppressed by the decreasing lifetime of the localized state as Esub(F) increases. The theoretical enhancement is sufficiently strong to explain the increase of Tsub(c) observed in eutectic alloys. (author)

  10. New theory of superconductivity

    International Nuclear Information System (INIS)

    Bell, A.B.; Bell, D.M.

    1978-01-01

    Based on three earlier papers which treat electromagnetic, elastogravitational, and radiant-nonradiant thermal phenomena in terms of six types of electric or nonelectric charges, the authors classify states of matter as hyperefficient, efficient, semiefficient, and hypoefficient in transmitting a particular type of charge, by means of a generalization of Ohm's law to two or three dimensions. Conventional states of matter (solid, liquid, gas, vacuum) are associated with torsional (gravitational) charges. Applications are made to electric superconductivity of crystals at elevated temperatures, and to frequency shift

  11. AGS superconducting bending magnets

    International Nuclear Information System (INIS)

    Robins, K.E.; Sampson, W.B.; McInturff, A.D.; Dahl, P.F.; Abbatiello, F.; Aggus, J.; Bamberger, J.; Brown, D.; Damm, R.; Kassner, D.; Lasky, C.; Schlafke, A.

    1976-01-01

    Four large aperture superconducting bending magnets are being built for use in the experimental beams at the AGS. Each of these magnets is 2.5 m long and has a room temperature aperture of 20 cm. The magnets are similar in design to the dipoles being developed for ISABELLE and employ a low temperature iron core. Results are presented on the ''training'' behavior of the magnets and a comparison will be made with the smaller aperture versions of this design. The magnet field measurements include end fields and leakage fields as well as the harmonic components of the straight section of the magnet

  12. 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

  13. Stabilized superconductive wires

    International Nuclear Information System (INIS)

    Randall, R.N.; Wong, J.

    1976-01-01

    A stable, high field, high current conductor is produced by packing multiple, multi-layer rods of a bronze core and niobium or vanadium inner jacket and copper outer jacket into a pure copper tube or other means for forming a pure copper matrix, sealing, working the packed tube to a wire, and by diffusion, heat treating to form a type II superconducting, Beta-Wolfram structure, intermetallic compound as a layer within each of several filaments derived from the rods. The layer of Beta-Wolfram structure compound may be formed in less than 2 h of diffusion heat treatment in a thickness of 0.5--2μ

  14. Superconducting ac cable

    International Nuclear Information System (INIS)

    Schmidt, F.

    1980-01-01

    The components of a superconducting 110 kV ac cable for power ratings >= 2000 MVA have been developed. The cable design especially considered was of the semiflexible type, with a rigid cryogenic envelope and flexible hollow coaxial cable cores pulled into the former. The cable core consists of spirally wound Nb-Al composite wires and a HDPE-tape wrapped electrical insulation. A 35 m long single phase test cable with full load terminations for 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of our cable design. (orig.) [de

  15. Superconducting low-noise oscillator

    International Nuclear Information System (INIS)

    Riebman, L.

    1992-01-01

    This patent describes a cryogenic oscillator having low phase noise and low noise. It comprises resonant circuit means formed of superconducting material for generating a signal at a desired frequency; linear amplifier means electrically connected to the resonant circuit means at first and second locations thereon; limiter means electrically connected to the resonant circuit means at a third location thereon; and buffer amplifier means for applying the signal generated by the resonant circuit means to a load and electrically connected to the resonant circuit means at a fourth location thereon. This patent also describes a method of minimizing phase noise and 1/f noise in an oscillator circuit of the type having a resonant circuit driving a load and at least a linear amplifier connected to the resonant circuit defining a closed loop having a loop gain greater than unity, and having a limiter for stabilizing the oscillator. It comprises connecting between the resonant circuit and the load a buffer amplifier and connecting the linear amplifier and the buffer amplifier to the resonant circuit

  16. 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

  17. Vortex properties of mesoscopic superconducting samples

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Leonardo R.E. [Laboratorio de Supercondutividade e Materiais Avancados, Departamento de Fisica, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil); Barba-Ortega, J. [Grupo de Fi' sica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia); Souza Silva, C.C. de [Laboratorio de Supercondutividade e Materiais Avancados, Departamento de Fisica, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil); Albino Aguiar, J., E-mail: albino@df.ufpe.b [Laboratorio de Supercondutividade e Materiais Avancados, Departamento de Fisica, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil)

