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Sample records for hts bulk magnet

  1. Waveform control pulse magnetization for HTS bulk magnet

    NASA Astrophysics Data System (ADS)

    Ida, Tetsuya; Shigeuchi, Koji; Okuda, Sayo; Watasaki, Masahiro; Izumi, Mitsuru

    2016-03-01

    For the past 10 years, we have studied high-temperature superconducting (HTS) bulk magnets for use in electromagnetic rotating machines. If the magnetic field effectively magnetizes the HTS bulk, then the size of the motor and generator can be reduced without a reduction in output. We showed that the melt-textured Gd-Ba-Cu-O HTS bulk effectively traps a high magnetic field using waveform control pulse magnetization (WCPM). WCPM makes it possible to generate any pulsed magnetic field waveform by appropriately changing the duty ratio of the pulse width modulation. By chopping so that the pulsed magnetic field has a period of about 1ms, the WCPM technology enables active control of the rise time and suppresses magnetic flux motion that decreases magnetization efficiency. This method is also useful for any HTS bulk magnet, and the high magnetic flux density is trapped in the HTS bulk by a single pulse magnetic field. We developed a magnetizer that has a feedback system from the penetrated magnetic flux density to realize WCPM. In this research, using only a single pulse magnetic field of WCPM method at 77K, an HTS bulk with a 45mm diameter and 19mm thickness trapped a maximum magnetic field of 1.63T, which is more than 90% of the trapped magnetic flux density by FC magnetization. This result suggests that the pulse magnetizing method can replace the conventional field-cooled method and promote the practical use of HTS magnets for electromagnetic power applications.

  2. Magnetizing of permanent magnets using HTS bulk magnets

    NASA Astrophysics Data System (ADS)

    Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

    2012-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole which contains the HTS bulk magnet generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnet plate inversely with various overlap distances between the tracks of the bulk magnet. The magnetic field of the "rewritten" magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated.

  3. Large-scale HTS bulks for magnetic application

    NASA Astrophysics Data System (ADS)

    Werfel, Frank N.; Floegel-Delor, Uta; Riedel, Thomas; Goebel, Bernd; Rothfeld, Rolf; Schirrmeister, Peter; Wippich, Dieter

    2013-01-01

    ATZ Company has constructed about 130 HTS magnet systems using high-Tc bulk magnets. A key feature in scaling-up is the fabrication of YBCO melts textured multi-seeded large bulks with three to eight seeds. Except of levitation, magnetization, trapped field and hysteresis, we review system engineering parameters of HTS magnetic linear and rotational bearings like compactness, cryogenics, power density, efficiency and robust construction. We examine mobile compact YBCO bulk magnet platforms cooled with LN2 and Stirling cryo-cooler for demonstrator use. Compact cryostats for Maglev train operation contain 24 pieces of 3-seed bulks and can levitate 2500-3000 N at 10 mm above a permanent magnet (PM) track. The effective magnetic distance of the thermally insulated bulks is 2 mm only; the stored 2.5 l LN2 allows more than 24 h operation without refilling. 34 HTS Maglev vacuum cryostats are manufactured tested and operate in Germany, China and Brazil. The magnetic levitation load to weight ratio is more than 15, and by group assembling the HTS cryostats under vehicles up to 5 t total loads levitated above a magnetic track is achieved.

  4. 5 MJ flywheel based on bulk HTS magnetic suspension

    NASA Astrophysics Data System (ADS)

    Poltavets, V.; Kovalev, K.; Ilyasov, R.; Glazunov, A.; Maevsky, V.; Verzbitsky, L.; Akhmadyshev, V.; Shikov, A.

    2014-05-01

    Nowadays the flywheel energy storage systems (FES) are developed intensively as uninterruptible power supply (UPS) devices for on-land and transport (especially airborne) applications worldwide. This work is devoted to the FES with magnetic suspension on the base of bulk HTS YBCO elements and permanent magnets. The developed FES is intended to be used as UPS in Russian atomic industry in case of an emergency. For the successful design of the FES the following questions should be solved: design of the motor/generator, design of the rotor (flywheel), design of the bearing system, design of the control system and system of power load matching, design of the cooling system. The developed small-scale FES with the stored energy 0.5 MJ was used to solve these basic questions. The elaborated FES consists of the synchronous electric machine with permanent magnets, the solid flywheel with axial magnetic suspension on the base of YBCO bulks and permanent magnets, the system of control and power load matching, and the system of liquid nitrogen cooling. The results of theoretical modeling of different schematics of magnetic suspension and experimental investigations of the constructed FES are presented. The design of the future full-scale FES with the stored energy ~5 MJ and output power up to 100 kW is described. The test results of the flywheel rotor and HTS magnetic suspension of 5 MJ FES are presented. This work is done under support of Rosatom within the frames of Russian Project "Superconducting Industry"

  5. Superconducting Electric Machine with Permanent Magnets and Bulk HTS Elements

    NASA Astrophysics Data System (ADS)

    Levin, A. V.; Vasich, P. S.; Dezhin, D. S.; Kovalev, L. K.; Kovalev, K. L.; Poltavets, V. N.; Penkin, V. T.

    Theoretical methods of calculating of two-dimensional magnetic fields, inductive parameters and output characteristics of the new type of high-temperature superconducting (HTS) synchronous motors with a composite rotor are presented. The composite rotor has the structure containing HTS flat elements, permanent magnets and ferromagnetic materials. The developed calculation model takes into account the concentrations and physical properties of these rotor elements. The simulation results of experimental HTS motor with a composite rotor are presented. The application of new type of HTS motor in different constructions of industrial high dynamic drivers is discussed.

  6. Magnetic Forces Simulation of Bulk HTS over Permanent Magnetic Railway with Numerical Method

    NASA Astrophysics Data System (ADS)

    Lu, Yiyun; Zhuang, Shujun

    2012-10-01

    Magnetic levitation forces of bulk high temperature superconductor (HTS) above two types permanent magnet railway (PMR) is simulated using finite element method (FEM). The models are formulated by H-formulation and resolving codes is developed using Finite Element Program Generator (FEPG). The E- J power law is used to describe the electrical field vs. current density nonlinear characteristic of HTS. The applied magnetic fields induced by the PMR are calculated by the standard analysis method with the equivalent surface current model. By the method, the calculation formulation of magnetic fields generated by Halbach PMR and symmetrical PMR is derived respectively. The simulation results show that the finite element dynamic mesh rebuilding problem of HTS magnetic levitation transportation system comprised of bulk HTS and PMR can be easily avoided by the methods.

  7. Application of shielding current in bulk HTS to control magnetic field distribution

    NASA Astrophysics Data System (ADS)

    Kii, T.

    2016-03-01

    Superconducting shielding current is excited when external field is applied to superconductor. In case for field cooling of bulk superconductor, shielding current is an origin of strong trapped field. When external field is changed to a properly arranged bulk HTS array, various magnetic field distribution can be formed by an excited shielding current in each bulk HTS. This paper presents a simple intuitively method to design magnetic field distribution using supercurrents in bulk high-temperature superconductor (HTS) array. In this method, an ideal current path for intended field distribution is represented by shielding currents in bulk HTS array. Expected performance can be roughly estimated by using Biot-Savart law. As examples, Maxwell coil pair and helical field generator are designed. This method can be applied to design various magnet devices using bulk HTS array.

  8. Reduction of flux-creep in magnetized bulk HTS by use of permanent magnets

    NASA Astrophysics Data System (ADS)

    Parks, D.; Weinstein, R.; Davey, K.; Sawh, R.-P.; Carpenter, K.

    2017-01-01

    We report the effect of permanent magnet (PM) collars on the flux-creep rate of magnetized bulk HTS. The creep rates of single-grain, cylindrical samples are measured with attached collars activated to various fields, B PM, in the range 0 ≤ B PM ≤ B PM,max, where B PM,max is the fully saturated field of the PM. As B PM varies, the creep rate of the HTS is found to maintain its well-known form—a constant fractional loss λ, of original residual field, per decade of time. However, the magnitude of λ decreases as B PM increases. The decrease in λ is found to be linearly dependent on increasing B PM. The collar field for which flux-creep extrapolates to zero is found to be comparable to the maximum trappable field of the HTS bulk, B T,max. The properties of the dependence of λ on the HTS peak field, B T,max, the PM field, B PM, and the creep rate λ 0 with B PM = 0 permit the reduced creep rate in these experiments to be predicted by a universal equation.

  9. Influence of AC external magnetic field on guidance force relaxation between HTS bulk and NdFeB guideway

    NASA Astrophysics Data System (ADS)

    Zhang, Longcai; Wang, Suyu; Wang, Jiasu; Zheng, Jun

    2007-12-01

    Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to time-varying external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. So it is required to study whether the guidance force of the bulks is influenced by the inhomogeneity. In this paper, we studied the characteristics of the guidance force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experiment results, it was found that the guidance force was decreased with the application of the AC external magnetic field, and the decay increased with the amplitude and was almost independent of the frequency.

  10. Uniform Magnetic Field Between Face-to-Face HTS Bulk Magnets Combining Concave and Convex Magnetic Field Distributions

    NASA Astrophysics Data System (ADS)

    Oka, T.; Takahashi, Y.; Yaginuma, S.; Ogawa, J.; Fukui, S.; Sato, T.; Yokoyama, K.; Nakamura, T.

    The authors have been attempting to obtain the uniform magnetic field distribution in the space between the face-to-face HTS bulk magnets. The magnetic poles containing the HTS bulk magnets are usually characterized as non-uniform magnetic field distribution. Since the distributions show the conical or convex shapes, it is difficult to obtain the uniform magnetic field spaces even when the magnetic poles would be placed face-to-face. The authors have modified the shape of the distribution of one-side magnetic pole by attaching an iron plate on the surface, and formed the concave magnetic field distribution on the pole surface. The steep concave or convex distributions at each pole surface change to be flat with increasing distance from the pole surface. After the experimental result recording the best uniformity of 358 ppm by combining the concave and convex field distributions face-to-face, we attempted to simulate the feasible performance in this configuration. In the numerical simulation, the concave field distribution modified by attaching an imaginary spiral coil on the pole surface was coupled with the original convex field. We succeeded in obtaining the best uniformity of 30 ppm at 1.1 T in 4 x 4 mm2x-y plane at 7 mm distant from the pole surface in the gap of 30 mm. This result suggests that the concave and convex magnetic field distributions compensate the field uniformity with each other with keeping the magnetic field strength in the gap, and also suggests the novel compact NMR/MRI devices in the future.

  11. HTS magnetic bearings

    NASA Astrophysics Data System (ADS)

    Werfel, Frank N.; Flögel-Delor, Uta; Rothfeld, Rolf; Wippich, Dieter; Riedel, Thomas

    2002-08-01

    Radial HTS magnetic bearings (SMB) up to 200 mm size are developed and tested in prototype fast rotating machines to demonstrate the potential to replace conventional bearings. The individual rotational bearing components HTS and PM, their physical interaction and technology is reviewed. Characterisation experiments are conducted to understand the rotor dynamic behaviour. In terms of unbalance and critical speeds the suspended wheels and rotors compare favourably with conventional bearing devices. The rationale of our present bearing technology lies in the assembling of both low-speed magnetic bearings for centrifugal and wafer processing units up to 20,000 rpm as well as a high-speed optical mirror accelerated to rim speed of more than 500 m/s (174,000 rpm) confirming stable low-drag and low energy operation. Two new-type U shaped semicircle HTS bearings coupled each with a 6 W/80 K cryocooler of the Stirling type allow the contact-free operation of a Si wafer carrier in semiconductor wet processes.

  12. High output power electric motors with bulk HTS elements

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Kovalev, K. L.; Penkin, V. T.; Poltavets, V. N.; Koneev, S. M.-A.; Akimov, I. I.; Gawalek, W.; Oswald, B.; Krabbes, G.

    2003-04-01

    New types of electric machines with the rotors containing bulk HTS (YBCO and Bi-Ag) elements are presented. Different schematics of hysteresis, reluctance, “trapped field” and composed synchronous HTS machines are discussed. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the single-domain and polycrystal YBCO ceramic samples and plate shape Bi-Ag elements. The test results of the series of hysteresis, reluctance, “trapped field” and composed with permanent magnets HTS motors with output power rating 0.1-18 kW and current frequency 50 and 400 Hz are given. These results show that in the media of liquid nitrogen the specific output power per one weight unit of HTS motors is 4-7 times better than for conventional electric machines. Comparison of the theoretical and experimental characteristics of the developed HTS motors show that they are in good agreement. The test results for liquid nitrogen cryogenic pump system with hysteresis 500 W HTS motor are discussed. The designs and first test results of HTS motor operating in the media of liquid nitrogen with output power 100 kW and power factor more than 0.8 are given. Future development and applications of new types of HTS motors for aerospace technology, on-land industry and transport systems are discussed.

  13. Materials processing and machine applications of bulk HTS

    NASA Astrophysics Data System (ADS)

    Miki, M.; Felder, B.; Tsuzuki, K.; Xu, Y.; Deng, Z.; Izumi, M.; Hayakawa, H.; Morita, M.; Teshima, H.

    2010-12-01

    We report a refrigeration system for rotating machines associated with the enhancement of the trapped magnetic flux of bulk high-temperature superconductor (HTS) field poles. A novel cryogenic system was designed and fabricated. It is composed of a low-loss rotary joint connecting the rotor and a closed-cycle thermosiphon under a GM cryocooler using a refrigerant. Condensed neon gas was adopted as a suitable cryogen for the operation of HTS rotating machines with field poles composed of RE-Ba-Cu-O family materials, where RE is a rare-earth metal. Regarding the materials processing of the bulks HTS, thanks to the addition of magnetic particles to GdBa2Cu3O7 - d (Gd123) bulk superconductors an increase of more than 20% in the trapped magnetic flux density was achieved at liquid nitrogen temperature. Field-pole Gd123 bulks up to 46 mm in diameter were synthesized with the addition of Fe-B alloy magnetic particles and assembled into the synchronous machine rotor to be tested. Successful cooling of the magnetized rotor field poles down to 35 K and low-output-power rotating operation was achieved up to 720 rpm in the test machine with eight field-pole bulks. The present results show a substantial basis for making a prototype system of rotating machinery of applied HTS bulks.

  14. Study of superconducting magnetic bearing applicable to the flywheel energy storage system that consist of HTS-bulks and superconducting-coils

    NASA Astrophysics Data System (ADS)

    Seino, Hiroshi; Nagashima, Ken; Tanaka, Yoshichika; Nakauchi, Masahiko

    2010-06-01

    The Railway Technical Research Institute conducted a study to develop a superconducting magnetic bearing applicable to the flywheel energy-storage system for railways. In the first step of the study, the thrust rolling bearing was selected for application, and adopted liquid-nitrogen-cooled HTS-bulk as a rotor, and adopted superconducting coil as a stator for the superconducting magnetic bearing. Load capacity of superconducting magnetic bearing was verified up to 10 kN in the static load test. After that, rotation test of that approximately 5 kN thrust load added was performed with maximum rotation of 3000rpm. In the results of bearing rotation test, it was confirmed that position in levitation is able to maintain with stability during the rotation. Heat transfer properties by radiation in vacuum and conductivity by tenuous gas were basically studied by experiment by the reason of confirmation of rotor cooling method. The experimental result demonstrates that the optimal gas pressure is able to obtain without generating windage drag. In the second stage of the development, thrust load capacity of the bearing will be improved aiming at the achievement of the energy capacity of a practical scale. In the static load test of the new superconducting magnetic bearing, stable 20kN-levitation force was obtained.

  15. Development of HTS Magnet for Rotating Gantry

    NASA Astrophysics Data System (ADS)

    Tasaki, Kenji; Koyanagi, Kei; Takayama, S. Shigeki; Ishii, Yusuke; Kurusu, Tsutomu; Amemiya, Naoyuki; Ogitsu, Toru; iwata, Yoshiyuki; Noda, Koji

    The effectiveness of heavy-ion radiotherapy for cancer treatment has been recognized by medical experts and the public. However, due to the large size of the equipment, this therapy has not been widely adopted. In particular, the rotating gantries used to irradiate patients with the heavy-ion beams from any direction may be as heavy as 600 tons in our estimation. By employing high-temperature superconducting (HTS) wires in these rotating gantries and increasing the magnetic field generated by the deflecting coils, the total weight of the rotating gantry can be reduced to around the weight of those used for proton radiotherapy. A project for developing an HTS deflecting magnet for heavy-ion radiotherapy has been underway since 2013, supported by the Japanese Ministry of Economy, Trade and Industry (METI) and the Japan Agency for Medical Research and Development (AMED). The aim of this project is to develop fundamental technologies for designing and fabricating HTS deflecting magnets, such as irregular magnetic field estimating techniques, design technology for HTS magnets, high-precision HTS coil winding technology, AC loss estimating techniques, and thermal runaway estimating techniques and to fabricate a small model of an HTS deflecting magnet and evaluate its performance. In this paper, the project's progress will be described.

  16. Development of REBCO HTS Magnet of Magnetic Bearing for Large Capacity Flywheel Energy Storage System

    NASA Astrophysics Data System (ADS)

    Mukoyama, Shinichi; Matsuoka, Taro; Furukawa, Makoto; Nakao, Kengo; Nagashima, Ken; Ogata, Masafumi; Yamashita, Tomohisa; Hasegawa, Hitoshi; Yoshizawa, Kazuhiro; Arai, Yuuki; Miyazaki, Kazuki; Horiuchi, Shinichi; Maeda, Tadakazu; Shimizu, Hideki

    A flywheel energy storage system (FESS) is a promising electrical storage system that moderates fluctuation of electrical power from renewable energy sources. The FESS can charge and discharge the surplus electrical power repetitively with the rotating energy. Particularly, the FESS that utilizes a high temperature superconducting magnetic bearing (HTS bearing) is lower loss than conventional FESS that has mechanical bearing, and has property of longer life operation than secondary batteries. The HTS bearing consists of a HTS bulk and double-pancake coils used 2nd generation REBCO wires. In the development, the HTS double-pancake coils were fabricated and were provided for a levitation test to verify the possibility of the HTS bearing. We successfully confirmed the magnetic field was achieved to design value, and levitation force in the configuration of one YBCO bulk and five double pan-cake coils was obtained to a satisfactory force of 39.2 kN (4 tons).

  17. The Dynamic Characteristics on the Wall Traveling of the HTS Bulk Superconducting Actuator

    NASA Astrophysics Data System (ADS)

    Sawae, M.; Kim, S. B.; Ozasa, S.; Nakano, H.; Kobayashi, H.

    The electric device applications of a high temperature superconducting (HTS) bulk having stable levitation and suspension properties due to their strong flux pinning force have been proposed and developed. We have been investigating the three-dimensional (3-D) superconducting actuator using HTS bulk to develop the transportation device with non-contact and moves in free space. It is expected that our proposed 3-D superconducting actuator to be useful as a transporter used in clean room which manufactures the silicon wafer where dislikes mechanical contact and dust. Proposed the actuator consists of a field-cooled HTS bulk for mover and two-dimensional arranged multiple electromagnets as a stator. In our previous study, the dynamic characteristics on the floor traveling of the HTS bulk mover had been studied. Therefore in this study, a system for the wall traveling was proposed to use the limited space effectively. It is expected that the wall traveling system is very useful to apply the transporter used in the tunnels which flammable gas may be produced. In this paper, the optimal angle between electromagnets located at floor and wall for moving to the wall traveling from the floor traveling was investigated experimentally. The position displacement on the rotating of the HTS bulk during the wall traveling was measured. As a result, the bulk with initial gap of 2 mm could move to the wall traveling from the floor traveling. Also, the position displacement on the height direction during the rotating of the HTS bulk was 18 mm from the initial position because of its gravity,but it was possible to rotate by changing the pattern NSNS of the trapped magnetic field in near the initial position.

  18. HTS electrical machines with YBCO bulk and Ag-BSCCO plate-shape HTS elements: recent results and future development

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; Koneev, S. M.-A.; Modestov, K. A.; Larionoff, S. A.; Gawalek, W.; Oswald, B.

    2001-05-01

    Novel types of electric HTS motors with the rotor containing bulk YBCO elements are presented. Different schematics of hysteresis, reluctance “trapped field” and composed HTS motors are discussed. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the multi-domain and single-domain YBCO ceramic samples. The test results of the series of these HTS motors with output power 1-20 kW and current frequency 50 and 400 Hz are given. These results show that in the media of liquid nitrogen the specific output power per one weight unit is four to five times better then for conventional electric machines. The design of a new high power HTS motor operating in the liquid nitrogen with output power 200 kW (and more) is discussed. Future applications of new types of HTS motors for airspace and on-land industry and transport systems are discussed.

  19. Applied Hts Bulks and Wires to Rotating Machines for Marine Propulsion

    NASA Astrophysics Data System (ADS)

    Miki, M.; Felder, B.; Kimura, Y.; Tsuzuki, K.; Taguchi, R.; Shiliang, Y.; Xu, Y.; Ida, T.; Izumi, M.

    2010-04-01

    High-temperature superconductors allow a compact and efficient way to provide high-torque density to rotating machines with excellent operation. A field pole, providing flux density of more than 1.5 T around the armature, was initially designed for an axial-gap type with the flux parallel to the rotor axis. Melt-growth Gd-123 bulks as well as Bi-2223 wire windings have been successfully assembled on the rotor disk. No iron core was used, though being an auxiliary flux control found in most HTS motors. Both bulk and wire types have realized a practical motor operation within a limited output range. For bulks, a 15 kW, 720 rpm, synchronous motor was designed and tested in the group of TUMSAT, Kitano Seiki and University of Fukui. A bulk field pole was cooled down by liquid nitrogen and was magnetized in the motor. To enhance the output power to more than 30 kW, we developed a thermosyphon system using condensed neon. Another field pole with HTS wire for large-scale marine propulsion is also discussed on a 100 kW, 230 rpm tested machine. A closed-cycle condensed neon associated with thermal insulation is also reported.

  20. Hysteresis and reluctance electric machines with bulk HTS elements. Recent results and future development

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; M-A Koneev, S.; Poltavets, V. N.; Larionoff, A. E.; Modestov, K. A.; Larionoff, S. A.; Gawalek, W.; Habisreuther, T.; Oswald, B.; Best, K.-J.; Strasser, T.

    2000-05-01

    Two new types of HTS electric machine are considered. The first type is hysteresis motors and generators with cylindrical and disc rotors containing bulk HTS elements. The second type is reluctance motors with compound HTS-ferromagnetic rotors. The compound HTS-ferromagnetic rotors, consisting of joined alternating bulk HTS (YBCO) and ferromagnetic (iron) plates, provide a new active material for electromechanical purposes. Such rotors have anisotropic properties (ferromagnetic in one direction and diamagnetic in the perpendicular one). Theoretical and experimental results for HTS hysteresis and reluctance motors are presented. A series of hysteresis HTS motors with output power rating from 1 kW (at 50 Hz) up to 4 kW (at 400 Hz) and a series of reluctance HTS motors with output power 2-18.5 kW (at 50 Hz) were constructed and successfully tested. It was shown that HTS reluctance motors could reach two to five times better overall dimensions and specific power than conventional asynchronous motors of the same size and will have higher values of power factor (cos ϕ≥0.7 to 0.8).

  1. H-formulation for simulating levitation forces acting on HTS bulks and stacks of 2G coated conductors

    NASA Astrophysics Data System (ADS)

    Sass, F.; Sotelo, G. G.; Junior, R. de Andrade; Sirois, Frédéric

    2015-12-01

    Several techniques to model high temperature superconductors (HTSs) are used throughout the world. At the same time, the use of superconductors in transportation and magnetic bearings promises an increase in energy efficiency. However, the most widespread simulation technique in the literature, the H-formulation, has not yet been used to simulate superconducting levitation. The goal of this work is to present solutions for the challenges concerning the use of the H-formulation to predict the behavior of superconducting levitators built either with YBCO bulks or stacks of 2G wires. It is worth mentioning the originality of replacing bulks with HTS stacks in this application. In our simulation methodology, the movement between the HTS and the permanent magnet was avoided by restricting the simulation domain to the HTS itself, which can be done by applying appropriate boundary conditions and analytical expressions for the source field. Commercial finite element software was used for the sake of ease of implementation. Simulation results were compared with experimental data, showing good agreement. We conclude that the H-formulation is suitable for problems involving moving objects and is a good alternative to other approaches for simulating superconducting magnetic bearings.

  2. Electrical machines with bulk HTS elements.. The achieved results and future development

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; Koneev, S. M.-A.; Modestov, K. A.; Larionoff, S. A.; Gawalek, W.; Oswald, B.

    2001-09-01

    Novel types of electric HTS motors with the rotor containing bulk YBCO and Bi-Ag elements are presented. Different schematics of hysteresis, reluctance “trapped field” and composed HTS motors are discussed. Two-dimensional mathematical models describing the processes in these types of HTS machines were developed on the basis of a theoretical analysis of the electrodynamic and hysteresis processes in multi-domain and single-domain HTS ceramic samples. The test results of these HTS motors with output power 1-37 kW and current frequencies 50 and 400 Hz are given. The results show that in liquid nitrogen the specific output power per one weight unit is 4-5 times better then for conventional electric machines. The design of a new high power HTS motor operating in the liquid nitrogen with output power 200 kW (and more) is discussed. Future applications of new types of HTS motors for airspace and on-land industry and transport systems are discussed.

  3. Development of Magnet Technologies for HTS Insert Coils

    NASA Astrophysics Data System (ADS)

    Wesche, Rainer; Uglietti, Davide; Bruzzone, Pierluigi; March, Stephen; Marinucci, Claudio; Stepanov, Boris; Glowa, Natalia

    An existing Nb3Sn laboratory magnet generating a magnetic field of 12 T is intended to be upgraded to 16 T by means of the use of a high temperature superconductor (HTS) insert coil. An outline design of the HTS insert coil is presented. In the design, the aspects of the maximum achievable operation current, the required copper cross-section to ensure a hot spot temperature below 200 K and the resulting forces and stresses have been considered. The length of the insert coil has been selected in such a way that the field uniformity will be better than 1% within a sphere of 3 cm diameter. The protection of the whole magnet system (LTS & HTS insert) is briefly described.

  4. HTS power lead testing at the Fermilab magnet test facility

    SciTech Connect

    Rabehl, R.; Carcagno, R.; Feher, S.; Huang, Y.; Orris, D.; Pischalnikov, Y.; Sylvester, C.; Tartaglia, M.; /Fermilab

    2005-08-01

    The Fermilab Magnet Test Facility has tested high-temperature superconductor (HTS) power leads for cryogenic feed boxes to be placed at the Large Hadron Collider (LHC) interaction regions and at the new BTeV C0 interaction region of the Fermilab Tevatron. A new test facility was designed and operated, successfully testing 20 pairs of HTS power leads for the LHC and 2 pairs of HTS power leads for the BTeV experiment. This paper describes the design and operation of the cryogenics, process controls, data acquisition, and quench management systems. Results from the facility commissioning are included, as is the performance of a new insulation method to prevent frost accumulation on the warm ends of the power leads.

  5. Design and optimization of a HTS insert for solenoid magnets

    NASA Astrophysics Data System (ADS)

    Tomassetti, Giordano; de Marzi, Gianluca; Muzzi, Luigi; Celentano, Giuseppe; della Corte, Antonio

    2016-12-01

    With the availability of High-Temperature Superconducting (HTS) prototype cables, based on high-performance REBCO Coated Conductor (CC) tapes, new designs can now be made for large bore high-field inserts in superconducting solenoids, thus extending the magnet operating point to higher magnetic fields. In this work, as an alternative approach to the standard trial-and-error design process, an optimization procedure for a HTS grading section design is proposed, including parametric electro-magnetic and structural analyses, using the ANSYS software coupled with a numerically-efficient optimization algorithm. This HTS grading section is designed to be inserted into a 12 T large bore Low-Temperature Superconducting (LTS) solenoid (diameter about 1 m) to increase the field up to a maximum value of at least 17 T. The optimization variables taken into consideration are the number of turns and layers and the circle-in-square jacket inner diameter in order to minimize the total needed conductor length to achieve a peak field of at least 17 T, while guaranteeing the structural integrity and manufacturing constraints. By means of the optimization, an optimal 360 m total conductor length was found, achieving 17.2 T with an operating current of 22.4 kA and a coil comprised of 18 × 12 turns, shortened of about 20% with respect to the best initial candidate architectural design. The optimal HTS insert has a bore compatible with manufacturing constraints (inner bore radius larger than 30 cm). A scaled HTS insert for validation purposes, with a reduced conductor length, to be tested in an advanced experimental facility currently under construction, is also mentioned.

  6. Development of Prototype HTS Components for Magnetic Suspension Applications

    NASA Technical Reports Server (NTRS)

    Haldar, P.; Hoehn, J., Jr.; Selvamanickam, V.; Farrell, R. A.; Balachandran, U.; Iyer, A. N.; Peterson, E.; Salazar, K.

    1996-01-01

    We have concentrated on developing prototype lengths of bismuth and thallium based silver sheathed superconductors by the powder-in-tube approach to fabricate high temperature superconducting (HTS) components for magnetic suspension applications. Long lengths of mono and multi filament tapes are presently being fabricated with critical current densities useful for maglev and many other applications. We have recently demonstrated the prototype manufacture of lengths exceeding 1 km of Bi-2223 multi filament conductor. Long lengths of thallium based multi-filament conductor have also been fabricated with practical levels of critical current density and improved field dependence behavior. Test coils and magnets have been built from these lengths and characterized over a range of temperatures and background fields to determine their performance. Work is in progress to develop, fabricate and test HTS windings that will be suitable for magnetic suspension, levitation and other electric power related applications.

  7. TEST RESULTS OF HTS COILS AND AN R AND D MAGNET FOR RIA.

    SciTech Connect

    GUPTA, R.; ANERELLA, M.; HARRISON, M.; SCHMALZLE, J.; SAMPSON, W.; ZELLER, A.

    2005-05-16

    This paper presents the successful construction and test results of a magnetic mirror model for the Rare Isotope Accelerator (RIA) that is based on High Temperature Superconductors (HTS). In addition, the performance of thirteen coils (each made with {approx}220 meters of commercially available HTS tape) is also presented. The proposed HTS magnet is a crucial part of the R&D for the Fragment Separator region where the magnets are subjected to several orders of magnitude more radiation and energy deposition than typical beam line and accelerator magnets receive during their entire lifetime. A preliminary design of an HTS dipole magnet for the Fragment Separator region is also presented.

  8. HTS Magnets for Advanced Magnetoplasma Space Propulsion Applications

    SciTech Connect

    Carte, M.D.; Chang-Diaz, F.R. Squire, J.P.; Schwenterly, S.W.

    1999-07-12

    Plasma rockets are being considered for both Earth-orbit and interplanetary missions because their extremely high exhaust velocity and ability to modulate thrust allow very efficient use of propellant mass. In such rockets, a hydrogen or helium plasma is RF-heated and confined by axial magnetic fields produced by coils around the plasma chamber. HTS coils cooled by the propellant are desirable to increase the energy efficiency of the system. We describe a set of prototype high-temperature superconducting (HTS) coils that are being considered for the VASIMR ( Variable Specific Impulse Magnetoplasma Rocket) thruster proposed for testing on the Radiation Technology Demonstration (RTD) satellite. Since this satellite will be launched by the Space Shuttle, for safety reasons liquid helium will be used as propellant and coolant. The coils must be designed to operate in the space environment at field levels of 1 T. This generates a unique set of requirements. Details of the overall winding geometry and current density, as well as the challenging thermal control aspects associated with a compact, minimum weight design will be discussed.

  9. Reduction of Thermal Loss in HTS Windings by Using Magnetic Flux Deflection

    NASA Astrophysics Data System (ADS)

    Tsuzuki, K.; Miki, M.; Felder, B.; Koshiba, Y.; Izumi, M.; Umemoto, K.; Aizawa, K.; Yanamoto, T.

    Efforts on the generation of intensified magnetic flux have been made for the optimized shape of HTS winding applications. This contributes to the high efficiency of the rotating machines using HTS windings. Heat generation from the HTS windings requires to be suppressed as much as possible, when those coils are under operation with either direct or alternative currents. Presently, the reduction of such thermal loss generated by the applied currents on the HTS coils is reported with a magnetic flux deflection system. The HTS coils are fixed together with flattened magnetic materials to realize a kind of redirection of the flux pathway. Eventually, the magnetic flux density perpendicular to the tape surface (equivalent to the a-b plane) of the HTS tape materials is reduced to the proximity of the HTS coil. To verify the new geometry of the surroundings of the HTS coils with magnetic materials, a comparative study of the DC coil voltage was done for different applied currents in prototype field-pole coils of a ship propulsion motor.

  10. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    NASA Astrophysics Data System (ADS)

    Huang, Zhen; Ruiz, H. S.; Coombs, T. A.

    2017-03-01

    High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied under the same experimental conditions, what results in about three times larger magnetic pole areas but with an average drop on the peaks of trapped magnetic field of about 50%.

  11. Development of high sensitive magnetic contaminant detection system using an HTS-rf-SQUID covered with HTS thin films

    NASA Astrophysics Data System (ADS)

    Hatsukade, Y.; Kurosawa, R.; Uchida, Y.; Tanaka, S.

    2012-03-01

    For high sensitive detection of magnetic contaminant in electrode of lithium-ion battery, high-temperature superconductor (HTS) radio-frequency (rf) superconducting quantum interference devices (SQUIDs) based on a bicrystal SrTiO3 (STO) substrate was designed, and fabricated employing YBa2Cu3O7-x thin films of about 200 nm in thickness. To improve characteristics such as effective area and 1/f noise profile of the SQUID, HTS thin films on normal STO substrates were overlapped on a wide superconducting weak link and/or a slit of the SQUID in flip-chip configuration. The noise profiles of the SQUID covered with the films on the respective positions were well improved compared to that of the bare SQUID. A magnetic contaminant detection system was developed employing the HTS-rf-SQUID covered with the films on both the positions. Using this system, a tungsten ball of 30 μm in diameter was successfully detected with a signal to noise ratio of about 14.

  12. Applications of bulk high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Hull, J. R.

    The development of high-temperature superconductors (HTS's) can be broadly generalized into thin-film electronics, wire applications, and bulk applications. We consider bulk HTS's to include sintered or crystallized forms that do not take the geometry of filaments or tapes, and we discuss major applications for these materials. For the most part applications may be realized with the HTS's cooled to 77 K, and the properties of the bulk HTS's are often already sufficient for commercial use. A non-exhaustive list of applications for bulk HTS's includes trapped field magnets, hysteresis motors, magnetic shielding, current leads, and magnetic bearings. These applications are briefly discussed in this paper.

  13. Fabrication and test of an axial-field HTS rotating machine with integrated magnetic coupling

    NASA Astrophysics Data System (ADS)

    Dolisy, B.; Mezani, S.; Lubin, T.; Lévêque, J.

    2017-03-01

    High temperature superconducting (HTS) electrical machines have high torque density with a very high efficiency. Torque tubes are usually used to transmit the torque from the cold to the warm environment which results in thermal losses and mechanical problems. To overcome these difficulties, we propose to transmit the torque of the HTS machine through an integrated HTS magnetic coupling. A prototype has been constructed and tested showing the effectiveness of the proposed solution. The machine and the coupling share the same HTS rotor while the torque produced by the machine is transmitted to the load via a permanent magnets rotor. This solution allows the reduction of the thermal losses and a natural protection against overload during fault. The electromagnetic design is carried out using 3D finite elements (FE). The HTS material electrical behavior is described using a power law so it was possible to determine the operating current of the HTS coils of the device. Many test results such as U(I) curves of the HTS coils, static torque, back-EMF and on-load characteristics are presented and checked by the FE computations.

  14. The Effect of Magnetic Field on HTS Leads What Happens when thePower Fails at RAL?

    SciTech Connect

    Green, Michael A.

    2007-02-14

    The key to being able to operate the MICE superconducting solenoids on small coolers is the use of high temperature superconducting (HTS) leads between the first stage of the cooler and the magnet, which operates at around 4.2 K. Because MICE magnets are not shielded, all of the MICE magnets have a stray magnetic field in the region where the coolers and the HTS leads are located. The behavior of the HTS leads in a magnetic field depends strongly on the HTS material used for the leads and the temperature of the cooler first stage temperature. The HTS leads can be specified to operate at the maximum current for the magnet. This report shows how the HTS leads can be specified for use the MICE magnets. MICE magnets take from 1.3 hours (the tracker solenoids) to 3.7 hours (the coupling magnet) to charge to the highest projected operating currents. If the power fails, the cooler and the upper ends of the HTS leads warm up. The question is how one can discharge the magnet to protect the HTS leads without quenching the MICE magnets. This report describes a method that one can use to protect the HTS leads in the event of a power failure at the Rutherford Appleton Laboratory (RAL).

  15. Design considerations and experimental results for MRI systems using HTS magnets

    NASA Astrophysics Data System (ADS)

    Parkinson, Ben

    2017-01-01

    An increasing number of magnetic resonance imaging (MRI) systems using high temperature superconductors (HTS) magnets have been designed and constructed, with detailed results of their performance now available. Features of REBCO and BSCCO conductors are described as they pertain to use in high homogeneity magnets, with emphasis placed on the practical use of these conductors in magnets. Methods of coil winding are discussed, in particular the differences between pancake and layer winding techniques. Design considerations for HTS magnets are presented in light of the difficulties presented by quench in these magnets, but also in terms of the features of HTS magnets afforded by their high operating temperatures, namely robust cryogen free operation and the potential to use unshielded gradient coils. Drawing on two example MRI systems, namely a 3 T BSCCO brain imaging magnet developed in Japan and a 1.5 T REBCO orthopaedic imaging system developed in New Zealand, the report details real-world stability and homogeneity of HTS-MRI systems, in particular with regards to the screening current effects observed in these systems. It is concluded that, apart from conductor cost, there are currently no technical obstacles to use of HTS-MRI systems.

  16. Influence of critical current density on magnetic force of HTSC bulk above PMR with 3D-modeling numerical solutions

    NASA Astrophysics Data System (ADS)

    Lu, Yiyun; Qin, Yujie

    2015-09-01

    Numerical simulations of thermo-electromagnetic properties of a high temperature superconducting (HTS) bulk levitating over a permanent magnetic guideway (PMG) are performed by resorting to the quasistatic approximation of the H-method coupling with the classical description of the heat conduction equation. The numerical resolving codes are practiced with the help of the finite element program generation system (FEPG) platform using finite element method (FEM). The E-J power law is used to describe the electric current nonlinear characteristics of HTS bulk. The simulation results show that the heat conduction and the critical current density are tightly relative to the thermal effects of the HTS bulk over the PMG. The heat intensity which responds to the heat loss of the HTS bulk is mainly distributed at the two bottom-corners of the bulk sample.

  17. Permanent magnet with MgB{sub 2} bulk superconductor

    SciTech Connect

    Yamamoto, Akiyasu; Ishihara, Atsushi; Tomita, Masaru; Kishio, Kohji

    2014-07-21

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB{sub 2}) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB{sub 2} permanent bulk magnet was determined. Because MgB{sub 2} is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB{sub 2} bulks promising for the next generation of Tesla-class permanent-magnet applications.

  18. Development of superconducting magnetic bearing using superconducting coil and bulk superconductor

    NASA Astrophysics Data System (ADS)

    Seino, H.; Nagashima, K.; Arai, Y.

    2008-02-01

    The authors conducted a study on superconducting magnetic bearing, which consists of superconducting rotor and stator to apply the flywheel energy-storage system for railways. In this study, high temperature bulk superconductor (HTS bulk) was combined with superconducting coils to increase the load capacity of the bearing. In the first step of the study, the thrust rolling bearing was selected for application by using liquid nitrogen cooled HTS bulk. 60mm-diameter HTS bulks and superconducting coil which generated a high gradient of magnetic field by cusp field were adopted as a rotor and a stator for superconducting magnetic bearing, respectively. The results of the static load test and the rotation test, creep of the electromagnetic forces caused by static flux penetration and AC loss due to eccentric rotation were decreased to the level without any problems in substantial use by using two HTS bulks. In the result of verification of static load capacity, levitation force (thrust load) of 8900N or more was supportable, and stable static load capacity was obtainable when weight of 460kg was levitated.

  19. Numerical investigations on applicability of permanent magnet method to crack detection in HTS film

    NASA Astrophysics Data System (ADS)

    Kamitani, A.; Takayama, T.; Saitoh, A.

    2014-09-01

    The scanning permanent-magnet (PM) method was originally developed for determining the spatial distribution of the critical current density in a high-temperature superconducting (HTS) film. In the present study, its applicability to the crack detection in an HTS film is investigated numerically. To this end, a defect parameter is defined for characterizing a crack position and it is calculated along various scanning lines. The results of computations show that, only when the scanning position is near a crack, the defect parameter shows a violent change. On the basis of the behavior of the defect parameter, the method for roughly identifying a crack is also proposed.

  20. Design, fabrication and testing of a dipole magnet made with 2G HTS wire

    NASA Astrophysics Data System (ADS)

    Bogdanov, I. V.; Kozub, S. S.; Sytnik, V. V.; Terskiy, I. S.; Tkachenko, L. M.; Trusov, O. V.; Shirshov, L. S.; Smirnov, V. M.; Shuvalov, V. I.; Shcherbakov, P. A.; Molodyk, A. A.; Lee, S. R.; Samoilenkov, S. V.

    2016-10-01

    An HTS dipole magnet with a 1 T (at 77 K) central magnetic field in a 40 × 80 mm2 aperture has been designed, fabricated and tested. The magnet coils were wound with SuperOx 2G HTS wire. The paper describes the magnet design, properties of the magnet materials, and results of calculations and measurements. The central field in the dipole reached 1.12 T at 77 K and 1.66 T at 65 K. In a liquid helium bath the maximum input current of 847 A was limited by the capacity of the power supply, and in that case the central field was 3.03 T. The measurement data were in good agreement with the calculation results.

  1. Magnetic Signals of High-Temperature Superconductor Bulk During the Levitation Force Measurement Process

    NASA Astrophysics Data System (ADS)

    Huang, Huan; Zheng, Jun; Qian, Nan; Che, Tong; Zheng, Botian; Jin, Liwei; Deng, Zigang

    2017-02-01

    In order to study the commonly neglected magnetic field information in the course of levitation force measurement process in a superconducting maglev system, a multipoint magnetic field measurement platform was employed to acquire magnetic signals of a bulk high-Tc superconductor on both the top and the bottom surface. Working conditions including field cooling (FC) and zero field cooling were investigated for these vertical down and up motions above a permanent magnet guideway performed on a HTS maglev measurement system. We have discussed the magnetic flux variation process based on the Bean model. A magnetic hysteresis effect similar to the levitation force hysteresis loop of the bulk superconductor was displayed and analyzed in this paper. What is more valuable, there exists some available magnetic flux on the top surface of the bulk superconductor, and the proportion is as high as 62.42% in the FC condition, which provides an experimental hint to design the superconductor bulk and the applied field for practical use in a more efficient way. In particular, this work reveals real-time magnetic flux variation of the bulk superconductor in the levitation application, which is the other important information in contrast to the macroscopic levitation and guidance force investigations in previous studies, and it enriches the existing research methods. The results are significant for understanding the magnetic characteristic of superconductors, and they can contribute to optimize the present HTS maglev system design.

  2. Cost Effective Open Geometry HTS MRI System amended to BSCCO 2212 Wire for High Field Magnets

    SciTech Connect

    Kennth Marken

    2006-08-11

    The original goal of this Phase II Superconductivity Partnership Initiative project was to build and operate a prototype Magnetic Resonance Imaging (MRI) system using high temperature superconductor (HTS) coils wound from continuously processed dip-coated BSCCO 2212 tape conductor. Using dip-coated tape, the plan was for MRI magnet coils to be wound to fit an established commercial open geometry, 0.2 Tesla permanent magnet system. New electronics and imaging software for a prototype higher field superconducting system would have added significantly to the cost. However, the use of the 0.2 T platform would allow the technical feasibility and the cost issues for HTS systems to be fully established. Also it would establish the energy efficiency and savings of HTS open MRI compared with resistive and permanent magnet systems. The commercial goal was an open geometry HTS MRI running at 0.5 T and 20 K. This low field open magnet was using resistive normal metal conductor and its heat loss was rather high around 15 kolwatts. It was expected that an HTS magnet would dissipate around 1 watt, significantly reduce power consumption. The SPI team assembled to achieve this goal was led by Oxford Instruments, Superconducting Technology (OST), who developed the method of producing commercial dip coated tape. Superconductive Components Inc. (SCI), a leading US supplier of HTS powders, supported the conductor optimization through powder optimization, scaling, and cost reduction. Oxford Magnet Technology (OMT), a joint venture between Oxford Instruments and Siemens and the world’s leading supplier of MRI magnet systems, was involved to design and build the HTS MRI magnet and cryogenics. Siemens Magnetic Resonance Division, a leading developer and supplier of complete MRI imaging systems, was expected to integrate the final system and perform imaging trials. The original MRI demonstration project was ended in July 2004 by mutual consent of Oxford Instruments and Siemens. Between

  3. Magnet design with 100-kA HTS STARS conductors for the helical fusion reactor

    NASA Astrophysics Data System (ADS)

    Yanagi, N.; Terazaki, Y.; Ito, S.; Tamura, H.; Hamaguchi, S.; Mito, T.; Hashizume, H.; Sagara, A.

    2016-12-01

    The high-temperature superconducting (HTS) option is employed for the conceptual design of the LHD-type helical fusion reactor FFHR-d1. The 100-kA-class STARS (Stacked Tapes Assembled in Rigid Structure) conductor is used for the magnet system including the continuously wound helical coils. Protection of the magnet system in case of a quench is a crucial issue and the hot-spot temperature during an emergency discharge is estimated based on the zero-dimensional and one-dimensional analyses. The number of division of the coil winding package is examined to limit the voltage generation. For cooling the HTS magnet, helium gas flow is considered and its feasibility is examined by simple analysis as a first step.

  4. Influence of lateral displacement on the levitation performance of a magnetized bulk high-Tc superconductor magnet

    NASA Astrophysics Data System (ADS)

    Liu, W.; Wang, J. S.; Ma, G. T.; Zheng, J.; Tuo, X. G.; Li, L. L.; Ye, C. Q.; Liao, X. L.; Wang, S. Y.

    2012-03-01

    Compared with the permanent magnet, the magnetized bulk high-Tc superconductor magnet (MBSCM) can trap higher magnetic field due to its strong flux pinning ability, so it is a good candidate to improve the levitation performance of high-Tc superconductive (HTS) maglev system. The trapped magnetic flux of a MBSCM is sustained by the inductive superconducting current produced by the magnetizing process and is susceptible to the current intensity as well as configuration. In the HTS maglev system, the lateral displacement is an important process to change the superconducting current within a MBSCM and then affects its levitation performance, which is essential for the traffic ability in curve-way, the loading capacity of lateral impact and so on. The research about influence of lateral displacement on the levitation performance of MBSCM is necessary when MBSCM is applied on the HTS maglev vehicle. The experimental investigations about the influence of lateral displacement on the levitation performance of a MBSCM with different trapped fluxes and applied fields are processed in this article. The analyses and conclusions of this article are useful for the practical application of MBSCM in HTS maglev system.

  5. AC loss evaluation of an HTS insert for high field magnet cooled by cryocoolers

    NASA Astrophysics Data System (ADS)

    Kajikawa, Kazuhiro; Awaji, Satoshi; Watanabe, Kazuo

    2016-12-01

    AC losses in a high temperature superconducting (HTS) insert coil for 25-T cryogen-free superconducting magnet during its initial energization are numerically calculated under the assumption of slab approximation. The HTS insert consisting of 68 single pancakes wound using coated conductors generates a central magnetic field of 11.5 T in addition to the contribution of 14.0 T from a set of low temperature superconducting (LTS) outsert coils. Both the HTS insert and the LTS coils are cooled using cryocoolers, and energized simultaneously up to the central field of 25.5 T with a constant ramp rate for 60 min. The influences of the magnitudes and orientations of locally applied magnetic fields, magnetic interactions between turns and transport currents flowing in the windings are taken into account in the calculations of AC losses. The locally applied fields are separated into axial and radial components, and the individual contributions of these field components to the AC losses are simply summed up to obtain the total losses. The AC losses due to the axial fields become major in the beginning of energization, whereas the total losses monotonically increase with time after the AC losses due to the radial fields become major.

  6. A Test of HTS Power Cable in a Sweeping Magnetic Field

    SciTech Connect

    Piekarz, H.; Hays, S.; Blowers, J.; Shiltsev, V.; /Fermilab

    2011-11-29

    Short sample HTS power cable composed of multiple 344C-2G strands and designed to energize a fast-cycling dipole magnet was exposed to a sweeping magnetic field in the (2-20) T/s ramping rate. The B-field orientation toward the HTS strands wide surface was varied from 0{sup 0} to 10{sup 0}, in steps of 1{sup 0}. The test arrangement allowed measurement of the combined hysteresis and eddy current power losses. For the validity of these measurements, the power losses of a short sample cable composed of multiple LTS wire strands were also performed to compare with the known data. The test arrangement of the power cable is described, and the test results are compared with the projections for the eddy and hysteresis power losses using the fine details of the test cable structures.

  7. Improvement of sensitivity of multisample biological immunoassay system using HTS SQUID and magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Tsukamoto, A.; Saitoh, K.; Sugita, N.; Kuma, H.; Sugiura, Y.; Hamaoka, S.; Hamasaki, N.; Enpuku, K.

    2006-10-01

    Recently, we have developed a prototype magnetic immunoassay system using a high temperature superconductor (HTS) superconducting quantum interference device (SQUID) to investigate the performance and usability of the magnetic immunoassay. In this study, we improved the immunoassay system to heighten the sensitivity of the immunoassay measurement. To reduce the SQUID-to-sample distance, we introduced a structure to compensate for thermal shrinkage in the cryostat and reduce the warpage of the window. The shape of pickup coil was also optimized to improve the field sensitivity. After these improvements, the magnetic signal intensity from Fe3O4 nanoparticles became about two times stronger than that achieved by our original system.

  8. An active homopolar magnetic bearing with high temperature superconductor (HTS) coils and ferromagnetic cores

    NASA Astrophysics Data System (ADS)

    Brown, G. V.; Dirusso, E.; Provenza, A. J.

    1995-08-01

    A proof-of-feasibility demonstration showed that high temperature superconductor (HTS) coils can be used in a high-load, active magnetic bearing in liquid nitrogen. A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 200 lb (890 N) radial load capacity (measured non-rotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that in Cu in liquid nitrogen. Design compromises permitted use of circular coils with rectangular cross section. Conductor improvements will eventually permit coil shape optimization, higher current density and higher bearing load capacity. The bias coil, wound with non-twisted, multifilament HTS conductor, required negligible power to carry its direct current. The control coils were wound with monofilament HTS sheathed in Ag. These dissipated negligible power for direct current (i.e. for steady radial load components). When an alternating current (AC) was added, the AC component dissipated power which increased rapidly with frequency and quadratically with AC amplitude. In fact at frequencies above about 2 hz, the effective resistance of the control coil conductor actually exceeds that of the silver which is in electrical parallel with the oxide superconductor. This is at least qualitatively understandable in the context of a Bean-type model of flux and current penetration into a Type II superconductor. Fortunately the dynamic currents required for bearing stability are of small amplitude. These results show that while twisted multifilament conductor is not needed for stable levitation, twisted multifilaments will be required to reduce control power for sizable dynamic loads, such as those due to unbalance.

  9. An active homopolar magnetic bearing with high temperature superconductor (HTS) coils and ferromagnetic cores

    NASA Technical Reports Server (NTRS)

    Brown, G. V.; Dirusso, E.; Provenza, A. J.

    1995-01-01

    A proof-of-feasibility demonstration showed that high temperature superconductor (HTS) coils can be used in a high-load, active magnetic bearing in liquid nitrogen. A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 200 lb (890 N) radial load capacity (measured non-rotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that in Cu in liquid nitrogen. Design compromises permitted use of circular coils with rectangular cross section. Conductor improvements will eventually permit coil shape optimization, higher current density and higher bearing load capacity. The bias coil, wound with non-twisted, multifilament HTS conductor, required negligible power to carry its direct current. The control coils were wound with monofilament HTS sheathed in Ag. These dissipated negligible power for direct current (i.e. for steady radial load components). When an alternating current (AC) was added, the AC component dissipated power which increased rapidly with frequency and quadratically with AC amplitude. In fact at frequencies above about 2 hz, the effective resistance of the control coil conductor actually exceeds that of the silver which is in electrical parallel with the oxide superconductor. This is at least qualitatively understandable in the context of a Bean-type model of flux and current penetration into a Type II superconductor. Fortunately the dynamic currents required for bearing stability are of small amplitude. These results show that while twisted multifilament conductor is not needed for stable levitation, twisted multifilaments will be required to reduce control power for sizable dynamic loads, such as those due to unbalance.

  10. Recent developments in processing HTS silver-clad Bi-2223 tapes, coils and test magnets

    SciTech Connect

    Haldar, P.; Hoehn, J.G. Jr.; Motowidlo, L.R.; Balachandran, U.; Iwasa, Y.; Yunus, M.

    1993-10-01

    Considerable progress has been made in fabricating Bi-2223 high temperature superconductor (HTS) wires and tapes with high critical current densities that are attractive for electric power and high-field magnet applications. Powder-in-tube processed silver-clad Bi-2223 short tape samples, small coils and test magnets have been fabricated and measured at liquid nitrogen (77K), pumped liquid nitrogen (64 K), liquid neon (27K) and liquid helium (4.2K) temperatures. Optimization of thermo-mechanical process parameters have yielded J{sub c}`s in the superconducting core > 4.0 {times} 10{sup 4} A/cm{sup 2} at 77K zero field and > 2.0 {times} 10{sup 5} A/cm{sup 2} at 4.2K, zero field. Long lengths (up to 70 m) of mono-core conductors were fabricated and tested to carry significant amounts of current (23 A, {approximately}15,000 A/cm{sup 2}) at liquid nitrogen temperature. Recent test magnets assembled from pancake wound coils were measured to generate magnetic fields as high as 2.6, 1.8 and 0.36 Tesla at 4.2K, 27K and 77K respectively. These results show promise towards practical utilization of HTS materials.

  11. Development of a Flat-plate Cryogenic Oscillating Heat Pipe for Improving HTS Magnet Cooling

    NASA Astrophysics Data System (ADS)

    Natsume, K.; Mito, T.; Yanagi, N.; Tamura, H.

    A new method of including cryogenic oscillating heat pipes (OHPs) in the HTS coil windings as a thermal transport device has been studied. In this work, two type of OHPs are tested in low temperature. Employed working fluids are H2, Ne, N2. We have attained high performance thermal property using a bent-pipe cryogenic OHP as a prototype. Obtained effective conductivities have reached to 46000 W/m K. Then a flat-plate cryogenic OHP has been developed, that is suitable for imbedding in magnet windings. Preliminary experiments have been conducted and the result has been promising.

  12. Comprehensive comparison of the levitation performance of bulk YBaCuO arrays above two different types of magnetic guideways

    NASA Astrophysics Data System (ADS)

    Deng, Zigang; Qian, Nan; Che, Tong; Jin, Liwei; Si, Shuaishuai; Zhang, Ya; Zheng, Jun

    2016-12-01

    The permanent magnet guideway (PMG) is an important part of high temperature superconducting (HTS) maglev systems. So far, two types of PMG, the normal PMG and Halbach-type PMG, are widely applied in present maglev transportation systems. In this paper, the levitation performance of high temperature superconductor bulks above the two PMGs was synthetically compared. Both static levitation performance and dynamic response characteristics were investigated. Benefiting from the reasonable magnetic field distribution, the Halbach-type PMG is able to gain larger levitation force, greater levitation force decay during the same relaxation time, bigger resonance frequency and dynamic stiffness for the bulk superconductor levitation unit compared with the normal PMG. Another finding is that the Halbach-type PMG is not sensitive to the levitation performance of the bulk levitation unit with different arrays. These results are helpful for the practical application of HTS maglev systems.

  13. 250 kW flywheel with HTS magnetic bearing for industrial use

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Floegel-Delor, U.; Riedel, T.; Rothfeld, R.; Wippich, D.; Goebel, B.; Reiner, G.; Wehlau, N.

    2008-02-01

    A 250 kW / 5 kWh engineering prototype Flywheel Energy Storage System (FESS) was designed, fabricated and component tested by Adelwitz Technologiezentrum GmbH (ATZ) and L-3 Communications Magnet - Motor GmbH (MM). A heavy - load vertical 0.6 ton rotor is suspended totally magnetically by an HTS radial-passive bearing on the top together with a PM bearing at the bottom. Further features are the flywheel rotor body which is manufactured from carbon fibre reinforced plastics (CFRP) in a multi-rim version and combined with an integrated high-power motor/generator. A 35 W/77 K single- stage Gifford McMahon cryo-cooler is cooling the HTS bearing to a temperature of 45 - 60 K. Functionality and efficiency of the magnetic bearing configurations, rotor control concepts and motor / generator power electric system is considered and established. Bearing stiffness parameters, damping performance, and rotational friction are measured. Testing of further components under vacuum conditions confirmed that low bearing drag and wear- free operation can be attained. The motor-generator operates with a power in excess of 250 kW and an efficiency of > 92%, including the losses of the inverters. A redundant mechanical touchdown bearing system can be activated to restore the rotor position. The separately tested flywheel components are now in the assembling status expecting first machine tests in November 2007. After studying and measuring all FESS parameters in -house the dynamical storage device will be tested in a German E.ON power station under industrial conditions.

  14. Current Bypassing Properties by Thermal Switch for PCS Application on NMR/MRI HTS Magnets

    NASA Astrophysics Data System (ADS)

    Kim, S. B.; Takahashi, M.; Saito, R.; Park, Y. J.; Lee, M. W.; Oh, Y. K.; Ann, H. S.

    We develop the compact NMR/MRI device using high temperature superconducting (HTS) wires with the persistent current mode operating. So, the joint techniques between 2G wires are very important issue and many studies have been carried out. Recently, the Kbigdot JOINS, Inc. has developed successfully the high performance superconducting joints between 2G wires by partial melting diffusion and oxygenation annealing process [1]. In this study, the current bypassing properties in a loop-shaped 2G wire are measured experimentally to develop the permanent current switch (PSC). The current bypassing properties of loop-shaped test coil wound with 2G wire (GdBCO) are evaluated by measured the self-magnetic field due to bypassed current by Hall sensors. The strain gauge was used as heater for persistent current switch, and thermal properties against various thermal inputs were investigated experimentally.

  15. Influence of current ramp rate on voltage current measurement of a conduction-cooled HTS magnet

    NASA Astrophysics Data System (ADS)

    Hiltunen, I.; Korpela, A.; Lehtonen, J.; Mikkonen, R.

    2008-06-01

    High-temperature superconductors (HTS) have notably different voltage current characteristic compared to the low-temperature superconductors (LTS). Due to the anisotropy and slanted electric field - current density characteristics the loss of stability in a Bi-2223/Ag magnet is viewed as a global temperature increase inside the coil rather than a local normal zone. Therefore, the quench current depends strongly on the cooling conditions. In this paper a finite element method based analysis method is presented and example runs are carried out in order to explain in detail the influence of the current ramp rate and cooling on the voltage current characteristics of a conduction-cooled Bi-2223/Ag coil at 20 and 45 K. The results show that in certain operation conditions the coil critical current has a maximum value with respect to the ramp rate used in the measurements.

  16. Tailoring Magnetic Properties in Bulk Nanostructured Solids

    NASA Astrophysics Data System (ADS)

    Morales, Jason Rolando

    Important magnetic properties and behaviors such as coercivity, remanence, susceptibility, energy product, and exchange coupling can be tailored by controlling the grain size, composition, and density of bulk magnetic materials. At nanometric length scales the grain size plays an increasingly important role since magnetic domain behavior and grain boundary concentration determine bulk magnetic behavior. This has spurred a significant amount of work devoted to developing magnetic materials with nanometric features (thickness, grain/crystallite size, inclusions or shells) in 0D (powder), 1D (wires), and 2D (thin films) materials. Large 3D nanocrystalline materials are more suitable for many applications such as permanent magnets, magneto-optical Faraday isolators etc. Yet there are relatively few successful demonstrations of 3D magnetic materials with nanoscale influenced properties available in the literature. Making dense 3D bulk materials with magnetic nanocrystalline microstructures is a challenge because many traditional densification techniques (HIP, pressureless sintering, etc.) move the microstructure out of the "nano" regime during densification. This dissertation shows that the Current Activated Pressure Assisted Densification (CAPAD) method, also known as spark plasma sintering, can be used to create dense, bulk, magnetic, nanocrystalline solids with varied compositions suited to fit many applications. The results of my research will first show important implications for the use of CAPAD for the production of exchange-coupled nanocomposite magnets. Decreases in grain size were shown to have a significant role in increasing the magnitude of exchange bias. Second, preferentially ordered bulk magnetic materials were produced with highly anisotropic material properties. The ordered microstructure resulted in changing magnetic property magnitudes (ex. change in coercivity by almost 10x) depending on the relative orientation (0° vs. 90°) of an externally

  17. Magnetic characterisation of large grain, bulk Y-Ba-Cu-O superconductor-soft ferromagnetic alloy hybrid structures

    NASA Astrophysics Data System (ADS)

    Philippe, M. P.; Fagnard, J.-F.; Kirsch, S.; Xu, Z.; Dennis, A. R.; Shi, Y.-H.; Cardwell, D. A.; Vanderheyden, B.; Vanderbemden, P.

    2014-07-01

    Large grain, bulk Y-Ba-Cu-O (YBCO) high temperature superconductors (HTS) have significant potential for use in a variety of practical applications that incorporate powerful quasi-permanent magnets. In the present work, we investigate how the trapped field of such magnets can be improved by combining bulk YBCO with a soft FeNi, ferromagnetic alloy. This involves machining the alloy into components of various shapes, such as cylinders and rings, which are attached subsequently to the top surface of a solid, bulk HTS cylinder. The effect of these modifications on the magnetic hysteresis curve and trapped field of the bulk superconductor at 77 K are then studied using pick-up coil and Hall probe measurements. The experimental data are compared to finite element modelling of the magnetic flux distribution using Campbell’s algorithm. Initially we establish the validity of the technique involving pick-up coils wrapped around the bulk superconductor to obtain its magnetic hysteresis curve in a non-destructive way and highlight the difference between the measured signal and the true magnetization of the sample. We then consider the properties of hybrid ferromagnet/superconductor (F/S) structures. Hall probe measurements, together with the results of the model, establish that flux lines curve outwards through the ferromagnet, which acts, effectively, like a magnetic short circuit. Magnetic hysteresis curves show that the effects of the superconductor and the ferromagnet simply add when the ferromagnet is saturated fully by the applied field. The trapped field of the hybrid structure is always larger than that of the superconductor alone below this saturation level, and especially when the applied field is removed. The results of the study show further that the beneficial effects on the trapped field are enhanced when the ferromagnet covers the entire surface of the superconductor for different ferromagnetic components of various shapes and fixed volume.

  18. High-throughput screening by Nuclear Magnetic Resonance (HTS by NMR) for the identification of PPIs antagonists

    PubMed Central

    Wu, Bainan; Barile, Elisa; De, Surya K.; Wei, Jun; Purves, Angela; Pellecchia, Maurizio

    2015-01-01

    In recent years the ever so complex field of drug discovery has embraced novel design strategies based on biophysical fragment screening (fragment-based drug design; FBDD) using nuclear magnetic resonance spectroscopy (NMR) and/or structure-guided approaches, most often using X-ray crystallography and computer modeling. Experience from recent years unveiled that these methods are more effective and less prone to artifacts compared to biochemical high-throughput screening (HTS) of large collection of compounds in designing protein inhibitors. Hence these strategies are increasingly becoming the most utilized in the modern pharmaceutical industry. Nonetheless, there is still an impending need to develop innovative and effective strategies to tackle other more challenging targets such as those involving protein-protein interactions (PPIs). While HTS strategies notoriously fail to identify viable hits against such targets, few successful examples of PPIs antagonists derived by FBDD strategies exist. Recently, we reported on a new strategy that combines some of the basic principles of fragment-based screening with combinatorial chemistry and NMR-based screening. The approach, termed HTS by NMR, combines the advantages of combinatorial chemistry and NMR-based screening to rapidly and unambiguously identify bona fide inhibitors of PPIs. This review will reiterate the critical aspects of the approach with examples of possible applications. PMID:25986689

  19. Current distribution evaluation of dye-sensitized solar cell using HTS-SQUID-based magnetic measurement system

    NASA Astrophysics Data System (ADS)

    Sakai, Kenji; Tanaka, Kohei; Kiwa, Toshihiko; Tsukada, Keiji

    2016-11-01

    The current flowing inside a dye-sensitized solar cell (DSSC) was measured using a high-temperature superconductor superconducting quantum interference device (HTS-SQUID)-based magnetic measurement system. Further, a new evaluation method of the DSSC, which is difficult to measure using the conventional method, was investigated to improve the characteristics of the DSSC. The tangential components of the magnetic field generated from the DSSC were measured using two HTS-SQUIDs, and the intensity and direction related to the electrical current were obtained by the measured magnetic field. The DSSCs prepared with different dyes and catalytic substances showed different current-intensity mapping. The current direction was different for the DSSC with low performance. In addition, the current flowing in the ITO layer of the ITO glass substrate was also measured and the results confirmed that it had uniform distribution. These results show that the current mapping and the direction of the electrical current depend on the internal factors of the DSSC, and the detection of the magnetic field distribution generated from it is expected to lead to its new evaluation method.

  20. Static and dynamic stability of the guidance force in a side-suspended HTS maglev system

    NASA Astrophysics Data System (ADS)

    Zhou, Dajin; Cui, Chenyu; Zhao, Lifeng; Zhang, Yong; Wang, Xiqing; Zhao, Yong

    2017-02-01

    The static and dynamic stability of the guidance force in a side-suspended HTS-PMG (permanent magnetic guideway) system were studied theoretically and experimentally. It is found that there are two types of guidance force that exist in the HTS-PMG system, which are sensitive to the levitation gap and the arrangement of YBCO bulks around the central axis of the PMG. An optimized YBCO array was used to stabilize the system, which enabled a side-suspended HTS-PMG maglev vehicle to run stably at 102 km h-1 on a circular test track with 6.5 m in diameter.

  1. Dependences of microwave surface resistance of HTS thin films on applied dc magnetic fields parallel and normal to the substrate

    NASA Astrophysics Data System (ADS)

    Sato, K.; Sato, S.; Ichikawa, K.; Watanabe, M.; Honma, T.; Tanaka, Y.; Oikawa, S.; Saito, A.; Ohshima, S.

    2014-05-01

    We investigated the dc magnetic field and temperature dependences of microwave surface resistance (Rs) of high-temperature superconductor (HTS) films. Previously, we reported that the surface resistance RsRs(n) under a dc magnetic field applied normaly to the substrate increased when increasing the applied magnetic field. For NMR application, we have to examine the Rs(p) under the dc magnetic field parallel to the substrate. We measured the Rs(p) of the YBCO and DyBCO thin films with a thickness of 500 nm deposited on a MgO (100) substrate using the dielectric resonator method at 21.8 GHz, and a dc magnetic field of up to 5 T. In a zero magnetic field, the values of Rs(n) and Rs(p) were 0.35 mQ at 20 K. Under the dc magnetic field, the Rs(n) and the Rs(p) also increased with increasing magnetic field, however, the Rs(p) had a lower magnetic field dependence and the value was about 1/10 of that of the Rs(n). The Rs(p) at 16.4 T and at 700 MHz could be estimated by the two-fluid model. The Rs(p) value was about 1/2600 compared with that of copper at 20 K. As a result, we clarified that 500 nm thick YBCO and DyBCO thin films could provide advantages for NMR application.

  2. Significant flux trapping in single grain GdBCO bulk superconductor under off-axis field cooled magnetization

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Ida, Tetsuya; Miki, Motohiro; Teshima, Hidekazu; Morita, Mitsuru; Izumi, Mitsuru

    2017-03-01

    A single grain bulk high-temperature superconductor (HTS) exhibits intensified flux trapping performance upon field cooled magnetization. The world record of trapped flux is 17.6 T achieved by using stacked two-fold GdBCO bulks. However, the majority of magnetization studies focused on the magnetization along the crystallographic c-axis. In the present study, we clarify the flux trapping performance under field cooled magnetization using an off-axis magnetic field with respect to the c-axis. The results show that the trapped flux is almost polarized along the applied field as expected. This tendency remains up to a high off-axis angle θ around 60°. It is worth mentioning that, with θ of 30°, the maximum trapped flux component B // max parallel to the c-axis significantly remains more than 96% of 1.6 T which occurs under on-axis magnetization. Meanwhile, the angular dependence of the c-axis parallel component exhibits that observed flux density is higher than that expected from 1.6 cosθ. In addition, to visualize the flux line upon magnetization at θ of 90°, we successfully demonstrate the continuous flux line trace using steel wires; different trapped flux behaviour appears when applied field penetrates the bulk through the growth sectors centre and along the growth sector boundary, respectively. We interpret these results may come from the microstructure as a result of melt growth. It is highly emphasized that the off-axis magnetization with the finite inclination angle is quite useful for introducing into the design of HTS applications.

  3. Performance and applications of quench melt-growth bulk magnets

    NASA Astrophysics Data System (ADS)

    Nariki, S.; Teshima, H.; Morita, M.

    2016-03-01

    This paper describes the progress in quench melt-growth (QMG) bulk magnets, developed by the Nippon Steel & Sumitomo Metal Corporation, which consist of single crystalline RE123 phase and finely dispersed RE211 particles. QMG bulks can trap high magnetic fields. The field-trapping ability of QMG bulks is largely increased with an improvement in its J c and size, promising the realization of various applications such as flywheel energy-storage systems, ship motors, NMR/MRI spectrometers, wind-power generators and so on. Intensive research has revealed that the optimal RE element is different depending on application requirements. Gd-QMG bulk is the most promising material for several high-field engineering applications. The trapped magnetic field of Gd-QMG bulk 60 mm in diameter at 77 K is twice as large as that of Y-QMG bulk with a similar size due to its excellent J c properties. The large Gd-based QMG bulks up to 150 mm in diameter are fabricated by incorporating the RE compositional gradient method. Compact NMR/MRI spectrometers are one of the promising applications of bulk superconductors. Eu-QMG bulks are suitable for NMR magnets. NMR applications require extremely homogeneous magnetic fields. In the Eu-system, the small paramagnetic moment of a Eu ion compared to a Gd ion improves the field homogeneity in the bulk. For the application of current leads, Dy-based QMG is available by utilizing a low thermal conductivity.

  4. Magnetic lenses using different MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Zhang, Z. Y.; Choi, S.; Matsumoto, S.; Teranishi, R.; Giunchi, G.; Figini Albisetti, A.; Kiyoshi, T.

    2012-02-01

    A magnetic lens allows the concentration of magnetic fields using the diamagnetism of superconductors. The important features of the magnetic lens are a tapered inner diameter from which the magnetic flux is extruded and a slit to suppress the circumference current that shields the magnetic flux. This concept was experimentally confirmed through the use of GdBaCuO bulks and a stack of NbTi/Nb/Cu sheets. We refer to this arrangement as a magnetic lens. The Mg-reactive liquid infiltration (Mg-RLI) process developed by Edison SpA is suitable for the production of large and high-density MgB2 bulks. Three MgB2 bulk magnetic lenses, each with a different microstructure, were fabricated following the Mg-RLI process. The properties of the MgB2 magnetic lenses were measured in a cryocooler system as well as in liquid helium. The results confirmed that the MgB2 bulk magnetic lenses could concentrate a magnetic field and that their field concentration properties were greatly affected by the temperature and the external field. In addition, the microstructure of the MgB2 bulk also had an influence on the magnetic properties at different external fields. The results indicated that the MgB2 lens might be utilized as a field amplifier in intermediate fields.

  5. Observation of self-magnetic field relaxations in Bi2223 and Y123 HTS tapes after over-current pulse and DC current operation

    NASA Astrophysics Data System (ADS)

    Tallouli, M.; Sun, J.; Chikumoto, N.; Otabe, E. S.; Shyshkin, O.; Charfi-Kaddour, S.; Yamaguchi, S.

    2016-07-01

    The development of power transmission lines based on long-length HTS tapes requires the production of high quality tapes. Due to fault conditions, technical mistakes and human errors during the operation of a DC power transmission line, an over-current pulse, several times larger than the rated current, could occur. To study the effect of such over-current pulses on the transport current density distribution in the HTS tapes, we simulated two start-up scenarios for one BSCCO and two YBCO tapes. The first start-up scenario is an initial over-current pulse during which the transport current was turned on rapidly, rising to 900 A during the first milliseconds, then reduced to a 100 A DC current. The second start-up scenario is normal operation, and involved increasing the transport current slowly from 0 A to 100 A at a rate of 1 A/s. For both scenarios, we then measured the vertical component of the self-magnetic field by means of a Hall probe above the tape, and afterward, by solving a linear equation of the inverse problem we obtain the current density profiles. We observe a change of the self-magnetic field above the edge of the BSCCO and YBCO tapes during 30 min after the 5 ms of over-current pulse and during the normal operation. The current density profiles are peaked in the centre for over-current pulse, and more peaked around the edge of the HTS tape for normal operation, which means that the limited time over-current pulse changes the current density profiles of the HTS tapes. We observe also a loop of current for YBCO tapes and we show the role of the HTS tape stabilizer.

  6. Development of a superconducting bulk magnet for NMR and MRI

    NASA Astrophysics Data System (ADS)

    Nakamura, Takashi; Tamada, Daiki; Yanagi, Yousuke; Itoh, Yoshitaka; Nemoto, Takahiro; Utumi, Hiroaki; Kose, Katsumi

    2015-10-01

    A superconducting bulk magnet composed of six vertically stacked annular single-domain c-axis-oriented Eu-Ba-Cu-O crystals was energized to 4.74 T using a conventional superconducting magnet for high-resolution NMR spectroscopy. Shim coils, gradient coils, and radio frequency coils for high resolution NMR and MRI were installed in the 23 mm-diameter room-temperature bore of the bulk magnet. A 6.9 ppm peak-to-peak homogeneous region suitable for MRI was achieved in the central cylindrical region (6.2 mm diameter, 9.1 mm length) of the bulk magnet by using a single layer shim coil. A 21 Hz spectral resolution that can be used for high resolution NMR spectroscopy was obtained in the central cylindrical region (1.3 mm diameter, 4 mm length) of the bulk magnet by using a multichannel shim coil. A clear 3D MR image dataset of a chemically fixed mouse fetus with (50 μm)3 voxel resolution was obtained in 5.5 h. We therefore concluded that the cryogen-free superconducting bulk magnet developed in this study is useful for high-resolution desktop NMR, MRI and mobile NMR device.

  7. Intercalation-driven reversible control of magnetism in bulk ferromagnets.

    PubMed

    Dasgupta, Subho; Das, Bijoy; Knapp, Michael; Brand, Richard A; Ehrenberg, Helmut; Kruk, Robert; Hahn, Horst

    2014-07-16

    An extension in magnetoelectric effects is proposed to include reversible chemistry-controlled magnetization variations. This ion-intercalation-driven magnetic control can be fully reversible and pertinent to bulk material volumes. The concept is demonstrated for ferromagnetic iron oxide where the intercalated lithium ions cause valence change and partial redistribution of Fe(3+) cations yielding a large and fully reversible change in magnetization at room temperature.

  8. AC losses in a HTS coil carrying DC current in AC external magnetic field

    NASA Astrophysics Data System (ADS)

    Ogawa, J.; Zushi, Y.; Fukushima, M.; Tsukamoto, O.; Suzuki, E.; Hirakawa, M.; Kikukawa, K.

    2003-10-01

    We electrically measured AC losses in a Bi2223/Ag-sheathed pancake coil excited by a DC current in AC external magnetic field. Losses in the coil contain two kinds of loss components that are the magnetization losses and dynamic resistance losses. In the measurement, current leads to supply a current to the coil were specially arranged to suppress electromagnetic coupling between the coil current and the AC external magnetic field. A double pick-up coils method was used to suppress a large inductive voltage component contained in voltage signal for measuring the magnetization losses. It was observed that the magnetization losses were dependent on the coil current and that a peak of a curve of the loss factor vs. amplitude of the AC external magnetic field shifted to lower amplitude of the AC magnetic field as the coil current increased. This result suggests the full penetration magnetic field of the coil tape decreases as the coil current increases. The dynamic resistance losses were measured by measuring a DC voltage appearing between the coil terminals. It was observed that the DC voltage appearing in the coil subject to the AC external magnetic field was much larger than that in the coil subject to DC magnetic field.

  9. Magnetic properties and microstructure of bulk Nd-Fe-B magnets solidified in magnetic field

    NASA Astrophysics Data System (ADS)

    Wang, C.; Lai, Y. S.; Hsieh, C. C.; Chang, W. C.; Chang, H. W.; Sun, A. C.

    2011-04-01

    The Nd-Fe-B bulk magnets with a slab shape of 0.9 × 4 × 15 mm3 were prepared by injection casting into a copper mold. The effects of applying a magnetic field during the casting process on the magnetic properties and microstructure of Nd9.5Fe71.5Ti2.5Zr0.5Cr1B14.5C0.5 alloy have been studied. The results show that the sample cast with magnetic field has a stronger (00L) texture of Nd2Fe14B phase with the c-axis perpendicular to the slab plane than the sample cast without magnetic field. The intensity of the texture weakens from surface to inner region of the bulk magnets. Applying a magnetic field during the casting process is helpful to refine the grain size effectively. As a result, the magnetic properties are improved from Br = 5.8 kG, iHc = 6.5 kOe, and (BH)max = 5.9 MGOe for thesample cast without magnetic field to Br = 6.1 kG, iHc = 10.3 kOe, and (BH)max = 7.3 MGOe for the sample cast with a 3.7 kOe magnetic field.

  10. Fabrication and characteristics of a test magnet from HTS Bi-2223 silver-clad tapes

    SciTech Connect

    Haldar, P.; Hoehn, J.G. Jr.; Motowidlo, L.R.; Iwasa, Y.

    1993-07-01

    Critical currents of powder-in-tube processed silver-clad Bi-2223 short tape samples and coils have been measured at liquid nitrogen (77 K), liquid neon (27 K) and liquid helium (4.2 K) temperatures. The short samples have been characterized in fields up to 20 T and indicate a large anisotropy at 27 K with resistive behavior above 15 T in the worst field direction. A test magnet consisting of pancake coils generated magnetic fields greater than 1.0, 0.7 and 0.11 T at 4.2 K, 27 K and 77 K respectively. The ctest magnet generates significant self-fields in background fields up to 14.5 T at 4.2 K and 27 K. Optimization of thermo-mechanical process parameters have yielded J{sub c}`s in the superconducting core > 4.0 {times} 10{sup 4} A/cm{sup 2} at 77 K, zero field and > 2.0 {times} 10{sup 5} A/cm{sup 2} at 4.2 K, zero field for short tape samples. Long lengths (>30 m) of silver-clad tape superconductors have also been fabricated and tested to carry significant amounts of current (J{sub c} core > 10,000 A/cm{sup 2}) at 77 K. Overall J{sub c} of short and long samples and characteristics of the test magnet are reported.

  11. Observation of Magnetic Signals from Earthquake Faulting Using High-resolution HTS-SQUID Magnetometer: Feasibility of Super-early Warning of Earthquakes

    NASA Astrophysics Data System (ADS)

    Katori, Y.; Okubo, K.; Hato, T.; Tsukamoto, A.; Tanabe, K.; Onishi, N.; Furukawa, H.; Isogami, S.; Takeuchi, N.

    2015-12-01

    Electromagnetic changes associated with earthquakes have been investigated previously. Our research group has also employed the magnetometers for seismomagnetic observations since March 2004. Our observation site happened to be situated at an epicentral distance of 26 km from the 2008 Iwate-Miyagi Nairiku earthquake ofM7.2, NE Japan. In this earthquake, we have reported successful observation of "co-faulting" Earth's magnetic field changes (Okubo et al., 2011 EPSL). Magnetic fields began to change almost simultaneously with the onset of the earthquake rupture and grew before the first P wave arrival. Such magnetic signals are most probably generated by the changing stress field due to earthquake rupturing, i.e. the piezomagnetic effect. On the other hand, this observation result suggested that the geomagnetic variation signal accompanying fault movement, whose sources are the piezomagnetic effects, is very small. The observed change of geomagnetic field might be approximately less than several hundred pico-tesla. Therefore, to obtain more observation data of "co-faulting" magnetic field change, development of a higher-sensitive magnetometer system is very important. Then, our research group tried to develop the HTS-SQUID (high-temperature-superconductor based superconducting-quantum-interference-device) magnetometer systems for high-resolution observation of Earth's magnetic field. Since March 2012 we have introduced long-term precise geomagnetic observations using the HTS-SQUID magnetometer system Unit No.1 (mark I) at Iwaki observation site (IWK) in Fukushima, Japan. Additionally, since October 2014, we have also introduced the new HTS- SQUID magnetometer system Unit No.2 (mark II). The sampling interval of the magnetometers is 0.02 sec (50Hz). The system clock has been synchronized by use of GPS signals. A high-resolution accelerometer is also installed at observation point. In this study, we show the observation results of geomagnetic field changes associated

  12. Progress in HTS Trapped Field Magnets: J(sub c), Area, and Applications

    NASA Technical Reports Server (NTRS)

    Weinstein, Roy; Ren, Yanru; Liu, Jian-Xiong; Sawh, Ravi; Parks, Drew; Foster, Charles; Obot, Victor; Arndt, G. Dickey; Crapo, Alan

    1995-01-01

    Progress in trapped field magnets is reported. Single YBCO grains with diameters of 2 cm are made in production quantities, while 3 cm, 4 1/2 cm and 6 cm diameters are being explored. For single grain tiles: J(sub c) - 10,000 A/sq cm for melt textured grains; J(sub c) - 40,000 A/sq cm for light ion irradiation; and J(sub c) - 85,000 A/J(sub c) for heavy ion irradiation. Using 2 cm diameter tiles bombarded by light ions, we have fabricated a mini-magnet which trapped 2.25 Tesla at 77K, and 5.3 Tesla at 65K. A previous generation of tiles, 1 cm x 1 cm, was used to trap 7.0 Tesla at 55K. Unirradiated 2.0 cm tiles were used to provide 8 magnets for an axial gap generator, in a collaborative experiment with Emerson Electric Co. This generator delivered 100 Watts to a resistive load, at 2265 rpm. In this experiment, activation of the TFMs was accomplished by a current pulse of 15 ms duration. Tiles have also been studied for application as a bumper-tether system for the soft docking of spacecraft. A method for optimizing tether forces, and mechanisms of energy dissipation are discussed. A bus bar was constructed by welding three crystals while melt-texturing, such that their a,b planes were parallel and interleaved. The bus bar, of area approx. 2 sq cm, carried a transport current of 1000 amps, the limit of the testing equipment available.

  13. Progress in HTS trapped field magnets: J(sub c), area, and applications

    NASA Technical Reports Server (NTRS)

    Weinstein, Roy; Ren, Yanru; Liu, Jianxiong; Sawh, Ravi; Parks, Drew; Foster, Charles; Obot, Victor; Arndt, G. Dickey; Crapo, Alan

    1995-01-01

    Progress in trapped field magnets is reported. Single YBCO grains with diameters of 2 cm are made in production quantities, while 3 cm, 4 1/2 cm and 6 cm diameters are being explored. For single grain tiles: J(sub c) is approximately 10,000 A/cm(exp 2) for melt textured grains; J(sub c) is approximately 40,000 A/cm2 for light ion irradiation; and J(sub c) is approximately 85,000 A/cm(exp 2) for heavy ion irradiation. Using 2 cm diameter tiles bombarded by light ions, we have fabricated a mini-magnet which trapped 2.25 Tesla at 77K, and 5.3 Tesla at 65K. A previous generation of tiles, 1 cm x 1 cm, was used to trap 7.0 Tesla at 55K. Unirradiated 2.0 cm tiles were used to provide 8 magnets for an axial gap generator, in a collaborative experiment with Emerson Electric Co. This generator delivered 100 Watts to a resistive load, at 2265 rpm. In this experiment activation of the TFMs was accomplished by a current pulse of 15 ms duration. Tiles have also been studied for application as a bumper-tether system for the soft docking of spacecraft. A method for optimizing tether forces, and mechanisms of energy dissipation are discussed. A bus bar was constructed by welding three crystals while melt-texturing, such that their a,b planes were parallel and interleaved. The bus bar, an area of approximately 2 cm(exp 2), carried a transport current of 1000 amps, the limit of the testing equipment available.

  14. Microstructure and Magnetic Properties of Bulk Nanocrystalline MnAl

    SciTech Connect

    Chaturvedi, A; Yaqub, R; Baker, I

    2014-01-22

    MnAl is a promising rare-earth free permanent magnet for technological use. We have examined the effects of consolidation by back-pressure, assisted equal channel angular extrusion processing on mechanically-milled, gas-atomized Mn-46% at. Al powder. X-ray diffraction showed both that the extruded rod consisted mostly of metastable tau phase, with some of the equilibrium gamma(2) and beta phases, and that it largely retained the as-milled nanostructure. Magnetic measurements show a coercivity of <= 4.4 kOe and a magnetization at 10 kOe of <= 40 emu/g. In addition, extrusions exhibit greater than 95% of the theoretical density. This study opens a new window in the area of bulk MnAl magnets with improved magnetic properties for technological use.

  15. Measurements of AC Loss In Second-Generation HTS Tapes in a DC Magnetic Field

    NASA Astrophysics Data System (ADS)

    Osofsky, M. S.; Soulen, R. J.; Gubser, D. U.; Datta, T.

    2008-03-01

    The successful application of superconductivity to motors and other power system components depends on the characterization and subsequent minimization of the ac loss in the superconductor used for fabrication of the component. The superconductive component, excited by an ac power source, may be exposed to large dc magnetic fields and/or ac fields. To further complicate the situation, the transport properties of the tapes are strongly dependent on the angle between the applied field and the YBCO c-axis (normal to the tape surface). We report on measurements of the transport ac loss of a YBaCuO tape at 65 K, at several frequencies, in applied dc fields of 1-3 T with the field parallel and perpendicular to the tape normal.

  16. Improvement of persistent magnetic field trapping in bulk Y-Ba-Cu-O superconductors

    NASA Technical Reports Server (NTRS)

    Chen, In-Gann; Weinstein, Roy

    1993-01-01

    For type-II superconductors, magnetic field can be trapped due to persistent internal supercurrent. Quasi-persistent magnetic fields near 2 T at 60 K (and 1.4 T at 77 K) have been measured in minimagnets made of proton-irradiated melt-textured Y-Ba-Cu-O (MT-Y123) samples. Using the trapping effect, high-field permanent magnets with dipole, quadrupole, or more complicated configurations can be made of existing MT-Y123 material, thus bypassing the need for high-temperature superconductor (HTS) wires. A phenomenological current model has been developed to account for the trapped field intensity and profile in HTS samples. This model is also a guide to select directions of materials development to further improve field trapping properties. General properties such as magnetic field intensities, spatial distributions, stabilities, and temperature dependence of trapped field are discussed.

  17. HTS magnetometers for fetal magnetocardiography.

    PubMed

    Li, Z; Wakai, R T; Paulson, D N; Schwartz, B

    2004-11-30

    High temperature superconducting (HTS) SQUID sensors have adequate magnetic field sensitivity for adult magnetocardiography (MCG) measurements, but it remains to be seen how well they perform for fetal MCG (fMCG), where the heart signals are typically ten times smaller than the adult signals. In this study, we assess the performance of a prototype HTS SQUID system; namely, a three-SQUID gradiometer formed from three vertically-aligned HTS dc-SQUID magnetometers integrated into a fiberglass liquid nitrogen dewar of diameter 12.5 cm and height 30 cm. Axial gradiometers with short or long baseline, as well as a second order gradiometer, can be formed out of these magnetometers via electronic subtraction. The calibrated magnetometer sensitivities at 1 kHz are 109 fT/square root of Hz, 155 fT/square root of Hz and 51 fT/square root of Hz. Direct comparison is made between the HTS SQUID system and a LTS SQUID system by making recordings with both systems during the same session on adult and fetal subjects. Although the fMCG could be resolved with the HTS SQUID system in most near-term subjects, the signal-to-noise ratio was relatively low and the system could not be operated outside of a shielded room.

  18. Bulk-hardened magnets based on Y2Co17

    NASA Astrophysics Data System (ADS)

    Gabay, A. M.; Zhang, Y.; Hadjipanayis, G. C.

    2001-07-01

    Bulk magnetic hardening of cast Y2Co17-based alloys was systematically studied for different compositions and heat treatments. Additions of Cu and Zr, Hf, or Ti to the Y-Co were found to be essential for developing coercivity. The performance of Y-Co-Cu-Zr magnets can be significantly improved by partial Pr and Fe substitutions for Y and Co, respectively. Anisotropic (Y0.8Pr0.2)11.5Zr2.75Co56.75Fe14Cu15 powders with intrinsic coercivity of 7.8 kOe and energy product of 14.4 MG Oe were obtained after annealing at 900 °C for 15 min and cooling to 200 °C at the rate of 4 °C/min. We also explored the effects of some other rare earths (La, Nd, Gd) and transition metals (Mn, Ni) on the magnetic properties of the Y-Co-Cu-Zr magnets. The phases present and the microstructure were analyzed with x-ray diffraction, thermomagnetic analysis, and transmission electron microscopy. The cellular/lamellar microstructure of the bulk-hardened alloys is similar to that of Sm-Co-Cu-Zr magnets. Among the most noticeable distinctions in the Y-Co-Cu-Zr alloys are a smaller average size of 2:17 cells and a variety of Zr-rich phases, like Zr2Co11 and Zr6Co23. Although the Y2Co17 phase is known to have an "easy-plane" anisotropy, the x-ray diffraction experiments with magnetically oriented powders suggest that in the bulk-hardened Y-Co-Cu-Zr and Y-Co-Cu-Fe-Zr magnets the 2:17 phase has uniaxial anisotropy.

  19. Effect of the magnetic material on AC losses in HTS conductors in AC magnetic field carrying AC transport current

    NASA Astrophysics Data System (ADS)

    Wan, Xing-Xing; Huang, Chen-Guang; Yong, Hua-Dong; Zhou, You-He

    2015-11-01

    This paper presents an investigation on the AC losses in several typical superconducting composite conductors using the H-formulation model. A single superconducting strip with ferromagnetic substrate or cores and a stack of coated conductors with ferromagnetic substrates are studied. We consider all the coated conductors carrying AC transport currents and simultaneously exposed to perpendicular AC magnetic fields. The influences of the amplitude, frequency, phase difference and ferromagnetic materials on the AC losses are investigated. The results show that the magnetization losses of single strip and stacked strips have similar characteristics. The ferromagnetic substrate can increase the magnetization loss at low magnetic field, and decrease the loss at high magnetic field. The ferromagnetic substrate can obviously increase the transport loss in stacked strips. The trends of total AC losses of single strip and stacked strips are similar when they are carrying current or exposed to a perpendicular magnetic field. The effect of the frequency on the total AC losses of single strip is related to the amplitude of magnetic field. The AC losses decrease with increasing frequency in low magnetic field region while increase in high magnetic field region. As the phase difference changes, there is a periodic variation for the AC losses. Moreover, when the strip is under only the transport current and magnetic field, the ferromagnetic cores will increase the AC losses for large transport current or field.

  20. Superior homogeneity of trapped magnetic field in superconducting MgB2 bulk magnets

    NASA Astrophysics Data System (ADS)

    Ishihara, A.; Akasaka, T.; Tomita, M.; Kishio, K.

    2017-03-01

    Homogeneity of trapped magnetic field in radial and circumferential directions of high temperature superconducting bulk magnets, MgB2 (T c ˜38.3 K) and YBa2Cu3O y (T c ˜91.5 K), have been measured. In polycrystalline MgB2 bulks, the circularity of trapped magnetic field in a cylindrical disk is over 97% at 20-32.5 K, while that of YBa2Cu3O y was ˜87% at 77 K. Magnetic field distribution of MgB2 bulk was satisfactorily homogeneous and these measurements suggest MgB2 bulks with highly efficient cryocoolers should be very useful for novel high field permanent magnet applications.

  1. High temperature magnetic properties of SmCo5/α-Fe(Co) bulk nanocomposite magnets

    NASA Astrophysics Data System (ADS)

    Rong, Chuanbing; Poudyal, Narayan; Liu, X. B.; Zhang, Ying; Kramer, M. J.; Ping Liu, J.

    2012-10-01

    To find alternative high temperature magnets containing no heavy rare earths for power applications, SmCo5/Fe bulk nanocomposite magnets with enhanced energy density and high thermal stability have been produced by using a ball-milling plus warm-compaction route. Up to 30% of the Fe soft magnetic phase has been added to the composites with grain size <20 nm distributed homogenously in the matrix of the SmCo5 hard magnetic phase. It was observed that the microstructure does not change with temperature up to 500 °C. It is also observed that the thermal stability of bulk nanocomposite samples is closely related to bulk density. Energy products above 11 MGOe have been obtained at 300 °C in fully dense bulk SmCo5/Fe nanocomposite magnets, which is 65% higher than that of a single-phase counterpart at the same temperature.

  2. Repairing and upgrading of the HTS insert in the 18T cryogen-free superconducting magnet

    NASA Astrophysics Data System (ADS)

    Awaji, S.; Oguro, H.; Watanabe, K.; Hanai, S.; Ioka, S.; Miyazaki, H.; Daibo, M.; Iijima, Y.; Saito, T.; Itoh, M.

    2014-01-01

    Since the development of the 18T cryogen-free superconducting magnet (18T-CSM) at the High Field Laboratory for Superconducting Materials (HFLSM), IMR, Tohoku University, it has been routinely utilized for the various high field researches such as the in-field materials processing and so on. After the Great East Japan Disaster, however, the 18T-CSM is under the repairing due to the serious damages of the system. At this time, a part of the middle Nb3Sn section coil and the Bi2223 inner most coil were renewed. The bronze-route Nb3Sn coil with a low ac-loss was adopted instead of the previous internal-Sn Nb3Sn coil for the reduction of the heat-generation during a field ramping. The new Bi2223 coil will generate the central field of 4.5 T under the background field of 15.5 T by the LTS outer coils, although the previous Bi2223 coil generated 2.5 T. Hence the 18T-CSM was successfully upgraded to the 20T-CSM. In addition to the Bi2223 insert, the Gd123 insert coil is being constructed as well. When the Gd123 insert coil is installed instead of the Bi2223 coil, it will be upgraded to the 22T-CSM from the 20T-CSM.

  3. High-entropy bulk metallic glasses as promising magnetic refrigerants

    NASA Astrophysics Data System (ADS)

    Huo, Juntao; Huo, Lishan; Li, Jiawei; Men, He; Wang, Xinmin; Inoue, Akihisa; Chang, Chuntao; Wang, Jun-Qiang; Li, Run-Wei

    2015-02-01

    In this paper, the Ho20Er20Co20Al20RE20 (RE = Gd, Dy, and Tm) high-entropy bulk metallic glasses (HE-BMGs) with good magnetocaloric properties are fabricated successfully. The HE-BMGs exhibit a second-order magnetic phase transition. The peak of magnetic entropy change ( ΔSMpk ) and refrigerant capacity (RC) reaches 15.0 J kg-1 K-1 and 627 J kg-1 at 5 T, respectively, which is larger than most rare earth based BMGs. The heterogeneous nature of glasses also contributes to the large ΔSMpk and RC. In addition, the magnetic ordering temperature, ΔSMpk and RC can be widely tuned by alloying different rare earth elements. These results suggest that the HE-BMGs are promising magnetic refrigerant at low temperatures.

  4. High permeability flexible bulk material for magnetic micro head applications

    NASA Astrophysics Data System (ADS)

    Belski, A.; Taptimthong, P.; Wurz, M. C.; Rissing, L.

    2013-01-01

    A magnetic field is generated by feeding electric current to micro coils. The higher the current, the higher the magnetic field is. A main disadvantage of coils in micro systems is the limited thermal resistance and as a result of a restriction concerning the maximum current densities. This work shows the modelling, design, numerical calculation and the initial test of a flexible write head, which not only allows the data storage on the surface but also inside of the components. Furthermore, the write head has to be flexible and able to adapt itself to the roughness of the component surface. The main goal of this paper is to increase the magnetic flux in the micro head core by partly using high permeability flexible bulk material instead of increasing the coil current or the number of the coil turns. For the approval of the data storage process a GMR sensor is used for the readout of the stored magnetization track.

  5. Recent advances in magnetic nanoparticles with bulk-like properties

    NASA Astrophysics Data System (ADS)

    Batlle, Xavier

    2013-03-01

    Magnetic nanoparticles (NP) are an excellent example of nanostructured materials and exhibit fascinating properties with applications in high-density recording and biomedicine. Controlling the effects of the nanostructure and surface chemistry and magnetism at the monolayer level have become relevant issues. As the size is reduced below 100 nm, deviations from bulk behavior have been attributed to finite-size effects and changes in the magnetic ordering at the surface, thus giving rise to a significant decrease in the magnetization and increase in the magnetic anisotropy. The existence of a surface spin glass-like state due to magnetic frustration has been widely suggested in ferrimagnetic NP. However, in this talk, we will show that high crystal quality magnetite Fe3-xO4 NP of about a few nanometers in diameter and coated with different organic surfactants display bulk-like structural, magnetic and electronic properties. Magnetic measurements, transmission electron microscopy, X-ray absorption and magnetic circular dichroism and Monte Carlo simulations, evidenced that none of the usual particle-like behavior is observed in high quality NP of a few nm. Consequently, the magnetic and electronic disorder phenomena typically observed in those single-phase ferrimagnetic NP should not be considered as an intrinsic effect. We also performed a real-space characterization at the sub-nanometer scale, combining scanning transmission electron microscopy, electron energy loss spectroscopy and electron magnetic chiral dichroism. For the first time, we found that the surface magnetization is as high as about 70% of that of the core. The comparison to density functional theory suggested the relevance of the strong surface bond between the Fe ions and the organic surfactant. All the foregoing demonstrates the key role of both the crystal quality and surface bond on the physical properties of ferrimagnetic NP and paves the way to the fabrication of the next generation of NP with

  6. Magnetic and levitation characteristics of bulk high-temperature superconducting magnets above a permanent magnet guideway

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Zheng, Botian; He, Dabo; Sun, Ruixue; Deng, Zigang; Xu, Xun; Dou, Shixue

    2016-09-01

    Due to the large levitation force or the large guidance force of bulk high-temperature superconducting magnets (BHTSMs) above a permanent magnet guideway (PMG), it is reasonable to employ pre-magnetized BHTSMs to replace applied-magnetic-field-cooled superconductors in a maglev system. There are two combination modes between the BHTSM and the PMG, distinguished by the different directions of the magnetization. One is the S-S pole mode, and the other is the S-N pole mode combined with a unimodal PMG segment. A multi-point magnetic field measurement platform was employed to acquire the magnetic field signals of the BHTSM surface in real time during the pre-magnetization process and the re-magnetization process. Subsequently, three experimental aspects of levitation, including the vertical movement due to the levitation force, the lateral movement due to the guidance force, and the force relaxation with time, were explored above the PMG segment. Moreover, finite element modeling by COMSOL Multiphysics has been performed to simulate the different induced currents and the potentially different temperature rises with different modes inside the BHTSM. It was found that the S-S pole mode produced higher induced current density and a higher temperature rise inside the BHTSM, which might escalate its lateral instability above the PMG. The S-N pole mode exhibits the opposite characteristics. In general, this work is instructive for understanding and connecting the magnetic flux, the inner current density, the levitation behavior, and the temperature rise of BHTSMs employed in a maglev system.

  7. Synchronous motor with HTS-2G wires

    NASA Astrophysics Data System (ADS)

    Dezhin, D.; Ilyasov, R.; Kozub, S.; Kovalev, K.; Verzhbitsky, L.

    2014-05-01

    One of the applications of new high-temperature superconductor materials (HTS) is field coils for synchronous electrical machines. The use of YBCO 2G HTS tapes (HTS-2G) allows increasing of magnetic flux density in the air gap, which will increase the output power and reduce the dimensions of the motor. Such motors with improved characteristics can be successfully used in transportation as traction motor. In MAI-based "Center of Superconducting machines and devices" with the support of "Rosatom" has been designed and tested a prototype of the 50 kW synchronous motor with radial magnetic flux from a field-coils based on HTS-2G tapes. The experimental and theoretical results are presented.

  8. A study on the required performance of a 2G HTS wire for HTS wind power generators

    NASA Astrophysics Data System (ADS)

    Sung, Hae-Jin; Park, Minwon; Go, Byeong-Soo; Yu, In-Keun

    2016-05-01

    YBCO or REBCO coated conductor (2G) materials are developed for their superior performance at high magnetic field and temperature. Power system applications based on high temperature superconducting (HTS) 2G wire technology are attracting attention, including large-scale wind power generators. In particular, to solve problems associated with the foundations and mechanical structure of offshore wind turbines, due to the large diameter and heavy weight of the generator, an HTS generator is suggested as one of the key technologies. Many researchers have tried to develop feasible large-scale HTS wind power generator technologies. In this paper, a study on the required performance of a 2G HTS wire for large-scale wind power generators is discussed. A 12 MW class large-scale wind turbine and an HTS generator are designed using 2G HTS wire. The total length of the 2G HTS wire for the 12 MW HTS generator is estimated, and the essential prerequisites of the 2G HTS wire based generator are described. The magnetic field distributions of a pole module are illustrated, and the mechanical stress and strain of the pole module are analysed. Finally, a reasonable price for 2G HTS wire for commercialization of the HTS generator is suggested, reflecting the results of electromagnetic and mechanical analyses of the generator.

  9. High output power reluctance electric motors with bulk high-temperature superconductor elements

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; Larionoff, A. E.; M-A Koneev, S.; Modestov, K. A.; Larionoff, S. A.; Poltavets, V. N.; Akimov, I. I.; Alexandrov, V. V.; Gawalek, W.; Oswald, B.; Krabbes, G.

    2002-05-01

    We present new types of electric machines with the rotors containing bulk high-temperature superconductor (HTS) - YBCO and Bi-Ag - elements. We discuss different schematics of hysteresis, reluctance, 'trapped field' and composed synchronous HTS machines. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the single-domain and polycrystal YBCO ceramic samples and plate shape Bi-Ag elements. We give the test results of the series of hysteresis, reluctance, 'trapped field' and composed with permanent magnets HTS motors with an output power rating of 0.1-18 kW and current frequencies 50 Hz and 400 Hz. These results show that in the media of liquid nitrogen the specific output power per one unit weight of the HTS motor is four to seven times better than for conventional electric machines. A comparison of the theoretical and experimental characteristics of the developed HTS motors show that they are in good agreement. We discuss the test results for a liquid nitrogen cryogenic pump system with a hysteresis 500 W HTS motor. We describe several designs of new HTS motors operating in the media of liquid nitrogen with an output power 125 kW (and more) and a power factor of more than 0.8. We discuss future applications of new types of HTS motors for aerospace technology, on-land industry and transport systems.

  10. Magnetism of iron: from the bulk to the monatomic wire

    NASA Astrophysics Data System (ADS)

    Autès, Gabriel; Barreteau, Cyrille; Spanjaard, Daniel; Desjonquères, Marie-Catherine

    2006-07-01

    The magnetic properties of iron (spin and orbital magnetic moments, magnetocrystalline anisotropy energy) in various geometries and dimensionalities are investigated by using a parametrized tight-binding model in an s, p and d atomic orbital basis set including spin polarization and the effect of spin-orbit coupling. The validity of this model is well established by comparing the results with those obtained by using an ab initio code. This model is applied to the study of iron in bulk bcc and fcc phases, (110) and (001) surfaces and the monatomic wire, at several interatomic distances. New results are derived. In the case of surfaces the variation of the component of the orbital magnetic moment on the spin quantization axis has been studied as a function of depth, revealing a significant enhancement in the first two layers, especially for the (001) surface. It is found that the magnetic anisotropy energy is drastically increased in the wire and can reach several meV. This is also true for the orbital moment, which in addition is highly anisotropic. Furthermore, it is shown that when the spin quantization axis is neither parallel nor perpendicular to the wire the average orbital moment is not aligned with the spin quantization axis. At equilibrium distance the easy magnetization axis is along the wire but switches to the perpendicular direction under compression. The success of this model opens up the possibility of obtaining accurate results on other elements and systems with much more complex geometries.

  11. Design and manufacture of a D-shape coil-based toroid-type HTS DC reactor using 2nd generation HTS wire

    NASA Astrophysics Data System (ADS)

    Kim, Kwangmin; Go, Byeong-Soo; Sung, Hae-Jin; Park, Hea-chul; Kim, Seokho; Lee, Sangjin; Jin, Yoon-Su; Oh, Yunsang; Park, Minwon; Yu, In-Keun

    2014-09-01

    This paper describes the design specifications and performance of a real toroid-type high temperature superconducting (HTS) DC reactor. The HTS DC reactor was designed using 2G HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The target inductance of the HTS DC reactor was 400 mH. The expected operating temperature was under 20 K. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. Performances of the toroid-type HTS DC reactor were analyzed through experiments conducted under the steady-state and charge conditions. The fundamental design specifications and the data obtained from this research will be applied to the design of a commercial-type HTS DC reactor.