    2010-10-01

    In this work we investigated theoretically the vortex properties of mesoscopic samples of different geometries, submitted to an external magnetic field. We use both London and Ginzburg-Landau theories and also solve the non-linear Time Dependent Ginzburg-Landau equations to obtain vortex configurations, equilibrium states and the spatial distribution of the superconducting electron density in a mesoscopic superconducting triangle and long prisms with square cross-section. For a mesoscopic triangle with the magnetic field applied perpendicularly to sample plane the vortex configurations were obtained by using Langevin dynamics simulations. In most of the configurations the vortices sit close to the corners, presenting twofold or three-fold symmetry. A study of different meta-stable configurations with same number of vortices is also presented. Next, by taking into account de Gennes boundary conditions via the extrapolation length, b, we study the properties of a mesoscopic superconducting square surrounded by different metallic materials and in the presence of an external magnetic field applied perpendicularly to the square surface. It is determined the b-limit for the occurrence of a single vortex in a mesoscopic square of area d{sup 2}, for 4{xi}(0){<=}d{<=}10{xi}(0).

  18. Superconducting nano-strip particle detectors

    International Nuclear Information System (INIS)

    Cristiano, R; Ejrnaes, M; Casaburi, A; Zen, N; Ohkubo, M

    2015-01-01

    We review progress in the development and applications of superconducting nano-strip particle detectors. Particle detectors based on superconducting nano-strips stem from the parent devices developed for single photon detection (SSPD) and share with them ultra-fast response times (sub-nanosecond) and the ability to operate at a relatively high temperature (2–5 K) compared with other cryogenic detectors. SSPDs have been used in the detection of electrons, neutral and charged ions, and biological macromolecules; nevertheless, the development of superconducting nano-strip particle detectors has mainly been driven by their use in time-of-flight mass spectrometers (TOF-MSs) where the goal of 100% efficiency at large mass values can be achieved. Special emphasis will be given to this case, reporting on the great progress which has been achieved and which permits us to overcome the limitations of existing mass spectrometers represented by low detection efficiency at large masses and charge/mass ambiguity. Furthermore, such progress could represent a breakthrough in the field. In this review article we will introduce the device concept and detection principle, stressing the peculiarities of the nano-strip particle detector as well as its similarities with photon detectors. The development of parallel strip configuration is introduced and extensively discussed, since it has contributed to the significant progress of TOF-MS applications. (paper)

  19. Overview on superconducting photoinjectors

    CERN Document Server

    Arnold, A

    2011-01-01

    The success of most of the proposed energy recovery linac (ERL) based electron accelerator projects for future storage ring replacements (SRR) and high power IR–free-electron lasers (FELs) largely depends on the development of an appropriate source. For example, to meet the FEL specifications [J.W. Lewellen, Proc. SPIE Int. Soc. Opt. Eng. 5534, 22 (2004)] electron beams with an unprecedented combination of high brightness, low emittance (0.1 µmrad), and high average current (hundreds of mA) are required. An elegant way to create a beam of such quality is to combine the high beam quality of a normal conducting rf photoinjector with the superconducting technology, i.e., to build a superconducting rf photoinjector (SRF gun). SRF gun R&D programs based on different approaches have been launched at a growing number of institutes and companies (AES, Beijing University, BESSY, BNL, DESY, FZD, TJNAF, Niowave, NPS, Wisconsin University). Substantial progress was achieved in recent years and the first long term ...

  20. Superconducting composites materials

    International Nuclear Information System (INIS)

    Kerjouan, P.; Boterel, F.; Lostec, J.; Bertot, J.P.; Haussonne, J.M.

    1991-01-01

    The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developed in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa 2 Cu 3 O 7-δ material. We first realized a composite material glass/YBa 2 Cu 3 O 7-δ , by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa 2 Cu 3 O 7-δ material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. 8 refs.; 14 figs.; 9 tabs [fr