  12. Total AC loss study of 2G HTS coils for fully HTS machine applications

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Yuan, Weijia; Kvitkovic, Jozef; Pamidi, Sastry

    2015-11-01

    The application of HTS coils for fully HTS machines has become a new research focus. In the stator of an electrical machine, HTS coils are subjected to a combination of an AC applied current and AC external magnetic field. There is a phase shift between the AC current and AC magnetic field. In order to understand and estimate the total AC loss of HTS coils for electrical machines, we designed and performed a calorimetric measurement for a 2G HTS racetrack coil. Our measurement indicates that the total AC loss is greatly influenced by the phase shift between the applied current and the external magnetic field when the magnetic field is perpendicular to the tape surface. When the applied current and the external magnetic field are in phase, the total AC loss is the highest. When there is a 90 degree phase difference, the total AC loss is the lowest. In order to explain this phenomenon, we employ H formulation and finite element method to model the 2G HTS racetrack coil. Our calculation agrees well with experimental measurements. Two parameters are defined to describe the modulation of the total AC loss in terms of phase difference. The calculation further reveals that the influence of phase difference varies with magnetic field direction. The greatest influence of phase difference is in the perpendicular direction. The study provides key information for large-scale 2G HTS applications, e.g. fully HTS machines and superconducting magnetic energy storage, where the total AC loss subjected to both applied currents and external magnetic fields is a critical parameter for the design.

  13. Magnetic and magnetocaloric properties of bulk dysprosium chromite

    SciTech Connect

    McDannald, A.; Kuna, L.; Jain, M.

    2013-09-21

    In this work, a polycrystalline bulk DyCrO{sub 3} sample was prepared by a solution route and the structural and magnetic properties were investigated. The phase purity and ionic valence state of the DyCrO{sub 3} sample were determined by x-ray diffraction/Raman spectroscopy and x-ray photoelectron spectroscopy, respectively. The AC and DC magnetization measurements revealed the onset of antiferromagnetic order at 146 K with an effective moment of 8.88 μ{sub B}. Isothermal magnetization measurements of this material are presented for the first time, showing a peak in the coercive field at 80 K that is explained by the competition between the paramagnetic Dy{sup 3+} and Cr{sup 3+} sublattices. DyCrO{sub 3} was found to display a large magnetocaloric effect (8.4 J/kg K) and relative cooling power (217 J/kg) at 4 T applied field, which renders DyCrO{sub 3} useful for magnetic refrigeration between 5 K and 30 K.

  14. Defect induced magnetism in highly oriented pyrolytic graphite: bulk magnetization and 19F hyperfine interaction studies.

    PubMed

    Mohanta, S K; Mishra, S N; Davane, S M; Srivastava, S K

    2012-02-29

    We have made bulk and local investigations on defect induced magnetism in highly oriented pyrolytic graphite (HOPG) irradiated with a 40 MeV carbon beam. The local magnetic response of irradiated HOPG was studied by measuring the hyperfine field of recoil implanted (19)F using γ-ray time differential perturbed angular distribution (TDPAD) measurements. While the bulk magnetic properties of the irradiated sample show features characteristic of room temperature ferromagnetism, the hyperfine field data reflect enhanced paramagnetism with no indication of long range magnetic ordering. The experimental studies are further supported by ab initio density functional calculations. We believe that the ferromagnetic response in irradiated HOPG arises mostly from defect induced magnetic moments of carbon atoms in the near surface region, while those deep inside the host matrix remain paramagnetic.

  15. The magnetostriction in a superconductor-magnet system under non-uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Li, Xueyi; Jiang, Lang; Wu, Hao; Gao, Zhiwen

    2017-03-01

    This paper describes a numerical model to examine the magnetostriction of bulk high-temperature superconductor (HTS) under non-uniform magnetic field in conjunction with finite element analysis. Through this model, the magnetostriction of homogeneous and nonhomogeneous HTS can be implemented under non-uniform magnetic field. Further, the effects of critical current density, applied field frequency and amplitude are also considered. The computational study can provide a fundamental mechanistic understanding the effects of non-uniform magnetic field on magnetostriction of HTS.

  16. Transport and Magnetism in Bulk and Thin Film Strontium Titanate

    NASA Astrophysics Data System (ADS)

    Ambwani, Palak

    SrTiO3 is a wide band-gap perovskite oxide semiconductor that is widely investigated in the bulk form, due to its remarkable electronic properties. These properties arise from its quantum paraelectric nature which enables unique features, such as, a high-mobility low-density metallic state, quantum transport in an unusual limit, and the most dilute superconducting state thus reported. Recent advances in deposition of oxide thin films and heterostructures have further led to some remarkable observations, such as, the strain-enhancement of mobility in doped thin films of SrTiO3, and the presence of 2D electron gases at interfaces and in delta-doped layers. The presence of magnetic moments and their possible ordering, and the simultaneous observation of quantum oscillations and superconductivity, have been reported in these 2D electron gases. While magnetism has been observed in heterostructures of SrTiO3 , there have been limited reports on magnetism in bulk SrTiO3. The first part of this thesis (Chapter 3) discusses how circularly polarized light can induce an extremely long-lived magnetic moment in slightly oxygen-deficient but otherwise nominally pure SrTiO3-delta bulk crystals. These magnetic signals, which are induced at zero applied magnetic field and at low temperatures below ˜ 18 K, can be controlled in both magnitude and sign by means of the circular polarization and wavelength of sub-bandgap illumination (400-500 nm), and point to the existence of optically polarizable VO-related complexes in the forbidden gap of SrTiO 3-delta, rather than collective or long-range magnetic order. The methods used to detect optically induced magnetization are also discussed (Appendix A). The phenomenal progress reported in thin films and heterostructures of SrTiO3 has been possible only by precise control of stoichiometry and defect density in SrTiO3 using techniques such as oxide/LASER MBE or high-temperature PLD. The next part of the thesis (Chapter 4) demonstrates that

  17. A method to enhance the curve negotiation performance of HTS Maglev

    NASA Astrophysics Data System (ADS)

    Che, T.; Gou, Y. F.; Deng, Z. G.; Zheng, J.; Zheng, B. T.; Chen, P.

    2015-09-01

    High temperature superconducting (HTS) Maglev has attracted more and more attention due to its special self-stable characteristic, and much work has been done to achieve its actual application, but the research about the curve negotiation is not systematic and comprehensive. In this paper, we focused on the change of the lateral displacements of the Maglev vehicle when going through curves under different velocities, and studied the change of the electromagnetic forces through experimental methods. Experimental results show that setting an appropriate initial eccentric distance (ED), which is the distance between the center of the bulk unit and the center of the permanent magnet guideway (PMG), when cooling the bulks is favorable for the Maglev system’s curve negotiation. This work will provide some available suggestions for improving the curve negotiation performance of the HTS Maglev system.

  18. Reflective HTS switch

    DOEpatents

    Martens, J.S.; Hietala, V.M.; Hohenwarter, G.K.G.

    1994-09-27

    A HTS (High Temperature Superconductor) switch includes a HTS conductor for providing a superconducting path for an electrical signal and an serpentine wire actuator for controllably heating a portion of the conductor sufficiently to cause that portion to have normal, and not superconducting, resistivity. Mass of the portion is reduced to decrease switching time. 6 figs.

  19. Reflective HTS switch

    SciTech Connect

    Martens, Jon S.; Hietala, Vincent M.; Hohenwarter, Gert K. G.

    1994-01-01

    A HTS switch includes a HTS conductor for providing a superconducting path for an electrical signal and an serpentine wire actuator for controllably heating a portion of the conductor sufficiently to cause that portion to have normal, and not superconducting, resistivity. Mass of the portion is reduced to decrease switching time.

  20. Effects of fluctuating magnetic fields on a superconducting bulk rotor shielded with superconducting rings

    NASA Astrophysics Data System (ADS)

    Yamagishi, K.; Ogawa, J.; Tsukamoto, O.

    2014-05-01

    We study the effect of a fluctuating magnetic field, which is one of the technical problems for trapped magnetic fields in a bulk superconductor, to realize a practical bulk superconductor rotating machine. Previous research and other's research has shown that fluctuating magnetic fields reduce the strength of trapped magnetic fields in superconducting bulk modules [1, 2]. This deters development of applications of AC rotating machines because superconducting bulk modules are always exposed to a fluctuating magnetic field. Therefore, it is necessary to develop a method to control decrease of the trapped magnetic field. We propose a method to use the shielding ring of a superconducting wire to achieve this goal and the effects are confirmed experimentally [3]. We are now building test equipment for examining the performance of a shielding ring in a bulk rotating machine. This paper reports the test result for the shielding ring applied to the bulk superconducting rotor that is a part of the test equipment.

  1. Bulk Superconductors in Mobile Application

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Delor, U. Floegel-; Rothfeld, R.; Riedel, T.; Wippich, D.; Goebel, B.; Schirrmeister, P.

    We investigate and review concepts of multi - seeded REBCO bulk superconductors in mobile application. ATZ's compact HTS bulk magnets can trap routinely 1 T@77 K. Except of magnetization, flux creep and hysteresis, industrial - like properties as compactness, power density, and robustness are of major device interest if mobility and light-weight construction is in focus. For mobile application in levitated trains or demonstrator magnets we examine the performance of on-board cryogenics either by LN2 or cryo-cooler application. The mechanical, electric and thermodynamical requirements of compact vacuum cryostats for Maglev train operation were studied systematically. More than 30 units are manufactured and tested. The attractive load to weight ratio is more than 10 and favours group module device constructions up to 5 t load on permanent magnet (PM) track. A transportable and compact YBCO bulk magnet cooled with in-situ 4 Watt Stirling cryo-cooler for 50 - 80 K operation is investigated. Low cooling power and effective HTS cold mass drives the system construction to a minimum - thermal loss and light-weight design.

  2. Conceptual design of a novel insertion device using bulk superconducting magnet

    NASA Astrophysics Data System (ADS)

    Kii, T.; Kinjo, R.; Bakr, M. A.; Choi, Y. W.; Yoshida, K.; Ueda, S.; Takasaki, M.; Ishida, K.; Kimura, N.; Sonobe, T.; Masuda, K.; Ohgaki, H.

    2011-11-01

    An undulator or a wiggler with a strong magnetic field will play an important role in future synchrotron light sources, free electron lasers, and linear colliders. We proposed the bulk high critical temperature superconductor staggered array undulator (Bulk HTSC SAU) in order to generate a strong periodic field. The Bulk HTSC SAU consists of stacked bulk high-Tc superconductors (HTSs) and a solenoid magnet which is used to magnetize the bulk HTSs. A periodic magnetic field was produced and controlled using a prototype of the Bulk HTSC SAU using 11 pairs of REBaCuO bulk HTSs at 77 K. The expected performance at low temperatures around 20 K is calculated using a loop current model.

  3. Fabrication of bulk nanostructured permanent magnets with high energy density: challenges and approaches.

    PubMed

    Yue, Ming; Zhang, Xiangyi; Liu, J Ping

    2017-03-17

    Nanostructured permanent magnetic materials, including exchange-coupled nanocomposite permanent magnets, are considered as the next generation of high-strength magnets for future applications in energy-saving and renewable energy technologies. However, fabrication of bulk nanostructured magnets remains very challenging because conventional compaction and sintering techniques cannot be used for nanostructured bulk material processing. In this paper we review recent efforts at producing bulk nanostructured single-phase and composite magnetic materials with emphasis on grain size control, anisotropy generation and interface modification.

  4. Trapping a magnetic field of 7.9 T using a bulk magnet fabricated from stack of coated conductors

    NASA Astrophysics Data System (ADS)

    Tamegai, T.; Hirai, T.; Sun, Y.; Pyon, S.

    2016-11-01

    We have fabricated a bulk magnet using double stack, each 130 layers, of short segments of coated conductors (CCs). The bulk magnet is magnetized by field-cooling in a magnetic field of 9 T down to 4.2 K. After reducing the magnetic field down to zero, we have successfully trapped a magnetic field of 7.9 T at the centre of the double stack. The magnetic field profile of the bulk magnet is calculated by fully considering the Jc(B) characteristics of the short segment of the CC. The trapped magnetic field values measured by Hall probes at three locations near the centre of the double stacks agree reasonably well with the calculated magnetic induction.

  5. Generation of strong magnetic field using 60 mm∅ superconducting bulk magnet and its application to magnetron sputtering device

    NASA Astrophysics Data System (ADS)

    Yanagi, Y.; Matsuda, T.; Hazama, H.; Yokouchi, K.; Yoshikawa, M.; Itoh, Y.; Oka, T.; Ikuta, H.; Mizutani, U.

    2005-10-01

    To make a practical application of a superconducting bulk magnet (SBM), it is necessary that the SBM generates a strong and stable magnetic field in a working space and the magnet can be handled without any special care that would be needed because of the use of a superconductor. To satisfy these requirements, we have designed a portable and user-friendly magnet system consisting of a small air-cooled type refrigerator and a bulk superconductor. By using the stress-controlling magnetization technique, we could achieve a magnetic flux density of 8.0 T on the bulk surface and 6.5 T over the vacuum chamber surface of the refrigerator, when a 60 mm∅ Gd-Ba-Cu-O bulk superconductor reinforced with a 5 mm thick stainless steel ring was magnetized by field cooling in 8.5 T to 27 K. We have confirmed that the bulk magnet system coupled with a battery is quite portable and can be delivered to any location by using a car with an electric power outlet in the cabin. We have constructed a magnetron sputtering device that employs a bulk magnet system delivered from the place of magnetization by this method. This sputtering device exhibits several unique features such as deposition at a very low Ar gas pressure because the magnetic field is 20 times stronger than that obtained by a conventional device in the working space.

  6. Magnetic domain walls in bulk and thin film Fe: first principles noncollinear magnetism study

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Takeda, Y.; Akiyama, T.; Ito, T.; Freeman, A. J.

    2004-03-01

    We investigate the electronic and magnetic structures of domain walls in ferromagnetic Fe bulk and Fe(110) monolayer by using the first-principles FLAPW method(Wimmer, Krakauer, Weinert and Freeman, PRB 24, 864(1981)) including noncollinear magnetism with no shape approximation of the magnetization density.(Nakamura, Freeman, Wang, Zhong, and Fernandez-de-Castro, PRB 65, 12402 (2002); 67, 14420 (2003)) In the bulk case, the self-consistent LSDA results demonstrate that the magnetic moments change continuously from one orientation to another as seen in a Bloch wall, and reveal that the formation energy of the domain wall significantly decreases when the domain wall thickness increases, as expected from phenomenological theory. The domain walls in thin film behave very differently: Surprisingly, the magnetic moment directions change rapidly; thus the wall width is only about 8 ÅThis consists and supports the atomically sharp domain wall in Fe/W(110) by the recently proposed SP-STM measurements.(Pratzer, Elmers, Bode, Pietzsch, Kubetzka and Wiesendanger, PRL 87, 127201 (2001))

  7. RADIATION RESISTANT HTS QUADRUPOLES FOR RIA.

    SciTech Connect

    GUPTA,R.; ANERELLA,M.; HARRISON,M.; ET AL.

    2004-10-03

    Extremely high radiation, levels with accumulated doses comparable to those in nuclear reactors than in accelerators, and very high heat loads ({approx}15 kw) make the quadrupole magnets in the fragment separator one of the most challenging elements of the proposed Rare Isotope Accelerator (RIA). Removing large heat loads, protecting the superconducting coils against quenching, the long term survivability of magnet components, and in particular, insulation that can retain its functionality in such a harsh environment, are the major challenges associated with such magnets. A magnet design based on commercially available high temperature superconductor (HTS) and stainless steel tape insulation has been developed. HTS will efficiently remove these large heat loads and stainless steel can tolerate these large radiation doses. Construction of a model magnet has been started with several coils already built and tested. This paper presents the basic magnet design, results of the coil tests, the status and the future plans. In addition, preliminary results of radiation calculations are also presented.

  8. Vertical Magnetic Levitation Force Measurement on Single Crystal YBaCuO Bulk at Different Temperatures

    NASA Astrophysics Data System (ADS)

    Celik, Sukru; Guner, Sait Baris; Ozturk, Kemal; Ozturk, Ozgur

    Magnetic levitation force measurements of HTS samples are performed with the use of liquid nitrogen. It is both convenient and cheap. However, the temperature of the sample cannot be changed (77 K) and there is problem of frost. So, it is necessary to build another type of system to measure the levitation force high Tc superconductor at different temperatures. In this study, we fabricated YBaCuO superconducting by top-seeding-melting-growth (TSMG) technique and measured vertical forces of them at FC (Field Cooling) and ZFC (Zero Field Cooling) regimes by using our new designed magnetic levitation force measurement system. It was used to investigate the three-dimensional levitation force and lateral force in the levitation system consisting of a cylindrical magnet and a permanent cylindrical superconductor at different temperatures (37, 47, 57, 67 and 77 K).

  9. Development of HTS power cable using YBCO coated conductor

    NASA Astrophysics Data System (ADS)

    Mukoyama, Shinichi; Yagi, Masashi; Hirano, Hironobu; Yamada, Yutaka; Izumi, Teruo; Shiohara, Yuh

    2006-10-01

    Reductions of AC losses and of cost of HTS power cables are important to put it into practical power networks. Since an YBCO-coated-conductor (YBCO tape) has higher Jc and better magnetic property than a Bi2223-Ag-sheathed-tape, an AC power cable using YBCO tapes will obtain higher performance than XLPE-cables and HTS cables using BSCCO tapes in future. Especially, an YBCO HTS cable will be expected to become a higher economical cable than a Bi cable because an YBCO tape reduced its AC losses and its wire cost. We have started developing HTS power cables using YBCO tapes. Mechanical properties, superconducting properties and other electro magnetic properties of YBCO tapes have been measured to estimate the applicability to the HTS cable. Moreover, we have developed some technologies to bring out latent potentials of YBCO tapes.

  10. Ultrafast time domain demonstration of bulk magnetization precession at zero magnetic field ferromagnetic resonance induced by terahertz magnetic field.

    PubMed

    Nakajima, M; Namai, A; Ohkoshi, S; Suemoto, T

    2010-08-16

    We report the first observation of sub-terahertz bulk-magnetization precession, using terahertz time-domain spectroscopy. The magnetization precession in gallium-substituted epsilon-iron oxide nano-ferromagnets under zero magnetic field is induced by the impulsive magnetic field of the THz wave through the gyromagnetic effect. Just at the resonance frequency, the linear to circular polarized wave conversion is realized. This is understood as the free induction decay signal radiated from a rotating magnetic dipole corresponding to the natural resonance. Furthermore, this demonstration reveals that the series of gallium-substituted epsilon-iron oxide nano-ferromagnets is very prospective for magneto-optic devices, which work at room temperature without external magnetic field, in next-generation wireless communication.

  11. Practical adaptation in bulk superconducting magnetic bearing applications

    NASA Astrophysics Data System (ADS)

    McMichael, C. K.; Ma, K. B.; Lamb, M. A.; Lin, M. W.; Chow, L.; Meng, R. L.; Hor, P. H.; Chu, W. K.

    1992-04-01

    Lifting capacities greater than 41 N/sq cm (60 psi) at 77 K have been achieved using a combination of permanent magnets and high quality melt-textured YBa2Cu3O(7-delta) (YBCO). The key concept of this hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets to support high loads in conjunction with flux pinning in a type II superconductor to counteract instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust and journal bearing configurations on a bearing prototype.

  12. Experimental deformation of synthetic magnetite-bearing calcite sandstones - Effects on remanence, bulk magnetic properties, and magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Jackson, Mike; Borradaile, Graham; Hudleston, Peter; Banerjee, Subir

    1993-01-01

    The simultaneous effects of deformation on the magnetic remanence, bulk magnetic properties, and magnetic anisotropy of magnetite-bearing calcite sandstones were investigated in a set of synthetic magnetite-bearing samples prepared as described by Borradaile and Alford (1987). Experimental deformations of synthetic sandstone analogs containing 40-micron magnetite were found to produce significant changes in the orientation of anhysteretic remanence, in bulk magnetic properties, and in magnetic anisotropy. These changes proceeded slowly for shortening strains below about 10 percent, but much more rapidly at higher strains.

  13. Development of a brushless HTS exciter for a 10 kW HTS synchronous generator

    NASA Astrophysics Data System (ADS)

    Bumby, Chris W.; Badcock, Rodney A.; Sung, Hae-Jin; Kim, Kwang-Min; Jiang, Zhenan; Pantoja, Andres E.; Bernardo, Patrick; Park, Minwon; Buckley, Robert G.

    2016-02-01

    HTS synchronous generators, in which the rotor coils are wound from high-T c superconducting wire, are exciting attention due to their potential to deliver very high torque and power densities. However, injection of the large DC currents required by the HTS rotor coils presents a technical challenge. In this paper we discuss the development of a brushless HTS exciter which operates across the cryostat wall to inject a superconducting DC current into the rotor coil circuit. This approach fundamentally alters the thermal load upon the cryogenic system by removing the need for thermally inefficient normal-conducting current leads. We report results from an experimental laboratory device and show that it operates as a constant voltage source with an effective internal resistance. We then discuss the design of a prototype HTS-PM exciter based on our experimental device, and describe its integration with a demonstration HTS generator. This 200 RPM, 10 kW synchronous generator comprises eight double pancake HTS rotor coils which are operated at 30 K, and are energised to 1.5 T field through the injection of 85 A per pole. We show how this excitation can be achieved using an HTS-PM exciter consisting of 12 stator poles of 12 mm YBCO coated-conductor wire and an external permanent magnet rotor. We demonstrate that such an exciter can excite the rotor windings of this generator without forming a thermal-bridge across the cryostat wall. Finally, we provide estimates of the thermal load imposed by our prototype HTS-PM exciter on the rotor cryostat. We show that duty cycle operation of the device ensures that this heat load can be minimised, and that it is substantially lower than that of equivalently-rated conventional current leads.

  14. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    SciTech Connect

    Lollobrigida, V.; Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F.; Borgatti, F.; Torelli, P.; Panaccione, G.; Tortora, L.; Stefani, G.; Offi, F.

    2014-05-28

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  15. Effect of Soft Phase on Magnetic Properties of Bulk Sm-Co/alpha-Fe Nanocomposite Magnets (Postprint)

    DTIC Science & Technology

    2012-11-01

    plasma sintering , and warm compaction [4][5]–[9]. In our previous study [10], bulk Sm–Co –Fe nanocomposite magnets were fabricated by hot pressing of...no. 5, pp. 2974–2976, Jul. 2003. [8] T. Saito and H. Miyoshi, “Magnetic properties of Sm5Fe17/Fe com- posite magnets produces by spark plasma ...Fe and Fe-Co. Bulk composite magnets have been prepared using compaction techniques such as hot pressing/deforma- tion, dynamic shock compaction, spark

  16. A novel HTS SMES application in combination with a permanent magnet synchronous generator type wind power generation system

    NASA Astrophysics Data System (ADS)

    Kim, G. H.; Kim, A. R.; Kim, S.; Park, M.; Yu, I. K.; Seong, K. C.; Won, Y. J.

    2011-11-01

    Superconducting magnetic energy storage (SMES) system is a DC current driven device and can be utilized to improve power quality particularly in connection with renewable energy sources due to higher efficiency and faster response than other devices. This paper suggests a novel connection topology of SMES which can smoothen the output power flow of the wind power generation system (WPGS). The structure of the proposed system is cost-effective because it reduces a power converter in comparison with a conventional application of SMES. One more advantage of SMES in the proposed system is to improve the capability of low voltage ride through (LVRT) for the permanent magnet synchronous generator (PMSG) type WPGS. The proposed system including a SMES has been modeled and analyzed by a PSCAD/EMTDC. The simulation results show the effectiveness of the novel SMES application strategy to not only mitigate the output power of the PMSG but also improve the capability of LVRT for PMSG type WPGS.

  17. Mobile conduction-cooled HTS SMES

    NASA Astrophysics Data System (ADS)

    Ren, L.; Tang, Y.; Li, J.; Shi, J.; Chen, L.; Guo, F.; Fang, J.; Wen, J.

    2010-11-01

    An immovable 35 kJ/7 kW high-Tc superconducting magnetic energy storage (HTS SMES) system had been developed in the Electric Power System Dynamic Simulation Laboratory, Huazhong University of Science and Technology in 2005. In order to adapt for on-site experimental conditions, the mechanical configuration of the magnet is reinforced and the SMES system is assembled in a special container to be freighted to the actual power system for the feasibility study on different applications at different sites. The mobile HTS SMES system had withstood various kinds of poor road surfaces and then arrived at the experimental site on August 18, 2009. In this paper, the reconstructed configuration and the shock absorption of the magnet are presented. The field test results show that the mobile SMES system can operate on the power network at different locations and suppress effectively power fluctuation of the generator terminal.

  18. Effect of permanent-magnet irregularities in levitation force measurements

    NASA Astrophysics Data System (ADS)

    Hull, John R.

    2000-06-01

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a non-negligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analogue of Earnshaw's theorem, in which the vertical stiffness is equal to the sum of the horizontal stiffness at the field-cooling position, independent of the angular distribution of magnetic moments within the PM.

  19. Effect of permanent-magnet irregularities in levitation force measurements.

    SciTech Connect

    Hull, J. R.

    1999-10-14

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a nonnegligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analog of Earnshaw's theorem, in which at the field-cooling position the vertical stiffness is equal to the sum of the horizontal stiffnesses, independent of angular distribution of magnetic moments within the PM.

  20. Thermal analysis for the HTS stator consisting of HTS armature windings and an iron core for a 2.5 kW HTS generator

    NASA Astrophysics Data System (ADS)

    Song, P.; Qu, T.-M.; Lai, L.-F.; Wu, M.-S.; Yu, X.-Y.; Han, Z.

    2016-05-01

    Most present demonstrations of high-temperature superconducting (HTS) synchronous motors/generators are partially superconducting, only installing HTS coils on the rotor as excitation windings. The possible applicability of HTS armature windings is an interesting research topic because these windings can certainly increase the power density attributed to a potentially high armature loading capacity. In this study, we analysed the thermal behaviours of a developed 2.5 kW-300 rpm synchronous generator prototype that consists of an HTS stator with Bi-2223-Ag armature windings on an iron core and a permanent magnet (PM) rotor. The entire HTS stator, including the iron core, is cooled with liquid nitrogen through conduction cooling. The rated frequency is set at 10 Hz to reduce AC loss. The properties of the HTS windings and the iron core are characterized, and the temperatures in the HTS stator under different operation conditions are measured. The estimated iron loss is 11.5 W under operation in 10 Hz at liquid nitrogen temperature. Conduction cooling through the silicon iron core is sufficient to cool the iron core and to compensate for the temperature increment caused by iron loss. The stable running capacity is limited to 1.6 kW when the armature current is 12.6 A (effective values) due to the increasing temperature in the slots as a result of the AC loss in the HTS coils. The thermal contact between the HTS coils and the cooling media should be improved in the future to take away the heat generated by AC loss.

  1. A superconducting conveyer system using multiple bulk Y-Ba-Cu-O superconductors and permanent magnets

    NASA Astrophysics Data System (ADS)

    Kinoshita, T.; Koshizuka, N.; Nagashima, K.; Murakami, M.

    Developments of non-contact superconducting devices like superconducting magnetic levitation transfer and superconducting flywheel energy storage system have been performed based on the interactions between bulk Y-Ba-Cu-O superconductors and permanent magnets, in that the superconductors can stably be levitated without any active control. The performances of noncontact superconducting devices are dependent on the interaction forces like attractive forces and stiffness. In the present study, we constructed a non-contact conveyer for which the guide rails were prepared by attaching many Fe-Nd-B magnets onto an iron base plate. Along the translational direction, all the magnets were arranged as to face the same pole, and furthermore their inter-distance was made as small as possible. The guide rail has three magnet rows, for which the magnets were glued on the iron plate such that adjacent magnet rows have opposite poles like NSN. At the center row, the magnetic field at zero gap reached 0.61T, while the field strengths of two rows on the side edges were only 0.48T due to magnetic interactions among permanent magnets. We then prepared a cryogenic box made with FRP that can store several bulk Y-Ba-Cu-O superconductors 25 mm in diameter cooled by liquid nitrogen. It was found that the levitation forces and stiffness increased with increasing the number of bulk superconductors installed in the box, although the levitation force per unit bulk were almost the same. We also confirmed that these forces are dependent on the configuration of bulk superconductors.

  2. Development of toroid-type HTS DC reactor series for HVDC system

    NASA Astrophysics Data System (ADS)

    Kim, Kwangmin; Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho; Lee, Sangjin; Oh, Yunsang; Park, Minwon; Yu, In-Keun

    2015-11-01

    This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.

  3. Image processing for HTS SQUID probe microscope

    NASA Astrophysics Data System (ADS)

    Hayashi, T.; Koetitz, R.; Itozaki, H.; Ishikawa, T.; Kawabe, U.

    2005-10-01

    An HTS SQUID probe microscope has been developed using a high-permeability needle to enable high spatial resolution measurement of samples in air even at room temperature. Image processing techniques have also been developed to improve the magnetic field images obtained from the microscope. Artifacts in the data occur due to electromagnetic interference from electric power lines, line drift and flux trapping. The electromagnetic interference could successfully be removed by eliminating the noise peaks from the power spectrum of fast Fourier transforms of line scans of the image. The drift between lines was removed by interpolating the mean field value of each scan line. Artifacts in line scans occurring due to flux trapping or unexpected noise were removed by the detection of a sharp drift and interpolation using the line data of neighboring lines. Highly detailed magnetic field images were obtained from the HTS SQUID probe microscope by the application of these image processing techniques.

  4. Rotor compound concept for designing an industrial HTS synchronous motor

    NASA Astrophysics Data System (ADS)

    Kashani, M.; Hosseina, M.; Sarrafan, K.; Darabi, A.

    2013-06-01

    Recently, producing power with smaller amount of losses become as a goal in our daily life. Today, large amount of energy waste in power networks all around the world. The main reason is “resistive electric equipments” of power networks. Since early 1980s, simultaneous with the development of high temperature superconductive (HTS) technology, superconductors gently attracted the mankind attentions. Using superconductive equipments instead of conventional resistive ones are result in salient electric loss reduction in power systems. Especially to reduce losses in power networks superconductive industrial rotating machines can potentially perform a significant role. In early recent century, first generation of HTS rotating machines was born. But unfortunately they have long way to penetrate the commercial markets yet. In HTS rotating machines the conventional copper made windings are replaced with the HTS superconductors. In this paper an industrial HTS synchronous motor with YBCO coated conductor field windings was designed. As a new approach, model was equipped with a compound rotor that includes both magnetic and non-magnetic materials. So, large amount of heavy iron made part was replaced by light non-magnetic material such as G-10 fiberglass. Furthermore, in this structure iron loss in rotor could be reduced to its lowest value. Also less weight and more air gap energy density were the additional advantages. Regarding zero electric loss production in field windings and less iron loss in rotor construction, this model potentially is more effective than the other iron made HTS motors.

  5. Magnetic Induction Machines Integrated into Bulk-Micromachined Silicon

    DTIC Science & Technology

    2006-04-01

    machines were characterized in three stages: (A) electrical measurements of the stators, (B) ferrofluid tests of the stator, and (C) tethered rotor torque...the upper and lower coils for each machine. B. Ferrofluid Tests A ferrofluid , a colloidal suspension of magnetic particles in a liquid (oil) carrier...Kapton film and placed over the stator, as shown in Fig. 10. The tub was filled with a thin layer of ferrofluid (Ferrotec Corporation, Nashua, NH) that

  6. Spin Orbit Torque in TbCo Films with Bulk Perpendicular Magnetic Anisotropy

    NASA Astrophysics Data System (ADS)

    Ueda, Kohei; Mann, Maxwell; Tan, Aik-Jun; Beach, Geoffrey. S. D.

    Spin-orbit torque (SOT) has generated considerable interest for manipulating magnetization in spintronic devices with ultra-low dissipation. Recent research has demonstrated that highly efficient magnetization control can be driven by current-induced SOT in ferromagnet/heavy metals bilayers with strong spin orbit coupling. However, most work on SOT has focused on ultra-thin magnetic films with interfacial perpendicular magnetic anisotropy (PMA), whereas future devices will require bulk PMA for sufficient thermal stability. Recently, Zhao et al reported SOT induced magnetization switching in a bulk PMA material; however, the films examined were still rather thin. Here we examine spin orbit torques in TbCo alloy films with bulk PMA, sandwiched between top and bottom Ta layers. By performing conventional harmonic and current-induced switching measurements, we quantified the current-induced effective fields generated by damping-like (DL) and field-like (FL) torques. The DL torque is much larger than FL torque, and corresponds to an effective spin Hall angle consistent with that of Ta. Owing to the relatively small saturation magnetized of these ferrimagnetic materials, the current-induced effective field is comparable to that observed in nm-thick Co films, despite the much larger film thicknesses used here. These results demonstrate ferromagnetic alloys with bulk PMA can be engineered to simultaneously provide thermal stability and efficient SOT switching.

  7. The transfer between electron bulk kinetic energy and thermal energy in collisionless magnetic reconnection

    SciTech Connect

    Lu, San; Lu, Quanming; Huang, Can; Wang, Shui

    2013-06-15

    By performing two-dimensional particle-in-cell simulations, we investigate the transfer between electron bulk kinetic and electron thermal energy in collisionless magnetic reconnection. In the vicinity of the X line, the electron bulk kinetic energy density is much larger than the electron thermal energy density. The evolution of the electron bulk kinetic energy is mainly determined by the work done by the electric field force and electron pressure gradient force. The work done by the electron gradient pressure force in the vicinity of the X line is changed to the electron enthalpy flux. In the magnetic island, the electron enthalpy flux is transferred to the electron thermal energy due to the compressibility of the plasma in the magnetic island. The compression of the plasma in the magnetic island is the consequence of the electromagnetic force acting on the plasma as the magnetic field lines release their tension after being reconnected. Therefore, we can observe that in the magnetic island the electron thermal energy density is much larger than the electron bulk kinetic energy density.

  8. Hard magnetic properties observed in bulk Mn1–xGax

    DOE PAGES

    Brown, Daniel R.; Han, Ke; Siegrist, Theo

    2014-02-19

    Here, Mn-Ga binary alloys have shown promising magnetic properties, even though these alloys contain no rare-earth metals. Both theoretical predictions and experimental work showed that nanoscaled Mn-Ga samples, such as thin films could have remarkable magnetic properties. Although the prediction provides a useful guideline and thin films supply us with materials in some application, bulk materials are required for majority of the applications that require a strong magnetic field. We have made bulk Mn1-xGax alloys by mechanically milling and heat treatments. In this paper, we report annealed Mn1-xGax bulk composites that exhibit coercivity up to 18.8 kOe.

  9. Soft magnetic composites manufactured by warm co-extrusion of bulk metallic glass and steel powders

    SciTech Connect

    Johnson, Francis; Raber, Thomas R.; Zabala, Robert J.; Buresh, Steve J.; Tanico, Brian

    2013-05-07

    Soft magnetic composites of Fe-based bulk metallic glass and low-alloy steel have been manufactured by warm co-extrusion of precursor powders at temperatures within the supercooled liquid region of the glass. Composites were manufactured with amorphous volume fractions of 75%, 67%, and 100%. Full consolidation of the constituent powders was observed with the bulk metallic glass remaining substantially amorphous. The composite electrical resistivity was observed to be anisotropic with a resistivity of 79 {mu}{Omega} cm measured transverse to the extrusion axis in a sample with 75% amorphous volume fraction. A 0-3 connectivity pattern with the low-resistivity steel phase embedded in a 3-dimensionally connected high-resistivity bulk metallic glass phase was observed with scanning electron microscopy. This confirms that the flow characteristics of the bulk metallic glass and the steel powders were comparable during extrusion at these temperatures. The saturation magnetization of 1.3 T was consistent with the volume weighted average of the saturation magnetization of the two phases. A relatively high quasistatic coercivity of 8 Oe was measured and is likely due to slight crystallization of the bulk metallic glass as well as domain wall pinning at prior particle boundaries. Careful control of the thermal environment during the extrusion process is required to minimize glass crystallization and achieve the desired balance of magnetic and electrical properties.

  10. Trapped Magnetic Field Properties of MgB2 Bulks Doped with Ti

    NASA Astrophysics Data System (ADS)

    Naito, Tomoyuki; Yoshida, Takafumi; Fujishiro, Hiroyuki

    We have studied the trapped magnetic field properties on doped MgB2 bulk with Ti (nominal content was Mg:Ti =0.9:0.1 and 0.8:0.2). The trapped magnetic field, BT, was enhanced by approximately 1.3 times from 2.6 T of the pristine bulk to 3.5 T of the Ti-doped bulks at 15 K. The extrapolated BT(T) curve reached 5 T below 4.2 K, indicating that 5 T class bulk magnet can be realized using MgB2 with Ti-doping. The critical current density, Jc, under the magnetic field was also enhanced by Ti-doping, therefore, an irreversibility field, Birr, of the Ti-doped bulks exceeded 5 T at 20 K. Ti and TiB2 impurities confirmed by the pow- der X-ray diffraction acted as the pinning centers and resulted in the enhancement of the trapped field and the critical current density.

  11. Soft magnetic composites manufactured by warm co-extrusion of bulk metallic glass and steel powders

    NASA Astrophysics Data System (ADS)

    Johnson, Francis; Raber, Thomas R.; Zabala, Robert J.; Buresh, Steve J.; Tanico, Brian

    2013-05-01

    Soft magnetic composites of Fe-based bulk metallic glass and low-alloy steel have been manufactured by warm co-extrusion of precursor powders at temperatures within the supercooled liquid region of the glass. Composites were manufactured with amorphous volume fractions of 75%, 67%, and 100%. Full consolidation of the constituent powders was observed with the bulk metallic glass remaining substantially amorphous. The composite electrical resistivity was observed to be anisotropic with a resistivity of 79 μΩ cm measured transverse to the extrusion axis in a sample with 75% amorphous volume fraction. A 0-3 connectivity pattern with the low-resistivity steel phase embedded in a 3-dimensionally connected high-resistivity bulk metallic glass phase was observed with scanning electron microscopy. This confirms that the flow characteristics of the bulk metallic glass and the steel powders were comparable during extrusion at these temperatures. The saturation magnetization of 1.3 T was consistent with the volume weighted average of the saturation magnetization of the two phases. A relatively high quasistatic coercivity of 8 Oe was measured and is likely due to slight crystallization of the bulk metallic glass as well as domain wall pinning at prior particle boundaries. Careful control of the thermal environment during the extrusion process is required to minimize glass crystallization and achieve the desired balance of magnetic and electrical properties.

  12. Development of superconducting magnetic bearing with superconducting coil and bulk superconductor for flywheel energy storage system

    NASA Astrophysics Data System (ADS)

    Arai, Y.; Seino, H.; Yoshizawa, K.; Nagashima, K.

    2013-11-01

    We have been developing superconducting magnetic bearing for flywheel energy storage system to be applied to the railway system. The bearing consists of a superconducting coil as a stator and bulk superconductors as a rotor. A flywheel disk connected to the bulk superconductors is suspended contactless by superconducting magnetic bearings (SMBs). We have manufactured a small scale device equipped with the SMB. The flywheel was rotated contactless over 2000 rpm which was a frequency between its rigid body mode and elastic mode. The feasibility of this SMB structure was demonstrated.

  13. A Bulk Superconducting Magnetic System for the CLAS12 Target at Jefferson Lab

    SciTech Connect

    Statera, Marco; Contalbrigo, Marco; Ciullo, Giuseppe; Lenisa, Paulo; Lowry, Michael M.; Sandorfi, Andrew M.

    2015-06-01

    A feasibility study of a bulk magnetic system for the target of an experiment to measure the transverse spin effects in semi-inclusive deep inelastic scattering (SIDIS) at 11 GeV with a transversely polarized target using the CLAS12 detector is presented. An experiment has been approved with the highest priority rating to study spin azimuthal asymmetries in SIDIS using 11-GeV polarized electron beams from the upgraded CEBAF facility and the CLAS12 detector equipped with a transversely polarized target. The transverse target in CLAS12 requires the shielding of a volume inside the longitudinal field of the main solenoid. In the shielded region, a transverse target magnet can operate; for the proposed magnetic configuration, the main solenoid maximum magnetic induction is 2 T. A bulk MgB2 cylinder cooled in liquid helium is proposed both to shield the longitudinal field of the main solenoid and to provide a transverse field induction up to 1.2 T for the hydrogen deuteride ice (HD-ice) target. The installation and magnetization procedure will be described. The magnetization procedure has to be compatible with the polarization and installation procedure of the HD-ice target. The design of a test bench to measure the transverse magnetization of a MgB2 bulk cylinder cooled by a coldhead is presented together with the scheduled measurements.

  14. Effect of milling time on magnetic properties and structures of bulk Sm-Co/{alpha}-(Fe, Co) nanocomposite magnets

    SciTech Connect

    Shen, Y.; Huang, M. Q.; Turgut, Z.; Lucas, M. S.; Michel, E.; Horwath, J. C.

    2012-04-01

    Bulk Sm-Co/{alpha}-(Fe,Co) nanocomposite magnets were fabricated by hot pressing composite powders prepared by high-energy ball milling of magnetically hard SmCo{sub 5} powder and magnetically soft Fe powder. The bulk magnets had a nanocomposite structure consisting of Sm-Co matrix (1:5 H and 1:7 H phases) and {alpha}-(Fe,Co) phases. The Fe-Co particles were distributed uniformly in the Sm-Co matrix. The milling time strongly affects the structures and the magnetic properties of the bulk magnets. Increasing milling time led to a decrease of the amount of 1:5 H phase, an increase in the phase fraction of the 1:7 H phase, and a decrease in the amount of soft phase, which resulted in an increase in magnetization and a decrease in coercivity. Scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) analyses revealed that inter-diffusion took place between the Sm-Co matrix and Fe particles during the processing.

  15. Effect of milling time on magnetic properties and structures of bulk Sm-Co/α-(Fe, Co) nanocomposite magnets

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Huang, M. Q.; Turgut, Z.; Lucas, M. S.; Michel, E.; Horwath, J. C.

    2012-04-01

    Bulk Sm-Co/α-(Fe,Co) nanocomposite magnets were fabricated by hot pressing composite powders prepared by high-energy ball milling of magnetically hard SmCo5 powder and magnetically soft Fe powder. The bulk magnets had a nanocomposite structure consisting of Sm-Co matrix (1:5 H and 1:7 H phases) and α-(Fe,Co) phases. The Fe-Co particles were distributed uniformly in the Sm-Co matrix. The milling time strongly affects the structures and the magnetic properties of the bulk magnets. Increasing milling time led to a decrease of the amount of 1:5 H phase, an increase in the phase fraction of the 1:7 H phase, and a decrease in the amount of soft phase, which resulted in an increase in magnetization and a decrease in coercivity. Scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) analyses revealed that inter-diffusion took place between the Sm-Co matrix and Fe particles during the processing.

  16. Some features of bulk melt-textured high-temperature superconductors subjected to alternating magnetic fields

    NASA Astrophysics Data System (ADS)

    Vanderbemden, P.; Molenberg, I.; Simeonova, P.; Lovchinov, V.

    2014-12-01

    Monolithic, large grain, (RE)Ba2Cu3O7 high-temperature superconductors (where RE denotes a rare-earth ion) are known to be able to trap fields in excess of several teslas and represent thus an extremely promising competing technology for permanent magnet in several applications, e.g. in motors and generators. In any rotating machine, however, the superconducting permanent magnet is subjected to variable (transient, or alternating) parasitic magnetic fields. These magnetic fields interact with the superconductor, which yields a reduction of the remnant magnetization. In the present work we quantify these effects by analysing selected experimental data on bulk melt-textured superconductors subjected to AC fields. Our results indicate that the non-uniformity of superconducting properties in rather large samples might lead to unusual features and need to be taken into account to analyse the experimental data. We also investigate the evolution of the DC remnant magnetization of the bulk sample when it is subjected to a large number of AC magnetic field cycles, and investigate the experimental errors that result from a misorientation of the sample or a mispositioning of the Hall probe. The time-dependence of the remnant magnetization over 100000 cycles of the AC field is shown to display distinct regimes which all differ strongly from the usual decay due to magnetic relaxation.

  17. Temperature measurements in small holes drilled in superconducting bulk during pulsed field magnetization

    NASA Astrophysics Data System (ADS)

    Fujishiro, H.; Naito, T.; Furuta, D.; Kakehata, K.

    2010-11-01

    The time dependence of the temperatures T(z, t) has been measured along the thickness direction z in several drilled holes in a superconducting bulk during pulsed field magnetization (PFM) and the heat generation and heat transfer in the bulk have been discussed. In the previous paper [H. Fujishiro, S. Kawaguchi, K. Kakehata, A. Fujiwara, T. Tateiwa, T. Oka, Supercond. Sci. Technol. 19 (2006) S540], we calculated the T(z, t) profiles in the bulk by solving a three-dimensional heat-diffusion equation to reproduce the measured T(t) on the bulk surface; the heat generation took place adiabatically and the calculated T(z, t) was isothermal along the z direction. In this study, the measured T(z, t) at the top surface was higher than that at the bottom surface just after the pulse field application at t < 0.5 s, and then became isothermal with increasing time. These results suggest that the magnetic flux intrudes inhomogeneously into the bulk from the edge of the top surface and the periphery at the early stage. The inhomogeneous magnetic flux intrusion and the flux trap during PFM change depending on the strength of the pulsed field and the pulse number in the successive pulse field application.

  18. Bulk viscosity of quark-gluon matter in a magnetic field

    SciTech Connect

    Agasian, N. O.

    2013-11-15

    On the basis of low-energy QCD theorems, the bulk viscosity {zeta}(T, Micro-Sign , H) is expressed in terms of basic thermodynamic quantities that characterizes quark-gluon matter at finite temperature and a finite baryon density in a magnetic field. Various limiting cases are considered.

  19. Magnetic levitation and its application for education devices based on YBCO bulk superconductors

    NASA Astrophysics Data System (ADS)

    Yang, W. M.; Chao, X. X.; Guo, F. X.; Li, J. W.; Chen, S. L.

    2013-10-01

    A small superconducting maglev propeller system, a small spacecraft model suspending and moving around a terrestrial globe, several small maglev vehicle models and a magnetic circuit converter have been designed and constructed. The track was paved by NdFeB magnets, the arrangement of the magnets made us easy to get a uniform distribution of magnetic field along the length direction of the track and a high magnetic field gradient in the lateral direction. When the YBCO bulks mounted inside the vehicle models or spacecraft model was field cooled to LN2 temperature at a certain distance away from the track, they could be automatically floating over and moving along the track without any obvious friction. The models can be used as experimental or demonstration devices for the magnetic levitation applications.

  20. Espisodic detachment of Martian crustal magnetic fields leading to bulk atmospheric plasma escape

    SciTech Connect

    Brain, D A; Baker, A H; Briggs, J; Eastwood, J P; Halekas, J S; Phan, T

    2009-06-02

    We present an analysis of magnetic field and suprathermal electron measurements from the Mars Global Surveyor (MGS) spacecraft that reveals isolated magnetic structures filled with Martian atmospheric plasma located downstream from strong crustal magnetic fields with respect to the flowing solar wind. The structures are characterized by magnetic field enhancements and rotations characteristic of magnetic flux ropes, and characteristic ionospheric electron energy distributions with angular distributions distinct from surrounding regions. These observations indicate that significant amounts of atmosphere are intermittently being carried away from Mars by a bulk removal process: the top portions of crustal field loops are stretched through interaction with the solar wind and detach via magnetic reconnection. This process occurs frequently and may account for as much as 10% of the total present-day ion escape from Mars.

  1. The effect of temperature on pinning mechanisms in HTS composites

    NASA Astrophysics Data System (ADS)

    Sotnikova, A. P.; Rudnev, I. A.

    2016-09-01

    Pinning mechanism in samples of second generation tapes (2G) of high-temperature superconductors (HTS) was studied The critical current and the pinning force were calculated from the magnetization curves measured in the temperature range of 4.2 - 77 K in magnetic fields up to 14 Tesla using vibration sample magnetometer. To determine the pinning mechanism the dependences of pinning force on magnetic field were constructed according to the Dew-Hughes model and Kramer's rule. The obtained dependences revealed a significant influence of the temperature on effectiveness of different types of pinning. At low temperatures the 2G HTS tapes of different manufacturers demonstrated an equal efficiency of the pinning centers but with temperature increase the differences in pinning mechanisms as well as in properties and effectiveness of the pinning centers become obvious. The influence of the pinning mechanism on the energy losses in HTS tapes was shown.

  2. Mechanism of thickness dependence of critical current density in HTS YBCO film and its elimination using nano-engineering

    NASA Astrophysics Data System (ADS)

    Wang, Xiang

    The most promising characteristic of a High Temperature Superconductor (HTS) is its ability to carry larger electrical current at liquid nitrogen boiling temperature and strong applied magnetic field with minimal dissipation. Numerous large scale applications such as HTS transmission cables, HTS magnets and HTS motors have been developed using HTS materials. The major limitation that prevents its wide commercialization is its high cost-to-performance ratio. However, the effort to further improve HTS current carrying capability is jeopardized by a mysterious thickness dependence of the critical current density (Jc) --- Jc monotonically decreases with increasing thickness (t) at 77 K and self-field (SF). This poses a great challenge for both HTS applications and the understanding of vortex dynamics. What further complicates this issue is the complex defect structure in HTS films as well as the creep nature of magnetic vortices at a finite temperature. After a systematic study of the temperature and magnetic field effects on Jc--t, we conclude that Jc--t is most likely the result of a collective pinning effect dictated by a random pinning potential. Besides that, thermal fluctuations also alter Jc--t in a predictable way. Therefore, by either modifying the vortex structure or pinning structure, J c--t can be eliminated. Indeed, a thin film J c has been restored in a HTS/insulator/HTS trilayer while the magnetic coupling is weakened. Moreover, Jc--t has been removed when the random distributed point pins are overpowered by strong linear defects.

  3. Intergrain magnetic properties and critical currents of T1-1223 bulk and tape superconductors

    NASA Astrophysics Data System (ADS)

    Zalecki, R.; Kolodziejczyk, A.; Chmist, J.; König, W.; Gritzner, G.

    2000-11-01

    The magnetic field and the temperature dependencies of the dispersive and the absorption components of the low frequency ac magnetic susceptibility for Pb and Bi single doped bulk superconductors as well as for Pb and Bi co-doped Ag-sheathed superconducting T1-1223 tapes have been measured and analyzed. The studies were accompanied by optical and electron microscopic observations of the microstructure. The ac susceptibility measured at various ac magnetic field amplitudes showed both intergrain and intragrain features. The temperature dependencies of the intergrain critical current densities were extracted from the absorption susceptibility via a modified Bean model. They were at relevant temperatures one order of magnitude larger for the tape than for the bulk specimens.

  4. Improved performance of SrFe12O19 bulk magnets through bottom-up nanostructuring

    NASA Astrophysics Data System (ADS)

    Saura-Múzquiz, Matilde; Granados-Miralles, Cecilia; Stingaciu, Marian; Bøjesen, Espen Drath; Li, Qiang; Song, Jie; Dong, Mingdong; Eikeland, Espen; Christensen, Mogens

    2016-01-01

    The influence of synthesis and compaction parameters is investigated with regards to formation of high performance SrFe12O19 bulk magnets. The produced magnets consist of highly aligned, single-magnetic domain nanoplatelets of SrFe12O19. The relationship between the magnetic performance of the samples and their structural features is established through systematic characterization by Vibrating Sample Magnetometry (VSM) and Rietveld refinement of powder X-ray diffraction data (PXRD). The analysis is supported by complementary techniques including Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and X-ray pole figure measurements. SrFe12O19 hexagonal nanoplatelets with various sizes are synthesized by a supercritical hydrothermal flow method. The crystallite sizes are tuned by varying the Fe/Sr ratio in the precursor solution. Compaction of SrFe12O19 nanoplatelets into bulk magnets is performed by Spark Plasma Sintering (SPS). Rietveld refinement of the pressed pellets and texture analysis of pole figure measurements reveal that SPS pressing produces a high degree of alignment of the nanoplatelets, achieved without applying any magnetic field prior or during compaction. The highly aligned nanocrystallites combined with crystal growth during SPS give rise to an enormous enhancement of the magnetic properties compared to the as-synthesized powders, leading to high performance bulk magnets with energy products of 26 kJ m-3.The influence of synthesis and compaction parameters is investigated with regards to formation of high performance SrFe12O19 bulk magnets. The produced magnets consist of highly aligned, single-magnetic domain nanoplatelets of SrFe12O19. The relationship between the magnetic performance of the samples and their structural features is established through systematic characterization by Vibrating Sample Magnetometry (VSM) and Rietveld refinement of powder X-ray diffraction data (PXRD). The analysis is supported by complementary

  5. Coexistence of bulk and surface polaritons in a magnetic-semiconductor superlattice influenced by a transverse magnetic field

    NASA Astrophysics Data System (ADS)

    Tuz, Vladimir R.; Fesenko, Volodymyr I.; Fedorin, Illia V.; Sun, Hong-Bo; Han, Wei

    2017-03-01

    It is demonstrated that the effect of coexistence of bulk and surface polaritons within the same frequency band and the wavevector space can be achieved in a magnetic-semiconductor superlattice, providing a conscious choice of characteristic resonant frequencies and material fractions of the structure's underlying components as well as geometry of the external static magnetic field. The study is based on the effective medium theory, which is involved to calculate dispersion characteristics of the long-wavelength electromagnetic modes of ordinary and extraordinary bulk polaritons, and hybrid surface polaritons with dominant longitudinal component of either magnetic (HE) or electric (EH) field derived via averaged expressions with respect to the effective constitutive parameters of the superlattice.

  6. A portable magnetic field of >3 T generated by the flux jump assisted, pulsed field magnetization of bulk superconductors

    NASA Astrophysics Data System (ADS)

    Zhou, Difan; Ainslie, Mark D.; Shi, Yunhua; Dennis, Anthony R.; Huang, Kaiyuan; Hull, John R.; Cardwell, David A.; Durrell, John H.

    2017-02-01

    A trapped magnetic field of greater than 3 T has been achieved in a single grain GdBa2Cu3O7-δ (GdBaCuO) bulk superconductor of diameter 30 mm by employing pulsed field magnetization. The magnet system is portable and operates at temperatures between 50 K and 60 K. Flux jump behaviour was observed consistently during magnetization when the applied pulsed field, Ba, exceeded a critical value (e.g., 3.78 T at 60 K). A sharp dBa/dt is essential to this phenomenon. This flux jump behaviour enables the magnetic flux to penetrate fully to the centre of the bulk superconductor, resulting in full magnetization of the sample without requiring an applied field as large as that predicted by the Bean model. We show that this flux jump behaviour can occur over a wide range of fields and temperatures, and that it can be exploited in a practical quasi-permanent magnet system.

  7. Flux jumps in high-J c MgB2 bulks during pulsed field magnetization

    NASA Astrophysics Data System (ADS)

    Fujishiro, H.; Mochizuki, H.; Naito, T.; Ainslie, M. D.; Giunchi, G.

    2016-03-01

    Pulsed field magnetization (PFM) of a high-J c MgB2 bulk disk has been investigated at 20 K, in which flux jumps frequently occur for high pulsed fields. Using a numerical simulation of the PFM procedure, we estimated the time dependence of the local magnetic field and temperature during PFM. We analyzed the electromagnetic and thermal instability of the high-J c MgB2 bulk to avoid flux jumps using the time dependence of the critical thickness, d c(t), which shows the upper safety thickness to stabilize the superconductor magnetically, and the minimum propagation zone length, l m(t), to obtain dynamical stability. The values of d c(t) and l m(t) change along the thermally-stabilized direction with increasing temperature below the critical temperature, T c. However, the flux jump can be qualitatively understood by the local temperature, T(t), which exceeds T c in the bulk. Finally, possible solutions to avoid flux jumps in high-J c MgB2 bulks are discussed.

  8. Effect of temperature and magnetic field on magnetomechanical damping of Fe-based bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Torrens-Serra, J.; Solivelles, F.; Corró, M. L.; Stoica, M.; Kustov, S.

    2016-12-01

    Temperature and magnetic field dependence of magnetomechanical damping (MMD) of two ferromagnetic Fe-based bulk metallic glasses with different Curie temperatures, T C, have been studied over a broad temperature interval from the para-ferromagnetic transition down to 15 K. The damping has been scanned under periodic magnetic field at certain preselected temperatures in the ferromagnetic and paramagnetic phases. The selection of bulk metallic glasses for investigations allowed us to eliminate all dislocation-related anelastic effects and facilitated separation of the MMD components. Under zero field, the non-linear MMD emerges at T C and first increases linearly with (T C  -  T), then levels off until a maximum is formed at around 36 K. At lower temperatures, the magnetic domain wall related non-linear MMD component is partially or completely supressed, depending on the alloy composition. Qualitatively similar anomaly is found in the temperature dependence of the linear macroeddy current damping. These anomalies in the temperature spectra are concomitant with the emergence of a notable hysteresis in MMD versus periodic field dependences and of a maximum of non-linear MMD close to the position of the macroeddy damping peak. The uncovered phenomena are attributed to abrupt change of magnetic properties of ferromagnetic bulk metallic glasses at low temperatures, presumably due to the re-entrant spin glass transition.

  9. Parametric Study of HTS Coil Quench Protection Strategies

    NASA Astrophysics Data System (ADS)

    Seibert, Joseph; Zarnstorff, Michael; Zhai, Yuhu

    2016-10-01

    Next generation fusion devices require high magnetic fields to adequately contain burning plasmas. Use of high temperature superconducting (HTS) coils to generate these magnetic fields would lower energy cost of operation as well as increase stability of the superconducting state compared to low temperature superconducting coils. However, use of HTS coils requires developing quench protection strategies to prevent damage to the coils. One technique involves the utilization of copper discs and other conductors mutually coupled to the HTS coil to quickly extract the current from the coil. Another technique allows conduction between HTS turns to reduce the current in the coil during quench. This project describes a parametric study of the HTS coil and resistive-conductor setup in order to determine limiting cases of the geometry in an attempt to optimize current extraction and coil protection during quench scenarios. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program.

  10. Fe-Zr-Nd-Y-B permanent magnet derived from crystallization of bulk amorphous alloy

    NASA Astrophysics Data System (ADS)

    Tan, Xiaohua; Xu, Hui; Bai, Qin; Dong, Yuanda

    2007-12-01

    The microstructure and magnetic properties of Nd2Fe14B/(Fe3B,α-Fe) nanocomposite magnet derived form crystallization of bulk amorphous Fe68Zr2Y4B21Nd5 alloy, which was prepared by copper mold casting, have been investigated. The obtaining maximum values of Ms, Mr, Hci, and (BH)max annealed at 963K for Fe68Zr2Nd5Y4B21 alloy are 86Am2/kg, 49Am2/kg, 380kA/m, and 43kJ/m3, respectively. δM plot, high resolution transmission electron microscopy observation, and three-dimensional atom probe technique clarified that the hard magnetic behavior is due to the exchange coupling between soft and hard magnetic nanophases.

  11. Bulk interface engineering for enhanced magnetization in multiferroic BiFeO3 compounds

    NASA Astrophysics Data System (ADS)

    Pillai, Shreeja; Bhuwal, Deepika; Banerjee, Alok; Shelke, Vilas

    2013-02-01

    We investigated composites of two antiferromagnetic perovskite oxides BiFeO3 and LaMnO3 to study change in bulk magnetic behavior. Composites with nominal compositions (1-x)BiFeO3-xLaMnO3 (x = 0, 5, 10, 20 wt. %) were synthesized by solid state reaction route. The structural analysis performed using X-ray diffraction and Raman spectroscopy indicated presence of phase separated compounds. Significant enhancement in magnetic moment is observed in composite samples, which was attributed to the uncompensated spins at the interface of two distinct antiferromagnetic phases.

  12. Influence of Critical Current Density on Magnetic Force of Htsc Bulk above Pmr with 3D-MODELING Numerical Solutions

    NASA Astrophysics Data System (ADS)

    Lu, Yiyun; Lu, Bingjuan; Ge, Yunwang; Chen, Wenqing

    Numerical electromagnetic field simulations of high-temperature superconductors (HTSC) bulk were carried out to calculate the magnetic force between the HTSC bulk and the permanent magnet railway (PMR). A 3D-modeling numerical calculation method is proposed using the finite element method. The model is formulated with the magnetic field vector (H-method). The resulting code was written with FORTRAN language. The electric field intensity E and the current density J constitutive relation of HTSC were described with E-J power law. The Kim macro-model is used to describe critical current density Jc of HTSC bulk. Two virtual HTSC bulks were used to solve the critical current density Jc anisotropic properties of HTSC materials. A superconducting levitation system composed of one HTSC bulk and PMR is successfully investigated using the proposed method. By this method, the influence of critical current density on magnetic levitation force of the superconducting levitation system is mathematically studied.

  13. Small-angle neutron scattering correlation functions of bulk magnetic materials

    PubMed Central

    Mettus, Denis; Michels, Andreas

    2015-01-01

    On the basis of the continuum theory of micromagnetics, the correlation function of the spin-misalignment small-angle neutron scattering cross section of bulk ferromagnets (e.g. elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels) is computed. For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin-misalignment scattering dΣM/dΩ along the forward direction. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣM/dΩ (e.g. the angular anisotropy on a two-dimensional detector or the asymptotic power-law exponent) are determined by the ratio of magnetic anisotropy field strength H p to the jump ΔM in the saturation magnetization at internal interfaces. Here, the corresponding one- and two-dimensional real-space correlations are analyzed as a function of applied magnetic field, the ratio H p/ΔM, the single-particle form factor and the particle volume fraction. Finally, the theoretical results for the correlation function are compared with experimental data on nanocrystalline cobalt and nickel. PMID:26500464

  14. Magnetic resonance study of bulk and thin film EuTiO3

    NASA Astrophysics Data System (ADS)

    Laguta, V. V.; Kamba, S.; Maryško, M.; Andrzejewski, B.; Kachlík, M.; Maca, K.; Lee, J. H.; Schlom, D. G.

    2017-03-01

    Magnetic resonance spectra of EuTiO3 in both bulk and thin film form were taken at temperatures from 3–350 K and microwave frequencies from 9.2–9.8 and 34 GHz. In the paramagnetic phase, magnetic resonance spectra are determined by magnetic dipole and exchange interactions between Eu2+ spins. In the film, a large contribution arises from the demagnetization field. From detailed analysis of the linewidth and its temperature dependence, the parameters of spin–spin interactions were determined: the exchange frequency is 10.5 GHz and the estimated critical exponent of the spin correlation length is  ≈0.4. In the bulk samples, the spectra exhibited a distinct minimum in the linewidth at the Néel temperature, T N  ≈  5.5 K, while the resonance field practically does not change even on cooling below T N. This is indicative of a small magnetic anisotropy ~320 G in the antiferromagnetic phase. In the film, the magnetic resonance spectrum is split below T N into several components due to excitation of the magnetostatic modes, corresponding to a non-uniform precession of magnetization. Moreover, the film was observed to degrade over two years. This was manifested by an increase of defects and a change in the domain structure. The saturated magnetization in the film, estimated from the magnetic resonance spectrum, was about 900 emu cm‑3 or 5.5 µ B/unit cell at T  =  3.5 K.

  15. Magnetic levitation using high temperature superconducting pancake coils as composite bulk cylinders

    NASA Astrophysics Data System (ADS)

    Patel, A.; Hopkins, S. C.; Baskys, A.; Kalitka, V.; Molodyk, A.; Glowacki, B. A.

    2015-11-01

    Stacks of superconducting tape can be used as composite bulk superconductors for both trapped field magnets and for magnetic levitation. Little previous work has been done on quantifying the levitation force behavior between stacks of tape and permanent magnets. This paper reports the axial levitation force properties of superconducting tape wound into pancake coils to act as a composite bulk cylinder, showing that similar stable forces to those expected from a uniform bulk cylinder are possible. Force creep was also measured and simulated for the system. The geometry tested is a possible candidate for a rotary superconducting bearing. Detailed finite element modeling in COMSOL Multiphysics was also performed including a full critical state model for induced currents, with temperature and field dependent properties and 3D levitation force models. This work represents one of the most complete levitation force modeling frameworks yet reported using the H-formulation and helps explain why the coil-like stacks of tape are able to sustain levitation forces. The flexibility of geometry and consistency of superconducting properties offered by stacks of tapes, make them attractive for superconducting levitation applications.

  16. Synchronous Generator with HTS-2G field coils for Windmills with output power 1 MW

    NASA Astrophysics Data System (ADS)

    Kovalev, K.; Kovalev, L.; Poltavets, V.; Samsonovich, S.; Ilyasov, R.; Levin, A.; Surin, M.

    2014-05-01

    Nowadays synchronous generators for wind-mills are developed worldwide. The cost of the generator is determined by its size and weight. In this deal the implementation of HTS-2G generators is very perspective. The application of HTS 2G field coils in the rotor allows to reduce the size of the generator is 1.75 times. In this work the design 1 MW HTS-2G generator is considered. The designed 1 MW HTS-2G generator has the following parameters: rotor diameter 800 mm, active length 400 mm, phase voltage 690V, rotor speed 600 min-1 rotor field coils with HTS-2G tapes. HTS-2G field coils located in the rotating cryostat and cooled by liquid nitrogen. The simulation and optimization of HTS-2G field coils geometry allowed to increase feed DC current up to 50A. Copper stator windings are water cooled. Magnetic and electrical losses in 1 MW HTS-2G generator do not exceed 1.6% of the nominal output power. In the construction of HTS-2G generator the wave multiplier with ratio 1:40 is used. The latter allows to reduce the total mass of HTS-2G generator down to 1.5 tons. The small-scale model of HTS-2G generator with output power 50 kW was designed, manufactured and tested. The test results showed good agreement with calculation results. The manufacturing of 1 MW HTS-2G generator is planned in 2014. This work is done under support of Rosatom within the frames of Russian Project "Superconducting Industry".

  17. The size effect on the magnetic levitation force of MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Savaskan, B.; Koparan, E. T.; Güner, S. B.; Celik, S.; Yanmaz, E.

    2016-12-01

    In this study, the size effect on the magnetic levitation performance of disk-shaped MgB2 bulk superconductors and permanent magnets was investigated. MgB2 samples with varying diameters of 13 mm, 15 mm and 18 mm, each of which were 2 g in mass, were prepared by two-step solid state reaction method. Vertical levitation force measurements under both zero-field-cooled (ZFC) and field-cooled (FC) regimes were carried out at different temperatures of 20, 24 and 28 K. It was determined that the levitation force of the MgB2 strongly depends on both the diameters of the sample and the permanent magnet. In ZFC regime, the maximum levitation force value for the permanent magnet and the sample 18 mm in diameters reached to the 8.41 N at 20 K. In addition, in FC regime, attractive and repulsive force increased with increasing diameters of the sample and the permanent magnet. In that, the sample with 18 mm in diameter showed the highest attractive force value -3.46 N at 20 K and FC regime. The results obtained in this study are very useful in magnetic levitation devices as there is no detailed study on the size of superconductors and permanent magnets.

  18. Enhanced trapped field performance of bulk high-temperature superconductors using split coil, pulsed field magnetization with an iron yoke

    NASA Astrophysics Data System (ADS)

    Ainslie, M. D.; Fujishiro, H.; Mochizuki, H.; Takahashi, K.; Shi, Y.-H.; Namburi, D. K.; Zou, J.; Zhou, D.; Dennis, A. R.; Cardwell, D. A.

    2016-07-01

    Investigating and predicting the magnetization of bulk superconducting materials and developing practical magnetizing techniques is crucial to using them as trapped field magnets in engineering applications. The pulsed field magnetization (PFM) technique is considered to be a compact, mobile and relative inexpensive way to magnetize bulk samples, requiring shorter magnetization times (on the order of milliseconds) and a smaller and less complicated magnetization fixture; however, the trapped field produced by PFM is generally much smaller than that of slower zero field cooling or field cooling techniques, particularly at lower operating temperatures. In this paper, the PFM of two, standard Ag-containing Gd-Ba-Cu-O samples is carried out using two types of magnetizing coils: (1) a solenoid coil, and (2) a split coil, both of which make use of an iron yoke to enhance the trapped magnetic field. It is shown that a significantly higher trapped field can be achieved using a split coil with an iron yoke, and in order to explain these how this arrangement works in detail, numerical simulations using a 2D axisymmetric finite element method based on the H -formulation are carried to qualitatively reproduce and analyze the magnetization process from both electromagnetic and thermal points of view. It is observed that after the pulse peak significantly less flux exits the bulk when the iron core is present, resulting in a higher peak trapped field, as well as more overall trapped flux, after the magnetization process is complete. The results have important implications for practical applications of bulk superconductors as such a split coil arrangement with an iron yoke could be incorporated into the design of a portable, high magnetic field source/magnet to enhance the available magnetic field or in an axial gap-type bulk superconducting electric machine, where iron can be incorporated into the stator windings to (1) improve the trapped field from the magnetization process

  19. Determination of Bulk Magnetic Volume Properties by Neutron Dark-Field Imaging

    NASA Astrophysics Data System (ADS)

    Grünzweig, Christian; Siebert, René; Betz, Benedikt; Rauscher, Peter; Schäfer, Rudolf; Lehmann, Eberhard

    For the production of high-class electrical steel grades a deeper understanding of the magnetic domain interaction with induced mechanical stresses is strongly required. This holds for non-oriented (NO) as well as grain-oriented (GO) steels. In the case of non-oriented steels the magnetic property degeneration after punching or laser cutting is essential for selecting correct obstructing material grades and designing efficient electrical machines. Until now these effects stay undiscovered due to the lack of adequate investigation methods that reveal local bulk information on processed laminations. Here we show how the use of a non-destructive testing method based on a neutron grating interferometry providing the dark-field image contrast delivers spatially-resolved transmission information about the local bulk domain arrangement and domain wall density. With the help of this technique it is possible to visualize magnetization processes within the NO laminations. Different representative manufacturing techniques are compared in terms of magnetic flux density deterioration such as punching, mechanically cutting by guillotine as well as laser fusion cutting using industrial high power laser beam sources. For GO steel laminations the method is applicable on the one hand to visualize the internal domain structure without being hindered by the coating layer. On the other hand, we can show the influence of the coating layer onto the underlying domain structure.

  20. Structure and magnetism of bulk Fe and Cr: from plane waves to LCAO methods.

    PubMed

    Soulairol, R; Fu, Chu-Chun; Barreteau, C

    2010-07-28

    Magnetic, structural and energetic properties of bulk Fe and Cr were studied using first-principles calculations within density functional theory (DFT). We aimed to identify the dependence of these properties on key approximations of DFT, namely the exchange-correlation functional, the pseudopotential and the basis set. We found a smaller effect of pseudopotentials (PPs) on Fe than on Cr. For instance, the local magnetism of Cr was shown to be particularly sensitive to the potentials representing the core electrons, i.e. projector augmented wave and Vanderbilt ultrasoft PPs predict similar results, whereas standard norm-conserving PPs tend to overestimate the local magnetic moments of Cr in bcc Cr and in dilute bcc FeCr alloys. This drawback is suggested to be closely correlated to the overestimation of Cr solution energy in the latter system. On the other hand, we point out that DFT methods with very reduced localized basis sets (LCAO: linear combination of atomic orbitals) give satisfactory results compared with more robust plane-wave approaches. A minimal-basis representation of '3d' electrons comes to be sufficient to describe non-trivial magnetic phases including spin spirals in both fcc Fe and bcc Cr, as well as the experimental magnetic ground state of bcc Cr showing a spin density wave (SDW) state. In addition, a magnetic 'spd' tight binding model within the Stoner formalism was proposed and validated for Fe and Cr. The respective Stoner parameters were obtained by fitting to DFT data. This efficient semiempirical approach was shown to be accurate enough for studying various collinear and non-collinear phases of bulk Fe and Cr. It also enabled a detailed investigation of different polarization states of SDW in bcc Cr, where the longitudinal state was suggested to be the ground state, consistent with existing experimental data.

  1. Microstructure and Magnetic Properties of PrMnO{sub 3} Bulk and Thin Film

    SciTech Connect

    Lim, K. P.; Halim, S. A.; Chen, S. K.; Ng, S. W.; Wong, J. K.; Gan, H. M. Albert; Woon, H. S.

    2011-03-30

    Perovskite PrMnO{sub 3}(PMO) had been prepared in bulk by solid state reaction and thin films on corning glass, fused silica and MgO (100) glass substrate by pulsed laser deposition technique. SEM micrographs show that grains with size 2{approx}3 {mu}m is observed in bulk PMO while thin films PMO show strongly connected grain structure with particle size that not larger than 100 nm. X-ray diffraction analysis shows that all samples are in single phase with orthorhombic crystal structure. Bulk PMO sample had lattice strain of 0.134% which is the lowest value among others. However, larger lattice strain was observed in thin film samples due to lattice mismatch between film-substrate and caused the MnO{sub 6} to deform. All samples shown paramagnetic or antiferromagnetic behavior, enhancement in magnetization value occurred for all PMO grew as film. We believe that larger lattice strain favor the grain growth of PMO towards more order phase. In summary, formation of structure and microstructure of thin film PMO depends on type of substrate used and it affect the magnetic property.

  2. A flux extraction device to measure the magnetic moment of large samples; application to bulk superconductors.

    PubMed

    Egan, R; Philippe, M; Wera, L; Fagnard, J F; Vanderheyden, B; Dennis, A; Shi, Y; Cardwell, D A; Vanderbemden, P

    2015-02-01

    We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm(3)) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m(2) (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K).

  3. A flux extraction device to measure the magnetic moment of large samples; application to bulk superconductors

    NASA Astrophysics Data System (ADS)

    Egan, R.; Philippe, M.; Wera, L.; Fagnard, J. F.; Vanderheyden, B.; Dennis, A.; Shi, Y.; Cardwell, D. A.; Vanderbemden, P.

    2015-02-01

    We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm3) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m2 (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K).

  4. Frequency-Induced Bulk Magnetic Domain-Wall Freezing Visualized by Neutron Dark-Field Imaging

    NASA Astrophysics Data System (ADS)

    Betz, B.; Rauscher, P.; Harti, R. P.; Schäfer, R.; Van Swygenhoven, H.; Kaestner, A.; Hovind, J.; Lehmann, E.; Grünzweig, C.

    2016-08-01

    We use neutron dark-field imaging to visualize and interpret the response of bulk magnetic domain walls to static and dynamic magnetic excitations in (110)-Goss textured iron silicon high-permeability steel alloy. We investigate the domain-wall motion under the influence of an external alternating sinusoidal magnetic field. In particular, we perform scans combining varying levels of dcoffset (0 - 30 A /m ) , oscillation amplitude Aac (0 - 1500 A /m ) , and frequency fac ((0 - 200 Hz ) . By increasing amplitude Aac while maintaining constant values of dcoffset and fac , we record the transition from a frozen domain-wall structure to a mobile one. Vice versa, increasing fac while keeping Aac and dcoffset constant led to the reverse transition from a mobile domain-wall structure into a frozen one. We show that varying both Aac and fac shifts the position of the transition region. Furthermore, we demonstrate that higher frequencies require higher oscillation amplitudes to overcome the freezing phenomena. The fundamental determination and understanding of the frequency-induced freezing process in high-permeability steel alloys is of high interest to the further development of descriptive models for bulk macromagnetic phenomena. Likewise, the efficiency of transformers can be improved based on our results, since these alloys are used as transformer core material.

  5. Magnetic property of a staggered-array undulator using a bulk high-temperature superconductor

    NASA Astrophysics Data System (ADS)

    Kinjo, Ryota; Mishima, Kenta; Choi, Yong-Woon; Omer, Mohamed; Yoshida, Kyohei; Negm, Hani; Torgasin, Konstantin; Shibata, Marie; Shimahashi, Kyohei; Imon, Hidekazu; Okumura, Kensuke; Inukai, Motoharu; Zen, Heishun; Kii, Toshiteru; Masuda, Kai; Nagasaki, Kazunobu; Ohgaki, Hideaki

    2014-02-01

    The magnetic field of a staggered-array undulator using a bulk high-temperature superconductor is calculated by analytical and numerical methods. Analytical formulas for the undulator field and the solenoid field required to generate the undulator field are derived from a simple two-dimensional model. The analytical calculation shows the degree of dependence of these fields on the undulator parameters, the generation of a high undulator field proportional to the critical current density of the bulk superconductor, and the good tunability of the undulator field over a wide range of values. The numerical calculation is performed in a three-dimensional geometry by two methods: the center field and energy minimization methods. The latter treats the current distribution inside the bulk, whereas the former neglects it as a natural extension of the analytical model. The calculation also reveals the dependence of the fields on the undulator parameters arising from the current distribution. From the comparison with experimental results, we find that the latter method reproduces the experimental results well, which indicates the importance of the current distribution inside the bulk. Therefore, we derive a semiempirical formula for the required solenoid field by modifying the analytical formula using the numerical results so as to include the effect of the current distribution. The semiempirical formula reproduces the numerical result with an error of 3%. Finally, we estimate the magnetic performance of the undulator as an example of using the formulas and values presented in this paper. The estimation shows that an undulator field twice as large as that of the present in-vacuum undulator but with an equal period and gap can be obtained at a temperature of approximately 20-40 K, and that deflection parameters (K values) of 1 and 2 can be achieved with periods of 5 and 10 mm at approximately 4-20 K.

  6. Magnetic modification at sub-surface of FeRh bulk by energetic ion beam irradiation

    SciTech Connect

    Koide, T.; Iwase, A.; Uno, H.; Sakane, H.; Sakamaki, M.; Amemiya, K.; Matsui, T.

    2015-05-07

    Ferromagnetic layered structure has been made at sub-surface of the antiferromagnetic FeRh bulk samples by high energy He ion beam irradiation. In accordance with the Transport of Ions in Matter simulation, such ion beam can effectively deposit the elastic collision energy in several μm regions in the depth from the surface. Measurement with a superconducting quantum interference device reveals the irradiated samples to be ferromagnetic. Assuming that only the part the energy deposited can be modified to be ferromagnetic, the corresponding irradiation induced magnetization is consistent with the data that we previously reported. On the other hand, the X-ray magnetic circular dichroism (XMCD) spectra for the irradiated samples are totally unchanged as those for the unirradiated samples. Since XMCD signal in total emission yield method is considered to be surface sensitive with a typical probing depth of several nm, the surface magnetic state is maintained to be antiferromagnetic. By utilizing these phenomena, three-dimensional magnetic patterning of FeRh can be realized, which may potentially be used for future magnetic exchange device application such as nano-scale sensors and memories.

  7. Magnetic modification at sub-surface of FeRh bulk by energetic ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Koide, T.; Uno, H.; Sakane, H.; Sakamaki, M.; Amemiya, K.; Iwase, A.; Matsui, T.

    2015-05-01

    Ferromagnetic layered structure has been made at sub-surface of the antiferromagnetic FeRh bulk samples by high energy He ion beam irradiation. In accordance with the Transport of Ions in Matter simulation, such ion beam can effectively deposit the elastic collision energy in several μm regions in the depth from the surface. Measurement with a superconducting quantum interference device reveals the irradiated samples to be ferromagnetic. Assuming that only the part the energy deposited can be modified to be ferromagnetic, the corresponding irradiation induced magnetization is consistent with the data that we previously reported. On the other hand, the X-ray magnetic circular dichroism (XMCD) spectra for the irradiated samples are totally unchanged as those for the unirradiated samples. Since XMCD signal in total emission yield method is considered to be surface sensitive with a typical probing depth of several nm, the surface magnetic state is maintained to be antiferromagnetic. By utilizing these phenomena, three-dimensional magnetic patterning of FeRh can be realized, which may potentially be used for future magnetic exchange device application such as nano-scale sensors and memories.

  8. Design and Development of a 100 MVA HTS Generator for Commercial Entry

    SciTech Connect

    2007-06-07

    In 2002, General Electric and the US Department of Energy (DOE) entered into a cooperative agreement for the development of a commercialized 100 MVA generator using high temperature superconductors (HTS) in the field winding. The intent of the program was to: (1) identify and develop technologies that would be needed for such a generator; (2) develop conceptual designs for generators with ratings of 100 MVA and higher using HTS technology; (3) perform proof of concept tests at the 1.5 MW level for GE's proprietary warm iron rotor HTS generator concept; and (4) design, build, and test a prototype of a commercially viable 100 MVA generator that could be placed on the power grid. This report summarizes work performed during the program and is provided as one of the final program deliverables. The design for the HTS generator was based on GE's warm iron rotor concept in which a cold HTS coil is wound around a warm magnetic iron pole. This approach for rotating HTS electrical machinery provides the efficiency benefits of the HTS technology while addressing the two most important considerations for power generators in utility applications: cost and reliability. The warm iron rotor concept uses the least amount of expensive HTS wire compared to competing concepts and builds on the very high reliability of conventional iron core stators and armature windings.

  9. Bulk magnetization properties of the Fra Mauro and Reiner Gamma Formations

    NASA Technical Reports Server (NTRS)

    Hood, L. L.

    1980-01-01

    In the reported investigation, bulk magnetization properties within two lunar surface geologic units have been inferred using low-altitude, high-resolution Apollo 16 subsatellite magnetometer data. On the basis of correlations of mapped anomalies with relatively surficial units on the central near side, a surface plate model with thickness much less than the subsatellite altitude was adopted and was used to represent the sources of largest anomalies. The results strongly suggest that directional coherence of the surface density of magnetization can occur over horizontal scales up to 100 km. Tentative evidence for a lack of directional coherence on scales greater than 100 km was found in the case of the Fra Mauro Formation.

  10. Comparison of Magnetic Behavior in Nanostructured and Bulk-Crystalline MnxTaS2

    NASA Astrophysics Data System (ADS)

    Shand, Paul; Beving, Lucas; Fleming, Matthew; Burken, Payton; Kidd, Tim; Strauss, Laura; Chen, Chih-Wei; Morosan, Emilia

    The magnetic behavior of nanostructured MnxTaS2 for several different Mn concentrations x have been studied and a magnetic phase diagram obtained. For x values between 0.15 (the lowest measured) and 0.19, the nanostructured system shows cluster-glass behavior as evidenced by spin relaxation well described by the Vogel-Fulcher-Tammann law as well as aging effects in the dc magnetization and ac susceptibility. For x values between 0.19 and 0.24, nanostructured MnxTaS2 displays re-entrant cluster-glass characteristics, with transitions from paramagnetism to ferromagnetism at higher temperature and ferromagnetism to cluster glass at lower temperature. The tricritical point where all three phases converge seems to be close to x = 0.19. Results for single-crystal MnxTaS2 from the literature show single transitions: paramagnetism to ferromagnetism for x = 0.25 and paramagnetism to cluster glass for x values in the range 0.02-0.1. For comparable x values, Curie temperatures seem to be slightly higher and cluster-glass transition temperatures slightly lower in the nanostructures. Bulk crystalline samples with Mn concentrations in the range 0.1-0.25 are currently being studied to more comprehensively compare the magnetic phase diagrams. Supported by NSF Grant DMR 1206530.

  11. Bulk SmCo5/α-Fe nanocomposite permanent magnets fabricated by mould-free Joule-heating compaction

    NASA Astrophysics Data System (ADS)

    Rong, Chuanbing; Zhang, Ying; Poudyal, Narayan; Wang, Dapeng; Kramer, M. J.; Liu, J. Ping

    2011-04-01

    Bulk SmCo5/α-Fe nanocomposite magnets have been prepared using a Joule-heating compaction technique. Nearly fully dense bulk magnets are obtained by compacting the milled powders under a pressure of 2 GPa at temperatures above 400 °C. Structural analysis shows that the grain size of both the SmCo5 and the α-Fe phases is in the range of 10 to 15 nm when the compaction temperature is lower than 500 °C, which ensures effective interphase exchange coupling. A further increase in compaction temperature leads to significant grain growth and deterioration of magnetic properties. A maximum energy product of about 18.5 MGOe was obtained in the bulk SmCo5/α-Fe nanocomposite magnets, which is 90% higher than that of the single-phase counterpart prepared under the same conditions.

  12. Theory of AC Loss in Cables with 2G HTS Wire

    SciTech Connect

    Clem, J.R.; Malozemoff, A.P.

    2009-09-13

    While considerable work has been done to understand AC losses in power cables made of first generation (1G) high temperature superconductor (HTS) wires, use of second generation (2G) HTS wires brings in some new considerations. The high critical current density of the HTS layer 2G wire reduces the surface superconductor hysteretic losses. Instead, gap and polygonal losses, flux transfer losses in imbalanced two layer cables and ferromagnetic losses for wires with NiW substrates constitute the principal contributions. Current imbalance and losses associated with the magnetic substrate can be minimized by orienting the substrates of the inner winding inward and the outer winding outward.

  13. In-situ visualization of stress-dependent bulk magnetic domain formation by neutron grating interferometry

    SciTech Connect

    Betz, B.; Rauscher, P.; Harti, R. P.; Kaestner, A.; Hovind, J.; Lehmann, E.; Grünzweig, C.; Schäfer, R.; Van Swygenhoven, H.

    2016-01-04

    The performance and degree of efficiency of industrial transformers are directly influenced by the magnetic properties of high-permeability steel laminations (HPSLs). Industrial transformer cores are built of stacks of single HPSLs. While the insulating coating on each HPSL reduces eddy-current losses in the transformer core, the coating also induces favorable inter-granular tensile stresses that significantly influence the underlying magnetic domain structure. Here, we show that the neutron dark-field image can be used to analyze the influence of the coating on the volume and supplementary surface magnetic domain structures. To visualize the stress effect of the coating on the bulk domain formation, we used an uncoated HPSL and stepwise increased the applied external tensile stress up to 20 MPa. We imaged the domain configuration of the intermediate stress states and were able to reproduce the original domain structure of the coated state. Furthermore, we were able to visualize how the applied stresses lead to a refinement of the volume domain structure and the suppression and reoccurrence of supplementary domains.

  14. In-situ visualization of stress-dependent bulk magnetic domain formation by neutron grating interferometry

    NASA Astrophysics Data System (ADS)

    Betz, B.; Rauscher, P.; Harti, R. P.; Schäfer, R.; Van Swygenhoven, H.; Kaestner, A.; Hovind, J.; Lehmann, E.; Grünzweig, C.

    2016-01-01

    The performance and degree of efficiency of industrial transformers are directly influenced by the magnetic properties of high-permeability steel laminations (HPSLs). Industrial transformer cores are built of stacks of single HPSLs. While the insulating coating on each HPSL reduces eddy-current losses in the transformer core, the coating also induces favorable inter-granular tensile stresses that significantly influence the underlying magnetic domain structure. Here, we show that the neutron dark-field image can be used to analyze the influence of the coating on the volume and supplementary surface magnetic domain structures. To visualize the stress effect of the coating on the bulk domain formation, we used an uncoated HPSL and stepwise increased the applied external tensile stress up to 20 MPa. We imaged the domain configuration of the intermediate stress states and were able to reproduce the original domain structure of the coated state. Furthermore, we were able to visualize how the applied stresses lead to a refinement of the volume domain structure and the suppression and reoccurrence of supplementary domains.

  15. Bulk synthesis of monodisperse magnetic FeNi3 nanopowders by flow levitation method.

    PubMed

    Chen, Shanjun; Chen, Yan; Kang, Xiaoli; Li, Song; Tian, Yonghong; Wu, Weidong; Tang, Yongjian

    2013-10-01

    In this work, a novel bulk synthesis method for monodisperse FeNi3 nanoparticles was developed by flow levitation method (FL). The Fe and Ni vapours ascending from the high temperature levitated droplet was condensed by cryogenic Ar gas under atmospheric pressure. X-ray diffraction was used to identify and characterize the crystal phase of prepared powders exhibiting a FeNi3 phase. The morphology and size of nanopowders were observed by transmission electron microscopy (TEM). The chemical composition of the nanoparticles was determined with energy dispersive spectrometer (EDS). The results indicated that the FeNi3 permalloy powders are nearly spherical-shaped with diameter about 50-200 nm. Measurement of the magnetic property of nanopowders by a superconducting quantum interference device (SQUID, Quantum Design MPMS-7) showed a symmetric hysteresis loop of ferromagnetic behavior with coercivity of 220 Oe and saturation magnetization of 107.17 emu/g, at 293 K. At 5 K, the obtained saturation magnetization of the sample was 102.16 emu/g. The production rate of FeNi3 nanoparticles was estimated to be about 6 g/h. This method has great potential in mass production of FeNi3 nannoparticles.

  16. Effects of Magnetic Nanoparticles and External Magnetostatic Field on the Bulk Heterojunction Polymer Solar Cells

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Yi, Chao; Liu, Chang; Hu, Xiaowen; Chuang, Steven; Gong, Xiong

    2015-03-01

    The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency.

  17. Effects of magnetic nanoparticles and external magnetostatic field on the bulk heterojunction polymer solar cells.

    PubMed

    Wang, Kai; Yi, Chao; Liu, Chang; Hu, Xiaowen; Chuang, Steven; Gong, Xiong

    2015-03-18

    The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency.

  18. Effects of Magnetic Nanoparticles and External Magnetostatic Field on the Bulk Heterojunction Polymer Solar Cells

    PubMed Central

    Wang, Kai; Yi, Chao; Liu, Chang; Hu, Xiaowen; Chuang, Steven; Gong, Xiong

    2015-01-01

    The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency. PMID:25783755

  19. Ambient-Pressure Bulk Superconductivity Deep in the Magnetic State of CeRhIn5

    SciTech Connect

    Paglione,J.; Ho, P.; Maple, M.; Tanatar, M.; Taillefer, L.; Lee, Y.; Petrovic, C.

    2008-01-01

    Specific heat, magnetic susceptibility and electrical transport measurements were performed at ambient pressure on high-quality single crystal specimens of CeRhIn5 down to ultra-low temperatures. We report signatures of an anomaly observed in all measured quantities consistent with a bulk phase transition to a superconducting state at T{sub c}=110 mK. Occurring far below the onset of antiferromagnetism at T{sub N}=3.8 K, this transition appears to involve a significant portion of the available low-temperature density of electronic states, exhibiting an entropy change in line with that found in other members of the 115 family of superconductors tuned away from quantum criticality.

  20. Effects of Magnetic Nanoparticles and External Magnetostatic Field on the Bulk Heterojunction Polymer Solar Cells

    SciTech Connect

    Wang, Kai; Yi, Chao; Liu, Chang; Hu, Xiaowen; Chuang, Steven; Gong, Xiong

    2015-03-18

    The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency.

  1. Threefold Increase of the Bulk Electron Temperature of Plasma Discharges in a Magnetic Mirror Device

    NASA Astrophysics Data System (ADS)

    Bagryansky, P. A.; Shalashov, A. G.; Gospodchikov, E. D.; Lizunov, A. A.; Maximov, V. V.; Prikhodko, V. V.; Soldatkina, E. I.; Solomakhin, A. L.; Yakovlev, D. V.

    2015-05-01

    This Letter describes plasma discharges with a high temperature of bulk electrons in the axially symmetric high-mirror-ratio (R =35 ) open magnetic system gas dynamic trap (GDT) in the Budker Institute (Novosibirsk). According to Thomson scattering measurements, the on-axis electron temperature averaged over a number of sequential shots is 660 ±50 eV with the plasma density being 0.7 ×1 019 m-3 ; in few shots, electron temperature exceeds 900 eV. This corresponds to at least a threefold increase with respect to previous experiments both at GDT and at other comparable machines, thus, demonstrating the highest quasistationary (about 1 ms) electron temperature achieved in open traps. The breakthrough is made possible by application of a new 0.7 MW /54.5 GHz electron cyclotron resonance heating system in addition to standard 5 MW heating by neutral beams, and application of a radial electric field to mitigate the flute instability.

  2. Metallic magnetism and change of conductivity in the nano to bulk transition of cobalt ferrite

    NASA Astrophysics Data System (ADS)

    Arunkumar, A.; Vanidha, D.; Oudayakumar, K.; Rajagopan, S.; Kannan, R.

    2013-11-01

    Variations in conductivity with particle size have been observed in cobalt ferrite, when synthesized by solgel auto-combustion method. Impedance analysis reveals metallic and semiconducting behavior at room temperature for a particle size of 6 nm and 52 nm, respectively. Upon thermal activation, metallic to semiconducting phase transition has been observed as a function of particle size and vice-versa. Grainboundary Resistance (Rgb), increased drastically with particle size (19 MΩ for 6 nm and 259 MΩ for 52 nm) at room temperature. AC conductivity and dielectric constants exhibit similar metallic to semiconducting phase transition at 6 nm and semiconducting behavior at 52 nm with temperature in the selected frequencies. Enhanced magnetic moment with an increase in the grain size along with decreased coercivity (1444 G to 1146 G) reveals transition from single domain to multi-domain. Increased inter-particle interaction is responsible for metallicity at the nano level and on the contrary semiconductivity is attributed to bulk.

  3. Hard magnetic properties observed in bulk Mn1–xGax

    SciTech Connect

    Brown, Daniel R.; Han, Ke; Siegrist, Theo

    2014-02-19

    Here, Mn-Ga binary alloys have shown promising magnetic properties, even though these alloys contain no rare-earth metals. Both theoretical predictions and experimental work showed that nanoscaled Mn-Ga samples, such as thin films could have remarkable magnetic properties. Although the prediction provides a useful guideline and thin films supply us with materials in some application, bulk materials are required for majority of the applications that require a strong magnetic field. We have made bulk Mn1-xGax alloys by mechanically milling and heat treatments. In this paper, we report annealed Mn1-xGax bulk composites that exhibit coercivity up to 18.8 kOe.

  4. Skyrmions in quasi-2D chiral magnets with broken bulk and surface inversion symmetry

    NASA Astrophysics Data System (ADS)

    Rowland, James; Banerjee, Sumilan; Randeria, Mohit

    2015-03-01

    Most theoretical studies of skyrmions have focused on chiral magnets with broken bulk inversion symmetry, stabilized by easy-axis anisotropy. Recently, we considered 2D systems with broken surface inversion and showed that skyrmion crystals are more stable than in 3D, pointing out the importance of easy-plane anisotropy. In the present work we investigate quasi-2D systems which break both bulk and surface inversion symmetry. The Landau-Ginzburg free energy functional thus contains two Dzyloshinskii-Moriya terms of strength DD and DR arising from Dresselhaus and Rashba spin-orbit coupling respectively. We trace the evolution of the phase diagram as DD /DR is varied, and find that skyrmions are increasingly destabilized with respect to the cone phase as DD increases relative to DR. We find an evolution from vortex-like skyrmions in the pure Dresselhaus limit to hedgehog-like skyrmions in the pure Rashba limit. We discuss the relevance of these results to existing experiments and the prospects of tuning the ratio of Dresselhaus and Rashba spin-orbit coupling via film thickness and strain. Supported by NSF DMR-1410364 (J.R. and M.R.) and DOE-BES DE-SC0005035 (S.B.)

  5. Skyrmions in quasi-2D chiral magnets with broken bulk and surface inversion symmetry (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Randeria, Mohit; Banerjee, Sumilan; Rowland, James

    2015-09-01

    Most theoretical studies of chiral magnetism, and the resulting spin textures, have focused on 3D systems with broken bulk inversion symmetry, where skyrmions are stabilized by easy-axis anisotropy. In this talk I will describe our results on 2D and quasi-2D systems with broken surface inversion, where we find [1] that skyrmion crystals are much more stable than in 3D, especially for the case of easy-plane anisotropy. These results are of particular interest for thin films, surfaces, and oxide interfaces [2], where broken surface-inversion symmetry and Rashba spin-orbit coupling naturally lead to both the chiral Dzyaloshinskii-Moriya (DM) interaction and to easy-plane compass anisotropy. I will then turn to systems that break both bulk and surface inversion, resulting in two distinct DM terms arising from Dresselhaus and Rashba spin-orbit coupling. I will describe [3] the evolution of the skyrmion structure and of the phase diagram as a function of the ratio of Dresselhaus and Rashba terms, which can be tuned by varying film thickness and strain. [1] S. Banerjee, J. Rowland, O. Erten, and M. Randeria, PRX 4, 031045 (2014). [2] S. Banerjee, O. Erten, and M. Randeria, Nature Phys. 9, 626 (2013). [3] J. Rowland, S. Banerjee and M. Randeria, (unpublished).

  6. On the adsorption properties of magnetic fluids: Impact of bulk structure

    NASA Astrophysics Data System (ADS)

    Kubovcikova, Martina; Gapon, Igor V.; Zavisova, Vlasta; Koneracka, Martina; Petrenko, Viktor I.; Soltwedel, Olaf; Almasy, László; Avdeev, Mikhail V.; Kopcansky, Peter

    2017-04-01

    Adsorption of nanoparticles from magnetic fluids (MFs) on solid surface (crystalline silicon) was studied by neutron reflectometry (NR) and related to the bulk structural organization of MFs concluded from small-angle neutron scattering (SANS). The initial aqueous MF with nanomagnetite (co-precipitation reaction) stabilized by sodium oleate and MF modified by a biocompatible polymer, poly(ethylene glycol) (PEG), were considered. Regarding the bulk structure it was confirmed in the SANS experiment that comparatively small and compact (size 30 nm) aggregates of nanoparticle in the initial sample transfer to large and developed (size>130 nm, fractal dimension 2.7) associates in the PEG modified MF. This reorganization in the aggregates correlates with the changes in the neutron reflectivity that showed that a single adsorption layer of individual nanoparticles on the oxidized silicon surface for the initial MF disappears after the PEG modification. It is concluded that all particles in the modified fluid are in the aggregates that are not adsorbed by silicon.

  7. Magneto transport in crossed electric and magnetic fields in compensated bulk GaN

    NASA Astrophysics Data System (ADS)

    Syngayivska, G. I.; Korotyeyev, V. V.; Kochelap, V. A.; Varani, L.

    2016-09-01

    Low-temperature high-field electron transport is studied for compensated bulk GaN subjected to crossed electric and magnetic fields. The electron kinetics, distribution function, and field dependencies of the magneto transport characteristics are analyzed by using the Monte-Carlo method. At zero magnetic field, for an ionized impurity concentration of 1016 cm-3 and an electron concentration of 1015 cm-3, it is shown that dissipative streaming transport with a strong anisotropic electron distribution in the momentum space is realized at electric fields in the range 3 -10 kV/cm and for a lattice temperature of 30 K. The magnetic field destroys the dissipative streaming transport. Indeed, for a magnetic field greater than 4 T, the electrons are predominantly confined in a region of the momentum space where their energy is smaller than the optical phonon energy and the strong inelastic scattering by optical phonons is practically eliminated. A quasi-ballistic electron transport occurs in the form of a vortex-like motion in the momentum space. The axis of rotation of this vortex coincides with the average electron momentum. A general analysis of the distribution function suitable for any configuration of the Hall circuit is presented. The main magneto transport characteristics (dissipative current, Hall current, and Hall electric field) are studied for the short and open Hall circuits. We show that the magneto transport measurements can provide valuable information on the main features of the electron distribution function and electron dynamics in GaN. Finally, we suggest that the strong dependency of the dissipative current on the parameters of the Hall circuit can be used for current modulation and current switching.

  8. Bulk combinatorial synthesis and high throughput characterization for rapid assessment of magnetic materials: Application of laser engineered net shaping (LENS)

    DOE PAGES

    Geng, J.; Nlebedim, I. C.; Besser, M. F.; ...

    2016-04-15

    A bulk combinatorial approach for synthesizing alloy libraries using laser engineered net shaping (LENS; i.e., 3D printing) was utilized to rapidly assess material systems for magnetic applications. The LENS system feeds powders in different ratios into a melt pool created by a laser to synthesize samples with bulk (millimeters) dimensions. By analyzing these libraries with autosampler differential scanning calorimeter/thermal gravimetric analysis and vibrating sample magnetometry, we are able to rapidly characterize the thermodynamic and magnetic properties of the libraries. Furthermore, the Fe-Co binary alloy was used as a model system and the results were compared with data in the literature.

  9. Bulk Combinatorial Synthesis and High Throughput Characterization for Rapid Assessment of Magnetic Materials: Application of Laser Engineered Net Shaping (LENS™)

    NASA Astrophysics Data System (ADS)

    Geng, J.; Nlebedim, I. C.; Besser, M. F.; Simsek, E.; Ott, R. T.

    2016-07-01

    A bulk combinatorial approach for synthesizing alloy libraries using laser engineered net shaping (LENS™; i.e., 3D printing) was utilized to rapidly assess material systems for magnetic applications. The LENS™ system feeds powders in different ratios into a melt pool created by a laser to synthesize samples with bulk (millimeters) dimensions. By analyzing these libraries with autosampler differential scanning calorimeter/thermal gravimetric analysis and vibrating sample magnetometry, we are able to rapidly characterize the thermodynamic and magnetic properties of the libraries. The Fe-Co binary alloy was used as a model system and the results were compared with data in the literature.

  10. Application of HTS technology to cardiac dysrhythmia detection

    SciTech Connect

    Sobel, A.L.; Avrin, W.F.

    1994-12-01

    This paper discusses the conceptual design considerations and challenges for development of a contactless, mobile, single channel biomagnetic sensor system based on High-Temperature Superconductor (HTS) Superconducting Quantum Interference Devices (SQUIDs) and employing the Three-SQUID Gradiometer (TSG) concept. Operating in magnetically unshielded environments, as are encountered in many medical scenarios, this instrument class would monitor cardiac electrical activity with minimal patient preparation and intrusiveness, and would notionally be coupled with a clinically adaptive human-system interface (HSI).

  11. Microstructure and magnetic viscosity of bulk amorphous Nd60Fe20Al5Co10B5 alloy

    NASA Astrophysics Data System (ADS)

    Tan, X. H.; Xu, H.; Man, H.; Tang, Y. J.; Yang, L. P.; Bai, Q.

    2011-04-01

    The microstructure and magnetic viscosity of bulk amorphous Nd60Fe20Al5Co10B5,prepared by suction casting the molten alloy into a copper mold under an argon atmosphere, have been investigated. The results show that clusters with size 3-5 nm are found to be embedded in the amorphous matrix of as-cast bulk amorphous Nd60Fe20Al5Co10B5 alloy. The Nd60Fe20Al5Co10B5 alloy shows hard magnetic behavior at room temperature, with an intrinsic coercivity of 360 kA/m and a remanence of 69.39 mT. The magnetic viscosity of bulk amorphous Nd60Fe20Al5Co10B5 has been investigated on the major hysteresis loop, and simple logarithmic time dependence is observed. A value for the fluctuation field of 8.24 kA/m is obtained. Analysis based on a Henkel plot is used to confirm the existence of magnetic interaction among clusters. The coercivity mechanism responsible for the hard magnetic behavior of bulk amorphous Nd60Fe20Al5Co10B5 alloy is also discussed.

  12. Correlation between structural, electrical and magnetic properties of GdMnO3 bulk ceramics

    NASA Astrophysics Data System (ADS)

    Samantaray, S.; Mishra, D. K.; Pradhan, S. K.; Mishra, P.; Sekhar, B. R.; Behera, Debdhyan; Rout, P. P.; Das, S. K.; Sahu, D. R.; Roul, B. K.

    2013-08-01

    This paper reports the effect of sintering temperature on ferroelectric properties of GdMnO3 (GMO) bulk ceramics at room temperature prepared by the conventional solid state reaction route following slow step sintering schedule. Ferroelectric hysteresis loop as well as sharp dielectric anomaly in pure (99.999%) GMO sintered ceramics has been clearly observed. Samples sintered at 1350 °C become orthorhombic with Pbnm space group and showed frequency independent sharp dielectric anomalies at 373 K and a square type of novel ferroelectric hysteresis loop was observed at room temperature. Interestingly, dielectric anomalies and ferroelectric behavior were observed to be dependent upon sintering temperature of GdMnO3. Room temperature dielectric constant (ɛr) value at different frequencies is observed to be abnormally high. The magnetic field and temperature dependent magnetization show antiferromagnetic behavior at 40 K for both 1350 °C and 1700 °C sintered GMO. Present findings showed the possibility of application of GdMnO3 at room temperature as multifunctional materials.

  13. Quantum Hall effect in a bulk antiferromagnet EuMnBi2 with magnetically confined two-dimensional Dirac fermions.

    PubMed

    Masuda, Hidetoshi; Sakai, Hideaki; Tokunaga, Masashi; Yamasaki, Yuichi; Miyake, Atsushi; Shiogai, Junichi; Nakamura, Shintaro; Awaji, Satoshi; Tsukazaki, Atsushi; Nakao, Hironori; Murakami, Youichi; Arima, Taka-hisa; Tokura, Yoshinori; Ishiwata, Shintaro

    2016-01-01

    For the innovation of spintronic technologies, Dirac materials, in which low-energy excitation is described as relativistic Dirac fermions, are one of the most promising systems because of the fascinating magnetotransport associated with extremely high mobility. To incorporate Dirac fermions into spintronic applications, their quantum transport phenomena are desired to be manipulated to a large extent by magnetic order in a solid. We report a bulk half-integer quantum Hall effect in a layered antiferromagnet EuMnBi2, in which field-controllable Eu magnetic order significantly suppresses the interlayer coupling between the Bi layers with Dirac fermions. In addition to the high mobility of more than 10,000 cm(2)/V s, Landau level splittings presumably due to the lifting of spin and valley degeneracy are noticeable even in a bulk magnet. These results will pave a route to the engineering of magnetically functionalized Dirac materials.

  14. Quantum Hall effect in a bulk antiferromagnet EuMnBi2 with magnetically confined two-dimensional Dirac fermions

    PubMed Central

    Masuda, Hidetoshi; Sakai, Hideaki; Tokunaga, Masashi; Yamasaki, Yuichi; Miyake, Atsushi; Shiogai, Junichi; Nakamura, Shintaro; Awaji, Satoshi; Tsukazaki, Atsushi; Nakao, Hironori; Murakami, Youichi; Arima, Taka-hisa; Tokura, Yoshinori; Ishiwata, Shintaro

    2016-01-01

    For the innovation of spintronic technologies, Dirac materials, in which low-energy excitation is described as relativistic Dirac fermions, are one of the most promising systems because of the fascinating magnetotransport associated with extremely high mobility. To incorporate Dirac fermions into spintronic applications, their quantum transport phenomena are desired to be manipulated to a large extent by magnetic order in a solid. We report a bulk half-integer quantum Hall effect in a layered antiferromagnet EuMnBi2, in which field-controllable Eu magnetic order significantly suppresses the interlayer coupling between the Bi layers with Dirac fermions. In addition to the high mobility of more than 10,000 cm2/V s, Landau level splittings presumably due to the lifting of spin and valley degeneracy are noticeable even in a bulk magnet. These results will pave a route to the engineering of magnetically functionalized Dirac materials. PMID:27152326

  15. Structure and magnetic properties of bulk anisotropic SmCo5/α-Fe nanocomposite permanent magnets with different α-Fe content

    NASA Astrophysics Data System (ADS)

    Liu, W. Q.; Zuo, J. H.; Yue, M.; Cui, Z. Z.; Zhang, D. T.; Zhang, J. X.; Zhang, P. Y.; Ge, H. L.; Guo, Z. H.; Li, W.

    2011-04-01

    Chemical coating, hot compaction, and hot deformation techniques have been applied to prepare bulk anisotropic SmCo5/α-Fe nanocomposite magnets. The effects of α-Fe content on the structure and magnetic properties of the magnets were studied. With the increase of the α-Fe content, both the saturation magnetization (Ms) and remanence (Mr) of the magnets rise first, peak at 10 vol. % α-Fe content and then fall while the coercivity (Hci) of the magnets drops simultaneously. Crystal structure analysis shows that the magnets exhibit a strong c-axis crystal texture of the SmCo5 phase, which, however, weakens gradually as the α-Fe content increases. Microstructure observation also shows that there are many SmCo5 equiaxial grains even after hot deformation in the magnets with 15 vol. % α-Fe.

  16. Electron transport behaviour and soft magnetic properties of bulk amorphous Fe72Si4B20Nb4 alloy

    NASA Astrophysics Data System (ADS)

    Panda, A. K.; Ghosh Chowdhury, S.; Mitra, A.; Nishiyama, N.; Inoue, A.

    2006-08-01

    The crystallization behaviour, electrical resistivity, magnetic and mechanical properties of as-quenched bulk amorphous Fe72Si4B20Nb4 alloy was investigated. The alloy, prepared in the form of rods by a copper mould casting technique, revealed an amorphous structure as observed from x-ray diffractometry. Differential scanning calorimetry and thermal variation of electrical resistivity measurements showed distinct glass transition temperature, Tg occurring 50-60 K below the crystallization onset (TX). Such a wide supercooled range was also attributed to the highly reduced glass transition temperature, Trg which was in the range of 0.56-0.58 found to be prevalent in good glass forming alloys. The alloy also showed a non-linear decrease in stability time at different temperatures between Tg and TX. The bulk amorphous alloy exhibited a drastic decrease in electrical resistivity around the glass transition temperature which was attributed to high electron propagation due to enhanced stress relaxation as result of a decrease in viscosity. The material exhibited superior soft magnetic properties with a coercivity value of 212 mOe, which is fairly low with respect to reported bulk amorphous alloys. The amorphous alloy also showed saturation induction of 12 kG and a moderate Curie temperature of 595 K. The as-quenched bulk amorphous alloy exhibited a high mechanical hardness of 1250 HV (Vickers). The superior soft magnetic properties coupled with high mechanical hardness opens up the scope for bulk amorphous Fe-Si-B systems with Nb incorporation.

  17. Spin Hall switching of the magnetization in Ta/TbFeCo structures with bulk perpendicular anisotropy

    SciTech Connect

    Zhao, Zhengyang; Jamali, Mahdi; Smith, Angeline K.; Wang, Jian-Ping

    2015-03-30

    Spin-orbit torques are studied in Ta/TbFeCo/MgO patterned structures, where the ferrimagnetic material TbFeCo provides a strong bulk perpendicular magnetic anisotropy (bulk-PMA) independent of the interfaces. The current-induced magnetization switching in TbFeCo is investigated in the presence of a perpendicular, longitudinal, or transverse field. An unexpected partial-switching phenomenon is observed in the presence of a transverse field unique to our bulk-PMA material. It is found that the anti-damping torque related with spin Hall effect is very strong, and a spin Hall angle is determined to be 0.12. The field-like torque related with Rashba effect is unobservable, suggesting that the interface play a significant role in Rashba-like torque.

  18. Development of (RE)BCO cables for HTS power transmission lines

    NASA Astrophysics Data System (ADS)

    Mukoyama, S.; Yagi, M.; Masuda, T.; Amemiya, N.; Ishiyama, A.; Kashima, N.; Nagaya, S.; Aoki, Y.; Yoshizumi, M.; Yamada, Y.; Izumi, T.; Shiohara, Y.

    2009-10-01

    High-temperature superconducting (HTS) power cables transmit bulk power with lower loss than conventional cables. Moreover, HTS cables are expected to be constructed as a new underground cable in urban areas at lower cost compared to a high voltage XLPE cable. To put promising HTS cables to practical use, we need (RE)BCO tapes with long length, high critical current, and low cost. Recently many organizations have improved the performance of the (RE)BCO tapes, such as YBCO tapes, or other coated conductor tapes that are made with a variety of different processes. We have fabricated the conductors for the HTS power cable that was constructed of different kinds of (RE)BCO tapes and measured the I c and AC losses. We achieved significantly low AC loss of 0.1 W/m at 1 kA in the HTS conductor using narrow slit tapes that were cut by laser. Moreover, a 20 m long HTS power cable model and a cable intermediate joint were developed. Short circuit current tests were conducted on the cable system that consisted of two 10 m cables, a cable joint, and two terminations. The cables and the joint withstood the short circuit current of 31.5 kA for 2 s without damage.

  19. Improvement of azimuthal homogeneity in permanent-magnet bearing rotors

    NASA Astrophysics Data System (ADS)

    Hull, J. R.; Rossing, T. D.; Mulcahy, T. M.; Uherka, K. L.

    1992-10-01

    Permanent magnets that are levitated and rotating over a bulk high-temperature superconductor (HTS) form the basis of many superconducting bearing designs. Experiments have shown that the rotational-loss 'coefficient of friction' for thrust bearings of this type can be as low as 8 x 10(exp -6). While the loss mechanisms of such bearings are not well understood, the azimuthal homogeneity of the rotating permanent magnet is believed to play an important role in determining the loss. One possible loss mechanism is magnetic hysteresis in the HTS, where the energy loss E per cycle is derived from the critical state model and given by E = K (Delta B)(sup 3)/J(sub c) where K is a geometric coefficient, Delta B is the variation in magnetic field at the surface of the HTS experienced during a rotation of the levitated magnet, and J(sub c) is the critical current density of the HTS. It is clear that a small decrease in Delta B (i.e., decreasing the azimuthal inhomogeneity of the rotating magnetic field) could have profound effects on decreasing E and the rotational coefficient of friction. The role of Delta B is also expected to be significant in reducing losses from eddy currents and other mechanisms. Low rotational losses in HTS bearings have been demonstrated only for levitated masses of several grams. For practical bearings, it is important to obtain these low losses with larger levitated masses. There are two main routes toward decreasing Delta B. The first is to improve the alignment of the magnetic particles during fabrication and to maintain close tolerances on grinding angles during manufacture of the permanent magnet. The second, the subject of this paper, is to provide correctional procedures after the magnet is fabricated.

  20. Improvement of azimuthal homogeneity in permanent-magnet bearing rotors

    SciTech Connect

    Hull, J.R.; Rossing, T.D.; Mulcahy, T.M.; Uherka, K.L.

    1992-10-23

    Permanent magnets that are levitated and rotating over a bulk high-temperature superconductor (HTS) form the basis of many superconducting bearing designs. Experiments have shown that the rotational-loss coefficient of friction'' for thrust bearings of this type can be as low as 8 [times] 10[sup [minus]6]. While the loss mechanisms of such bearings are not well understood, the azimuthal homogeneity of the rotating permanent magnet is believed to play an important role in determining the loss. One possible loss mechanism is magnetic hysteresis in the HTS, where the energy loss E per cycle is derived from the critical state model and given by E = K ([Delta]B[sup 3]/J[sub c]) where K is a geometric coefficient, [Delta]B is the variation in magnetic field at the surface of the HTS experienced during a rotation of the levitated magnet, and J[sub c] is the critical current density of the HTS. It is clear that a small decrease in [Delta]B (i.e., decreasing the azimuthal inhomogeneity of the rotating magnetic field) could have profound effects on decreasing E and the rotational coefficient of friction. The role of [Delta]B is also expected to be significant in reducing losses from eddy currents and other mechanisms. Low rotational losses in HTS bearings have been demonstrated only for levitated masses of several grams. For practical bearings, it is important to obtain these low losses with larger levitated masses. There are two main routes toward decreasing [Delta]B. The first is to improve the alignment of the magnetic particles during fabrication and to maintain close tolerances on grinding angles during manufacture of the permanent magnet. The second, the subject of this paper, is to provide correctional procedures after the magnet is fabricated.

  1. Improvement of azimuthal homogeneity in permanent-magnet bearing rotors

    SciTech Connect

    Hull, J.R.; Rossing, T.D.; Mulcahy, T.M.; Uherka, K.L.

    1992-10-23

    Permanent magnets that are levitated and rotating over a bulk high-temperature superconductor (HTS) form the basis of many superconducting bearing designs. Experiments have shown that the rotational-loss``coefficient of friction`` for thrust bearings of this type can be as low as 8 {times} 10{sup {minus}6}. While the loss mechanisms of such bearings are not well understood, the azimuthal homogeneity of the rotating permanent magnet is believed to play an important role in determining the loss. One possible loss mechanism is magnetic hysteresis in the HTS, where the energy loss E per cycle is derived from the critical state model and given by E = K ({Delta}B{sup 3}/J{sub c}) where K is a geometric coefficient, {Delta}B is the variation in magnetic field at the surface of the HTS experienced during a rotation of the levitated magnet, and J{sub c} is the critical current density of the HTS. It is clear that a small decrease in {Delta}B (i.e., decreasing the azimuthal inhomogeneity of the rotating magnetic field) could have profound effects on decreasing E and the rotational coefficient of friction. The role of {Delta}B is also expected to be significant in reducing losses from eddy currents and other mechanisms. Low rotational losses in HTS bearings have been demonstrated only for levitated masses of several grams. For practical bearings, it is important to obtain these low losses with larger levitated masses. There are two main routes toward decreasing {Delta}B. The first is to improve the alignment of the magnetic particles during fabrication and to maintain close tolerances on grinding angles during manufacture of the permanent magnet. The second, the subject of this paper, is to provide correctional procedures after the magnet is fabricated.

  2. Large Scale Applications of HTS in New Zealand

    NASA Astrophysics Data System (ADS)

    Wimbush, Stuart C.

    New Zealand has one of the longest-running and most consistently funded (relative to GDP) programmes in high temperature superconductor (HTS) development and application worldwide. As a consequence, it has a sustained breadth of involvement in HTS technology development stretching from the materials discovery right through to burgeoning commercial exploitation. This review paper outlines the present large scale projects of the research team at the newly-established Robinson Research Institute of Victoria University of Wellington. These include the construction and grid-based testing of a three-phase 1 MVA 2G HTS distribution transformer utilizing Roebel cable for its high-current secondary windings and the development of a cryogen-free conduction-cooled 1.5 T YBCO-based human extremity magnetic resonance imaging system. Ongoing activities supporting applications development such as low-temperature full-current characterization of commercial superconducting wires and the implementation of inductive flux-pump technologies for efficient brushless coil excitation in superconducting magnets and rotating machines are also described.

  3. Test and Analysis of Spliced DI-BSCCO HTS Tapes

    NASA Astrophysics Data System (ADS)

    Fetisov, S. S.; Sotnikov, D. V.; Radchenko, I. P.; Vysotsky, V. S.; Osabe, G.; Kinoshita, K.; Fujikami, J.; Kobayashi, S.; Yamazaki, K.

    For some applications, short unit lengths of HTS wires should be spliced if longer lengths are necessary and short unit lengths of HTS wires should be utilize by applying the splice technology to reduce the total wire cost in the application. The splice technology has been developed for DI-BSCCO Type HT-CA tapes by Sumitomo Electric and spliced tapes were tested in Russian Cable Institute. The test program included: measurements of splice's resistance, critical current anisotropy, thermo cycling tolerance, mechanical properties, overload tests and magnetization measurements. In the paper the results of tests are presented and discussed. The test results demonstrated that splices can be used for cable production if twisting and bending limitations are taken into account.

  4. Fundamental study of phosphor separation by controlling magnetic force

    NASA Astrophysics Data System (ADS)

    Wada, Kohei; Mishima, Fumihito; Akiyama, Yoko; Nishijima, Shigehiro

    2013-11-01

    The phosphor wastes consist of phosphors with different emission colors, green (LAP), red (YOX), blue (BAM) and white (HP). It is required to recover and reuse the rare earth phosphors with high market value. In this study, we tried to separate the phosphor using the magnetic separation by HTS bulk magnet utilizing the differences of magnetic susceptibility by the type of phosphors. We succeeded in the successive separation of HP with low market value from YOX and BAM including the rare earth using the magnetic Archimedes method. In this method, vertical and radial components of the magnetic force were used.

  5. Effect of addition of soft magnetic alloy particles on the flux trapping in Gd123 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Tsuzuki, K.; Zhang, Y.; Kimura, Y.; Izumi, M.

    2010-06-01

    Pinning stability and the introduction of magnetic flux pinning is an essential problem in applications of high-Tc superconductors. Study on the role of addition of a variety of metal oxides into GdBa2Cu3O7-δ (Gd123) bulk superconductors was carried out. We found that the addition of 0.05 wt. % of soft magnetic alloy particles Fe-Cu-Nb-Si-Cr-B (Fe-B) into the Gd123 contributes to the enhancement of the critical current density (Jc) under a wide range of applied magnetic fields up to 3 T. The Fe-B particles refined less than 10 μm by ball milling indicate no remarkable contribution on the Jc under the magnetic field. The reduction of the Ba content resulted in the appearance of a peak of Jc which has been observed in the Gd/Ba solid solution with rich Ba content. These results let us discriminate the effect of the magnetic particles from other conventional flux pinning mechanism. The peak of Jc under magnetic field was not only observed in the part along the c-axis under the seed of the sample but also in the growth sector around the periphery of the Gd123 bulk with Fe-B addition. It indicates that the magnetic particles inclusions play an important role on the homogeneous enhancement of Jc and the high flux pinning performance.

  6. Anomalous results observed in magnetization of bulk high temperature superconductors—A windfall for applications

    NASA Astrophysics Data System (ADS)

    Weinstein, Roy; Parks, Drew; Sawh, Ravi-Persad; Carpenter, Keith; Davey, Kent

    2016-04-01

    Recent experiments on pulsed-zero field cool magnetization of bulk high Jc YBCO (YBa2Cu3O7-δ) have shown unexpected results. For example, reproducible, non-destructive, rapid, giant field leaps (GFLs) to higher penetrated field are observed. The observations are inconsistent with the critical state model (CSM), in several aspects. Additional experiments have been pursued in an attempt to clarify the physics involved in the observed anomalies. Here, we present experimental results for the Jc dependence of the anomalous features. It is found that the sudden field increase in the GFL is a monotonically increasing function of Jc. The ratio of required pulsed field amplitude, BA,max, to obtain maximum trappable field, BT,max, which CSM predicts to be ≥2.0, gradually approaches 1.0 at high Jc. Tests using values of pulsed, applied field BA,max just below the GFL exhibit two additional anomalies: (i) At high Jc, the highest trapped field is up to ˜6 times lower than predicted by CSM, and (ii) the measured Lorentz force as a function of Jc deviates sharply from CSM predictions. The data rule out heating effects and pinning center geometry as possible physical causes of these anomalies. A speculative cause is considered.

  7. Effects of Magnetic Nanoparticles and External Magnetostatic Field on the Bulk Heterojunction Polymer Solar Cells

    DOE PAGES

    Wang, Kai; Yi, Chao; Liu, Chang; ...

    2015-03-18

    The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated withmore » MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency.« less

  8. Behavior of bulk high-temperature superconductors of finite thickness subjected to crossed magnetic fields: Experiment and model

    NASA Astrophysics Data System (ADS)

    Vanderbemden, Ph.; Hong, Z.; Coombs, T. A.; Denis, S.; Ausloos, M.; Schwartz, J.; Rutel, I. B.; Hari Babu, N.; Cardwell, D. A.; Campbell, A. M.

    2007-05-01

    Crossed-magnetic-field effects on bulk high-temperature superconductors have been studied both experimentally and numerically. The sample geometry investigated involves finite-size effects along both (crossed-)magnetic-field directions. The experiments were carried out on bulk melt-processed Y-Ba-Cu-O single domains that had been premagnetized with the applied field parallel to their shortest direction (i.e., the c axis) and then subjected to several cycles of the application of a transverse magnetic field parallel to the sample ab plane. The magnetic properties were measured using orthogonal pickup coils, a Hall probe placed against the sample surface, and magneto-optical imaging. We show that all principal features of the experimental data can be reproduced qualitatively using a two-dimensional finite-element numerical model based on an E-J power law and in which the current density flows perpendicularly to the plane within which the two components of magnetic field are varied. The results of this study suggest that the suppression of the magnetic moment under the action of a transverse field can be predicted successfully by ignoring the existence of flux-free configurations or flux-cutting effects. These investigations show that the observed decay in magnetization results from the intricate modification of current distribution within the sample cross section. The current amplitude is altered significantly only if a field-dependent critical current density Jc(B) is assumed. Our model is shown to be quite appropriate to describe the cross-flow effects in bulk superconductors. It is also shown that this model does not predict any saturation of the magnetic induction, even after a large number (˜100) of transverse field cycles. These features are shown to be consistent with the experimental data.

  9. Development of synchronous machines with HTS rotor

    NASA Astrophysics Data System (ADS)

    Kummeth, P.; Frank, M.; Nick, W.; Nerowski, G.; Neumueller, H.-W.

    2005-10-01

    Optimized design of synchronous machines can be achieved by use of HTS tape conductors. The introduction of an iron-free air-core stator winding and replacement of the rotor's copper windings by Bi-2223 tapes allows to develop very compact HTS machines with less than half the weight and volume, higher efficiency and excellent operational behavior compared to conventional devices. In consequence these rotating machines with HTS rotors become very attractive for ship drives, power generation and industrial applications. A 400 kW synchronous HTS machine was designed, manufactured and tested at Siemens. Main goal was to demonstrate the feasibility of basic concepts. Development of a 4 MVA synchronous HTS generator is currently under way.

  10. Dielectrically Loaded HTS Spiral Antenna

    NASA Astrophysics Data System (ADS)

    Ramasamy, J.; Hanna, D.; Vlasov, Y. A.; Larkins, G. L.; Moeckly, B. H.

    2004-06-01

    The objective of this work is to fabricate, test, and study a dielectrically loaded high temperature superconductor (HTS) spiral antenna that would operate in the frequency band of 10 MHz to 200 MHz. The antenna is formed by depositing and patterning a YBa2Cu3O7 (YBCO) thin film on top of 4-inch-diameter sapphire and Yittria Stabilized ZrO2 substrates. The presence of the HTS material guarantees low conductor loss in the antenna. A thick epitaxial layer of strontium titanate (STO) is then deposited on top of the YBCO for high dielectric constant loading. This set-up can be simulated using the Fidelity software routine, a Finite Difference Time Domain based program from Zeland, Inc. We have simulated the performance of this antenna structure, first in free space and then after loading with the dielectric slabs. Important parameters such as feed point impedance and antenna gain are studied for different simulation conditions. The dielectric ensures reduced feed point impedance as well as improvement of the low frequency response of the antenna.

  11. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    NASA Technical Reports Server (NTRS)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For

  12. Improving magnetic properties of MgB2 bulk superconductors by synthetic engine oil treatment

    NASA Astrophysics Data System (ADS)

    Taylan Koparan, E.; Savaskan, B.; Yanmaz, E.

    2016-08-01

    The present study focuses on the effects of standby time of the MgB2 samples immersed in synthetic engine oil on the critical current density (Jc(H)), magnetic field dependence of the pinning force density fp(b) and Tc performances of MgB2 bulk superconductors. Synthetic engine oil was used as a product which is cheap and a rich carbon source. Manufactured MgB2 pellet samples were immersed at different standby time of 30 min, 120 min, 300 min and 1440 min in synthetic engine oil after the first heating process. Finally, MgB2 samples immersed in synthetic engine oil were sintered at 1000 °C and kept for 15 min in Ar atmosphere. The critical current density of all of MgB2 samples immersed at different standby time in engine oil in whole field range was better than that of the pure MgB2 sample because of the number of the pinning centers. The MgB2 sample immersed at 300 min standby time in synthetic engine oil has the best performance compared to other samples. The Jc value for the pure sample is 2.0 × 103 A/cm2, whereas for the MgB2 sample immersed at 300 min standby time in engine oil the Jc is enhanced to 4.8 × 103A/cm2 at 5 K and 3 T. The superconducting transition temperature (Tc) did not change with the increasing standby time of the samples in synthetic engine oil at all. The best diamagnetic property was obtained from the sample which kept in synthetic engine oil for 300 min. Synthetic engine oil treatment results in remarkable improvement of the critical current density and pinning force performances of MgB2 superconductors. It was found that all MgB2 samples have a different pinning property at different measuring temperatures. Using synthetic engine oil as a product which is cheap and a rich carbon source in MgB2 bulk superconductors makes MgB2 samples immersed in synthetic engine oil a good candidate for industrial applications.

  13. Magnetism tuned by the charge states of defects in bulk C-doped SnO2 materials.

    PubMed

    Lu, Ying-Bo; Ling, Z C; Cong, Wei-Yan; Zhang, Peng

    2015-10-21

    To analyze the controversial conclusions on the magnetism of C-doped SnO2 (SnO2:C) bulk materials between theoretical calculations and experimental observations, we propose the critical role of the charge states of defects in the geometric structures and magnetism, and carry out a series of first principle calculations. By changing the charge states, we can influence Bader charge distributions and atomic orbital occupancies in bulk SnO2:C systems, which consequently conduct magnetism. In all charged SnO2:C supercells, C-2px/py/pz electron occupancies are significantly changed by the charge self-regulation, and thus they make the C-2p orbitals spin polarized, which contribute to the dominant magnetic moment of the system. When the concentration of C dopant in the SnO2 supercell increases, the charge redistribution assigns extra electrons averagely to each dopant, and thus effectively modulates the magnetism. These findings provide an experimentally viable way for controlling the magnetism in these systems.

  14. Cryogenic Cooling System for 5 kA, 200 μH Class HTS DC Reactor

    NASA Astrophysics Data System (ADS)

    Park, Heecheol; Kim, Seokho; Kim, Kwangmin; Park, Minwon; Park, Taejun; Kim, A.-rong; Lee, Sangjin

    DC reactors, made by aluminum busbar, are used to stabilize the arc of an electric furnace. In the conventional arc furnace, the transport current is several tens of kilo-amperes and enormous resistive loss is generated. To reduce the resistive loss at the DC reactor, a HTS DC reactor can be considered. It can dramatically improve the electric efficiency as well as reduce the installation space. Similar with other superconducting devices, the HTS DC reactor requires current leads from a power source in room temperature to the HTS coil in cryogenic environment. The heat loss at the metal current leads can be minimized through optimization process considering the geometry and the transport current. However, the transport current of the HTS DC reactor for the arc furnace is much larger than most of HTS magnets and the enormous heat penetration through the current lead should be effectively removed to keep the temperature around 70∼77 K. Current leads are cooled down by circulation of liquid nitrogen from the cooling system with a stirling cryocooler. The operating temperature of HTS coil is 30∼40 K and circulation of gaseous helium is used to remove the heat generation at the HTS coil. Gaseous helium is transported through the cryogenic helium blower and a single stage GM cryocooler. This paper describes design and experimental results on the cooling system for current leads and the HTS coil of 5 kA, 200 μH class DC reactor as a prototype. The results are used to verify the design values of the cooling systems and it will be applied to the design of scale-up cooling system for 50 kA, 200 μH class DC reactor.

  15. High coercivity microcrystalline Nd-rich Nd-Fe-Co-Al-B bulk magnets prepared by direct copper mold casting

    NASA Astrophysics Data System (ADS)

    Zhao, L. Z.; Hong, Y.; Fang, X. G.; Qiu, Z. G.; Zhong, X. C.; Gao, X. S.; Liu, Z. W.

    2016-06-01

    High coercivity Nd25Fe40Co20Al15-xBx (x=7-15) hard magnets were prepared by a simple process of injection casting. Different from many previous investigations on nanocomposite compositions, the magnets in this work contain hard magnetic Nd2(FeCoAl)14B, Nd-rich, and Nd1+ε(FeCo)4B4 phases. The magnetic properties, phase evolution, and microstructure of the as-cast and annealed magnets were investigated. As the boron content increased from 7 to 11 at%, the intrinsic coercivity Hcj of the as-cast magnet increased from 816 to 1140 kA/m. The magnets annealed at 750 °C have shown more regular and smaller grains than the as-cast alloys, especially for the x=11 alloy. The high intrinsic coercivities for the annealed alloys with x=8~11 result from the presence of small-sized grains in the microstructure. The highest Hcj of 1427 kA/m was obtained for the heat treated alloy with x=10. This work provides an alternative approach for preparing fully dense Nd-rich bulk hard magnets with relatively good properties.

  16. New Magnetic Materials and Phenomena for Radar and Microwave Signal Processing Devices - Bulk and Thin Film Ferrites and Metallic Films

    DTIC Science & Technology

    2009-02-15

    methods have been used to produce in-plane c-axis (IPCA) oriented barium ferrite (BaM) films on o-plane (1120) sapphire substrates with low microwave ...New magnetic materials and phenomena for radar and microwave signal processing devices - bulk and thin film ferrites and metallic films 6. AUTHOR(S...excitation properties in delay line structures. (173 words) 14. SUBJECT TERMS Microwave ferrites , yttrium iron garnet, hexagonal ferrites

  17. Superconductor-Mediated Modification of Gravity? AC Motor Experiments with Bulk YBCO Disks in Rotating Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Noever, David A.; Koczor, Ronald J.; Roberson, Rick

    1998-01-01

    We have previously reported results using a high precision gravimeter to probe local gravity changes in the neighborhood of large bulk-processed high-temperature superconductors. Podkietnov, et al (Podkietnov, E. and Nieminen, R. (1992) A Possibility of Gravitational Force Shielding by Bulk YBa2 Cu3 O7-x Superconductor, Physica C, C203:441-444.) have indicated that rotating AC fields play an essential role in their observed distortion of combined gravity and barometric pressure readings. We report experiments on large (15 cm diameter) bulk YBCO ceramic superconductors placed in the core of a three-phase, AC motor stator. The applied rotating field produces up to a 12,000 revolutions per minute magnetic field. The field intensity decays rapidly from the maximum at the outer diameter of the superconducting disk (less than 60 Gauss) to the center (less than 10 Gauss). This configuration was applied with and without a permanent DC magnetic field levitating the superconducting disk, with corresponding gravity readings indicating an apparent increase in observed gravity of less than 1 x 10(exp -6)/sq cm, measured above the superconductor. No effect of the rotating magnetic field or thermal environment on the gravimeter readings or on rotating the superconducting disk was noted within the high precision of the observation. Implications for propulsion initiatives and power storage flywheel technologies for high temperature superconductors will be discussed for various spacecraft and satellite applications.

  18. Comparison study of the magnetic permeability and dc conductivity of Co-Ni-Li ferrite nanoparticles and their bulk counterparts

    NASA Astrophysics Data System (ADS)

    Assar, S. T.; Abosheiasha, H. F.; El Nimr, M. K.

    2014-03-01

    The temperature dependence of relative permeability and dc electrical conductivity of nanosamples and their bulk counterparts of Co0.5Ni0.5-2xLixFe2+xO4 (from x=0.00 to 0.25 in step of 0.05) was investigated. The values of the relative permeability of the nano-samples are lower than their bulk counterparts as a result of porous and nano-grained structure besides the effect of the larger volume of grain boundaries in the nanosamples. Moreover, the dc conductivity of the nanosamples is higher than their bulk counterparts. This is probable explained according to the shorter metal-oxygen bonding length and higher lattice vibrations of the nanosamples. Also, the values of the relative permeability of both nano and bulk samples exhibit stability over a considerable range of temperatures. This may make them useful in practical applications that require stability. All the nanosamples show high rising Curie temperature values with increasing the Li content up to the sample of x=0.15 thereafter a decrease of the Curie temperature occurs while the inverse behavior was observed in their bulk counterparts. The interpretation of these findings is explained in the discussion. Moreover, in general doping Co-Ni ferrites with Li ions improves their electrical and magnetic properties and this is clearly observed in the nanosample of x=0.15 which can be regarded as the most promising sample for microwave applications.

  19. Strengthening future electricity grid of the Netherlands by integration of HTS transmission cables

    NASA Astrophysics Data System (ADS)

    Zuijderduin, Roy; Chevtchenko, Oleg; Smit, Johan; Aanhaanen, Gert; Ross, Rob

    2014-05-01

    The electricity grid of the Netherlands is changing. There is a call of society to use more underground cables, less overhead lines (OHL) and to reduce magnetic emissions. At the same time, parts of the future transmission grid need strengthening depending on the electricity demand in the coming decades [1]. Novel high temperature superconductor (HTS) AC transmission cables can play a role in strengthening the grid. The advantages as compared to alternatives, are: economic, underground, higher power capacity, lower losses, reduced magnetic field emissions in (existing) OHL, compact: less occupation of land and less permits needed, a possibility to keep 380 kV voltage level in the grid for as long as needed. The main obstacles are: the relatively high price of HTS tapes and insufficient maturity of the HTS cable technology. In the paper we focus on a 34 km long connection in the transmission grid (to be strengthened in three of the four of TenneT scenarios [1]), present the network study results, derive the requirements for corresponding HTS transmission cable system and compare HTS system to the alternatives (OHLs and XLPE cables).

  20. Spin-orbit torques in Ta/TbxCo100-x ferrimagnetic alloy films with bulk perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Ueda, Kohei; Mann, Maxwell; Pai, Chi-Feng; Tan, Aik-Jun; Beach, Geoffrey S. D.

    2016-12-01

    We quantified the bulk perpendicular magnetic anisotropy (PMA) and spin-orbit torques (SOTs) in bilayer Ta/TbxCo100-x ferrimagnetic alloy films with varying Tb concentration. The coercivity increases dramatically with increasing TbxCo100-x thickness and is enhanced by the presence of a Ta underlayer. The Ta underlayer simultaneously serves as a source of SOT due to the spin Hall effect, which we show provides an efficient means to manipulate the magnetization in bulk PMA materials. It is further shown that the sign of the anomalous Hall voltage is different for rare-earth (RE) and transition-metal (TM) dominated alloy compositions, whereas the sign of the SOT effective field remains the same, suggesting that the former is related to the TM sublattice magnetization whereas the latter is related to the net magnetization. Our results suggest that Ta/TbxCo100-x is a potential candidate for spin-orbitronic device applications and give insight into spin transport and SOTs in rare-earth/transition-metal alloys.

  1. Spin-orbit torque in a bulk perpendicular magnetic anisotropy Pd/FePd/MgO system.

    PubMed

    Lee, Hwang-Rae; Lee, Kyujoon; Cho, Jaehun; Choi, Young-Ha; You, Chun-Yeol; Jung, Myung-Hwa; Bonell, Frédéric; Shiota, Yoichi; Miwa, Shinji; Suzuki, Yoshishige

    2014-10-08

    Spin-orbit torques, including the Rashba and spin Hall effects, have been widely observed and investigated in various systems. Since interesting spin-orbit torque (SOT) arises at the interface between heavy nonmagnetic metals and ferromagnetic metals, most studies have focused on the ultra-thin ferromagnetic layer with interface perpendicular magnetic anisotropy. Here, we measured the effective longitudinal and transverse fields of bulk perpendicular magnetic anisotropy Pd/FePd (1.54 to 2.43 nm)/MgO systems using harmonic methods with careful correction procedures. We found that in our range of thicknesses, the effective longitudinal and transverse fields are five to ten times larger than those reported in interface perpendicular magnetic anisotropy systems. The observed magnitude and thickness dependence of the effective fields suggest that the SOT do not have a purely interfacial origin in our samples.

  2. Spin-orbit torque in a bulk perpendicular magnetic anisotropy Pd/FePd/MgO system

    PubMed Central

    Lee, Hwang-Rae; Lee, Kyujoon; Cho, Jaehun; Choi, Young-Ha; You, Chun-Yeol; Jung, Myung-Hwa; Bonell, Frédéric; Shiota, Yoichi; Miwa, Shinji; Suzuki, Yoshishige

    2014-01-01

    Spin-orbit torques, including the Rashba and spin Hall effects, have been widely observed and investigated in various systems. Since interesting spin-orbit torque (SOT) arises at the interface between heavy nonmagnetic metals and ferromagnetic metals, most studies have focused on the ultra-thin ferromagnetic layer with interface perpendicular magnetic anisotropy. Here, we measured the effective longitudinal and transverse fields of bulk perpendicular magnetic anisotropy Pd/FePd (1.54 to 2.43 nm)/MgO systems using harmonic methods with careful correction procedures. We found that in our range of thicknesses, the effective longitudinal and transverse fields are five to ten times larger than those reported in interface perpendicular magnetic anisotropy systems. The observed magnitude and thickness dependence of the effective fields suggest that the SOT do not have a purely interfacial origin in our samples. PMID:25293693

  3. Structure and magnetic properties of bulk nanocrystalline Tm{sub 2}(Co{sub 1-x}Fe{sub x}){sub 17} permanent magnet

    SciTech Connect

    Zhang, D. T.; Yang, J. J.; Yue, M.; Cao, S.; Liu, W. Q.; Zhang, J. X.; Yi, X. F.; Qiang, Y.

    2010-05-15

    Structure and magnetic properties were studied for Tm{sub 2}(Co{sub 1-x}Fe{sub x}){sub 17} bulk nanocrystalline magnet synthesized by spark plasma sintering technique. X-ray diffraction results indicate both ingot and sintered magnet of Tm{sub 2}(Co{sub 0.7}Fe{sub 0.3}){sub 17} alloy exhibit hexagonal Th{sub 2}Ni{sub 17} type structure. The microstructure of the magnet is composed of Th{sub 2}Ni{sub 17} type nanograins with an average size of 35 nm detected by transmission electron microscopy and selected area electron diffraction patterns. Magnetic measurement shows that the remanence of the magnet is higher at 573 K than at 300 K, indicating there is a positive remanence temperature coefficient in the magnet. The anisotropy field of Tm{sub 2}(Co{sub 0.7}Fe{sub 0.3}){sub 17} alloy is 3.8 T, which is much higher than the H{sub A} of 2.3 T for the pure Tm{sub 2}Co{sub 17} alloy. The coercivity of the sintered magnet increases from 0.25 to 0.354 T after optimal annealing.

  4. MMS Electric Field Observations of Electron-Scale Magnetic Holes in the Earth's Bursty Bulk Flow Braking Region

    NASA Astrophysics Data System (ADS)

    Goodrich, Katherine; Ergun, Robert; Wilder, Frederick; Sturner, Andrew; Holmes, Justin; Stawarz, Julia; Torbert, Roy; Lindqvist, Per-Arne; Khotyaintsev, Yuri; Burch, Jim; Strangeway, Robert; Werner, Magnes; Le Contel, Olivier; Giles, Barbara; Gershman, Daniel

    2016-04-01

    Electron-scale magnetic holes have been observed multiple times in the Earth's magnetosphere, particularly in the near-earth (6 RE to 12 RE) plasma sheet, or Bursty Bulk Flow (BBF) Braking region. This particular subset of magnetic holes has observed scale sizes perpendicular to the magnetic field (B) less than the environment's ion gyroradius. Previous observations from the THEMIS mission indicate that this subset of magnetic holes have negative potential in the center, which creates a diverging (outward) electric field at the boundary. The region of diverging electric field can drive an electron current via the ExB drift of electrons. Ions do not participate in the ExB drift due to the small scale size of the electric field. The Magnetospheric Multi-scale (MMS) spacecraft, launched March 2015, are currently orbiting the Earth with the objective of observing the microphysics of magnetic reconnection. During its commissioning phase (March - August 2015), all four spacecraft apogees were primarily in the BBF Braking region. MMS offers multi-spacecraft observations of electron-scale magnetic holes, which can possibly offer better insight to their structure and evolution.

  5. Simulation studies on the magnetization of (RE)BCO bulk superconductors using various split-coil arrangements

    NASA Astrophysics Data System (ADS)

    Xu, Zhihan; Lewin, Richard; Campbell, Archie M.; Cardwell, David A.; Jones, Harry

    2012-02-01

    Simulation studies were conducted on the magnetization of (RE)BCO (RE-Ba-Cu-O, where RE represents a rare earth element) bulk superconductors using various split-coil arrangements by solving the critical state equation using the commercial software FlexPDE. A pair of coaxial coils of identical size is identified as an optimum arrangement for practical magnetization at 77 K by the ‘zero-field cooling’ technique. In general, the magnetization process is likely to be most effective when the outer radius of the coils lies between 100% and 50% of the sample radius. A relatively large coil pair is necessary for samples with either a smaller aspect ratio or larger values of Jc0. Two different regimes of flux penetration are found to be involved in the magnetization process. For a sufficiently small sample, the penetration field is determined by flux propagation from beneath the coil to the centre of the sample; for a sufficiently large sample, the definitive propagation route is from beneath the coil to the periphery of the sample. Effective split-coil magnetization occurs only in the former regime, and both penetration regimes are completely different from that involved in the solenoidal-coil magnetization process.

  6. HTS Wire Development Workshop: Proceedings

    SciTech Connect

    Not Available

    1994-07-01

    The 1994 High-Temperature Superconducting Wire Development Workshop was held on February 16--17 at the St. Petersburg Hilton and Towers in St. Petersburg, Florida. The meeting was hosted by Florida Power Corporation and sponsored by the US Department of Energy`s Superconductivity Program for Electric Power Systems. The meeting focused on recent high-temperature superconducting wire development activities in the Department of Energy`s Superconductivity Systems program. The meeting opened with a general discussion on the needs and benefits of superconductivity from a utility perspective, the US global competitiveness position, and an outlook on the overall prospects of wire development. The meeting then focused on four important technology areas: Wire characterization: issues and needs; technology for overcoming barriers: weak links and flux pinning; manufacturing issues for long wire lengths; and physical properties of HTS coils. Following in-depth presentations, working groups were formed in each technology area to discuss the most important current research and development issues. The working groups identified research areas that have the potential for greatly enhancing the wire development effort. These areas are discussed in the summary reports from each of the working groups. This document is a compilation of the workshop proceedings including all general session presentations and summary reports from the working groups.

  7. Parameter identification of the complete-moving-hysteresis model for HTS steel

    SciTech Connect

    Kahler, G.R.; Della Torre, E.; Vajda, F. . Inst. for Magnetics Research)

    1994-11-01

    This paper discusses an extension to soft magnetic materials of the identification method of the CMH model which was originally introduced for medium hard magnetic materials. The proposed Preisach function for HTS steel, a soft magnetic material, is normal in the interaction field and is assumed to be lognormal in the critical field. Although the Preisach function is not symmetrical, the logarithm of the operative Preisach function is. However, the moving parameter, [alpha], can not be obtained by finding the value that removes this asymmetry because of the presence of apparent reversible magnetization and the lognormal nature of the Preisach function. All the Preisach parameters can be obtained using the major curve and the virgin curve only. For HTS steel, the squareness is 0.004, indicating a small irreversible magnetization component. The coercivity is 8.6 Oe; whereas the remanence coercivity is an order of magnitude larger, namely 123.5 Oe.

  8. An introduction to the design and fabrication progress of a megawatt class 2G HTS motor for the ship propulsion application

    NASA Astrophysics Data System (ADS)

    Moon, Heejong; Kim, Yeong-Chun; Park, Heui-Joo; Yu, In-Keun; Park, Minwon

    2016-03-01

    This paper introduces the design and fabrication progress of a megawatt class 2G high temperature superconductor (HTS) motor for the ship propulsion application at Doosan Heavy Industries and Construction. The purpose of this 2G HTS propulsion motor is to launch the business area for marine applications such as surface ship, submarine, merchant ship etc. The principles and interpretation of the magnetic field for 2G HTS motor and permanent magnet type motors are similar on the basis of 3D design and production. The most important component of an HTS motor is the rotor, which is composed of HTS coil, non-ferrous metal, torque disk, damper, and hollow shaft. A HTS rotor using hastelloy-based 2G HTS coils was designed and built. Open-circuit and short-circuit characteristics of the superconducting motor were investigated and compared with the analysis results at reduced excitation to verify the design. Preliminary testing of a 2G HTS motor has been conducted at a few hundred kilowatts as per the design. Through these results, we anticipate that most of the design criteria can be satisfied. However, we have faced several issues during the testing of the motor and these issues need to be resolved in order to take the design further.

  9. The coexistence of surface magnetoplasmons (SMPs) and bulk magnetoplasmons (BMPs) in SIS waveguide with the Voigt configuration magnetization

    NASA Astrophysics Data System (ADS)

    Zhu, Qiong-gan; Wang, Zhi-guo

    2016-05-01

    The coexistence behavior of surface magnetoplasmons (SMPs) and bulk magnetoplasmons (BMPs) is discussed on a platform constructed by the Semicondutor-Insulator-Semiconductor (SIS) waveguide with the Voigt configuration magnetization. It is found that the coexistence of SMPs and BMPs stems from the nonzero off-diagonal terms of permittivity tensors of the top and the bottom semiconductor materials (SM) claddings which are induced by the external magnetic field. In this case, the impendence of SM for SMPs contains two contributions associated with both the transversal and the longitudinal wave vectors of SMPs. When the impendence matching condition of SMPs exciting in SIS waveguide is satisfied in the propagating band of BMPs, the coexistence of these two modes thus appears. The results show that the forward-propagating SMPs only coexists with the lower BMPs mode, however, the backward-propagating SMPs coexists with the higher BMPs mode when the top and the bottom SM claddings are magnetized by equal amplitude magnetic field but with opposite direction. In addition, the influences of external-magnetic-field intensity, insulator permittivity and waveguide width on the coexisting frequency widths are also presented.

  10. Electrical performance analysis of HTS synchronous motor based on 3D FEM

    NASA Astrophysics Data System (ADS)

    Baik, S. K.; Kwon, Y. K.; Kim, H. M.; Lee, J. D.; Kim, Y. C.; Park, G. S.

    2010-11-01

    A 1-MW class superconducting motor with High-Temperature Superconducting (HTS) field coil is analyzed and tested. This machine is a prototype to make sure applicability aimed at generator and industrial motor applications such as blowers, pumps and compressors installed in large plants. This machine has the HTS field coil made of Bi-2223 HTS wire and the conventional copper armature (stator) coils cooled by water. The 1-MW class HTS motor is analyzed by 3D electromagnetic Finite Element Method (FEM) to get magnetic field distribution, self and mutual inductance, and so forth. Especially excitation voltage (Back EMF) is estimated by using the mutual inductance between armature and field coils and compared with experimental result. Open and short circuit tests were conducted in generator mode while a 1.1-MW rated induction machine was rotating the HTS machine. Electrical parameters such as mutual inductance and synchronous inductance are deduced from these tests and also compared with the analysis results from FEM.

  11. Integration of HTS Cables in the Future Grid of the Netherlands

    NASA Astrophysics Data System (ADS)

    Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Aanhaanen, G.; Melnik, I.; Geschiere, A.

    Due to increasing power demand, the electricity grid of the Netherlands is changing. The future transmission grid will obtain electrical power generated by decentralized renewable sources, together with large scale generation units located at the coastal region. In this way electrical power has to be distributed and transmitted over longer distances from generation to end user. Potential grid issues like: amount of distributed power, grid stability and electrical loss dissipation merit particular attention. High temperature superconductors (HTS) can play an important role in solving these grid problems. Advantages to integrate HTS components at transmission voltages are numerous: more transmittable power together with less emissions, intrinsic fault current limiting capability, lower ac loss, better control of power flow, reduced footprint, less magnetic field emissions, etc. The main obstacle at present is the relatively high price of HTS conductor. However as the price goes down, initial market penetration of several HTS components (e.g.: cables, fault current limiters) is expected by year 2015. In the full paper we present selected ways to integrate EHV AC HTS cables depending on a particular future grid scenario in the Netherlands.

  12. An HTS flux pump operated by directly driving a superconductor into flux flow region in the E- J curve

    NASA Astrophysics Data System (ADS)

    Geng, Jianzhao; Coombs, T. A.

    2016-09-01

    High-T c superconducting (HTS) flux pumps are capable of compensating the persistent current decay in HTS magnets without electrical contact. In this paper, following work on a low-T c superconducting self-switching flux pump, we propose a new HTS flux pump by directly driving a high-T c superconductor into the flux flow region in the E- J curve. The flux pump consists of a transformer which has a superconducting secondary winding shorted by an YBCO-coated conductor bridge. A high alternating current with a much higher positive peak value than the negative peak value is induced in the secondary winding. The current always drives the bridge superconductor into the flux flow region only at around its positive peak value, thus resulting in flux pumping. The proposed flux pump is much simpler than existing HTS flux pumps.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

  14. Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization

    SciTech Connect

    Onbasli, M. C. Kim, D. H.; Ross, C. A.; Kehlberger, A.; Jakob, G.; Kläui, M.; Chumak, A. V.; Hillebrands, B.

    2014-10-01

    Yttrium iron garnet (YIG, Y {sub 3}Fe{sub 5}O{sub 12}) films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd{sub 3}Ga{sub 5}O{sub 12}) substrates with (100) orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe), near-bulk room temperature saturation moments (∼135 emu cm{sup −3}), in-plane easy axis, and damping parameters as low as 2.2 × 10{sup −4}. These high quality YIG thin films are useful in the investigation of the origins of novel magnetic phenomena and magnetization dynamics.

  15. A Cryogenic Magnetostrictive Actuator using a Persistent High Temperature Superconducting Magnet, Part 1: Concept and Design. Part 1; Concept and Design

    NASA Technical Reports Server (NTRS)

    Horner, Garnett C.; Bromberg, Leslie; Teter, J. P.

    2001-01-01

    Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications, such as Next Generation Space Telescope (NGST), the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Very fast charging and discharging of HTS tubes, as short as 100 microseconds, has been demonstrated. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSSCO 2212 with a

  16. Automatic HTS force measurement instrument

    DOEpatents

    Sanders, Scott T.; Niemann, Ralph C.

    1999-01-01

    A device for measuring the levitation force of a high temperature superconductor sample with respect to a reference magnet includes a receptacle for holding several high temperature superconductor samples each cooled to superconducting temperature. A rotatable carousel successively locates a selected one of the high temperature superconductor samples in registry with the reference magnet. Mechanism varies the distance between one of the high temperature superconductor samples and the reference magnet, and a sensor measures levitation force of the sample as a function of the distance between the reference magnet and the sample. A method is also disclosed.

  17. Automatic HTS force measurement instrument

    DOEpatents

    Sanders, S.T.; Niemann, R.C.

    1999-03-30

    A device is disclosed for measuring the levitation force of a high temperature superconductor sample with respect to a reference magnet includes a receptacle for holding several high temperature superconductor samples each cooled to superconducting temperature. A rotatable carousel successively locates a selected one of the high temperature superconductor samples in registry with the reference magnet. Mechanism varies the distance between one of the high temperature superconductor samples and the reference magnet, and a sensor measures levitation force of the sample as a function of the distance between the reference magnet and the sample. A method is also disclosed. 3 figs.

  18. Bulk Nanocomposite LaCo5/LaCo13 Magnets (POSTPRINT)

    DTIC Science & Technology

    2012-08-01

    La2Co7 weight fraction of 25–30% (La content of 34–34.5 wt. %) when hot pressed at 760 C. The ratio of the remanence magnetization (Mr) to the...magnetization at 1.5 T, Mr/M (1.5 T), is roughly 0.9. The ratio Hk/Hc (where Hk is the reversal field when the moment 4pM drops down to 90% of the remanent 4pMr

  19. R&D ERL: HTS Solenoid

    SciTech Connect

    Gupta, R.; Muratore, J.; Plate, S.

    2010-01-01

    An innovative feature of the ERL project is the use of a solenoid made with High Temperature Superconductor (HTS) with the Superconducting RF cavity. The HTS solenoid design offers many advantages because of several unique design features. Typically the solenoid is placed outside the cryostat which means that the beam gets significantly defused before a focusing element starts. In the current design, the solenoid is placed inside the cryostat which provides an early focusing structure and thus a significant reduction in the emittance of the electron beam. In addition, taking full advantage of the high critical temperature of HTS, the solenoid has been designed to reach the required field at {approx}77 K, which can be obtained with liquid nitrogen. This significantly reduces the cost of testing and allows a variety of critical pre-tests which would have been prohibitively expensive at 4 K in liquid helium because of the additional requirements of cryostat and associated facilities.

  20. Symmetry and Bulk-Edge Correspondence in the Dimerized Spin-1/2 Heisenberg Ladder with External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kariyado, Toshikaze; Hatsugai, Yasuhiro

    2015-03-01

    The dimerized spin-1/2 Heisenberg ladder is topologically characterized from the viewpoints of symmetry protection and bulk-edge correspondence. Our focus is on the plateau phase at the half of the saturation induced by dimerization and magnetic field. The Berry phase associated with the twisted boundary condition is employed as a topological order parameter. The magnetic field reduces the symmetry of the system, but there is a topological phase protected by a spatial inversion symmetry that is characterized by a Berry phase quantized to 0/ π. For a Berry phase quantization, usage of a symmetry-preserving boundary, which leaves at least one inversion center after the system is cut at the boundary, is essential. As a comparison, a symmetry-breaking boundary is also analyzed. Naively, such a boundary is inadequate to make the Berry phase quantized and topological. However, for a specific type of boundary, we found a unique quantization of the Berry phase into +/- π / 2 , instead of 0/ π [1]. Further, for the case of +/- π / 2 -quantization, there appears an edge state distinct from the one for the 0/ π-quantization, which reveals new aspects of the bulk-edge correspondence for symmetry-breaking boundary.

  1. Unexpectedly wide reversible vortex region in β -pyrochlore RbOs2O6 : Bulk magnetization measurements

    NASA Astrophysics Data System (ADS)

    Legendre, Pierre; Fasano, Yanina; Maggio-Aprile, Ivan; Fischer, Øystein; Bukowski, Zbigniew; Katrych, Sergiy; Karpinski, Janusz

    2008-10-01

    We study the extent of the reversible region in the vortex phase diagram of recently available RbOs2O6 single crystals [Rogacki , Phys. Rev. B 77, 134514 (2008)] by means of bulk magnetization measurements. We found that the irreversible magnetic response sets in at a field Hirr(T)˜0.3Hc2(T) for 0.5≲T/Tc≲0.8 yielding a reversible vortex region that is wide in comparison with other low- Tc materials. The relevance of thermal fluctuations is limited since we estimate a Ginzburg number Gi=5×10-7 . However, the relevance of quenched disorder is low since the critical-current density ratio at low fields and temperatures is of the order of that found in high Tc ’s. We therefore conclude that an intrinsically low bulk pinning magnitude favors the existence of an unexpectedly wide reversible vortex region in RbOs2O6 .

  2. US effort on HTS power transformers

    NASA Astrophysics Data System (ADS)

    Mehta, S.

    2011-11-01

    Waukesha Electric Systems has been working in HTS power transformers development program under the auspices of US Government Department of Energy since 1994. This presentation will describe various milestones for this program and program history along with the lessons learned along the way. Our motivations for working on this development program based on man benefits offered by HTS power transformers to power delivery systems will be discussed. Based on various issues encountered during execution of many HTS projects, DOE has set up an independent program review process that is lead by team of experts. This team reviews are integral part of all DOE HTS projects. Success of all projects would be greatly enhanced by identifying critical issues early in the program. Requiring appropriate actions to mitigate the issues before processing further will lead to proactive interrogation and incorporation of expert's ideas in the project plans. Working of this review process will be also described in this presentation. Waukesha Electric Systems team including: Superpower-Inc, Oak Ridge National Laboratory, University of Houston Center for Superconductivity and Southern California Edison company was awarded a cost share grant by US Government in 2010 for development of a fault current limiting HTS power transformer. This multi year's program will require design, manufacture, installation, and monitoring of a 28 MVA tree phase transformer installed at Irvine CA. Smart Grid demonstration site. Transformer specifications along with requirements for fault current limiting and site requirement will be discussed. Design and development of various sub systems in support of this program including: HTS conductor performance specification, Dielectric system design approach, Dewar development for containing phase assemblies, cryo-cooling system design approach, etc. will be described. Finally; overall program schedule, critical milestone events, test plans and progress to date will be

  3. Bulk permittivity, low frequency relaxation and the magnetic properties of Pb(Fe½Nb½)O3 ceramics.

    PubMed

    Mishra, R K; Choudhary, R N P; Banerjee, A

    2010-01-20

    A Pb(Fe(½)Nb(½))O(3) ceramic sample was prepared through a high temperature solid-state reaction technique. The formation of a single-phase perovskite compound was confirmed by an x-ray diffraction technique. Dielectric and impedance parameters were measured as a function of frequency (10(2)-10(6) Hz) at different temperatures (28-200 °C). The results were described using an equivalent circuit model and by extending the universal capacitor concept introduced by Jonscher. Bulk permittivity of the material and the power law exponent (extracted from impedance data) exhibits an anomaly at a particular temperature related to the ferroelectric-paraelectric transition. A slow relaxation process has been observed in the vicinity of the transition temperature. Temperature dependent magnetization (2-300 K) was measured at different magnetic fields in both zero-field-cooled (ZFC) and field-cooled (FC) modes. An antiferromagnetic transition was observed at 158 K but an unusual increase in magnetization below this transition indicates the onset of weak ferromagnetism at low temperature in this system. Nonlinear M-H and a finite opening in the hysteresis loop at 2 K substantiate the presence of ferromagnetic interactions. Significantly, a thermomagnetic history-dependent feature is observed below 9 K. The ZFC magnetization shows a sharp fall and it bifurcates from the monotonically increasing FC counterpart on decreasing temperature. This temperature, where ZFC magnetization shows a sharp peak, decreases with the increase in measurement field and it indicates the presence of a metastable magnetic state at low temperature.

  4. Concepts for using trapped-flux HTS in motors and generators

    NASA Astrophysics Data System (ADS)

    Hull, John R.; Strasik, Michael

    2013-01-01

    We examine the expected performance of a brushless motor/generator that uses trapped-flux (TF) bulk high-temperature superconductors (HTSs) to provide magnetomotive force, where the stator windings are used to create the TF. A key feature is the use of dysprosium (Dy) for the stator and rotor cores. We also examine methods to energize TF in HTS for generators used in pulsed-power applications.

  5. Using thermal boundary conditions to engineer the quantum state of a bulk magnet

    PubMed Central

    Schmidt, M. A.; Silevitch, D. M.; Aeppli, G.; Rosenbaum, T. F.

    2014-01-01

    The degree of contact between a system and the external environment can alter dramatically its proclivity to quantum mechanical modes of relaxation. We show that controlling the thermal coupling of cubic-centimeter–sized crystals of the Ising magnet LiHoxY1-xF4 to a heat bath can be used to tune the system between a glassy state dominated by thermal excitations over energy barriers and a state with the hallmarks of a quantum spin liquid. Application of a magnetic field transverse to the Ising axis introduces both random magnetic fields and quantum fluctuations, which can retard and speed the annealing process, respectively, thereby providing a mechanism for continuous tuning between the destination states. The nonlinear response of the system explicitly demonstrates quantum interference between internal and external relaxation pathways. PMID:24567389

  6. Improved Characteristics of Integrated HTS rf SQUID on Bicrystal SrTiO3 Substrate Resonator Covered with HTS Thin Films in Flip-Chip Geometry

    NASA Astrophysics Data System (ADS)

    Hatsukade, Yoshimi; Takemoto, Makoto; Kurosawa, Ryuichi; Uchida, Yousuke; Tanaka, Saburo

    Integrated high-temperature superconductor (HTS) radio-frequency (rf) superconducting quantum interference devices (SQUIDs) based on a bicrystal SrTiO3 substrate was investigated for application to magnetic contaminant detection. By covering a wide superconducting weak link and/or a slit of the YBa2Cu3O7-x SQUID with HTS thin films in flip-chip geometry, characteristics such as effective area and 1/f noise profile of the SQUID were successfully improved. By installing the covered SQUID in a magnetic contaminant detection system, it was demonstrated that the system can detect a tungsten ball of 15μm in diameter with a signal to noise ratio of about 2.

  7. Operating characteristic analysis of a 400 mH class HTS DC reactor in connection with a laboratory scale LCC type HVDC system

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Kyu; Kim, Kwangmin; Park, Minwon; Yu, In-Keun; Lee, Sangjin

    2015-11-01

    High temperature superconducting (HTS) devices are being developed due to their advantages. Most line commutated converter based high voltage direct current (HVDC) transmission systems for long-distance transmission require large inductance of DC reactor; however, generally, copper-based reactors cause a lot of electrical losses during the system operation. This is driving researchers to develop a new type of DC reactor using HTS wire. The authors have developed a 400 mH class HTS DC reactor and a laboratory scale test-bed for line-commutated converter type HVDC system and applied the HTS DC reactor to the HVDC system to investigate their operating characteristics. The 400 mH class HTS DC reactor is designed using a toroid type magnet. The HVDC system is designed in the form of a mono-pole system with thyristor-based 12-pulse power converters. In this paper, the investigation results of the HTS DC reactor in connection with the HVDC system are described. The operating characteristics of the HTS DC reactor are analyzed under various operating conditions of the system. Through the results, applicability of an HTS DC reactor in an HVDC system is discussed in detail.

  8. Molar volume, thermal expansion, and bulk modulus in liquid Fe-Ni alloys at 1 bar: Evidence for magnetic anomalies?

    NASA Astrophysics Data System (ADS)

    Nasch, P. M.; Manghnani, M. H.

    New experimental data on the molar volume Ω, thermal expansion coefficient α, and ultrasonic sound velocity vp in liquid Fe-Ni systems at temperatures between melting and 1975 K are reported. The molar volume and thermal expansion data were acquired using a penetrating γ radiation method; the sound velocity data were obtained by ultrasonic interferometry. In the temperature range of this study, the molar volume Ω increases and the sound velocity vp decreases, both linearly with temperature. The adiabatic bulk modulus KS ∝ v2p/Ωp of liquid Fe-Ni alloys is nearly independent of composition at Fe content greater than 65 wt%. The temperature derivative ∂K/∂T of both adiabatic and isothermal bulk modulus of pure liquid Fe decreases by approximately 50% upon being alloyed with 15 wt% Ni. The mixing behavior of thermodynamic and cohesive properties of liquid Fe-Ni is interpreted as resulting from the existence of disordered and localized magnetic states and correlations in the liquid state, i.e., well above the Curie temperature and extending from pure Fe into the Fe-Ni stability field. These magnetic contributions have strong mechanical effects on the structure in modifying the volume and elastic modulus by as much as 13% and 31%, respectively, in the case of pure liquid Fe. It is believed that the magnetic contribution, which is likely to be absent at core temperatures, should be removed from the measured 1-bar values of density and elastic moduli if these latter were to be used as precise anchoring points in high pressure-temperature EOS.

  9. Irreversibility Line Measurement and Vortex Dynamics in High Magnetic Fields in Ni- and Co-Doped Iron Pnictide Bulk Superconductors

    DOE PAGES

    Nikolo, Martin; Singleton, John; Zapf, Vivien S.; ...

    2016-07-20

    The de-pinning or irreversibility lines were determined by ac susceptibility, magnetization, radio-frequency proximity detector oscillator (PDO), and resistivity methods in Ba(Fe0.92Co0.08)2As2 ( Tc = 23.2 K), Ba(Fe0.95Ni0.05)2As2 ( Tc = 20.4 K), and Ba(Fe0.94Ni0.06)2As2 ( Tc = 18.5 K) bulk superconductors in ac, dc, and pulsed magnetic fields up to 65 T. A new method of extracting the irreversibility fields from the radio-frequency proximity detector oscillator induction technique is described. Wide temperature broadening of the irreversibility lines, for any given combination of ac and dc fields, is dependent on the time frame of measurement. Increasing the magnetic field sweep ratemore » (dH/dt) shifts the irreversibility lines to higher temperatures up to about dH/d t = 40,000 Oe/s; for higher dH/dt, there is little impact on the irreversibility line. There is an excellent data match between the irreversibility fields obtained from magnetization hysteresis loops, PDO, and ac susceptibility measurements, but not from resistivity measurements in these materials. Lower critical field vs. temperature phase diagrams are measured. Their very low values near 0 T indicate that these materials are in mixed state in nonzero magnetic fields, and yet the strength of the vortex pinning enables very high irreversibility fields, as high as 51 T at 1.5 K for the Ba(Fe0.92Co0.08)2As2 polycrystalline sample, showing a promise for liquid helium temperature applications.« less

  10. A Cryogenic Magnetostrictive Actuator Using a Persistent High Temperature Superconducting Magnet. Part 1; Concept and Design

    NASA Technical Reports Server (NTRS)

    Horner, Garnett; Bromberg, Leslie; Teter, J. P.

    2000-01-01

    Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSCCO 2212 with a magnetostrictive element will be discussed.

  11. Study on effect of annealing conditions on structural, magnetic and superconducting properties of MgB{sub 2} bulk samples

    SciTech Connect

    Phaneendra, Konduru Asokan, K. Kanjilal, D.; Awana, V. P. S.; Sastry, S. Sreehari

    2014-04-24

    Effect of annealing conditions on structural, magnetic and superconducting properties of Magnesium Diboride (MgB{sub 2}) bulk superconductor samples prepared by solid state route method are compared. The samples are made by taking Magnesium and Boron powders in stoichiometric ratio, grounded well and pelletized at pressure of about 10Tonnes. These pellets are annealed in both Argon and vacuum environment separately up to 800°c for two hours. Both the samples show clear superconducting transition at Tc ∼ 38 k. This is further conformed by AC/DC magnetization (M-T), Resistivity [ρ (T, H)] measurements under magnetic field up to 14 Tesla as well. Rietveld refinement of X-ray diffraction of both samples conformed the MgB{sub 2} phase formation with P6/mmm space group symmetry. Scanning Electron Microscopy images of the surface revile more agglomeration of grains in case of Argon annealed samples. This result in more critical current density (J{sub c}) of Argon annealed samples than vacuum annealed one calculated from Bean's critical state model. This high Jc is explained in terms of more inter grain connectivity for Argon annealed sample than vacuum annealed sample.

  12. Magnetization Response of the Bulk and Supplementary Magnetic Domain Structure in High-Permeability Steel Laminations Visualized In Situ by Neutron Dark-Field Imaging

    NASA Astrophysics Data System (ADS)

    Betz, B.; Rauscher, P.; Harti, R. P.; Schäfer, R.; Irastorza-Landa, A.; Van Swygenhoven, H.; Kaestner, A.; Hovind, J.; Pomjakushina, E.; Lehmann, E.; Grünzweig, C.

    2016-08-01

    Industrial transformer cores are composed of stacked high-permeability steel laminations (HPSLs). The performance and degree of efficiency of transformers are directly determined by the magnetic properties of each HPSL. In this article, we show how the neutron dark-field image (DFI) allows for the in situ visualization of the locally resolved response of the bulk and supplementary magnetic domain structures in HPSLs under the influence of externally applied magnetic fields. In particular, we investigate the domain formation and growth along the initial magnetization curve up to the saturated state. For decreasing field, we visualize the recurrence of the hysteretic domain structure down to the remanent state. Additionally, the DFI allows us to derive a correlation between the grain orientation and the corresponding volume and supplementary domain structure. Furthermore, we visualize the influence of the insulation coating, introducing desired tensile stresses on the domain structures. To compare our DFI findings to traditional methods, we perform complementary surface-sensitive magneto-optical Kerr-microscopy investigations.

  13. Bipolar electrical coil based on YBCO bulks: initial tests

    NASA Astrophysics Data System (ADS)

    Alvarez, A.; Suárez, P.; Ceballos, J. M.; Pérez, B.; Werfel, F.; Floegel-Delor, U.

    2008-02-01

    In the field of the application of HTS in electrical motors, most prototypes are made using superconducting coils based on tape and located in the position where copper coils work in a similar conventional motor. Other prototypes use superconducting bulks (usually disk-shaped) in those positions where normal magnets should work in similar conventional motors. But it is very unusual to find designs using electrical coils based on bulks. This is a challenge whose main problem is the difficulty in machining the superconductor bulks to get the proper shape because of the impossibility of bending the material to wind coils. The design of a bipolar single-turn coil made from a superconducting YBCO disk was proposed by the group of Electrical Application of Superconductors, at the University of Extremadura, several years ago to be an element for the design of a modular two-phase inductor for an air core axial-flux motor. The shape of each coil looks like an 'S'. When a current flows through the circuit, two opposite magnetic fields appear in the upper and lower halves of the piece. Until now, attempts to get a good superconducting circuit by cutting a YBCO disk into the required shape have failed because of cracks appearing in the crystal during the process. Last year, our group at the University of Extremadura began to work with ATZ GmbH who have improved the machining process and made the coils. In this paper we present the coil and the first tests carried out.

  14. Theory of the magnetic and metal-insulator transitions in RNiO3 bulk and layered structures.

    PubMed

    Lau, Bayo; Millis, Andrew J

    2013-03-22

    A slave rotor--Hartree-Fock formalism is presented for studying the properties of the p-d model describing perovskite transition metal oxides, and a flexible and efficient numerical formalism is developed for its solution. The methodology is shown to yield, within a unified formulation, the significant aspects of the rare-earth nickelate phase diagram, including the paramagnetic metal state observed for the LaNiO3 and the correct ground-state magnetic order of insulating compounds. It is then used to elucidate ground state changes occurring as morphology is varied from bulk to strained and unstrained thin-film form. For ultrathin films, epitaxial strain and charge transfer to the apical out-of-plane oxygen sites are shown to have significant impact on the phase diagram.

  15. Theory of the Magnetic and Metal-Insulator Transitions in RNiO3 Bulk and Layered Structures

    NASA Astrophysics Data System (ADS)

    Lau, Bayo; Millis, Andrew J.

    2013-03-01

    A slave rotor—Hartree-Fock formalism is presented for studying the properties of the p-d model describing perovskite transition metal oxides, and a flexible and efficient numerical formalism is developed for its solution. The methodology is shown to yield, within a unified formulation, the significant aspects of the rare-earth nickelate phase diagram, including the paramagnetic metal state observed for the LaNiO3 and the correct ground-state magnetic order of insulating compounds. It is then used to elucidate ground state changes occurring as morphology is varied from bulk to strained and unstrained thin-film form. For ultrathin films, epitaxial strain and charge transfer to the apical out-of-plane oxygen sites are shown to have significant impact on the phase diagram.

  16. Theory of the magnetic and metal-insulator transitions in RNiO3 bulk and layered

    NASA Astrophysics Data System (ADS)

    Lau, Bayo; Millis, Andrew J.

    2013-03-01

    A slave rotor-Hartree Fock formalism is presented for studying the properties of the p-d model describing perovskite transition metal oxides, and a flexible and efficient numerical formalism is developed for its solution. The methodology is shown to yield, within an unified formulation, the significant aspects of the rare earth nickelate phase diagram, including the paramagnetic metal state observed for the LaNiO3 and the correct ground-state magnetic order of insulating compounds. It is then used to elucidate ground state changes occurring as morphology is varied from bulk to strained and un-strained thin-film form. For ultrathin films, epitaxial strain and charge-transfer to the apical out-of-plane oxygen sites are shown to have significant impact on the phase diagram. This effort is supported by US National Science Foundation under grant NSF-DMR-1006282

  17. Analytical Study of Stress State in HTS Solenoids

    SciTech Connect

    Barzi, E.; Terzini, E.; /Fermilab

    2009-01-01

    A main challenge for high field solenoids made of in High Temperature Superconductor (HTS) is the large stress developed in the conductor. This is especially constraining for BSCCO, a brittle and strain sensitive ceramic material. To find parametric correlations useful in magnet design, analytical models can be used. A simple model is herein proposed to obtain the radial, azimuthal and axial stresses in a solenoid as a function of size, i.e. self-field, and of the engineering current density for a number of different constraint hypotheses. The analytical model was verified against finite element modeling (FEM) using the same hypotheses of infinite rigidity of the constraints and room temperature properties. FEM was used to separately evaluate the effect of thermal contractions at 4.2 K for BSCCO and YBCO coils. Even though the analytical model allows for a finite stiffness of the constraints, it was run using infinite stiffness. For this reason, FEM was again used to determine how much stresses change when considering an outer stainless steel skin with finite rigidity for both BSCCO and YBCO coils. For a better understanding of the actual loads that high field solenoids made of HTS will be subject to, we have started some analytical studies of stress state in solenoids for a number of constraint hypotheses. This will hopefully show what can be achieved with the present conductor in terms of self-field. The magnetic field (B) exerts a force F = B x J per unit volume. In superconducting magnets, where the field and current density (J) are both high, this force can be very large, and it is therefore important to calculate the stresses in the coil.

  18. Effect of Interface Shape and Magnetic Field on the Microstructure of Bulk Ge:Ga

    NASA Technical Reports Server (NTRS)

    Cobb, S. D.; Szofran, F. R.; Volz, M. P.

    1999-01-01

    Thermal and compositional gradients induced during the growth process contribute significantly to the development of defects in the solidified boule. Thermal gradients and the solid-liquid interface shape can be greatly effected by ampoule material. Compositional gradients are strongly influenced by interface curvature and convective flow in the liquid. Results of this investigation illustrate the combined influences of interface shape and convective fluid flow. An applied magnetic field was used to reduce the effects of convective fluid flow in the electrically conductive melt during directional solidification. Several 8 mm diameter boules of Ga-doped Ge were grown at different field strengths, up to 5 Tesla, in four different ampoule materials. Compositional profiles indicate mass transfer conditions ranged from completely mixed to diffusion controlled. The influence of convection in the melt on the developing crystal microstructure and defect density was investigated as a function of field strength and ampoule material. Chemical etching and electron backscattered electron diffraction were used to map the crystal structure of each boule along the center plane. Dislocation etch pit densities were measured for each boule. Results show the influence of magnetic field strength and ampoule material on overall crystal quality.

  19. Theory of Magnetic Response and Hall Effect in Bulk Rashba System

    NASA Astrophysics Data System (ADS)

    Ando, Tsuneya; Suzuura, Hidekatsu

    2017-01-01

    The magnetic susceptibility and transport quantities are calculated in a three-dimensional system with a giant Rashba spin-orbit interaction for scatterers with short-range potential in a self-consistent Born approximation. The susceptibility exhibits a sharp peak toward the diamagnetic direction at the band crossing, being broadened depending on disorder. No special feature appears in the diagonal conductivity in both in-plane and vertical directions. The orbital Hall conductivity due to cyclotron motion is considerably reduced from -(nec)-1 in the low-energy region and exhibits a small step-like jump at the band crossing, becoming almost the same as -(nec)-1, where n is the carrier concentration. The Hall conductivity due to the spin-Zeeman energy has a sharp peak at the band crossing, but is significantly reduced due to inter-band scattering.

  20. Structural modeling of HTS tapes and cables

    NASA Astrophysics Data System (ADS)

    Allen, N. C.; Chiesa, L.; Takayasu, M.

    2016-12-01

    Structural finite element analysis (FEA) has been used as an insightful tool to investigate the electromechanical behavior of HTS REBCO tapes and twisted stacked-tape cables under tension, torsion, bending and combined loads. A novel technique was developed for modeling the layered composite structure of the 2G tapes with structural solid-shell elements in ANSYS®. The FEA models produced detailed strain information for the REBCO superconducting layer which was then paired with an analytical model to predict the critical current performance of the 2G HTS tapes under various loads. Two commercially available HTS tapes (SuperPower and SuNAM) under tension, torsion and combined tension-torsion were first analyzed with FEA and compared with available experimental results at 77 K. A sharp critical current degradation was experienced at the yield strength of the tapes under tension and below a 100 mm twist-pitch under torsion. Combined tension-torsion loads had a more gradual degradation of critical current for twist-pitches of 115 mm or shorter but had a negligible difference compared to pure tension for longer twist-pitches. Using the structural solid-shell technique for modeling 2G tapes in ANSYS®, an FEA methodology for simulating full scale three-dimensional HTS stacked-tape cables under pure bending was created. A model of a Twisted-Stacked Tape Cable (TSTC), a configuration first proposed at MIT, was initially developed and then adapted to the slotted-core HTS Cable-In-Conduit Conductor produced by the ENEA laboratory in Italy. The numerical axial strain of the HTS REBCO tapes within the cables as calculated by FEA were found to agree with an analytical model for two cases: perfect-slip (frictionless) and no-slip (bonded). The ENEA CICC model was also compared with recent experimental critical current data at 77 K and was found to match best using a low friction coefficient of 0.02 indicating that the tapes within the cable freely slide with respect to each other

  1. Using Bulk Magnetic Susceptibility to Resolve Internal and External Signals in the NMR Spectra of Plant Tissues

    NASA Astrophysics Data System (ADS)

    Shachar-Hill, Yair; Befroy, Douglas E.; Pfeffer, Philip E.; Ratcliffe, R. George

    1997-07-01

    Internal and external NMR signals from a variety of plant cells and plant tissues can be resolved by changing the bulk magnetic susceptibility (BMS) of the perfusing medium with [Gd (EDTA)]-or Dy(DTPA-BMA). This separation is observed in samples consisting of cylindrical cells oriented along theB0field, and is consistent with established theoretical predictions about BMS effects. Evidence is presented that the shifted signals represent material outside the tissue as well as some contribution from intercellular spaces and cell walls, while intracellular signals are unshifted. The paramagnetic complexes used to separate the signals are shown to be nontoxic and to have no effect on a number of transport processes. The method has been applied to roots, shoots, and giant algal cells, facilitating the interpretation of thein vivospectra from a range of biologically important magnetic isotopes. The potential of the method for studies of transport is illustrated with experiments showing: (i)14N/15N isotopic exchange of nitrate in roots; (ii) the influx of HDO into root and shoot segments; and (iii) the use of saturation transfer to follow water movement into and out of plant cells.

  2. Combined effects of magnetic interaction and domain wall pinning on the coercivity in a bulk Nd60Fe30Al10 ferromagnet

    PubMed Central

    Tan, X. H.; Chan, S. F.; Han, K.; Xu, H.

    2014-01-01

    Understanding the coercivity mechanism has a substantial impact on developing novel permanent materials. However, the current coercivity mechanisms used widely in permanent alloys cannot explain well the amorphous phase produced hard magnetic behavior of Nd-based bulk amorphous alloys (BAAs). Here, we propose that the coercivity in as-cast Nd60Fe30Al10 alloy is from the combination of magnetic interaction and strong pinning of domain walls. Moreover, the role of domain wall pinning is less affected after crystallization, while the magnetic interaction is dependent on the annealing temperature. Our findings give further insight into the coercivity mechanism of Nd-based bulk ferromagnets and provide a new idea to design prospective permanent alloys with coercivity from the combination of magnetic interaction and pinning of domain walls. PMID:25348232

  3. Cryocooler applications for high-temperature superconductor magnetic bearings.

    SciTech Connect

    Niemann, R. C.

    1998-05-22

    The efficiency and stability of rotational magnetic suspension systems are enhanced by the use of high-temperature superconductor (HTS) magnetic bearings. Fundamental aspects of the HTS magnetic bearings and rotational magnetic suspension are presented. HTS cooling can be by liquid cryogen bath immersion or by direct conduction, and thus there are various applications and integration issues for cryocoolers. Among the numerous cryocooler aspects to be considered are installation; operating temperature; losses; and vacuum pumping.

  4. Electrical parameter evaluation of a 1 MW HTS motor via analysis and experiments

    NASA Astrophysics Data System (ADS)

    Baik, S. K.; Kwon, Y. K.; Kim, H. M.; Kim, S. H.; Lee, J. D.; Kim, Y. C.; Park, H. J.; Kwon, W. S.; Park, G. S.

    2009-06-01

    A 1 MW class HTS (high-temperature superconducting) synchronous motor has been developed. Design concerns of the developed motor are focused on smaller machine size and higher efficiency than conventional motors or generators with the same rating simultaneously reducing expensive Bi-2223 HTS wire which is used for superconducting field coil carrying the operating current around 30 K (-243 °C). Influence of an important parameter, synchronous reactance, has been analyzed on the machine performances such as voltage variation and output power during motor and generator operation. The developed motor was also analyzed by three-dimensional electromagnetic FEM (finite element method) to get magnetic field distribution, inductance, electromagnetic stress and so forth. This motor is aimed to be utilized for industrial application such as large motors operating in large plants. The HTS field coil of the developed motor is cooled by way of Neon thermosiphon mechanism and the stator (armature) coil is cooled by water through hollow copper conductor. This paper also describes evaluation of some electrical parameters from performance test results which were obtained at steady state in generator and motor mode of our HTS machine.

  5. Irreversibility Line Measurement and Vortex Dynamics in High Magnetic Fields in Ni- and Co-Doped Iron Pnictide Bulk Superconductors

    SciTech Connect

    Nikolo, Martin; Singleton, John; Zapf, Vivien S.; Jiang, Jianyi; Weiss, Jeremy D.; Hellstrom, Eric E.

    2016-07-20

    The de-pinning or irreversibility lines were determined by ac susceptibility, magnetization, radio-frequency proximity detector oscillator (PDO), and resistivity methods in Ba(Fe0.92Co0.08)2As2 ( Tc = 23.2 K), Ba(Fe0.95Ni0.05)2As2 ( Tc = 20.4 K), and Ba(Fe0.94Ni0.06)2As2 ( Tc = 18.5 K) bulk superconductors in ac, dc, and pulsed magnetic fields up to 65 T. A new method of extracting the irreversibility fields from the radio-frequency proximity detector oscillator induction technique is described. Wide temperature broadening of the irreversibility lines, for any given combination of ac and dc fields, is dependent on the time frame of measurement. Increasing the magnetic field sweep rate (dH/dt) shifts the irreversibility lines to higher temperatures up to about dH/d t = 40,000 Oe/s; for higher dH/dt, there is little impact on the irreversibility line. There is an excellent data match between the irreversibility fields obtained from magnetization hysteresis loops, PDO, and ac susceptibility measurements, but not from resistivity measurements in these materials. Lower critical field vs. temperature phase diagrams are measured. Their very low values near 0 T indicate that these materials are in mixed state in nonzero magnetic fields, and yet the strength of the vortex pinning enables very high irreversibility fields, as high as 51 T at 1.5 K for the Ba(Fe0.92Co0.08)2As2 polycrystalline sample, showing a promise for liquid helium temperature applications.

  6. X-ray and bulk magnetic properties of aluminium substituted ferrites

    NASA Astrophysics Data System (ADS)

    Kakatkar, S. V.; Kakatkar, S. S.; Patil, R. S.; Maskar, P. K.; Sankapal, A. M.; Suryawanshi, S. S.; Chaudhari, N. D.; Sawant, S. R.

    1996-07-01

    The compositions having the general formula Ni 0.55Zn 0.45Al tFe 2- tO 4 and Ni 0.65Zn 0.35Al tFe 2- tO 4 with t = 0.0, 0.1, 0.2, 0.3 have been prepared by the standard ceramic technique and sintered at 1100, 1150, 1200 and 1240°C to attain different microstructures. The lattice parameter a, magnetization Ms are seen to decrease with increasing Al 3+ content whereas the coercive force Hc shows an increasing trend with Al 3+ content. Ms is found to be invariant with the changes in sintering temperature. The coercivity Hc and the remanent ratio R = MR/ Ms are seen to depend on the sintering temperature and hence on the grain size D. The anisotropy field HKA increases with increase of aluminium content. Ms and HKA enable calculation of the anisotropy field constant K1 which decreases with increase of Al 3+. The compositional, thermal and microstructural variations of hysteresis parameters like Ms, Hc and R reveal that grains in the compositions investigated are of multidomain (M-D) type. This result is supported by ac susceptibility data.

  7. Theoretical investigation of the electronic structures and magnetic properties of the bulk and surface (001) of the quaternary Heusler alloy NiCoMnGa

    NASA Astrophysics Data System (ADS)

    Al-zyadi, Jabbar M. Khalaf; Gao, G. Y.; Yao, Kai-Lun

    2015-03-01

    In this paper, we study the electronic structures, magnetic properties, and half-metallicity of the bulk and (001) surface of Heusler alloy NiCoMnGa. Our first-principles calculations exhibit that, within the generalized gradient approximation (GGA) of the electronic exchange-correlation functional, the quaternary Heusler alloy NiCoMnGa is a half-metallic ferromagnet at the equilibrium lattice constant of 5.795 Ǻ with a total spin magnetic moment of 5 μB per formula unit. The calculated total atomic magnetic moment follows the Slater-Pauling rule. At the same equilibrium lattice constant, the half-metallicity confirmed in the bulk NiCoMnGa, is destroyed at both MnGa- and NiCo-terminated (001) surfaces and subsurfaces. Based on the magnetic property calculations, the magnetic moments of Co, Mn, and Ga atoms at the NiCo- and MnGa-terminated surfaces increase with respect to the corresponding bulk values while the atomic magnetic moment of Ni at the NiCo-terminated surface decreases.

  8. Design and testing of the HTS bearing for a 10 kWh flywheel system

    NASA Astrophysics Data System (ADS)

    Day, A. C.; Strasik, M.; McCrary, K. E.; Johnson, P. E.; Gabrys, J. W.; Schindler, J. R.; Hawkins, R. A.; Carlson, D. L.; Higgins, M. D.; Hull, J. R.

    2002-05-01

    Flywheels are of interest for a wide range of energy storage applications, from support of renewable resources to distributed power applications and uninterruptible power systems (UPS) (Day et al 2000 Proc. EESAT 2000 (Orlando, FL, Sept. 2000)). The use of high-temperature superconducting (HTS) bearings for such systems has significant advantages for applications requiring large amounts of energy to be stored with low parasitic losses and with minimal system maintenance. As flywheel systems increase in size, it becomes a significant challenge to provide adequate stiffness in these bearings without exceeding the strength limits of rotating magnet assemblies. The Boeing Company is designing and building a prototype flywheel of 10 kWh total stored energy and has focused much effort on the HTS bearing system. This paper will describe the general structure of the bearing and the steps taken to optimize its magnetic and structural performance and show recent test results.

  9. AC Losses of Prototype HTS Transmission Cables

    SciTech Connect

    Demko, J.A.; Dresner, L.; Hughey, R.L.; Lue, J.W.; Olsen, S.K.; Sinha, U.; Tolbert, J.C.

    1998-09-13

    Since 1995 Southwire Company and Oak Ridge National Laboratory (ORNL) have jointly designed, built, and tested nine, l-m long, high temperature superconducting (HTS) transmission cable prototypes. This paper summarizes the AC loss measurements of five of the cables not reported elsewhere, and compares the losses with each other and with theory developed by Dresner. Losses were measured with both a calorimetric and an electrical technique. Because of the broad resistive transition of the HTS tapes, the cables can be operated stably beyond their critical currents. The AC losses were measured in this region as well as below critical currents. Dresner's theory takes into account the broad resistive transition of the HTS tapes and calculates the AC losses both below and above the critical current. The two sets of AC 10SS data agree with each other and with the theory quite welL In particular, at low currents of incomplete penetration, the loss data agree with the theoretical prediction of hysteresis loss based on only the outer two Iayers carrying the total current.

  10. First Russian long length HTS power cable

    NASA Astrophysics Data System (ADS)

    Volkov, Eduard P.; Vysotsky, Vitaly S.; Firsov, Valery P.

    2012-11-01

    The Russian R&D Program for superconducting power devices is underway, supported both by government and electric power companies. In this program R&D on HTS power cables is considered as most advanced and close to commercialization. In the framework of the program, several, heavily instrumented, 5 m cables have been tested following by the 30 m - 3 phase experimental power cable development and testing in 2008-2009. The latest achievement is development and testing of the first long length 3 × 200 m power cable with rating 1.5/2 kA-20 kV. In parallel with just the cable development the innovative cryogenic system has been developed as well for the cable cooling. The system is using neon as working substance and radial turbo-machines in refrigerator. Cooling power is up to ∼8 kW at 65 K, inter-maintenance time ∼30,000 h. The cryogenic pump with superconducting motor can be used to provide subcooled liquid nitrogen flow ∼0.1-1.5 kg/s at 0.1-2.5 MPa pressure. After extensive tests at special test facility, HTS power cable and cryogenic system are planning to be installed at some substation in Moscow utility grid. In this review some details about Russian HTS power application program, 200 m cable and cryogenic system designs and tests results are presented.

  11. THE UTILIZATION OF THE NTP-HTS DATA IN CHEMICAL ...

    EPA Pesticide Factsheets

    To explore efficient approaches to assessing the toxicity of environmental chemicals, the NIEHS National Toxicology Program (NTP) recently initiated a High Throughput Screening (HTS) Project. To date, HTS results for a set of 1,408 compounds tested in 6 cell viability assays have been released via PubChem. This abstract explores herein the utility of the HTS data for predicting animal and human toxicity. To explore efficient approaches to assessing the toxicity of environmental chemicals, the NIEHS National Toxicology Program (NTP) recently initiated a High Throughput Screening (HTS) Project. To date, HTS results for a set of 1,408 compounds tested in 6 cell viability assays have been released via PubChem. This abstract explores herein the utility of the HTS data for predicting animal and human toxicity.

  12. Two applications of HTS technology on an airborne platform

    SciTech Connect

    Robertson, M.A.

    1994-12-31

    This paper describes two applications for HTS technology on an airborne platform. The first application is a RF front-end for an 8 to 40 GHz microwave/ millimeter-wave ESM system. The second application is a 2 to 4 GHz HTS Spiral Antenna Array System. The HTS microwave front-end unit consists of an HTS diplexer, and two low noise preamplifiers. The design demonstrates the benefits of HTS technology while providing a near-term insertion on a military airborne platform. The HTS Spiral Antenna Array System utilizes a 4 element conical spiral array (conventional technology) and a beamforming network consisting of a HTS power combiner, a HTS bandpass filter, HTS coupler, and a conventional technology low noise preamplifier. Both applications utilize low insertion loss HTS devices coupled with the cryogenic cooling of conventional low noise preamplifiers to lower the overall noise figure of the systems. The HTS Spiral Antenna Array System provides a 3 dB improvement in SNR over the best available conventional technology system. A 3 dB improvement in SNR can be compared to the doubling of the antenna aperture which provides a 3 dB gain increase, but at the expense of a decreased field of view. A 3 dB increase in SNR can also be viewed as a 41% increase in usable target range. The HTS antenna system maintains a wide field of view with a performance that approaches a steerable beam antenna. This is a cost effective approach for improving the collection capability of a system without the expense of developing a steerable beam antenna and the associated beam control hardware (tracker) and software.

  13. Multi-channel Data Acquisition System for a 500 m DC HTS Power Cable in Ishikari

    NASA Astrophysics Data System (ADS)

    Ivanov, Yury V.; Chikumoto, Noriko; Watanabe, Hirofumi; Takano, Hirohisa; Inoue, Noriyuki; Yamaguchi, Satarou

    Reduction of heat penetrating into the cryogenic region is the important method of optimization of superconducting devices. In the cases of short-range power transmission lines and compact HTS devices like magnets, the heat leakage through current leads is relatively large. In order to decrease this contribution, current leads equipped with Peltier elements can be used. The mentioned technology is being actively developed in the Chubu University. Commercial samples of Peltier current leads are installed at the terminals of 500-meter DC HTS cable in Ishikari (Hokkaido). This cable is designed for 5 kA. The inner conducting layer consists of 37 DI-BSCCO HTS tapes from Sumitomo Electric Industries, Ltd. with a critical current of 180 A; and the outer one consists of 35 tapes of the same type. Each end of the cable's tape is connected to the individual Peltier current lead. Accordingly, each of the two terminals is equipped with 72 Peltier current leads, 144 pieces in total. In order to examine behavior of the current leads in detail, each piece is supplied with two thermocouples; there are also voltage taps on feedthrough and on HTS tape end. In addition, current through Peltier current lead can be measured by means of individual current transformer. The hardware part of the data acquisition system includes four Keithley 3706A multimeters equipped with 60-channel model 3724 FET multiplexer cards. Therefore, 144 data blocks are formed. Furthermore, there are 72 measurements of a voltage drop across HTS tape. Sampling period is set to be 3 s. The program part of the data acquisition system was written using LabVIEW software solution (National Instruments Corp.).

  14. Low temperature diffusion process using rare earth-Cu eutectic alloys for hot-deformed Nd-Fe-B bulk magnets

    SciTech Connect

    Akiya, T. Sepehri-Amin, H.; Ohkubo, T.; Liu, J.; Hono, K.; Hioki, K.; Hattori, A.

    2014-05-07

    The low temperature grain boundary diffusion process using RE{sub 70}Cu{sub 30} (RE = Pr, Nd) eutectic alloy powders was applied to sintered and hot-deformed Nd-Fe-B bulk magnets. Although only marginal coercivity increase was observed in sintered magnets, a substantial enhancement in coercivity was observed when the process was applied to hot-deformed anisotropic bulk magnets. Using Pr{sub 70}Cu{sub 30} eutectic alloy as a diffusion source, the coercivity was enhanced from 1.65 T to 2.56 T. The hot-deformed sample expanded along c-axis direction only after the diffusion process as RE rich intergranular layers parallel to the broad surface of the Nd{sub 2}Fe{sub 14}B are thickened in the c-axis direction.

  15. Development of Non-destructive Evaluation System Using an HTS-SQUID Gradiometer with an External Pickup Coil

    NASA Astrophysics Data System (ADS)

    Kawano, J.; Kawauchi, S.; Ishikawa, F.; Tanabe, K.

    We are developing a new eddy-current non-destructive evaluation (NDE) system using a high-temperature superconducting quantum interference device (HTS-SQUID) gradiometer with the aim of applying it to power plants. Electric power facilities such as ducts and vessels are generally untransportable because of their size, and thus it is difficult to apply a conventional SQUID NDE system. The new NDE system employs an external Cu pickup coil which is supposed to be driven flexibly by a robot arm at room temperature and an HTS-SQUID chip which is placed in a magnetically shielded vessel. In the present research, we investigated the performance of an HTS-SQUID sensor connected with external pickup coils before mounting them to a robot arm. By varying the Cu coil conditions such as their sizes, the number of turns, and the diameter of wire, we qualitatively evaluated the frequency dependence of the effective area and the cutoff frequency.

  16. Design of Conduction-cooled HTS Coils for a Rotating Gantry

    NASA Astrophysics Data System (ADS)

    Takayama, Shigeki; Koyanagi, Kei; Yamaguchi, Akiko; Tasaki, Kenji; Kurusu, Tsutomu; Ishii, Yusuke; Amemiya, Naoyuki; Ogitsu, Toru; Noda, Koji

    Carbon ion cancer therapy is becoming more widespread due to its high curative effects and low burden on patients. Carbon ions are delivered to patients through electromagnets on a rotating gantry.A rotating gantry is attractive because it allows carbon ions to irradiate a tumor from any direction without changing the posture of the patient. On the other hand, because of the high magnetic rigidity of carbon ions, the weight of a rotating gantry for carbon cancer therapy is about three times higher than one for proton cancer therapy, according to our estimation. The use of high-temperature superconducting (HTS) magnets has been considered for reducing the size of the rotating gantry for carbon cancer therapy. The target weight is 200 t or less,which is equivalent to the weight of a typical rotating gantry for proton cancer therapy.In this study, the magnet layout of the rotating gantry and the superconducting magnets were designed from the viewpoint of beam optics.When applying high-temperature superconductors to accelerator magnets, there are some issues that should be considered, for example, the influence of tape magnetization and manufacturing accuracy on the field quality, the thermal stability of the conduction-cooled HTS coils under an alternating magnetic field, and methods to protect the coils from thermal runaway caused by an anomalous thermal input such as that due to beam loss. First, the thermal stability of the conduction-cooled HTS coils was simulated numerically, and the thermal runaway current was calculated in a static situation.

  17. Development of HTS-SQUID Gradiometer with an External HTS Multiturn Thin Film Pickup Coil

    NASA Astrophysics Data System (ADS)

    Teraoka, M.; Tsukamoto, A.; Adachi, S.; Takai, H.; Tanabe, K.

    Highly-sensitive HTS-SQUIDs are applied to various systems such as eddy-current non-destructive evaluation (NDE) and compact magnetometer systems. To avoid unstable operation of the SQUID due to an excitation field, a flux transformer made of normal Cu wire is used to separate the pickup coil and SQUID. However, the resistance of the flux transformer generates thermal noise and reduces the signal bandwidth at low frequencies. In this study, we investigate use of a superconducting flux transformer with resistive connections (SFTR). The SFTR consists of pickup and input coils made of HTS thin films. The two coils are connected by using an HTS coated conductor. The input coil is stacked on an HTS thin film gradiometer. From the measured results of resistances of the connections between each coil and the coated conductor, it was found that the resistance of bonding wire was a dominant component. The estimated resistance of the SFTR was 7.2 mΩ, corresponding to a lower cut-off frequency of 11.7 Hz.

  18. Commercialization of Medium Voltage HTS Triax TM Cable Systems

    SciTech Connect

    Knoll, David

    2012-12-31

    The original project scope that was established in 2007 aimed to install a 1,700 meter (1.1 mile) medium voltage HTS Triax{TM} cable system into the utility grid in New Orleans, LA. In 2010, however, the utility partner withdrew from the project, so the 1,700 meter cable installation was cancelled and the scope of work was reduced. The work then concentrated on the specific barriers to commercialization of HTS cable technology. The modified scope included long-length HTS cable design and testing, high voltage factory test development, optimized cooling system development, and HTS cable life-cycle analysis. In 2012, Southwire again analyzed the market for HTS cables and deemed the near term market acceptance to be low. The scope of work was further reduced to the completion of tasks already started and to testing of the existing HTS cable system in Columbus, OH. The work completed under the project included: • Long-length cable modeling and analysis • HTS wire evaluation and testing • Cable testing for AC losses • Optimized cooling system design • Life cycle testing of the HTS cable in Columbus, OH • Project management. The 200 meter long HTS Triax{TM} cable in Columbus, OH was incorporated into the project under the initial scope changes as a test bed for life cycle testing as well as the site for an optimized HTS cable cooling system. The Columbus cable utilizes the HTS TriaxTM design, so it provided an economical tool for these of the project tasks.

  19. Analysis and experimental study of wireless power transfer with HTS coil and copper coil as the intermediate resonators system

    NASA Astrophysics Data System (ADS)

    Wang, Xiufang; Nie, Xinyi; Liang, Yilang; Lu, Falong; Yan, Zhongming; Wang, Yu

    2017-01-01

    Intermediate resonator (repeater) between transmitter and receiver can significantly increase the distance of wireless power transfer (WPT) and the efficiency of wireless power transfer. The wireless power transfer via strongly coupled magnetic resonances with an high temperature superconducting (HTS) coil and copper coil as intermediate resonators was presented in this paper. The electromagnetic experiment system under different conditions with different repeating coils were simulated by finite element software. The spatial distribution patterns of magnetic induction intensity at different distances were plotted. In this paper, we examined transfer characteristics with HTS repeating coil and copper repeating coil at 77 K and 300 K, respectively. Simulation and experimental results show that HTS and copper repeating coil can effectively enhance the space magnetic induction intensity, which has significant effect on improving the transmission efficiency and lengthening transmission distance. We found that the efficiency and the distance of wireless power transfer system with an HTS coil as repeater is much higher by using of copper coil as repeater.

  20. THE USE OF NTP-HTS DATA FOR PREDICTIVE ...

    EPA Pesticide Factsheets

    To explore efficient approaches to assessing the toxicity of envoronmental chemicals, the NIEHS National Toxicology Program (NTP) recently initiated a High Throughput Screening (HTS) Project. To explore efficient approaches to assessing the toxicity of envoronmental chemicals, the NIEHS National Toxicology Program (NTP) recently initiated a High Throughput Screening (HTS) Project.

  1. Evaluation of High-resolution Geomagnetic Field Observation System Using HTS-SQUID Magnetometer and its Application.

    NASA Astrophysics Data System (ADS)

    Katori, Y.; Okubo, K.; Hato, T.; Tsukamoto, A.; Tanabe, K.; Onishi, N.; Furukawa; Isogami, S.; Takeuchi, N.

    2014-12-01

    Magnetic field changes associated with earthquakes have been investigated previously (1964 Stacey, 1994 Johnston et al.). Our research group also reported successful observation of "co-faulting" Earth's magnetic field changes due to piezomagnetic effects caused by earthquake rupturing in 2008 Iwate-Miyagi Nairiku earthquake of M7.2 (2011 Okubo et al.) using optoelectronic observation system with flux-gate magnetometers. This is an important finding; the electromagnetic fields originating from such sources satisfy the Maxwell equations and hence they propagate from the sources to the observation site at a speed of light in the crustal materials. Further efforts could lead us to a new system for super-early warning of destructive earthquakes with the magnetic measurements. On the other hand, the observed result in 2008 Iwate-Miyagi Nairiku earthquake was suggested that the geomagnetic variation signal accompanying fault movement, whose sources are the piezomagnetic effects, is very small; therefore development of a high-sensitive magnetometer system is very important. To solve this problem, we introduce long-term precise geomagnetic observations using high-temperature-superconductor based superconducting-quantum-interference-device (HTS-SQUID) magnetometer system. That is, our research group developed the HTS-SQUID magnetometer system for high-resolution observation of Earth's magnetic field. Since March 2012, we have observed the geomagnetic field using a HTS-SQUID magnetometer at Iwaki observation site (IWK) in Fukushima, Japan. The sampling interval of the magnetometer is 0.04 sec. The observation clock has been synchronized by use of GPS signals. An accelerometer is also installed at observation point. Additionally, in the next stage, we develop the HTS- SQUID magnetometer system Unit No.2 (mark II). In the present study, we show the results observed by our HTS-SQUID magnetometer system and make an evaluation of our geomagnetic field observation system.

  2. The status and prospects for flywheels and SMES that incorporate HTS

    NASA Astrophysics Data System (ADS)

    Wolsky, A. M.

    2002-08-01

    With one firm offering to provide SMES with HTS current leads and several other entities developing flywheels with bearings that incorporate bulk ReBaCuO, the progress made toward meeting their technical goals appears promising. Another question needs attention from the research, development, and demonstration (RD&D) community: “Will technical success yield equipment that will sell?” Here, we recall what is being done and review issues touching on the specifications for equipment that customers might want. These specifications pose technical challenges that have received little attention from the community.

  3. Spark-plasma-sintering magnetic field assisted compaction of Co{sub 80}Ni{sub 20} nanowires for anisotropic ferromagnetic bulk materials

    SciTech Connect

    Ouar, Nassima; Schoenstein, Frédéric; Mercone, Silvana; Farhat, Samir; Jouini, Noureddine; Villeroy, Benjamin; Leridon, Brigitte

    2013-10-28

    We developed a two-step process showing the way for sintering anisotropic nanostructured bulk ferromagnetic materials. A new reactor has been optimized allowing the synthesis of several grams per batch of nanopowders via a polyol soft chemistry route. The feasibility of the scale-up has been successfully demonstrated for Co{sub 80}Ni{sub 20} nanowires and a massic yield of ∼97% was obtained. The thus obtained nanowires show an average diameter of ∼6 nm and a length of ∼270 nm. A new bottom-up strategy allowed us to compact the powder into a bulk nanostructured system. We used a spark-plasma-sintering technique under uniaxial compression and low temperature assisted by a permanent magnetic field of 1 T. A macroscopic pellet of partially aligned nanowire arrays has been easily obtained. This showed optimized coercive properties along the direction of the magnetic field applied during compaction (i.e., the nanowires' direction)

  4. Effects of Mo additions on the glass-forming ability and magnetic properties of bulk amorphous Fe-C-Si-B-P-Mo alloys

    NASA Astrophysics Data System (ADS)

    Jiao, Zengbao; Li, Hongxiang; Wu, Yuan; Gao, Jingen; Wang, Shanlin; Yi, Seonghoon; Lu, Zhaoping

    2010-03-01

    Glass formation, mechanical and magnetic properties of the Fe76- x C7.0Si3.3B5.0P8.7Mo x ( x=0, 1 at.%, 3 at.% and 5 at.%) alloys prepared using an industrial Fe-P master alloy have been studied. With the substitution of Mo for Fe, glass-forming ability (GFA) was significantly enhanced and fully amorphous rods with a diameter of up to 5 mm were produced in the alloy with 3% Mo. The Mo-containing amorphous alloys also exhibited high fracture strength of 3635-3881 MPa and excellent magnetic properties including a high saturation magnetization of 1.10-1.41 T, a high Curie temperature and a low coercive force. The unique combination of high GFA, high fracture strength and excellent magnetic properties make the newly developed bulk metallic glasses viable for practical engineering applications.

  5. International Workshop on Cooling-system for HTS Applications 2015 (IWC-HTS 2015) 14-16 October 2015

    NASA Astrophysics Data System (ADS)

    Kamioka, Yasuharu

    2016-12-01

    International Workshop on Cooling-system for HTS Applications 2015 (IWC-HTS 2015) was held on 14-16 October 2015 at Kunibiki Messe (Shimane Prefectural Convention Center), Matsue, Shimane, Japan. The workshop was organized by the local committee on behalf of Cryogenics and Superconductivity Society of Japan (CSSJ).

  6. Distinguishing Between Activated and Non-Activated Eosinophils Using a Microelectrode: Theoretical Investigations of Bulk and Surface Polaritons in Magnetic Multilayers

    NASA Astrophysics Data System (ADS)

    Lacy, Fred

    In Part I of this dissertation, a whole cell biosensor which can detect the activation state of eosinophils (one of several types of white blood cells) will be developed and tested. This biosensor, which consists of a small gold electrode (50 μm x 50 μm) and a large gold electrode (1.5 cm x 0.5 cm) on a glass substrate, has been fabricated by photolithographic techniques. The eosinophils are known to exhibit different physical properties when they change from the activated state to the non-activated state. Based on some of these property changes, there should be a corresponding change in the measured electrical impedance. In this research, this biosensor will measure the electrical impedance of the eosinophils. This will show that the biosensor can detect the different states of the eosinophils (through the electrical impedance technique). And from these measurements, the different parameters associated with the electrical impedance can be determined. In Part II of this dissertation, a theoretical calculation will be performed in which bulk and surface magnetic polaritons in magnetic materials will be found. A polariton is the coupling of electromagnetic radiation and the elementary excitation of the given material (in our case, a magnetic material). The structure that we will be considering is a periodic semi-infinite material consisting of alternating antiferromagnetic and nonmagnetic layers. An antiferromagnetic material is a material in which individual atoms exhibit magnetic moments, but the overall magnetization of the material is zero because the moments of every other atom are antiparallel. We will use a method known as the transfer matrix technique to find an expression for the dispersion relation of the bulk and surface waves in these materials. Then we will create plots of omega(k) as we vary the geometric configurations of the layers which make-up the magnetic multilayer. We also will calculate the effect of an external magnetic field on these

  7. Low temperature magnetic ground state in bulk Co0.3Zn0.7Fe2O4 spinel ferrite system: Neutron diffraction, magnetization and ac-susceptibility studies

    NASA Astrophysics Data System (ADS)

    Parmar, Harshida; Acharya, Prashant; Upadhyay, R. V.; Siruguri, V.; Rayaprol, Sudhindra

    2013-01-01

    The system under study is a bulk Co0.3Zn0.7Fe2O4 ferrite, synthesized by wet chemical route technique and having magnetic in-homogeneity at the microscopic scale, due to the concentration of magnetic ion at a tetrahedral site below the site percolation threshold for the ferrimagnetic ordering. To unravel the magnetic ground state of this system, low temperature neutron diffraction, magnetization and ac-susceptibility measurements were carried out. In the temperature-dependent neutron diffraction analysis, a diffused scattering signal appears at the low Q region below (1 1 1) magnetic Bragg peak at all temperature, indicating the presence of a finite magnetic cluster with infinite magnetic network. The diffused scattering signal intensity decreases with increases in magnetic field at T=10 K. The ac-susceptibility measurement exhibits three peak behavior in χ' and χ″ indicating the presence of finite magnetic clusters and cluster-cluster interaction in the system. The absence of magnetic (2 0 0) peak in neutron diffraction at 2 K and bifurcation of zero field and field cooled magnetization indicate the phase transition from uniaxial random ferromagnetic (URF) phase to semi spin glass or canted random ferromagnetic (CRF) phase in the system with temperature.

  8. Magnetic properties of bulk, and rapidly solidified nanostructured (Nd1-xCex)2Fe14-yCoyB ribbons

    DOE PAGES

    Pathak, Arjun K.; Khan, M.; Gschneidner, Jr., K. A.; ...

    2015-11-06

    Magnetic properties of Ce and Co co-doped (Nd1-xCex)2Fe14-yCoyB compounds have been investigated both in bulk polycrystalline and rapidly solidified nanostructured ribbon forms. For certain Ce concentrations the materials exhibit spin re-orientation transitions below 140 K. The Curie temperatures, saturation magnetizations, and other magnetic properties relevant for applications as permanent magnets are controlled by Ce and Co substitutions for Nd and Fe, respectively. Most importantly, the results show that Ce, Co co-doped compounds are excellent replacements for several Dy-based high performance permanent magnets (dysprosium is one of the critical elements and is, therefore, in short supply). As a result, the highmore » temperature (>375 K) magnetic properties for Nd–Ce–Fe–Co–B based alloys show promise not only as a replacement for Dy-doped Nd2Fe14B permanent magnets, but the new alloys also require significantly lower amounts of Nd, which too is the critical element that can be replaced by a more abundant Ce.« less

  9. Structural and magnetic properties of the Gd-based bulk metallic glasses GdFe2, GdCo2, and GdNi2 from first principles

    NASA Astrophysics Data System (ADS)

    Lizárraga, Raquel

    2016-11-01

    A structural and magnetic characterization of Gd-based bulk metallic glasses, GdFe2, GdCo2, and GdNi2, was performed. Models for the amorphous structures for two magnetic configurations, ferromagnetic and ferrimagnetic, were obtained by means of a first-principles-based method, the stochastic quenching. In all three cases, the ferrimagnetic configuration was energetically more stable than the ferromagnetic one, in perfect agreement with experiments. In the structural analysis, radial and angle distribution functions as well as calculations of bond lengths and average coordination numbers were included. Structural properties are in good agreement with experiments and do not depend on the magnetic configuration. The distribution of magnetic moments shows that amorphous GdFe2 and GdCo2 are both ferrimagnets, with antiparallel alignment of the magnetic moments of the two magnetic sublattices, whereas Ni nearly loses its magnetic moment in amorphous GdNi2, similar to the situation in its crystalline counterpart.

  10. Study - Radiation Shielding Effectiveness of the Prototyped High Temperature Superconductivity (HTS) 'Artificial' Magnetosphere for Deep Space Missions

    NASA Technical Reports Server (NTRS)

    Denkins, Pamela

    2010-01-01

    The high temperature superconductor (HTS) is being used to develop the magnets for the Variable Specific Impulse Magneto-plasma Rocket (VASIMR ) propulsion system and may provide lightweight magnetic radiation shielding to protect spacecraft crews from radiation caused by GCR and SPEs on missions to Mars. A study is being planned to assess the radiation shielding effectiveness of the artificial magnetosphere produced by the HTS magnet. VASIMR is an advanced technology propulsion engine which is being touted as enabling one way transit to Mars in 90 days or less. This is extremely important to NASA. This technology would enable a significant reduction in the number of days in transit to and from Mars and significantly reduce the astronauts exposure to a major threat - high energy particles from solar storms and GCR during long term deep space missions. This paper summarizes the plans for the study and the subsequent testing of the VASIMR technology onboard the ISS slated for 2013.

  11. Theoretical and FEM analysis of suspension and propulsion system with HTS hybrid electromagnets in an EMS Maglev model

    NASA Astrophysics Data System (ADS)

    Chung, Y. D.; Lee, C. Y.; Jang, J. Y.; Yoon, Y. S.; Ko, T. K.

    2011-11-01

    We have been constructed a proto-type electromagnetic suspension (EMS) based maglev vehicle system. The maglev concept utilizes magnetic forces for noncontact suspension, guidance and propulsion. The suspension system with high temperature superconducting (HTS) hybrid electromagnet (EM) is composed of HTS coils and normal coils, which consume little power to keep large suspension gap. The magnetic forces realize to guide the vehicle, propel the vehicle along the guide-way and assist in braking action. The proto-type EMS-based Maglev model is designed to keep the suspension gap of 20 mm. This paper presents the theoretical analysis of the maglev vehicle based on the EMS model to obtain the designing parameters for levitation and propulsion forces. The magnetic field distributions of the electromagnetic forces with hybrid EM and propulsion stator coils are analyzed based on three dimension (3D) finite element method (FEM) analysis. From the simulation results, appropriately design parameters of the suspension, guidance and propulsion were obtained.

  12. Modeling and simulation of HTS cables for scattering parameter analysis

    NASA Astrophysics Data System (ADS)

    Bang, Su Sik; Lee, Geon Seok; Kwon, Gu-Young; Lee, Yeong Ho; Chang, Seung Jin; Lee, Chun-Kwon; Sohn, Songho; Park, Kijun; Shin, Yong-June

    2016-11-01

    Most of modeling and simulation of high temperature superconducting (HTS) cables are inadequate for high frequency analysis since focus of the simulation's frequency is fundamental frequency of the power grid, which does not reflect transient characteristic. However, high frequency analysis is essential process to research the HTS cables transient for protection and diagnosis of the HTS cables. Thus, this paper proposes a new approach for modeling and simulation of HTS cables to derive the scattering parameter (S-parameter), an effective high frequency analysis, for transient wave propagation characteristics in high frequency range. The parameters sweeping method is used to validate the simulation results to the measured data given by a network analyzer (NA). This paper also presents the effects of the cable-to-NA connector in order to minimize the error between the simulated and the measured data under ambient and superconductive conditions. Based on the proposed modeling and simulation technique, S-parameters of long-distance HTS cables can be accurately derived in wide range of frequency. The results of proposed modeling and simulation can yield the characteristics of the HTS cables and will contribute to analyze the HTS cables.

  13. Passive radiative cooling of a HTS coil for attitude orbit control in micro-spacecraft

    NASA Astrophysics Data System (ADS)

    Inamori, Takaya; Ozaki, Naoya; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki

    2015-02-01

    This paper proposes a novel radiative cooling system for a high temperature superconducting (HTS) coil for an attitude orbit control system in nano- and micro-spacecraft missions. These days, nano-spacecraft (1-10 kg) and micro-spacecraft (10-100 kg) provide space access to a broader range of spacecraft developers and attract interest as space development applications. In planetary and high earth orbits, most previous standard-size spacecraft used thrusters for their attitude and orbit control, which are not available for nano- and micro-spacecraft missions because of the strict power consumption, space, and weight constraints. This paper considers orbit and attitude control methods that use a superconducting coil, which interacts with on-orbit space plasmas and creates a propulsion force. Because these spacecraft cannot use an active cooling system for the superconducting coil because of their mass and power consumption constraints, this paper proposes the utilization of a passive radiative cooling system, in which the superconducting coil is thermally connected to the 3 K cosmic background radiation of deep space, insulated from the heat generation using magnetic holders, and shielded from the sun. With this proposed cooling system, the HTS coil is cooled to 60 K in interplanetary orbits. Because the system does not use refrigerators for its cooling system, the spacecraft can achieve an HTS coil with low power consumption, small mass, and low cost.

  14. HTS-FCL EMTDC model considering nonlinear characteristics on fault current and temperature

    NASA Astrophysics Data System (ADS)

    Yoon, Jae-Young; Lee, Seung-Ryul

    2010-06-01

    One of the most serious problems of the KEPCO system is a higher fault current than the CB(Circuit breaker's SCC (Short Circuit Capacity). There are so many alternatives to reduce the higher fault current, such as the isolation of bus ties, enhancement of the CB's SCC, and the application of HVDC-BTB (Back to Back) or FCL (fault current limiter). However, these alternatives have drawbacks from the viewpoint of system stability and cost. As superconductivity technology has been developed, the resistive type (R-type) HTS-FCL (High Temperature Superconductor Fault Current Limiter) offers one of the important alternatives in terms of power loss and cost reduction in solving the fault current problem. To evaluate the accurate transient performance of R-type HTS-FCL, it is necessary for the dynamic simulation model to consider transient characteristics during the quenching and the recovery state. Against this background, this paper presents the new HTS-FCL EMTDC (Electro-Magnetic Transients including Direct Current) model considering the nonlinear characteristics on fault current and temperature.

  15. Protecting Superconducting HTS-Antennas by Meta-Material Cloaks

    DTIC Science & Technology

    2014-04-30

    AFRL-OSR-VA-TR-2014-0101 PROTECTING SUPERCONDUCTING HTS-ANTENNAS BY META-MATERIAL CLOAKS Horst Rogalla REGENTS OF THE UNIVERSITY OF COLORADO THE...Superconducting HTS-Antennas by Meta-Material Cloaks Contract/Grant #: FA9550-10-1-0413 Reporting Period: 1 Aug 2010 to 31 Jan 2014 Protecting...Superconducting HTS-Antennas by Meta-Material Cloaks Frank Trang1, Horst Rogalla1, 2, and Zoya Popović1 1Dept.of ECEE, University of Colorado, Boulder

  16. Efficient growth of HTS films with volatile elements

    DOEpatents

    Siegal, Michael P.; Overmyer, Donald L.; Dominguez, Frank

    1998-01-01

    A system for applying a volatile element-HTS layer, such as Tl-HTS, to a substrate in a multiple zone furnace, said method includes heating at higher temperature, in one zone of the furnace, a substrate and adjacent first source of Tl-HTS material, to sublimate Tl-oxide from the source to the substrate; and heating at lower temperature, in a separate zone of the furnace, a second source of Tl-oxide to replenish the first source of Tl-oxide from the second source.

  17. Efficient growth of HTS films with volatile elements

    DOEpatents

    Siegal, M.P.; Overmyer, D.L.; Dominguez, F.

    1998-12-22

    A system is disclosed for applying a volatile element-HTS layer, such as Tl-HTS, to a substrate in a multiple zone furnace, said method includes heating at higher temperature, in one zone of the furnace, a substrate and adjacent first source of Tl-HTS material, to sublimate Tl-oxide from the source to the substrate; and heating at lower temperature, in a separate zone of the furnace, a second source of Tl-oxide to replenish the first source of Tl-oxide from the second source. 3 figs.

  18. 2G HTS wires made on 30 μm thick Hastelloy substrate

    NASA Astrophysics Data System (ADS)

    Sundaram, A.; Zhang, Y.; Knoll, A. R.; Abraimov, D.; Brownsey, P.; Kasahara, M.; Carota, G. M.; Nakasaki, R.; Cameron, J. B.; Schwab, G.; Hope, L. V.; Schmidt, R. M.; Kuraseko, H.; Fukushima, T.; Hazelton, D. W.

    2016-10-01

    REBCO (RE = rare earth) based high temperature superconducting (HTS) wires are now being utilized for the development of electric and electromagnetic devices for various industrial, scientific and medical applications. In the last several years, the increasing efforts in using the so-called second generation (2G) HTS wires for some of the applications require a further increase in their engineering current density (J e). The applications are those typically related to high magnetic fields where the higher J e of a REBCO wire, in addition to its higher irreversibility fields and higher mechanical strength, is already a major advantage over other superconducting wires. An effective way to increase the J e is to decrease the total thickness of a wire, for which using a thinner substrate becomes an obvious and attractive approach. By using our IBAD-MOCVD (ion beam assisted deposition-metal organic chemical vapor deposition) technology we have successfully made 2G HTS wires using a Hastelloy® C276 substrate that is only 30 μm in thickness. By using this thinner substrate instead of the typical 50 μm thick substrate and with a same critical current (I c), the J e of a wire can be increased by 30% to 45% depending on the copper stabilizer thickness. In this paper, we report the fabrication and characterization of the 2G HTS wires made on the 30 μm thick Hastelloy® C276 substrate. It was shown that with the optimization in the processing protocol, the surface of the thinner Hastelloy® C276 substrate can be readily electropolished to the quality needed for the deposition of the buffer stack. Same in the architecture as that on the standard 50 μm thick substrate, the buffer stack made on the 30 μm thick substrate showed an in-plane texture with a Δϕ of around 6.7° in the LaMnO3 cap layer. Low-temperature in-field transport measurement results suggest that the wires on the thinner substrate had achieved equivalent superconducting performance, most importantly the I

  19. Determination of the easy axes of small ferromagnetic precipitates in a bulk material by combined magnetic force microscopy and electron backscatter diffraction techniques.

    PubMed

    Batista, L; Rabe, U; Hirsekorn, S

    2014-11-01

    A method to determine the magnetic easy axes of micro- and nanoscopic ferromagnetic precipitates embedded in a bulk material is proposed and applied to globular cementite (Fe₃C) embedded in a ferrite matrix. The method combines magnetic force microscopy (MFM) with electron backscattered diffraction (EBSD) measurements. Magnetic domain structures in globular and in lamellar cementite precipitates in unalloyed pearlitic steels were imaged using MFM. The domain structure of the precipitates was analyzed in dependency of their size, shape and crystallographic orientation. It was found that the magnetic moments of the cementite precipitates are highly geared to their crystalline axes. The combined MFM and EBSD studies allow the conclusion that the cementite easy direction of magnetization is the long [010] axis. For fine lamellae cementite the determination of their crystallographic orientations using electron diffraction techniques is very difficult. With the previous knowledge of the behavior of the domain structure in globular cementite, the crystalline orientations of the fine lamellae cementite can be estimated by simply observing the magnetic microstructures and the topographic profiles.

  20. Development of High Capacity Split Stirling Cryocooler for HTS

    NASA Astrophysics Data System (ADS)

    Yumoto, Kenta; Nakano, Kyosuke; Hiratsuka, Yoshikatsu

    Sumitomo Heavy Industries, Ltd. (SHI) developed a high-power Stirling-type pulse tube cryocooler for cooling high-temperature superconductor (HTS) devices, such as superconductor motors, superconducting magnetic energy storage (SMES), and fault current limiters. The experimental results of a prototype pulse tube cryocooler were reported in September 2013. For a U-type expander, the cooling capacity was 151 W at 70 K with a compressor input power of 4 kW. Correspondingly, the coefficient of performance (COP) was about 0.038. However, the efficiency of the cryocooler is required to be COP > 0.1 and it was found that, theoretically, it is difficult to further improve the efficiency of a pulse tube cryocooler because the workflow generated at the hot end of the pulse tube cannot be recovered. Therefore, it was decided to change the expander to a free-piston type from a pulse tube type. A prototype was developed and preliminary experiments were conducted. A cooling capacity of 120 W at 70 K with a compressor input power of 2.15 kW with corresponding COP of 0.056, was obtained. The detailed results are reported in this paper.

  1. Neon turbo-Brayton cycle refrigerator for HTS power machines

    NASA Astrophysics Data System (ADS)

    Hirai, Hirokazu; Hirokawa, M.; Yoshida, Shigeru; Nara, N.; Ozaki, S.; Hayashi, H.; Okamoto, H.; Shiohara, Y.

    2012-06-01

    We developed a prototype turbo-Brayton refrigerator whose working fluid is neon gas. The refrigerator is designed for a HTS (High Temperature Superconducting) power transformer and its cooling power is more than 2 kW at 65 K. The refrigerator has a turboexpander and a turbo-compressor, which utilize magnetic bearings. These rotational machines have no rubbing parts and no oil-components. Those make a long maintenance interval of the refrigerator. The refrigerator is very compact because our newly developed turbo-compressor is volumetrically smaller than a displacement type compressor in same operating specification. Another feature of the refrigerator is a wide range operation capability for various heat-loads. Cooling power is controlled by the input-power of the turbo-compressor instead of the conventional method of using an electric heater. The rotational speed of the compressor motor is adjusted by an inverter. This system is expected to be more efficient. We show design details, specification and cooling test results of the new refrigerator in this paper.

  2. Impact of flux gap upon dynamic resistance of a rotating HTS flux pump

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenan; Bumby, Chris W.; Badcock, Rodney A.; Sung, Hae-Jin; Long, Nicholas J.; Amemiya, Naoyuki

    2015-11-01

    HTS flux pumps enable superconducting currents to be directly injected into a magnet coil without the requirement for thermally inefficient current leads. Here, we present results from an experimental mechanically rotating HTS flux pump employing a coated-conductor stator and operated at 77 K. We show the effect of varying the size of the flux gap between the rotor magnets and coated conductor stator from 1 to 7.5 mm. This leads to a corresponding change in the peak applied perpendicular magnetic field at the stator from approximately 350 to 50 mT. We observe that our experimental device ceases to maintain a measurable output at flux gaps above 7.5 mm, which we attribute to the presence of screening currents in the stator wire. We show that our mechanically rotating flux pump is well described by a simple circuit model which enables the output performance to be described using two simple parameters, the open-circuit voltage V oc and the internal resistance, R d. Both of these parameters are found to be directly proportional to magnet-crossing frequency and decrease with increasing flux gap. We show that the trend in R d can be understood by considering the dynamic resistance experienced at the stator due to the oscillating amplitude of the applied rotor field. We adopt a literature model for the dynamic resistance within our coated-conductor stator and show that this gives good agreement with the experimentally measured internal resistance of our flux pump.

  3. A new method of reconstructing current paths in HTS tapes with defects

    NASA Astrophysics Data System (ADS)

    Podlivaev, Alexey; Rudnev, Igor

    2017-03-01

    We propose a new method for calculating current paths in high-temperature superconductive (HTS) tapes with various defects including cracks, non-superconducting inclusions, and superconducting inclusions with lower local critical current density. The calculation method is based on a model of critical state which takes into account the dependence of the critical current on the magnetic field. The method allows us to calculate the spatial distribution of currents flowing through the defective HTS tape for both currents induced by the external magnetic field and transport currents from an external source. For both cases, we performed simulations of the current distributions in these tapes with different types of defects and have shown that the combination of the action of the magnetic field and transport current leads to a more detailed identification of the boundaries and shape of the defects. The proposed method is adapted for calculating modern superconductors in real superconducting devices and may be more useful as compared to the conventional magnetometric diagnostic studies, when the tape is affected by the magnetic field only.

  4. The physical mechanism of magnetic field controlled magnetocaloric effect and magnetoresistance in bulk PrGa compound

    PubMed Central

    Zheng, X. Q.; Wu, H.; Chen, J.; Zhang, B.; Li, Y. Q.; Hu, F. X.; Sun, J. R.; Huang, Q. Z.; Shen, B. G.

    2015-01-01

    The PrGa compound shows excellent performance on the magnetocaloric effect (MCE) and magnetoresistance (MR). The physical mechanism of MCE and MR in PrGa compound was investigated and elaborated in detail on the basis of magnetic measurement, heat capacity measurement and neutron powder diffraction (NPD) experiment. New types of magnetic structure and magnetic transition are found. The results of the NPD along with the saturation magnetic moment (MS) and magnetic entropy (SM) indicate that the magnetic moments are randomly distributed within the equivalent conical surface in the ferromagnetic (FM) temperature range. PrGa compound undergoes an FM to FM transition and an FM to paramagnetic (PM) transition as temperature increases. The magnetizing process was discussed in detail and the physical mechanism of the magnetic field controlled magnetocaloric effect (MCE) and the magnetoresistance (MR) was studied. The formation of the plateau on MCE curve was explained and MR was calculated in detail on the basis of the magnetic structure and the analysis of the magnetizing process. The experimental results are in excellent agreement with the calculations. Finally, the expression of MR = β(T)X2 and its application conditions were discussed, where X is M(H)/Meff, and Meff is the paramagnetic effective moment. PMID:26455711

  5. Fe 65B 22Nd 9Mo 4 bulk nanocomposite permanent magnets produced by crystallizing amorphous precursors

    NASA Astrophysics Data System (ADS)

    Tao, Shan; Ahmad, Zubair; Ma, Tianyu; Jian, Hong; Jiang, Yinzhu; Yan, Mi

    2012-04-01

    The Fe65B22Nd9Mo4 nanocomposite permanent magnets in the form of a rectangular cross sectioned rod have been prepared by annealing the amorphous precursors. The thermal behavior, structure and magnetic properties of the magnets have been investigated by differential scanning calorimetry, X-ray diffractometry, electron microscopy and magnetometry techniques. The as-cast Fe65B22Nd9Mo4 alloy showed soft magnetic properties, which changed into magnetically hard after annealing. Results provoke that the magnetic properties of the alloy are sensitive to thermal processing conditions. The optimum hard magnetic properties with a remanence (Br) of 0.56 T, coercivity (iHc) of 920.7 kA/m and maximum energy product (BH)max of 50.15 kJ/m3 were achieved after annealing the alloy at 983 K for 10 min. The good magnetic properties of Fe65B22Nd9Mo4 magnets are ascribed to the exchange coupling between the nano-scaled soft α-Fe, Fe3B and hard Nd2Fe14B magnetic grains.

  6. Surface resistance measurement of modified QMG superconducting bulks

    NASA Astrophysics Data System (ADS)

    Saito, A.; Sekiya, N.; Teshima, H.; Obara, H.; Noguchi, Y.; Hirano, H.; Hirano, S.; Ohshima, S.

    2006-10-01

    We investigated the microwave properties of high-temperature superconductor (HTS) bulks for high-power microwave applications. The HTS bulk samples of Dy-Ba-Cu-O and Gd-Ba-Cu-O, were prepared using the modified quench and melt growth (QMG) process. The relationship among the bulk surface mirror polishing process, oxygen annealing process, and surface resistance (Rs) was also investigated. The Rs of the HTS bulks was measured using the dielectric resonator method at 21.8 GHz for the TE011 mode. The measurement temperature was varied from 20 to 95 K. We found that the annealing after surface mirror polishing was more effective to obtain low Rs than polishing after annealing. Although the Rs value of the optimized Dy-Ba-Cu-O bulk sample at 20 K was twofold larger than that of the high-quality YBa2Cu3O7-δ thin film fabricated by THEVA GmbH, the Rs value was even low enough to be used for microwave devices. These results indicate that Dy-Ba-Cu-O bulk superconductors are feasible for applications to high-power transmit filters for mobile communication systems.

  7. Enhanced quench propagation in 2G-HTS coils co-wound with stainless steel or anodised aluminium tapes

    NASA Astrophysics Data System (ADS)

    Núñez-Chico, A. B.; Martínez, E.; Angurel, L. A.; Navarro, R.

    2016-08-01

    Early quench detection and thermal stability of superconducting coils are of great relevance for practical applications. Magnets made with second generation high temperature superconducting (2G-HTS) tapes present low quench propagation velocities and therefore slow voltage development and high local temperature rises, which may cause irreversible damage. Since quench propagation depends on the anisotropy of the thermal conductivity, this may be used to achieve an improvement of the thermal stability and robustness of 2G-HTS coils. On pancake type coils, the thermal conductivity along the tapes (coil’s azimuthal direction) is mostly fixed by the 2G-HTS tape characteristics, so that the reduction of anisotropy relies on the improvement of the radial thermal conductivity, which depends on the used materials between superconducting tapes, as well as on the winding and impregnation processes. In this contribution, we have explored two possibilities for such anisotropy reduction: by using anodised aluminium or stainless steel tapes co-wound with the 2G-HTS tapes. For all the analysed coils, critical current distribution, minimum quench energy values and both tangential and radial quench propagation velocities at different temperatures and currents are reported and compared with the results of similar coils co-wound with polyimide (Kapton®) tapes.

  8. Pulsed field magnetization of 0°-0° and 45°-45° bridge-seeded Y-Ba-Cu-O bulk superconductors

    NASA Astrophysics Data System (ADS)

    Ainslie, M. D.; Zou, J.; Mochizuki, H.; Fujishiro, H.; Shi, Y.-H.; Dennis, A. R.; Cardwell, D. A.

    2015-12-01

    Large, single-grain (RE)BCO (where RE = rare earth or Y) bulk superconductors with complicated geometries are required for a variety of potential applications, such as rotating machines, magnetic bearings and magnetic separation. As a consequence, the top multi-seeded melt growth process has been studied over many years in an attempt to deliver large, single grains for practical applications. Among these techniques, the so-called bridge-seeding produces the best alignment of two seeds during melt processing of multi-seed samples. In this paper, the trapped field performance and magnetic flux dynamics of two bridge-seeded, multi-seed samples magnetized by pulsed field magnetization are analyzed: one with a 45°-45° and another with a 0°-0° bridge seed. Based on an analysis of the flux penetration across the seeds and in-between the seeds of the 45°-45° multi-seed sample, an estimated J c distribution over the ab-plane is determined, which provides the basis for further analysis via numerical simulation. A three-dimensional finite-element model, developed to qualitatively reproduce and interpret the experimental results, was employed to investigate the influence of the length of the bridge seed for such multi-seed samples. The simulation results agree well with the observed experimental results, in that the multi-seed sample’s particular inhomogeneous J c distribution acts to distort the trapped field profile from a traditional conical Bean’s profile, which is determined by the length and direction of the bridge seed on the bulk surface.

  9. HTS thin films: Passive microwave components and systems integration issues

    SciTech Connect

    Miranda, F.A.; Chorey, C.M.; Bhasin, K.B.

    1994-12-31

    The excellent microwave properties of the High-Temperature-Superconductors (HTS) have been amply demonstrated in the laboratory by techniques such as resonant cavity, power transmission and microstrip resonator measurements. The low loss and high Q passive structures made possible with HTS, present attractive options for applications in commercial, military and space-based systems. However, to readily insert HTS into these systems improvement is needed in such areas as repeatability in the deposition and processing of the HTS films, metal-contact formation, wire bonding, and overall film endurance to fabrication and assembly procedures. In this paper we present data compiled in our lab which illustrate many of the problems associated with these issues. Much of this data were obtained in the production of a space qualified hybrid receiver-downconverter module for the Naval Research Laboratory`s High Temperature Superconductivity Space Experiment II (HTSSE-II). Examples of variations observed in starting films and finished circuits will be presented. It is shown that under identical processing the properties of the HTS films can degrade to varying extents. Finally, we present data on ohmic contacts and factors affecting their adhesion to HTS films, strength of wire bonds made to such contacts, and aging effects.

  10. HTS thin films: Passive microwave components and systems integration issues

    NASA Technical Reports Server (NTRS)

    Miranda, F. A.; Chorey, C. M.; Bhasin, K. B.

    1995-01-01

    The excellent microwave properties of the High-Temperature-Superconductors (HTS) have been amply demonstrated in the laboratory by techniques such as resonant cavity, power transmission and microstrip resonator measurements. The low loss and high Q passive structures made possible with HTS, present attractive options for applications in commercial, military and spacebased systems. However, to readily insert HTS into these systems improvement is needed in such areas as repeatability in the deposition and processing of the HTS films, metal-contact formation, wire bonding, and overall film endurance to fabrication and assembly procedures. In this paper we present data compiled in our lab which illustrate many of the problems associated with these issues. Much of this data were obtained in the production of a space qualified hybrid receiver-downconverter module for the Naval Research Laboratory's High Temperature Superconductivity Space Experiment 2 (HTSSE-2). Examples of variations observed in starting films and finished circuits will be presented. It is shown that under identical processing the properties of the HTS films can degrade to varying extents. Finally, we present data on ohmic contacts and factors affecting their adhesion to HTS films, strength of wire bonds made to such contacts, and aging effects.

  11. Two Methods for a First Order Hardware Gradiometer Using Two HTS SQUID's

    SciTech Connect

    Espy, M.A.; Flynn, E.R.; Kraus, R.H., Jr.; Matlachov, A.

    1998-09-15

    Two different systems for noise cancellation (first order gradiometers) have been developed using two similar high temperature superconducting (HTS) SQUIDs. ''Analog'' gradiometry is accomplished in hardware by either (1) subtracting the signals from the sensor and background SQUIDs at a summing amplifier (parallel technique) or (2) converting the inverted background SQUID signal to a magnetic field at the sensor SQUID (series technique). Balance levels achieved are 2000 and 1000 at 20 Hz for the parallel and series methods respectively. The balance level as a function of frequency is also presented. The effect which time delays in the two sets of SQUID electronics have on this balance level is presented and discussed.

  12. Two methods for a first order hardware gradiometer using two HTS SQUIDs

    SciTech Connect

    Espy, M.A.; Flynn, E.R.; Kraus, R.H. Jr.; Matlachov, A.

    1998-12-31

    Two different systems for noise cancellation (first order gradiometers) have been developed using two similar high temperature superconducting (HTS) SQUIDs. Analog gradiometry is accomplished in hardware by either (1) subtracting the signals from the sensor and background SQUIDs at a summing amplifier (parallel technique) or (2) converting the inverted background SQUID signal to a magnetic field at the sensor SQUID (series technique). Balance levels achieved are 2000 and 1000 at 20 Hz for the parallel and series methods respectively. The balance level as a function of frequency is also presented. The effect which time delays in the two sets of SQUID electronics have on this balance level is presented and discussed.

  13. Method for Determining Local Current Density in 2G HTS Tapes

    NASA Astrophysics Data System (ADS)

    Bludova, A. I.

    Practically important problem is to determine the density and direction of 2G HTS induced currents at each point on the tape in order to examine its local deviations. This problem is resolved indirectly by spatial measurement of generated magnetic field with a scanning Hall sensor at a given height above the tape surface. Current density is subsequently determined by the Biot-Savart law inversion in Fourier domain. Tikhonov regularization is used in order to increase precision. Method is verified with the model current density reconstruction. Optimal calculation parameters and resulting precision are described.

  14. High temperature superconductors for magnetic suspension applications

    NASA Technical Reports Server (NTRS)

    Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

    1994-01-01

    High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

  15. The low magnetic field properties of superconducting bulk yttrium barium copper oxide - Sintered versus partially melted material

    NASA Technical Reports Server (NTRS)

    Hein, R. A.; Hojaji, H.; Barkatt, A.; Shafii, H.; Michael, K. A.; Thorpe, A. N.; Ware, M. F.; Alterescu, S.

    1989-01-01

    A comparison of the low magnetic field properties of sintered (990 C) and partially melted samples (1050 C) has been performed. Changes in the microstructure produced by recrystallization from the melt result in a significant increase in flux pinning at 77 K. Low-frequency (10-100 Hz), low-ac magnetic-field (0.01-9.0 Oe) ac susceptibility data show that gross changes in the loss component accompany the observed changes in microstructure. The effects of applied dc magnetic fields (10-220 Oe) on the ac responses of these microstructures have also been probed.

  16. Synthesis of bulk FeHfBO soft magnetic materials and its loss characterization at megahertz frequency

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Kou, Xiaoming; Mu, Mingkai; Warsi Muhammad, Asif; Lin, Shuo; Harris, Brendan S.; Parsons, Paul E.; Zhu, Hao; Lee, Fred C.; Xiao, John Q.

    2013-05-01

    Magnetic core materials with low loss, high saturation magnetization, large permeability, and operating frequency above 1 MHz are in high demands for the next generation of miniaturized power electronics. Amorphous FeHfB ribbons with thickness around 20 μm have been fabricated through melt-spinning. Different heat treatments were performed on the FeHfB ribbons, and the relations among heat treatments, microstructure, and magnetic properties have been explored. Properties such as coercivity (Hc) of 2.0 Oe and saturation magnetic flux density (BS) of 1.2 T have been achieved in samples with exchange coupling. The losses can be minimized by balancing the hysteretic and eddy current losses and can be further reduced with additional magnetic field annealing. At 5 MHz with peak magnetic flux density of 20 mT, the materials show core losses comparable to the best ferrites, but with higher permeability value of about 200 and superior saturation induction of more than 1 T.

  17. Experimental analysis of the magnetic field shielding and trapping properties of bulk melt-processed YBa 2Cu 3O 7-δ

    NASA Astrophysics Data System (ADS)

    Jiang, X. H.; Astill, D. M.; Lo, W.; Cardwell, D. A.; Coombs, T. A.; Campbell, A. M.; Larsen, J. G.

    1995-02-01

    A scanning Hall probe has been used to map the distributions of magnetic field in melt-processed YBa 2Cu 3O 7-δ (YBCO) discs prepared by seeded and controlled molten-zone techniques. Both shielded and trapped fields were studied as a function of applied magnetic field for each speciment. A clear four-fold symmetry has been observed in the field distribution of the seeded melt-processed sample, suggesting that there are two planes in the disc which exhibit a weak response to an applied field. Similar magnetic properties were observed for the molten-zone processed sample and attributed to the presence of cracks in the specimen. It was found that the applied field required to saturate each sample was much higher than the maximum observed trapped field, in contradiction to the Bean model for a slab geometry. This effect, which is probably due to the plate geometry of the specimens and the variation of critical current density with magnetic field, has implications for practical applications of bulk melt-processed YBCO.

  18. Li(Zn,Co,Mn)As: A bulk form diluted magnetic semiconductor with Co and Mn co-doping at Zn sites

    NASA Astrophysics Data System (ADS)

    Chen, Bijuan; Deng, Zheng; Li, Wenmin; Gao, Moran; Zhao, Jianfa; Zhao, Guoqiang; Yu, Shuang; Wang, Xiancheng; Liu, Qingqing; Jin, Changqing

    2016-11-01

    We report the synthesis and characterization of a series of bulk forms of diluted magnetic semiconductors Li(Zn1-x-yCoxMny)As with a crystal structure close to that of III-V diluted magnetic semiconductor (Ga,Mn)As. No ferromagnetic order occurs with single (Zn,Co) or (Zn, Mn) substitution in the parent compound LiZnAs. Only with co-doped Co and Mn ferromagnetic ordering can occur at the Curie temperature ˜40 K. The maximum saturation moment of the this system reached to 2.17 μB /Mn , which is comparable to that of Li (Zn,Mn)As. It is the first time that a diluted magnetic semiconductor with co-doping Co and Mn into Zn sites is achieved in "111" LiZnAs system, which could be utilized to investigate the basic science of ferromagnetism in diluted magnetic semiconductors. In addition, ferromagnetic Li(Zn,Co,Mn)As, antiferromagnetic LiMnAs, and superconducting LiFeAs share square lattice at As layers, which may enable the development of novel heterojunction devices in the future.

  19. Cooperative coupling of static magnetism and bulk superconductivity in the stripe phase of La2 -xBaxCuO4 : Pressure- and doping-dependent studies

    NASA Astrophysics Data System (ADS)

    Guguchia, Z.; Khasanov, R.; Shengelaya, A.; Pomjakushina, E.; Billinge, S. J. L.; Amato, A.; Morenzoni, E.; Keller, H.

    2016-12-01

    Static spin-stripe order and superconductivity were systematically studied in La2 -xBaxCuO4 (0.11 ≤x ≤0.17 ) at ambient pressure by means of magnetization and μ SR experiments. We find that all the investigated La2 -xBaxCuO4 samples exhibit static spin-stripe order and that the quasi-two-dimensional superconducting (SC) transition temperature Tc 1 and the static spin-stripe order temperature Tso have very similar values throughout the phase diagram. Moreover, the magnetic and the SC properties of the x =0.155 (LBCO-0.155) and x =0.17 (LBCO-0.17) samples were studied under hydrostatic pressure. As a remarkable result, in these bulk cuprate superconductors, the three-dimensional SC transition temperature Tc and Tso nearly coincide [Tc(p ) ≃Tso(p ) ] at all pressure investigated (0 ≤p ≤2.3 GPa). We also observed a pressure induced transition from long-range spin stripe order to a disordered magnetic state at p≃1.6 GPa in LBCO-0.155, coexisting with a SC state with substantial superfluid density. In LBCO-0.17, a disordered magnetic state is present at all p . The present results indicate that static magnetic order and SC pairing correlations develop in a cooperative fashion in La2 -xBaxCuO4 , and provide a new route of understanding the complex interplay between static magnetism and superconductivity in the stripe phase of cuprates.

  20. Modelling ac ripple currents in HTS coated conductors

    NASA Astrophysics Data System (ADS)

    Xu, Zhihan; Grilli, Francesco

    2015-10-01

    Dc transmission using high temperature superconducting (HTS) coated conductors (CCs) offers a promising solution to the globally growing demand for effective, reliable and economic transmission of green energy up to the gigawatt level over very long distances. The credible estimation of the losses and thereby the heat dissipation involved, where ac ripples (introduced in rectification/ac-dc conversion) are viewed as a potential source of notable contribution, is highly essential for the rational design of practical HTS dc transmission cables and corresponding cryogenic systems to fulfil this demand. Here we report a targeted modelling study into the ac losses in a HTS CC subject to dc and ac ripple currents simultaneously, by solving Maxwell’s equations using the finite element method (FEM) in the commercial software package COMSOL. It is observed that the instantaneous loss exhibits only one peak per cycle in the HTS CC subject to sinusoidal ripples, given that the amplitude of the ac ripples is smaller than approximately 20% of that of the dc current. This is a distinct contrast to the usual observation of two peaks per cycle in a HTS CC subject to ac currents only. The unique mechanism is also revealed, which is directly associated with the finding that, around any local minima of the applied ac ripples, the critical state of -J c is never reached at the edges of the HTS CC, as it should be according to the Bean model. When running further into the longer term, it is discovered that the ac ripple loss of the HTS CC in full-wave rectification decays monotonically, at a speed which is found to be insensitive to the frequency of the applied ripples within our targeted situations, to a relatively low level of approximately 1.38 × 10-4 W m-1 in around 1.7 s. Comparison between this level and other typical loss contributions in a HTS dc cable implies that ac ripple currents in HTS CCs should only be considered as a minor source of dissipation in superconducting dc

  1. Development of HTS-SQUID magnetometer system with high slew rate for exploration of mineral resources

    NASA Astrophysics Data System (ADS)

    Hato, T.; Tsukamoto, A.; Adachi, S.; Oshikubo, Y.; Watanabe, H.; Ishikawa, H.; Sugisaki, M.; Arai, E.; Tanabe, K.

    2013-11-01

    For the transient electromagnetic (TEM) method using a high-temperature superconducting interference device (HTS-SQUID), we have developed a magnetometer system with a wide dynamic range, a high slew rate, and superior transportability. To achieve high tolerance to a higher excitation magnetic field, we utilized a SQUID magnetometer containing ramp-edge junctions with La0.1Er0.95Ba1.95Cu3Oy and SmBa2Cu3Oy electrode layers, which was fabricated by using an HTS multi-layer fabrication technique. To operate the magnetometer stably in a rapidly changing magnetic field, we chose the proper materials for the RF shield of liquid nitrogen (LN2) glass Dewar and cables. The white noise level and the slew rate of the system were measured to be 30 fT Hz-1/2 and 10.5 mT s-1, respectively. The resultant signal-to-noise ratio was higher than that of the previous system and improved the exploration depth, which was successfully demonstrated in field tests. The weight of the Dewar, which retains the LN2 for 17 h, is 2.5 kg. The total weight of our system including the LN2 Dewar, a probe with a flux-locked loop (FLL) circuit, a battery, a receiver, and a 30 m-long cable between the FLL and the receiver is as low as 25.6 kg.

  2. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Grain Size Effect on Electrical Conductivity and Giant Magnetoresistance of Bulk Magnetic Polycrystals

    NASA Astrophysics Data System (ADS)

    Luo, Wei; Zhu, Lin-Li; Zheng, Xiao-Jing

    2009-11-01

    By solving the Boltzmann transport equation and considering the spin-dependent grain boundary scattering, the distribution of electrons in grains and the electrical transport properties in the applied magnetic field are studied. With regard to the dominant influence of grain boundary scattering which is taken as a boundary condition for the electrical transport, the grain size-dependent electrical conductivity is investigated. In addition, the reorientation of the relative magnetization between grains brings the change of the electron spin when the magnetonanocrystalline material is subjected to the magnetic field, resulting in the remarkable giant magnetoresistance effect.

  3. Monolithic HTS microwave phase shifter and other devices

    SciTech Connect

    Jackson, C.M.; Kobayashi, J.H.; Guillory, E.B.; Pettiette-Hall, C.; Burch, J.F. )

    1992-08-01

    We describe a monolithic high-temperature superconductor (HTS) phase shifter based on the distributed Josephson inductance (DJI) design integrated monolithically into a 10-GHz microstrip line. This microwave circuit incorporates >1000 HTS rf SQUIDS. Recent data demonstrate the performance of this broadband HTS circuit. We observed phase shifts greater than 150[degrees] in resonant structures, and 20[degrees] in broadband circuits. The nonlinear inductance of the superconducting transmission line can be used for other novel applications, including parametric amplification. A comparison of the DJI circuit to a series array of Josephson elements (used for pulse sharpening) will contrast these two new and exciting nonlinear transmission line circuits. 19 refs., 4 figs., 2 tabs.

  4. Loss analysis of a 1 MW class HTS synchronous motor

    NASA Astrophysics Data System (ADS)

    Baik, S. K.; Kwon, Y. K.; Kim, H. M.; Lee, J. D.; Kim, Y. C.; Park, H. J.; Kwon, W. S.; Park, G. S.

    2009-03-01

    The HTS (High-Temperature Superconducting) synchronous motor has advantages over the conventional synchronous motor such as smaller size and higher efficiency. Higher efficiency is due to smaller loss than the conventional motor, so it is important to do loss analysis in order to develop a machine with higher efficiency. This paper deals with machine losses those are dissipated in each part of a HTS synchronous motor. These losses are analyzed theoretically and compared with loss data obtained from experimental results of a 1 MW class HTS synchronous motor. Each machine loss is measured based on IEEE 115 standard and the results are analyzed and considered based on the manufacturing of the test machine.

  5. Comparative Study of Magnetic Ordering and Electrical Transport in Bulk and Nano-Grained Nd0.67Sr0.33MnO3 Manganites

    NASA Astrophysics Data System (ADS)

    Arun, B.; Suneesh, M. V.; Vasundhara, M.

    2016-11-01

    We have prepared bulk and nano-sized Nd0.67Sr0.33MnO3 manganites by solid state and low-temperature mild solgel methods respectively. Both the compounds crystallized into an orthorhombic structure with Pbnm space group confirmed from Rietveld refinement of X-ray powder diffraction patterns. Nano-grained compound shows an average particle size of 22 nm with broad grain size distribution revealed from the Transmission electron micrographs. It appeared that the long range ferromagnetic order becomes unstable upon the reduction of the samples dimension down to nano meter scale. DC magnetization and AC susceptibility results showed frustration of spins in nano-grained compound and thereby it could lead to a cluster glass-like behaviour. Temperature dependence of electrical resistivity under different magnetic fields shows the broad maxima at higher temperatures and a low temperature upturn in both the compounds, however, the latter is more prominent in the nano grained compound. Combination of Kondo effect with electron and phonon interactions govern the low temperature resistivity and a small polaron hopping mechanism dominates at high temperatures for both the compounds. The magnetoresistance is understood by the effect of spin polarized tunneling through the grain boundary. The experimental results revealed that the reduction in particle size influences severely on the magnetic, electrical and magneto transport properties.

  6. Effect of minor Fe substitution for Ni on the magnetic properties of a Gd55Al20Ni25 bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Ding, Ding; Li, Zheng; Wang, Zheng Wen; Wu, Cheng; Zhang, Yi Qing

    2016-03-01

    In this work, we studied the effect of micro-alloying on the glass-forming ability (GFA) and magnetic properties of Gd55Al20Ni25 bulk metallic glass (BMG). By minor Fe substitution for Ni, we obtained Gd55Al20Ni23Fe2 BMG with enhanced magneto-caloric effect (MCE) and GFA similar to Gd55Al20Ni25 BMG. The maximum magnetic entropy change (-ΔSmpeak) and the magnetic refrigerant capacity (Rc) of Gd55Al20Ni23Fe2 BMG within the field range of 5 T are about 9.05 J kg-1 K-1 and 850J ṡkg-1, respectively, both of which are larger than the values of Gd55Ni25Al20 BMG. The mechanism for the improved MCE of the Gd55Al20Ni23Fe2 BMG was investigated and the magneto-caloric behaviors were studied by constructing the field dependence of - ΔSmpeak of Gd55Al20Ni23Fe2 BMG.

  7. Vortex flux dynamics and harmonic ac magnetic response of Ba(Fe0.94Ni0.06)2As2 bulk superconductor

    DOE PAGES

    Nikolo, Martin; Zapf, Vivien S.; Singleton, John; ...

    2016-07-22

    Vortex dynamics and nonlinear ac response are studied in a Ba(Fe0.94Ni0.06)2As2(Tc= 18.5 K) bulk superconductor in magnetic fields up to 12 T via ac susceptibility measurements of the first ten harmonics. A comprehensive study of the ac magnetic susceptibility and its first ten harmonics finds shifts to higher temperatures with increasing ac measurement frequencies (10 to 10,000 Hz) for a wide range of ac (1, 5, and 10 Oe) and dc fields (0 to 12 T). The characteristic measurement time constant t1 is extracted from the exponential fit of the data and linked to vortex relaxation. The Anderson-Kim Arrhenius lawmore » is applied to determine flux activation energy Ea/k as a function dc magnetic field. The de-pinning, or irreversibility lines, were determined by a variety of methods and extensively mapped. The ac response shows surprisingly weak higher harmonic components, suggesting weak nonlinear behavior. Lastly, our data does not support the Fisher model; we do not see an abrupt vortex glass to vortex liquid transition and the resistivity does not drop to zero, although it appears to approach zero exponentially.« less

  8. Modeling AC ripple currents in HTS coated conductors by integral equations

    NASA Astrophysics Data System (ADS)

    Grilli, Francesco; Xu, Zhihan

    2016-12-01

    In several HTS applications, the superconducting tapes experience the simultaneous presence of DC and AC excitations. For example in high-current DC cables, where the transport current is not perfectly constant, but it exhibits some ripples at different frequencies introduced by the rectification process (AC-DC conversion). These ripples give rise to dissipation, whose magnitude and possible influence on the device's cooling requirements need to be evaluated. Here we report a study of the AC losses in a HTS coated conductor subjected to DC currents and AC ripples simultaneously. The modeling approach is based on an integral equation method for thin superconductors: the superconducting tape is modeled as a 1-D object with a non-linear resistivity, which includes the dependence of the critical current density Jc on the magnetic field. The model, implemented in a commercial finite-element program, runs very fast (the simulation of one AC cycle typically takes a few seconds on standard desktop workstation): this allows simulating a large number of cycles and estimating when the AC ripple losses stabilize to a constant value. The model is used to study the influence of the flux creep power index n on the stabilization speed and on the AC loss values, as well as the effect of using a field-dependent Jc instead of a constant one. The simulations confirm that the dissipation level should not be a practical concern in HTS DC cables. At the same time, however, they reveal a strong dependence of the results upon the power index n and the form of Jc , which spurs the question whether the power-law is the most suitable description of the superconductor's electrical behavior for this kind of analysis.

  9. A silver-bearing, High-Temperature, Superconducting (HTS) paint

    NASA Astrophysics Data System (ADS)

    Ferrando, William A.

    1990-02-01

    A substantial set of device applications awaits development of a workable, durable, high-temperature superconducting (HTS) paint. Such a paint should be truly superconducting with its critical temperature T sub c greater than 77K. For most of these applications, a high critical current (J sub c) is not required, although probably desirable. A process is described which can be used to produce silver-bearing HTS paint coatings on many engineering materials. Preliminary tests have shown good adherence to several ceramics and the ability to meet the superconducting criteria. Moreover, the coatings withstand multiple thermal cycling and stability under laboratory ambient storage conditions for periods of at least several months.

  10. Review of activities in USA on HTS materials

    SciTech Connect

    Peterson, D.E.

    1995-02-01

    Rapid progress in attaining practical applications of High Temperature Superconductors (HTS) has been made since the discovery of these new materials. Many critical parameters influencing HTS powder synthesis and wire processing have been identified through a combination of fundamental exploration and applied research. The complexity of these novel materials with regard to phase behavior and physical properties has become evident as a result of these careful studies. Achieving optimal mechanical and superconducting properties in wires and tapes will require further understanding and synergy among several different technical disciplines. Highlights of efforts towards producing practical superconductors for electric power applications based on rare earth-, bismuth-, and thallium-based systems are reviewed.

  11. DEVELOPMENT OF HTS CONDUCTORS FOR ELECTRIC POWER APPLICATIONS

    SciTech Connect

    Goyal, A.; Rupich, M.

    2012-10-23

    Second generation (2G) technologies to fabricate high-performance superconducting wires developed at the Oak Ridge National Laboratory (ORNL) were transferred to American Superconductor via this CRADA. In addition, co-development of technologies for over a decade was done to enable fabrication of commercial high-temperature superconducting (HTS) wires with high performance. The massive success of this CRADA has allowed American Superconductor Corporation (AMSC) to become a global leader in the fabrication of HTS wire and the technology is fully based on the Rolling Assisted Biaxially Textured Substrates (RABiTS) technology invented and developed at ORNL.

  12. Real-time monitoring of fatigue damage in Carbon Fiber Reinforced Polymers for aeronautical applications using HTS SQUID magnetometer

    NASA Astrophysics Data System (ADS)

    Valentino, M.; Bonavolontà, C.; Peluso, G.; Pepe, G. P.

    2006-06-01

    The main advantage of using SQUIDs in NDE is its unrivalled magnetic sensitivity down to very low frequencies, which allows the detection of weak magnetic fields due to defects also in very low electrical conductive materials like CFRP, commonly used in aerospace structures. In this work the fatigue damage evaluation on CFRP laminates, cross-ply or quasi-isotropic, in real-time during quasi-static loading is monitored. The material responses are detected by using an Eddy Current technique with HTS dc SQUID magnetometer.

  13. Test Results for a 25 Meter Prototype Fault Current Limiting Hts Cable for Project Hydra

    NASA Astrophysics Data System (ADS)

    Rey, C. M.; Duckworth, R. C.; Demko, J. A.; Ellis, A.; James, D. R.; Gouge, M. J.; Tuncer, E.

    2010-04-01

    The Oak Ridge National Laboratory (ORNL) has tested a 25-m long prototype High Temperature Superconducting (HTS) cable with inherent Fault-Current Limiting (FCL) capability at its HTS cable test facility. The HTS-FCL cable and terminations were designed and fabricated by Ultera, which is a joint venture between Southwire and nkt cables. System integration and HTS wire were provided by American Superconductor Corporation who was the overall team leader of the project. The ultimate goal of the 25-m HTS-FCL cable test program was to verify the design and ensure the operational integrity for the eventual installation of a ˜200-m fully functional HTS-FCL cable in the Consolidated Edison electric grid located in downtown New York City. The 25-m HTS-FCL cable consisted of a three-phase (3-Φ) HTS Triax™ design with a cold dielectric between the phases. The HTS-FCL cable had an operational voltage of 13.8 kV phase-to-phase (7967 V phase-to-ground) and an operating current of 4000 Arms per phase, which is the highest operating current to date of any HTS cable. The 25-m HTS-FCL cable was subjected to a series of cryogenic and electrical tests. Test results from the 25-m HTS-FCL cable are presented and discussed.

  14. Numerical simulations of electromagnetic behavior and AC loss in rectangular bulk superconductor with an elliptical flaw under AC magnetic fields

    NASA Astrophysics Data System (ADS)

    Xia, Jing; Zhou, Youhe

    2015-07-01

    This paper presents a finite element model based on the H-formulation to solve the electromagnetic behavior and AC loss in rectangular bulk superconductor with an elliptical flaw in AC external field condition. Both the interior flaw and the edge flaw are considered. A modified E-J power law which is valid for an arbitrary current density range is adopted in order to predict the strong local enhancement of the current density in the vicinity of the flaw tip. The results for the usual E-J power law are calculated for comparison as well. The simulation results show that the existence of the flaw significantly blocks the flow of the induced current and forces the current to redistribute around it. Meanwhile, the strong local enhancement of the current density is observed in the vicinity of the flaw tip. Furthermore, the influences of the size and position of the flaw on the local enhancement of the current density in the vicinity of the flaw tip are investigated. In addition, it is found that the influence of the flaw on the AC loss of the sample is slight for both cases of the interior flaw and the edge flaw.

  15. Refinement of atomic and magnetic structures using neutron diffraction for synthesized bulk and nano-nickel zinc gallate ferrite

    NASA Astrophysics Data System (ADS)

    Ata-Allah, S. S.; Balagurov, A. M.; Hashhash, A.; Bobrikov, I. A.; Hamdy, Sh.

    2016-01-01

    The parent NiFe2O4 and Zn/Ga substituted spinel ferrite powders have been prepared by solid state reaction technique. As a typical example, the Ni0.7Zn0.3Fe1.5Ga0.5O4 sample has been prepared by sol-gel auto combustion method with the nano-scale crystallites size. X-ray and Mössbauer studies were carried out for the prepared samples. Structure and microstructure properties were investigated using the time-of-flight HRFD instrument at the IBR-2 pulsed reactor, at a temperatures range 15-473 K. The Rietveld refinement of the neutron diffraction data revealed that all samples possess cubic symmetry corresponding to the space group Fd3m. Cations distribution show that Ni2+ is a complete inverse spinel ion, while Ga3+ equally distributed between the two A and B-sublattices. The level of microstrains in bulk samples was estimated as very small while the size of coherently scattered domains is quite large. For nano-structured sample the domain size is around 120 Å.

  16. HTS DC Transmission Line for Megalopolis Grid Development

    NASA Astrophysics Data System (ADS)

    Kopylov, S.; Sytnikov, V.; Bemert, S.; Ivanov, Yu; Krivetskiy, I.; Romashov, M.; Shakaryan, Yu; Keilin, V.; Shikov, A.; Patrikeev, V.; Lobyntsev, V.; Shcherbakov, V.

    2014-05-01

    Using of HTS AC and DC cables in electric power grids allows increasing of the transferred power, losses diminishing, decreasing of exclusion zone areas, the enhancement of the environmental conditions and fire/explosion safety of electric power systems. However, the use of DC superconducting cable lines together with converters brings additional advantages as reduction of losses in cables and suitable lowering of refrigerating plant capacity, as well as the realization of the function of short-circuit currents limitation by means of the appropriate setting of converter equipment. Russian Federal Grid Company and its R&D Center started the construction of the DC HTS power transmission line which includes the cable itself, cryogenic equipment, AC/DC converters, terminals and cable coupling boxes. This line will connect two substations in Saint-Petersburg - 330 kV "Centralnaya" and 220 kV "RP-9". The length of this HTS transmission line will be about 2500 meters. Nowadays are developed all the elements of the line and technologies of the cable manufacturing. Two HTS cable samples, each 30 m length, have been made. This paper describes the results of cables tests.

  17. Manufacturing and test of 2G-HTS coils for rotating machines: Challenges, conductor requirements, realization

    NASA Astrophysics Data System (ADS)

    Oomen, Marijn; Herkert, Werner; Bayer, Dietmar; Kummeth, Peter; Nick, Wolfgang; Arndt, Tabea

    2012-11-01

    We investigate the use of 2nd-generation High-Temperature Superconductors (2G-HTSs) in the rotors of electrical motors and generators. For these devices the conductor must be wound into robust impregnated coils, which are operated in vacuum at temperatures around 30 K, in strong magnetic fields of about 2T. Differences in thermal contraction between the coil former, conductor constituents, impregnation resin, bandage and heat-sink materials (assembled at room temperature) cause mechanical stresses at operating temperature. Rotating-machine operation adds Lorentz forces and challenging centripetal accelerations up to thousands of g. Second generation-HTS conductors withstand large tensile stresses in axial direction and compression in normal direction. However, shear stresses, axial compression, and tension normal to the conductor can cause degradation in superconducting properties. Such stresses can be mitigated by correct choice of materials, coil lay-out and manufacturing process. A certain stress level will remain, which the conductor must withstand. We have manufactured many impregnated round and race-track coils, using different 2G-HTS conductors, and tested them at temperatures from 25 K to 77 K. Degradation of the superconductor in early coils was traced to the mentioned differences in thermal contraction, and was completely avoided in coils produced later. We will discuss appropriate coil-winding techniques to assure robust and reliable superconductor performance.

  18. Structural Design and Analysis of a 150 kJ HTS SMES Cryogenic System

    NASA Astrophysics Data System (ADS)

    Han, Peng; Wu, Yu; Liu, Huajun; Li, Laifeng; Yang, Huihui

    A 150 kJ high temperature superconducting magnetic energy storage (HTS-SMES) system is under manufacturing in China. This paper focuses on the structural design and analysis of the SMES cryogenic system. The cryogenic system is designed and fabricated to maintain the working temperature. The system includes a vacuum vessel, its thermal radiation shield, its supporting devices, conduction plates, and current leads. Two G-M cryocoolers are used for the system cooling, the main one is connected to the HTS coils and the other is connected to the thermal shield and the lower ends of the current leads. In this study, the 3D models of the SMES cryogenic system were created with CATIA, a 3D model design software, and the analysis of the SMES cryogenic system was done by ANSYS. The mechanical analysis results on the vacuum vessel, suspension devices and supporting devices are presented, particularly the analyses on suspenders and shelf supports are of vital importance since the finished SMES system should meet vehicle-mounted requirements in long time transport. The heat load and the temperature distribution of the thermal shield were analyzed. A cooling experiment of the cryogenic system was made and the thermal shield was cooled down to about 50 K.

  19. K and Mn co-doped BaCd{sub 2}As{sub 2}: A hexagonal structured bulk diluted magnetic semiconductor with large magnetoresistance

    SciTech Connect

    Yang, Xiaojun; Zhang, Pan; Jiang, Hao; Luo, Yongkang; Chen, Qian; Feng, Chunmu; Tao, Qian; Cao, Guanghan; Xu, Zhu-An; Li, Yuke; Cao, Chao; Dai, Jianhui

    2013-12-14

    A bulk diluted magnetic semiconductor was found in the K and Mn co-doped BaCd{sub 2}As{sub 2} system. Different from recently reported tetragonal ThCr{sub 2}Si{sub 2}-structured II-II-V based (Ba,K)(Zn,Mn){sub 2}As{sub 2}, the Ba{sub 1−y}K{sub y}Cd{sub 2−x}Mn{sub x}As{sub 2} system has a hexagonal CaAl{sub 2}Si{sub 2}-type structure with the Cd{sub 2}As{sub 2} layer forming a honeycomb-like network. The Mn concentration reaches up to x ∼ 0.4. Magnetization measurements show that the samples undergo ferromagnetic transitions with Curie temperature up to 16 K. With low coercive field of less than 10 Oe and large magnetoresistance of about −70%, the hexagonal structured Ba{sub 1−y}K{sub y}Cd{sub 2−x}Mn{sub x}As{sub 2} can be served as a promising candidate for spin manipulations.

  20. Effect of Ni-substitution on glass forming ability, mechanical, and magnetic properties of FeBNbY bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Masood, Ansar; Ström, V.; Belova, L.; Rao, K. V.; Ågren, J.

    2013-01-01

    We present a method to identify bulk glass forming ability by partial substitution of Fe by Ni in FeBNbY based amorphous alloy ribbons and as a consequence obtain enhanced mechanical and soft magnetic properties of bulk glassy rods of diameter as large as 4.5 mm. A detailed investigation of thermal, mechanical, and magnetic properties of (Fe0.72-x NixB0.24Nb0.04)95.5Y4.5 alloys (with x ˜ 0.02, 0.04, 0.06, 0.08, 0.1) was carried out. The supercooled regime (ΔTx) and other glass forming parameters, e.g., reduced glass transition temperature (Trg), the gamma (γ) parameter, etc., were found to be enhanced due to the Ni substitution resulting in improvement of glass forming ability (GFA). The maximum values of such parameters (ΔTx ˜ 94 K, Trg ˜ 0.644, and γ ˜ 0.435) were obtained for the alloy with x ˜ 0.06, making it possible to cast cylindrical rods with 4.5 mm diameter for this composition. Nanoindentation studies on glassy rods also point out that (Fe0.66Ni0.06B0.24Nb0.04)95.5Y4.5 alloy exhibit the maximum value of hardness (H ˜ 12 GPa) as well as elastic modulus (E ˜ 193 GPa) among all of these samples. In addition to these, that particular sample shows the lowest room temperature coercivity (Hc ˜ 210 mOe). By annealing at 823 K, Hc can be further reduced to 60 mOe due to its structural relaxation. We attribute the improved soft magnetic and mechanical properties of as-quenched (Fe0.66Ni0.06B0.24Nb0.04)95.5Y4.5 alloy to higher packing density attained due to its large glass forming ability.

  1. First-principles modeling of metal (ii) ferrocyanide: electronic property, magnetism, bulk moduli, and the role of C  ≡  N- defect

    NASA Astrophysics Data System (ADS)

    Le, Hung M.; Pham, Tan-Tien; Duy Dat, Vo; Kawazoe, Yoshiyuki

    2017-01-01

    The ferrocyanide structures of transition metals (M) Ti2+, Cr2+, Mn2+, or Co2+ are investigated using a first-principles modeling approach. The crystal structure of cobalt ferrocyanide is found to resemble previous experimental data with good accuracy (~1% error). The considered porous structures possess magnetic moments of 8.00 µ B/cell, 8.00 µ B/cell, 4.00 µ B/cell, and 4.00 µ B/cell given by the [TiFe(CN)6]2-, [CrFe(CN)6]2-, [MnFe(CN)6]2-, and [CoFe(CN)6]2- frameworks, respectively. There is only one spin-state occupation at the Fermi level, which leads to the conclusion of semi-metallicity of the four structures. To verify the reliability of the electronic and magnetic properties, linear-response DFT  +  U calculations are performed and establish excellent agreement with the conventional DFT calculations. Then, the mechanical strength is evaluated by estimating the bulk moduli of the four structures, which fall in the range of 114 GPa-133 GPa. Upon the consideration of one C  ≡  N- linker defect, the magnetic moments of cobalt ferrocyanide and manganese ferrocyanide rise dramatically to 8 µ B/cell, while that of the titanium structure drops to 6 µ B/cell. In light of the electronic structure evidence, we believe that the low-spin Fe cation nearby the C  ≡  N- defect has an indirect effect on spin polarization of the four Co cations in the unit cell.

  2. Test Results For a 25-m Prototype Fault Current Limiting HTS Cable for Project Hydra

    SciTech Connect

    Rey, Christopher M; Duckworth, Robert C; Demko, Jonathan A; Ellis, Alvin R; Gouge, Michael J; James, David Randy; Tuncer, Enis

    2010-01-01

    The Oak Ridge National Laboratory (ORNL) has tested a 25-m long prototype High Temperature Superconducting (HTS) cable with inherent Fault-Current Limiting (FCL) capability at its recently upgraded HTS cable test facility in Oak Ridge, TN. The HTS-FCL cable and terminations were designed and fabricated by Ultera, which is a joint venture of Southwire and nkt cables with FCL features and HTS wire provided by American Superconductor Corporation. The overall project is sponsored by the U.S. Department of Homeland Security. The ultimate goal of the 25-m HTS-FCL cable test program was to verify the design and ensure the operational integrity for the eventual installation of a ~ 200-m fully functional HTS-FCL cable in the Consolidated Edison electric grid located in downtown New York City. The 25-m HTS-FCL cable consisted of a three-phase (3- ) Triax design with a cold dielectric between the phases. The HTS-FCL cable had an operational voltage of 13.8 kV phase-to-phase and an operating current of 4000 Arms per phase, which is the highest operating current to date of any HTS cable. The 25-m HTS-FCL cable was subjected to a series of cryogenic and electrical tests. Test results from the 25-m HTS-FCL cable are presented and discussed.

  3. Spatial normalization, bulk motion correction and coregistration for functional magnetic resonance imaging of the human cervical spinal cord and brainstem.

    PubMed

    Stroman, Patrick W; Figley, Chase R; Cahill, Catherine M

    2008-07-01

    Functional magnetic resonance imaging (fMRI) of the cortex is a powerful tool for neuroscience research, and its use has been extended into the brainstem and spinal cord as well. However, there are significant technical challenges with extrapolating the developments that have been achieved in the cortex to their use in the brainstem and spinal cord. Here, we develop a normalized coordinate system for the cervical spinal cord and brainstem, demonstrating a semiautomated method for spatially normalizing and coregistering fMRI data from these regions. fMRI data from 24 experiments in eight volunteers are normalized and combined to create the first anatomical reference volume, and based on this volume, we define a standardized region-of-interest (ROI) mask, as well as a map of 52 anatomical regions, which can be applied automatically to fMRI results. The normalization is demonstrated to have an accuracy of less than 2 mm in 93% of anatomical test points. The reverse of the normalization procedure is also demonstrated for automatic alignment of the standardized ROI mask and region-label map with fMRI data in its original (unnormalized) format. A reliable method for spatially normalizing fMRI data is essential for analyses of group data and for assessing the effects of spinal cord injury or disease on an individual basis by comparing with results from healthy subjects.

  4. Bulk undercooling

    NASA Technical Reports Server (NTRS)

    Kattamis, T. Z.

    1984-01-01

    Bulk undercooling methods and procedures will first be reviewed. Measurement of various parameters which are necessary to understand the solidification mechanism during and after recalescence will be discussed. During recalescence of levitated, glass-encased large droplets (5 to 8 mm diam) high speed temperature sensing devices coupled with a rapid response oscilloscope are now being used at MIT to measure local thermal behavior in hypoeutectic and eutectic binary Ni-Sn alloys. Dendrite tip velocities were measured by various investigators using thermal sensors or high speed cinematography. The confirmation of the validity of solidification models of bulk-undercooled melts is made difficult by the fineness of the final microstructure, the ultra-rapid evolution of the solidifying system which makes measurements very awkward, and the continuous modification of the microstructure which formed during recalescence because of precipitation, remelting and rapid coarsening.

  5. Continuous critical current measurement of high-temperature superconductor tapes with magnetic substrates using magnetic-circuit method.

    PubMed

    Zou, S N; Gu, C; Qu, T M; Han, Z

    2013-10-01

    The critical current (I(c)) of high-temperature superconductor (HTS) tapes has to be examined not only for short samples, but also for the entire tape, because local weak points can possibly lead to the quenching of the whole HTS device. Some methods were reported for continuous I(c) measurement along the length of a HTS tape, but few of them were applicable to tapes with magnetic substrates represented by YBa2Cu3O(7-δ)(YBCO)-coated conductors based on Ni5W alloy substrate by rolling assisted bi-axially textured substrate process. We previously presented a contact-free method using magnetic circuits to measure I(c) continuously of long HTS tapes, namely the magnetic-circuit (MC) method. This method has been previously applied with high speed and resolution to measure I(c) of HTS tapes with non-magnetic substrates, due to its resistance to noise aroused by mechanical vibration. In this work, its ability to measure HTS tapes with magnetic substrates is demonstrated both theoretically and experimentally. A 100 m long commercial YBCO tape based on Ni5W alloy substrate was measured and regular I(c) fluctuations were discovered. The MC method can be a powerful tool for quality control of HTS tapes, especially for tapes with magnetic substrates.

  6. Design and preliminary tests of a twin coil HTS SMES for pulse power operation

    NASA Astrophysics Data System (ADS)

    Badel, Arnaud; Tixador, Pascal; Berger, Kevin; Deleglise, Marc

    2011-05-01

    The design of a twin coil 2 × 200 kJ-1 MW pulse power high temperature superconductor (HTS) superconducting magnetic energy storage (SMES) demonstrator is presented. Its aim is to test at small scale various possibilities of electromagnetic launcher powering. The foreseen operation modes include high voltage discharge in power capacitors, sequential discharges of identical energies from two coupled coils, and XRAM current multiplication. Special attention was paid to the arrangement of the coils for the energies discharged to be equal. The coils are cooled by conduction from three cryocoolers; the thermal design was optimized in order to maintain the coils around 15 K in spite of the high number of current leads required for XRAM operation (eight). Preliminary tests of the demonstrator are also presented, showing that the thermal and electrical characteristics are in very good agreement with the design objectives.

  7. DC current distribution mapping system of the solar panels using a HTS-SQUID gradiometer

    NASA Astrophysics Data System (ADS)

    Miyazaki, Shingo; Kasuya, Syohei; Mawardi Saari, Mohd; Sakai, Kenji; Kiwa, Toshihiko; Tsukamoto, Akira; Adachi, Seiji; Tanabe, Keiichi; Tsukada, Keiji

    2014-05-01

    Solar panels are expected to play a major role as a source of sustainable energy. In order to evaluate solar panels, non-destructive tests, such as defect inspections and response property evaluations, are necessary. We developed a DC current distribution mapping system of the solar panels using a High Critical Temperature Superconductor Superconducting Quantum Interference Device (HTS-SQUID) gradiometer with ramp edge type Josephson junctions. Two independent components of the magnetic fields perpendicular to the panel surface (∂Bz/∂x, ∂Bz/∂y) were detected. The direct current of the solar panel is visualized by calculating the composition of the two signal components, the phase angle, and mapping the DC current vector. The developed system can evaluate the uniformity of DC current distributions precisely and may be applicable for defect detection of solar panels.

  8. First-principles study on magnetism and half-metallicity in bulk and various (001) surfaces of Heusler alloy Zr2VSn with Hg2CuTi-type structure

    NASA Astrophysics Data System (ADS)

    Deng, Zun-Yi; Zhang, Jian-Min

    2016-07-01

    Structural, electronic and magnetic properties in the bulk and five different (001) surfaces (ZrV-, ZrSn-, VV-, ZrZr- and SnSn-terminations) of Zr2 VSn Heusler alloy with Hg2 CuTi -type structure are studied by using first-principles calculations based on density-functional theory. The bulk Zr2 VSn Heusler alloy is ferrimagnetic half-metallicity with equilibrium lattice constant 6.815 Å and total magnetic moment -1.000 μB / f.u . , following the Slater-Pauling rule μt =Zt - 18 . The atoms on different surface layers exhibit different displacements, electronic and magnetic properties. All five (001) surfaces lose the half-metallicity and are not usable in spintronics devices.

  9. HTS step-edge Josephson junction terahertz harmonic mixer

    NASA Astrophysics Data System (ADS)

    Du, Jia; Weily, Andrew R.; Gao, Xiang; Zhang, Ting; Foley, Cathy P.; Guo, Yingjie Jay

    2017-02-01

    A high-temperature superconducting (HTS) terahertz (THz) frequency down-converter or mixer based on a thin-film ring-slot antenna coupled YBa2Cu3O7-x (YBCO)/MgO step-edge Josephson junction is reported. The frequency down-conversion was achieved using higher order harmonics of an applied lower frequency (19-40 GHz) local oscillator signal in the Josephson junction mixing with a THz signal of over 600 GHz, producing a 1-3 GHz intermediate frequency signal. Up to 31st order of harmonic mixing was obtained and the mixer operated stably at temperatures up to 77 K. The design details of the antenna, HTS Josephson junction mixer, the matching and isolation circuits, and the DC and RF performance evaluation are described in this paper.

  10. High voltage insulation of bushing for HTS power equipment

    NASA Astrophysics Data System (ADS)

    Kim, Woo-Jin; Choi, Jae-Hyeong; Kim, Sang-Hyun

    2012-12-01

    For the operation of high temperature superconducting (HTS) power equipments, it is necessary to develop insulating materials and high voltage (HV) insulation technology at cryogenic temperature of bushing. Liquid nitrogen (LN2) is an attractive dielectric liquid. Also, the polymer insulating materials are expected to be used as solid materials such as glass fiber reinforced plastic (GFRP), polytetra-fluoroethylene (PTFE, Teflon), Silicon (Si) rubber, aromatic polyamide (Nomex), EPDM/Silicon alloy compound (EPDM/Si). In this paper, the surface flashover characteristics of various insulating materials in LN2 are studied. These results are studied at both AC and impulse voltage under a non-uniform field. The use of GFRP and Teflon as insulation body for HTS bushing should be much desirable. Especially, GFRP is excellent material not only surface flashover characteristics but also mechanical characteristics at cryogenic temperature. The surface flashover is most serious problem for the shed design in LN2 and operation of superconducting equipments.

  11. High accuracy NMR chemical shift corrected for bulk magnetization as a tool for structural elucidation of microemulsions. Part 2 - Anionic and nonionic dilutable microemulsions.

    PubMed

    Hoffman, Roy E; Darmon, Eliezer; Aserin, Abraham; Garti, Nissim

    2016-02-01

    In our previous report we suggested a new analytical tool, high accuracy NMR chemical shift corrected for bulk magnetization as a supplementary tool to study structural transitions and droplet size and shape of dilutable microemulsions. The aim of this study was to show the generality of this technique and to demonstrate that in almost any type of microemulsion this technique provides additional valuable structural information. The analysis made by the technique adds to the elucidation of some structural aspects that could not be clearly determined by other classical techniques. Therefore, in this part we are extending the study to three additional systems differing in the type of oil phase (toluene and cyclohexane), the nature of the surfactants (anionic and nonionic), and other microemulsion characteristics. We studied sodium dodecyl sulfate (SDS)-based anionic microemulsions with different oils and a nonionic microemulsion based on Tween 20 as the surfactant and toluene as the oil phase. All the microemulsions were fully dilutable with water. We found that the change in the slope of chemical shift against dilution reflects phase transition points of the microemulsion (O/W, bicontinuous, W/O). Chemical shift changes were clearly observed with the transition between spherical and non-spherical (wormlike, etc.) droplet shapes. We compared the interaction of cyclohexane and toluene and used the anisotropic effect of toluene's ring current to determine its preferred orientation relative to SDS. Chemical shifts of the microemulsion components are therefore a useful addition to the arsenal of techniques for characterizing microemulsions.

  12. Electrical Model of Balanced AC HTS Power Cable

    NASA Astrophysics Data System (ADS)

    Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Willén, D.; Melnik, I.; Geschiere, A.

    The future electricity grid will be more sustainable and it will have more power transmission and distribution capability with more electrical power added from decentralized sources on distribution level and from wind parks and other large sources on transmission level. More interconnections and more underground transmission and distribution will be put up. Use of high temperature superconducting (HTS) power cables provides solutions to many of the future grid problems caused by these trends. In this paper we present an electrical model of a balanced 6 km-long three phase triaxial HTS power cable for the Dutch project being developed by a consortium of Alliander, Ultera™ and TUD. The cable currents in all three phases are balanced by selecting proper twist pitches and insulation thickness. The paper focuses on determining inductances, capacitances and AC losses of the balanced cable. Using the developed model, we also determine the voltage drop as function of the cable length, the neutral current and the effect of the imbalanced capacitances on the current distribution of the Dutch distribution cable. The model is validated and it can be used for accurate simulation of the electrical behaviour of triaxial HTS cables in electrical grids.

  13. Enhanced HTS hit selection via a local hit rate analysis.

    PubMed

    Posner, Bruce A; Xi, Hualin; Mills, James E J

    2009-10-01

    The postprocessing of high-throughput screening (HTS) results is complicated by the occurrence of false positives (inactive compounds misidentified as active by the primary screen) and false negatives (active compounds misidentified as inactive by the primary screen). An activity cutoff is frequently used to select "active" compounds from HTS data; however, this approach is insensitive to both false positives and false negatives. An alternative method that can minimize the occurrence of these artifacts will increase the efficiency of hit selection and therefore lead discovery. In this work, rather than merely using the activity of a given compound, we look at the presence and absence of activity among all compounds in its "chemical space neighborhood" to give a degree of confidence in its activity. We demonstrate that this local hit rate (LHR) analysis method outperforms hit selection based on ranking by primary screen activity values across ten diverse high throughput screens, spanning both cell-based and biochemical assay formats of varying biology and robustness. On average, the local hit rate analysis method was approximately 2.3-fold and approximately 1.3-fold more effective in identifying active compounds and active chemical series, respectively, than selection based on primary activity alone. Moreover, when applied to finding false negatives, this method was 2.3-fold better than ranking by primary activity alone. In most cases, novel hit series were identified that would have otherwise been missed. Additional uses of and observations regarding this HTS analysis approach are also discussed.

  14. Cryostat Design for an HTS Transformer

    NASA Astrophysics Data System (ADS)

    Trollier, T.; Ravex, A.; Poncet, J. M.; Tixador, P.; Donnier-Valentin, G.; Maher, E.

    2004-06-01

    A single-phase 41-kVA 2050V / 410V single-phase transformer demonstrator has been designed and manufactured as an integrated complete device with cooling system. A cold magnetic circuit design has been chosen for overall structural simplicity in a single metallic cryostat. The superconducting coils are solenoids. The primary winding uses a PIT-Bi-2223 tape. A secondary is wound with two lengths of YBCO coated conductors. The cooler used is a single-stage, high cooling power, coaxial GM-type pulse tube offering a cooling capacity of 80 W at 60 K or 100 W at 80 K using a 5 kW compressor. The original design of the cryostat architecture is detailed. The thermal and electrical performance tests (no-load and short-circuit tests) with an half primary and a reduced secondary (75 V - 50 A @ 77 K) are also presented.

  15. The insulation design for transmission class HTS transformer with continuous disk winding

    NASA Astrophysics Data System (ADS)

    Cheon, H. G.; Kwag, D. S.; Choi, J. H.; Kim, S. H.

    2007-10-01

    In the response to the demands for electrical energy, much effort aimed to develop and commercialize HTS power equipments have been made around the world. Among them HTS transformer is one of very promising one. In Korea, companies and universities are developing a power distribution and transmission class HTS transformer that is one of the 21st century superconducting frontier projects. The composite continuous disk winding of transmission class HTS transformer is concentrically arranged H1-L-H2 from center. For the development of transmission HTS transformer with continuous disk winding, the cryogenic insulation technology should be established. We have been analyzed insulation composition and investigated electrical characteristics such as the breakdown of LN2, barrier, kapton films, flashover on FRP in LN2. We are going to compare with measured each value and apply the value to most suitable insulating design of the HTS transformer.

  16. Present status and future trends of R&D for HTS rotational machines in Japan

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Osami

    2014-09-01

    Various HTS rotating machines, from multiple MW class to several 10 kW class, are being developed in Japan. R&D statuses of those machines are reviewed. Design studies of various types of HTS wind power generators are also conducted in Japan and their merits and demerits are discussed. Based on the present R&D statuses, future technical trends of HTS machines are discussed.

  17. RAPID COMMUNICATION: High performance superconducting wire in high applied magnetic fields via nanoscale defect engineering

    NASA Astrophysics Data System (ADS)

    Wee, Sung Hun; Goyal, Amit; Zuev, Yuri L.; Cantoni, Claudia

    2008-09-01

    High temperature superconducting (HTS) wires capable of carrying large critical currents with low dissipation levels in high applied magnetic fields are needed for a wide range of applications. In particular, for electric power applications involving rotating machinery, such as large-scale motors and generators, a high critical current, Ic, and a high engineering critical current density, JE, in applied magnetic fields in the range of 3-5 Tesla (T) at 65 K are required. In addition, exceeding the minimum performance requirements needed for these applications results in a lower fabrication cost, which is regarded as crucial to realize or enable many large-scale bulk applications of HTS materials. Here we report the fabrication of short segments of a potential superconducting wire comprised of a 4 µm thick YBa2Cu3O7-δ (YBCO) layer on a biaxially textured substrate with a 50% higher Ic and JE than the highest values reported previously. The YBCO film contained columns of self-assembled nanodots of BaZrO3 (BZO) roughly oriented along the c-axis of YBCO. Although the YBCO film was grown at a high deposition rate, three-dimensional self-assembly of the insulating BZO nanodots still occurred. For all magnetic field orientations, minimum Ic and JE at 65 K, 3 T for the wire were 353 A cm-1 and 65.4 kA cm-2, respectively.

  18. High Performance Superconducting Wire in High Applied Magnetic Fields via Nanoscale Defect Engineering

    SciTech Connect

    Goyal, Amit; Wee, Sung Hun; Zuev, Yuri L; Cantoni, Claudia

    2008-01-01

    High temperature superconducting (HTS) wires capable of carrying large critical currents with low dissipation levels in high applied magnetic fields are needed for a wide range of applications. In particular, for electric power applications involving rotating machinery, such as large-scale motors and generators, a high critical current, Ic, and a high engineering critical current density, JE, in applied magnetic fields in the range of 3 5 Tesla (T) at 65 K are required. In addition, exceeding the minimum performance requirements needed for these applications results in a lower fabrication cost, which is regarded as crucial to realize or enable many large-scale bulk applications of HTS materials. Here we report the fabrication of short segments of a potential superconducting wire comprised of a 4 m thick YBa2Cu3O7− (YBCO) layer on a biaxially textured substrate with a 50% higher Ic and JE than the highest values reported previously. The YBCO film contained columns of self-assembled nanodots of BaZrO3 (BZO) roughly oriented along the c-axis of YBCO. Although the YBCO film was grown at a high deposition rate, three-dimensional self-assembly of the insulating BZO nanodots still occurred. For all magnetic field orientations, minimum Ic and JE at 65 K, 3 T for the wire were 353 A cm−1 and 65.4 kA cm−2, respectively.

  19. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: The phenomenon of even bulk mode variance in a ferromagnetic A-A bilayer system

    NASA Astrophysics Data System (ADS)

    Zhou, Wen-Ping; Yun, Guo-Hong; Liang, Xi-Xia

    2009-12-01

    The eigenproblems of spin waves in a symmetrical ferromagnetic bilayered system with periodic boundary conditions are solved using the interface-rescaling approach (IRA). The results show that interface coupling between two sublayers would not change the excitation energy of odd bulk modes, but change excitation energy of even bulk modes. We call this peculiar phenomenon the phenomenon of even bulk mode variance (PEBMV). There are two kinds of mechanisms which cause PEBMV: phase reversal and phase translation of the magnon at the interface, corresponding, respectively, to the antiferromagnetic and ferromagnetic interface coupling cases. PEBMV embodies the selective effect of the interface on different bulk magnons.

  20. Magnetic anisotropy of Fe{sub 1−y}X{sub y}Pt-L1{sub 0} [X = Cr, Mn, Co, Ni, Cu] bulk alloys

    SciTech Connect

    Cuadrado, R.; Chantrell, R. W.; Klemmer, Timothy J.

    2014-10-13

    We demonstrate by means of fully relativistic first principles calculations that, by substitution of Fe by Cr, Mn, Co, Ni, or Cu in FePt-L1{sub 0} bulk alloys, with fixed Pt content, it is possible to tune the magnetocrystalline anisotropy energy by adjusting the content of the non-magnetic species in the material. The changes in the geometry due to the inclusion of each element induces different values of the tetragonality and hence changes in the magnetic anisotropy and in the net magnetic moment. The site resolved magnetic moments of Fe increase with the X content while those of Pt and X are simultaneously reduced. The calculations are in good quantitative agreement with experimental data and demonstrate that models with fixed band structure but varying numbers of electrons per unit cell are insufficient to describe the experimental data for doped FePt-L1{sub 0} alloys.

  1. Robot-arm-based NDE of hydrogen fuel tank using a 3D-movable HTS-SQUID gradiometer

    NASA Astrophysics Data System (ADS)

    Hatsukade, Y.; Hayashi, K.; Tanaka, S.; Tanabe, K.

    2010-06-01

    In this study, we constructed a robot-arm-based SQUID-NDE system utilizing a novel HTS-SQUID gradiometer with ramp-edge Josephson junctions for hydrogen fuel tank inspection, and developed an automatic 3D-scanning program. A cylindrical hydrogen fuel tank with a double-layer structure, in which a 3mm-thick Al liner was reinforced by a 3mm-thick carbon-fibre reinforced plastic (CFRP) cover, was prepared. The tank had a 10-mm-long through crack in the Al liner made by pressure cycle test. To inspect the tank using the SQUID-NDE system, we adopted a low-frequency eddy current technique that enables to excite deep part in the Al liner. By applying an excitation field of 7.5 μT at 0.4 to 10 kHz to the tank from a double-D coil, the tank was scanned by the system while moving the HTS-SQUID gradiometer along curved surface of the tank in magnetically unshielded environment. Magnetic responses from the deep-lying crack in the tank were successfully detected by the system.

  2. Characteristic and magnetic field analysis of a high temperature superconductor axial-flux coreless induction maglev motor

    NASA Astrophysics Data System (ADS)

    Wei, Qin; Yu, Fan; Jin, Fang; Shuo, Li; Guoguo, Li; Gang, Lv

    2012-04-01

    A new high temperature superconductor axial-flux coreless maglev motor (HTS AFIM) is proposed, of which the primary windings are made of HTS tapes and the secondary is a non-magnetic conductor. The main works of this paper are the magnetic-field computation and characteristics analysis of HTS AFIM. For the first one, the reduction of magnetic fields near outer and inner radius of the HTS AFIM is solved by introducing the sub-loop electro-magnetic model along the radial position. For the second one, the AC losses of HTS coils are calculated. The relationships between the device's characteristics and device parameters are presented, and the results indicate that under certain frequency and current levitation device can output enough lift force. The conclusions are verified by finite element calculations.

  3. THE UTILIZATION OF THE NTP-HTS DATA IN CHEMICAL TOXICITY MODELING

    EPA Science Inventory

    To explore efficient approaches to assessing the toxicity of environmental chemicals, the NIEHS National Toxicology Program (NTP) recently initiated a High Throughput Screening (HTS) Project. To date, HTS results for a set of 1,408 compounds tested in 6 cell viability assays have...

  4. Development of superconducting magnetic bearing for flywheel energy storage system

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yoshiki; Mizuno, Katsutoshi; Yamashita, Tomohisa; Ogata, Masafumi; Hasegawa, Hitoshi; Nagashima, Ken; Mukoyama, Shinichi; Matsuoka, Taro; Nakao, Kengo; Horiuch, Shinichi; Maeda, Tadakazu; Shimizu, Hideki

    2016-12-01

    We have been developing a superconducting magnetic bearing (SMB) that has high temperature superconducting (HTS) coils and bulks for a flywheel energy storage system (FESS) that have an output capability of 300 kW and a storage capacity of 100 kW h (Nagashima et al., 2008, Hasegawa et al., 2015) [1,2]. The world largest-class FESS with a SMB has been completed and test operation has started. A CFRP flywheel rotor that had a diameter of 2 m and weight of 4000 kg had a capability to be rotated at a maximum speed of 6000 min-1. The SMB using superconducting material both for its rotor and stator is capable of supporting the flywheel that had the heavy weight and the high seed rotation mentioned above. This paper describes the design of the SMB and results of the cooling test of the SMB.

  5. Magnetic properties of bulk, and rapidly solidified nanostructured (Nd1-xCex)2Fe14-yCoyB ribbons

    SciTech Connect

    Pathak, Arjun K.; Khan, M.; Gschneidner, Jr., K. A.; McCallum, R. W.; Zhou, L.; Sun, K.; Kramer, M. J.; Pecharsky, V. K.

    2015-11-06

    Magnetic properties of Ce and Co co-doped (Nd1-xCex)2Fe14-yCoyB compounds have been investigated both in bulk polycrystalline and rapidly solidified nanostructured ribbon forms. For certain Ce concentrations the materials exhibit spin re-orientation transitions below 140 K. The Curie temperatures, saturation magnetizations, and other magnetic properties relevant for applications as permanent magnets are controlled by Ce and Co substitutions for Nd and Fe, respectively. Most importantly, the results show that Ce, Co co-doped compounds are excellent replacements for several Dy-based high performance permanent magnets (dysprosium is one of the critical elements and is, therefore, in short supply). As a result, the high temperature (>375 K) magnetic properties for Nd–Ce–Fe–Co–B based alloys show promise not only as a replacement for Dy-doped Nd2Fe14B permanent magnets, but the new alloys also require significantly lower amounts of Nd, which too is the critical element that can be replaced by a more abundant Ce.

  6. Thermal analysis of HTS air-core transformer used in voltage compensation type active SFCL

    NASA Astrophysics Data System (ADS)

    Song, M.; Tang, Y.; Li, J.; Zhou, Y.; Chen, L.; Ren, L.

    2010-11-01

    The three-phase voltage compensation type active superconducting fault current limiter (SFCL) is composed of three HTS air-core transformers and a three-phase four-wire Pulse Width Modulation (PWM) converter. The primary winding of the each phase HTS air-core transformer is in series with the main system, and the second winding is connected with the PWM converter. The single-phase conduction-cooled HTS air-core transformer is consisting of four double-pancakes wound by the Bi2223/Ag tape. In this paper, according to the electromagnetic analysis on the single-phase HTS air-core transformer, its AC loss corresponding to different operation modes is calculated. Furthermore, the thermal behaviors are studied by the time-stepping numerical simulations. On the basis of the simulation results, the related problems with the HTS air-core transformer's thermal stability are discussed.

  7. Sub-Micron Long HTS Ho Electron Mixers

    NASA Technical Reports Server (NTRS)

    Harnack, 0.; Karasik, B. S.; McGrath, W. R.; Kleinsasser, A. W.; Barner, J. B.

    2000-01-01

    The hot-electron bolometer mixer made from a high-T, superconductor (HTS) was introduced recently as an alternative to a Schottky mixer at THz frequencies. The performance of the mixer depends on the total thermal conductance for heat removal from the phonon sub-system due to either length-dependent phonon diffusion or phonon escape to the substrate. We have measured both the length and temperature dependencies of the IF bandwidth of the mixers fabricated from 25-35 mn thick YBCO films on MgO and sapphire substrates. The films were grown by a laser deposition technique and electron-beam lithography was used to define bridge lengths down to 50 nm. Mixer measurements were done using signal frequencies in the range of 1-100 GHz. For 50 nm and 400 nm long devices on MgO, the 3-dB bandwidth was about 100 MHz. At temperatures below 60 K, the hot-electron plateau was clearly seen starting around 2-3 GHz. At temperatures above 70 K, the flux-flow effects begin to dominate and the IF bandwidth increases to 1-8 GHz, while the conversion efficiency drops by several dB. This temperature dependence of the IF bandwidth can account for previously reported unexpectedly high bandwidth of HTS mixers.

  8. Development of Y-Ba-Cu-O Superconductors for Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Selvamanickam, V.; Pfaffenbach, K.; Sokolowski, R. S.; Zhang, Y.; Salama, K.

    1996-01-01

    The material requirements, material manufacturing and magnetic properties that are relevant to fabrication of High Temperature Superconductor (HTS) magnetic bearings have been discussed. It is found that the seeded-melt-texturing method can be used to fabricate the single domain material that is required to achieve the best magnetic properties. Trapped-field mapping has been used as a non-destructive tool to determine the single-domain nature of the HTS material and quantity of the HTS disks. Both the trapped field and the levitation force of the Y-Ba-Cu-O disks are found to be strongly sensitive to the oxygen content.

  9. Homogeneous performance and strain tolerance of long Bi-2223 HTS conductors under hoop stress

    NASA Astrophysics Data System (ADS)

    Miyoshi, Y.; Kitaguchi, H.; Chaud, X.; Debray, F.; Nishijima, G.; Tsuchiya, Y.

    2014-02-01

    Two types of high-strength industrial Bi-2223 conductor, one laminated by copper alloy and the other laminated by stainless steel, have been tested to examine the effect of hoop stress on the transport property. The specimens (˜2 m long) were prepared by winding one layer around a GFRP mandrel and the measurements were made in a liquid helium bath with the hoop stress calculated from the BJR product applied by external magnetic field. A careful measurement wire configuration was necessary to cancel the noise pick-up from the environment for more accurate determination of Ic and n-value. We show for the first time that both conductors showed homogeneous voltage-current characteristics over a long length and degradations with hoop stress occurred uniformly, which is crucial information for the development of HTS magnet technology. The onset of degradation occurred at 200 MPa and 220 MPa, with additional bending stress present from the winding diameter of 108 mm, for copper alloy laminated and stainless steel laminated conductors, respectively. After considering the effect of bending strain, our result agrees well with the previously measured data.

  10. Designing HTS Roebel cables for low-field applications with open-source code

    NASA Astrophysics Data System (ADS)

    Grilli, Francesco; Zermeño, Victor M. R.; Kario, Anna

    2016-11-01

    In HTS Roebel cables for low-field applications the tightly packed strands produce a substantial self-field, which can be comparable to the background field the cable operates in. As a result, the self-field critical current (Ic) of a cable is lower than the value obtained by multiplying the self-field Ic of the strands by the number of strands. In addition, the in-field reduction of the superconducting material plays an important role for a cable's Ic. Numerical models can accurately calculate the magnetic field distribution inside a cable and estimate its Ic. In this contribution we employ a recently developed open-source model to estimate the Ic of Roebel cables. In particular, we investigate the influence of the spacing between the superconducting layers, of the Jc(B, θ) dependence, and of the presence of an external magnetic field. For the present analysis, we consider tapes from two manufactures, whose properties were characterized in our group.

  11. Development of high speed continuous transport critical current measurement system for long piece of HTS conductor

    NASA Astrophysics Data System (ADS)

    Kim, Seokho; Park, Minwon; Yu, In-Keun; Kim, Gyeong-Hun; Ha, Hong-Su; Sim, Kideok; Oh, Sang-Soo; Moon, Seung-Hyun

    2013-01-01

    In case of long pieces of HTS conductor, their critical current measurement is an important process for the conductor manufacturer and the customer, however, it is very time consuming process. Conventional critical current measurement is carried out by ‘four probe method’, which increase the transport current and measure the voltage between the fixed voltage taps. Therefore, it consists of conductor moving and measuring process. To speed up the measuring process, longer distance between voltage taps is required. In this case, the measured critical current is averaged and small defects, which can be very crucial for thermal stability, cannot be found. Therefore, the limitation of the voltage tap length should be carefully decided considering the cooling environment. Another non-contact or indirect method is to measure the screening effect of magnetic field and converting the field signal to the critical current, which is called as hall probe method. This process is known as a very efficient way to find local defects and estimate the distribution of the critical current, however, it contains inevitable error and noise because it should measure the small magnetic field signals. This paper describes a new critical current measurement system, which have similar hardware structure of conventional ‘four probe method’. However, it is much faster than other systems using fast feedback control of the transport current while the conductor is continuously moving with high speed. The measured results are compared with the conventional method and hall probe method.

  12. MAGNET ENGINEERING AND TEST RESULTS OF THE HIGH FIELD MAGNET R AND D PROGRAM AT BNL.

    SciTech Connect

    COZZOLINO,J.; ANERELLA,M.; ESCALLIER,J.; GANETIS,G.; GHOSH,A.; GUPTA,R.; HARRISON,M.; JAIN,A.; MARONE,A.; MURATORE,J.; PARKER,B.; SAMPSON,W.; SOIKA,R.; WANDERER,P.

    2002-08-04

    The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) has been carrying out design, engineering, and technology development of high performance magnets for future accelerators. High Temperature Superconductors (HTS) play a major role in the BNL vision of a few high performance interaction region (IR) magnets that would be placed in a machine about ten years from now. This paper presents the engineering design of a ''react and wind'' Nb{sub 3}Sn magnet that will provide a 12 Tesla background field on HTS coils. In addition, the coil production tooling as well as the most recent 10-turn R&D coil test results will be discussed.

  13. Superconductor-Magnet Bearings With Inherent Stability and Velocity-Independent Drag Torque

    NASA Technical Reports Server (NTRS)

    Lee, Eun-Jeong; Ma, Ki Bui; Wilson, Thomas L.; Chu, Wei-Kan

    1999-01-01

    A hybrid superconductor magnet bearing system has been developed based on passive magnetic levitation and the flux pinning effect of high-temperature superconductivity. The rationale lies in the unique capability of a high-temperature superconductor (HTS) to enhance system stability passively without power consumption. Characterization experiments have been conducted to understand its dynamic behavior and to estimate the required motor torque for its driving system design. These experiments show that the hybrid HTS-magnet bearing system has a periodic oscillation of drag torque due mainly to the nonuniform magnetic field density of permanent magnets. Furthermore, such a system also suffers from a small superimposed periodic oscillation introduced by the use of multiple HTS disks rather than a uniform annulus of HTS material. The magnitude of drag torque is velocity independent and very small. These results make this bearing system appealing for high-speed application. Finally, design guidelines for superconducting bearing systems are suggested based on these experimental results.

  14. Accelerating the introduction of HTS products for a broad range of electric power and industrial applications

    NASA Astrophysics Data System (ADS)

    Eaton, Russell

    2002-01-01

    The Department of Energy (DOE), as part of its Superconductivity Program for Electric Systems, is successfully pursuing the development of electric power and industrial devices, incorporating significant high-temperature superconducting (HTS) components or subsystems, through its innovative Superconducting Partnership Initiative (SPI). The objective of the SPI is to accelerate the commercial introduction of the HTS products for a broad range of electric power and industrial applications. DOE's approach to accomplishing the SPI objective is to support cost shared projects carried out by industry led teams. DOE will fund projects to develop HTS devices that are either in (1) the research and development stage (Phase 1), (2) the pre-commercialization stage (Phase II), or (3) the commercial entry stage (Phase III). DOE's industry partners must contribute at least half a project's costs. These teams will include capabilities needed to develop the device as well as to develop the business plan for the commercial product introduction. DOE's partners consist of vertically integrated teams consisting of equipment manufacturers, HTS wire and coil suppliers, national laboratories, and end users, primarily utilities. These partners carry out the multi-year technology development efforts, consisting generally of design, construction, and testing of the HTS system. Finally, commercialization of HTS products will be discussed primarily in terms of benefits these products will have over competing products based upon conventional conductors and the critical need for affordable, practical HTS materials and conductors for these applications. .

  15. Design Construction and Test Results of a HTS Solenoid For Energy Recovery Linac

    SciTech Connect

    Anerella, M; Ben-Zvi, I; Kayran, D; McIntyre, G; Muratore, J; Plate, S; Sampson, W; Cole, M; Holmes, D

    2011-03-28

    An innovative feature of the proposed Energy Recovery Linac (ERL) is the use of a solenoid made with High Temperature Superconductor (HTS) with the Superconducting RF cavity. The use of HTS allows solenoid to be placed in close proximity to the cavity and thus provides early focusing of the electron beam. In addition, cryogenic testing at {approx}77 K is simpler and cheaper than 4 K testing. This paper will present the design, construction and test results of this HTS solenoid. The HTS solenoid in the proposed ERL will be situated in the transition region between the superconducting cavity at {approx}4 K and the cryostat at the room temperature. Solenoid inside the cryogenic structure provides an early focusing and hence low emittance beam. The temperature in the transition region will be too high for a conventional low temperature superconductor and resistive heat load from copper coils will be too high on cryogenic system. HTS coils also allow much higher current density and significant reduction in size as compared to copper coils. Hence HTS solenoid provide a unique and technically superior solution. The use of a HTS solenoid with superconducting cavity offers a unique option as it can be placed in a cold to warm transition region to provide early focussing without using additional space. Construction and test results so far are very encouraging for its use in the ERL project.

  16. Analysis on heat loss characteristics of a 10 kV HTS power substation

    NASA Astrophysics Data System (ADS)

    Teng, Yuping; Dai, Shaotao; Song, Naihao; Zhang, Jingye; Gao, Zhiyuan; Zhu, Zhiqin; Zhou, Weiwei; Wei, Zhourong; Lin, Liangzhen; Xiao, Liye

    2014-09-01

    A 10 kV High Temperature Superconducting power substation (10 kV HTS substation), supported by Chinese State 863 projects, was developed and has been running to supply power for several factories for more than two years at an industrial park of Baiyin, Gansu province in Northwest China. The system of the 10 kV HTS substation compositions, including a HTS cable, a HTS transformer, a SFCL, and a SMES, are introduced. The SMES works at liquid helium temperature and the other three apparatus operates under liquid nitrogen condition. There are mainly four types of heat losses existing in each HTS apparatus of the 10 kV HTS substation, including AC loss, Joule heat loss, conductive heat, and leak-in heat from cryostat. A small quantity of AC loss still exists due to the harmonic component of the current when it carries DC for HTS apparatus. The principle and basis for analysis of the heat losses are introduced and the total heat loss of each apparatus are calculated or estimated, which agree well with the test result. The analysis and result presented are of importance for the design of the refrigeration system.

  17. Closed Form Formulas for Distributed Circuit Model of Discontinuities in HTS Microstrip Transmission Lines

    NASA Astrophysics Data System (ADS)

    Javadzadeh, S. Mohammad Hassan; Mamaghany, Zahra Mardy; Farzaneh, Forouhar; Fardmanesh, Mehdi

    A distributed circuit model for different kinds of discontinuities in high temperature superconducting (HTS) microstrip transmission lines (TLs), is proposed. In each case, closed form formula for lumped element model is presented based on the configuration of the discontinuity and the characterizations of HTS microstrip TLs. These discontinuities consist of steps in width, open ends, gaps and 90-degree bends. In the case of normal conductor microstrip TLs there are a lot of numerical and analytical equations that can accurately model them, however those formulas are not efficient for HTS TLs. Thus modified relations are extracted utilizing the superconducting characterizations to obtain much more accurate formulas. Additionally temperature dependence of HTS TLs is considered in the relations. Moreover regarding the kinetic inductance in HTS TLs a closed form formula is proposed for characteristic impedance of HTS TLs. Furthermore correction factors based on fringe fields is used to optimize all formulas. Using these formulations can lead to modeling and analysis of some superconducting microwave devices such as resonators, microwave filters, couplers, etc. In contrast to EM analysis, using the distributed circuit model is much easier for analysis of HTS microwave devices. The accuracy of the proposed model is confirmed in comparison with some electromagnetic full-wave simulations. This full analytical approach shows great accuracy in this test case as well.

  18. Torsion Strain Effects on Critical Currents of Hts Superconducting Tapes

    NASA Astrophysics Data System (ADS)

    Takayasu, Makoto; Minervini, Joseph V.; Bromberg, Leslie

    2010-04-01

    A torsional twist strain effect on the critical current of a thin HTS tape has been found to be well described by a longitudinal strain model taking into account the internal shortening compressive strains accompanied with the tensile longitudinal strains due to a torsional twist. The critical current of a twisted tape is given by the integration of the critical current densities corresponding to the strain distribution over the tape cross-section using axial strain data of the tape. The model is supported with experimental results of YBCO and BSCCO-2223 tapes. It has been also found that torsional twisting effects on the critical currents of a tape composing of the conventional lapped-tape cable and the twisted stacked-tape cable are described by the same equation as that of a twisted single tape.

  19. Thermal property of insulation material for HTS power cable

    NASA Astrophysics Data System (ADS)

    Choi, Yeon Suk; Kim, D. L.; Shin, D. W.; Hwang, S. D.

    2012-06-01

    The thermal property of insulation material is essential in developing a high temperature superconductor (HTS) power cable operating at around liquid nitrogen temperature. The accurate estimate of the heat flux is difficult in the nonmetallic materials because nonmetallic materials have a high thermal resistance and low temperature gradient along the specimen. The objective of the present work is to develop a precise instrument for measuring the thermal conductivity of insulating materials over a temperature range of 30 K to approximately the room temperature by using a cryocooler. The thermal conductivity of Teflon is measured and the accuracy confirmation is carried out by comparing published data. In addition, the experimental results of apparent thermal conductivity of polypropylene laminated paper (PPLP) are presented and the temperature dependency is also discussed

  20. Electrical and Mechanical Characterizations of Nanocomposite Insulation for HTS Systems

    SciTech Connect

    Walsh, J K; Fabian, Paul E; Hooker, M W; Lizotte, M J; Tuncer, Enis; Sauers, Isidor

    2011-01-01

    As HTS wire technology continues to advance, a critical need has emerged for dielectric materials that can be used in superconducting components such as terminations, fault current limiters, transformers, and motors. To address this need, CTD is developing nanocomposite insulations based on epoxy and benzoxazine chemistries. Depending on part geometry, some processing methods are more efficient than others. For this reason, CTD is investigating both fiber-reinforced and filled resin systems for use in these applications. A thorough set of electrical testing including AC breakdown, breakdown as a function of thickness, and flashover shows promising performance characteristics. In addition, mechanical testing (short beam shear and compression) indicate that these new materials to have as good or better performance than G10.

  1. Theoretical estimation of quench occurrence and propagation based on generalized thermoelasticity for LTS/HTS tapes triggered by a spot heater

    NASA Astrophysics Data System (ADS)

    Tong, Yujin; Guan, Mingzhi; Wang, Xingzhe

    2017-04-01

    The present study deals with the thermal characteristics and mechanical behaviors of low/high temperature superconducting (LTS/HTS) composite tapes during quench processes triggered by a spot heater. Based on the generalized thermoelastic theory, a dynamic thermoelastic model with a relaxation time is developed which takes into account the temperature dependence and finite speed of heat propagation for the superconducting tapes under cryogenic condition. The analyses were performed using the finite element method to solve the coupled differential equations of dynamic heat conduction and elastic equilibrium. The results show that the thermoelastic behaviors exhibit a strong relevance to quench characteristics of the superconductors. As a quench occurs, the thermoelastic strain-rate has an obvious jumping variation with the instant of time of its peak being fortunately coincident with the time at which the critical temperature is reached. Such a jumping change of strain-rate could be a way of estimation and detection of quench occurrence, and the theoretical predictions coincide with the existing experimental observations on thermoelastic strain-rate in LTS magnets. For a HTS tape, the thermoelastic strain-rate or temperature-rate variation and a small jump also are illustrated as the quench occurrence is determined. Additionally, the normal zone propagation velocities for the LTS/HTS tapes are predicted by the critical temperature and thermoelastic strain-rate to show quite good agreements with the results evaluated by Wilson’s formula for a LTS tape or the experimental measurements for a HTS tape. The influences of the relaxation time of heat conduction and thermoelastic coupling on the thermal distribution and strain profile are also discussed in details.

  2. Simulation and measurement of a Ka-band HTS MMIC Josephson junction mixer

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Pegrum, Colin; Du, Jia; Guo, Yingjie Jay

    2017-01-01

    We report modeling and simulation results for a Ka band high-temperature superconducting (HTS) monolithic microwave integrated circuit (MMIC) Josephson junction mixer. A Verilog-A model of a Josephson junction is established and imported into the system simulator to realize a full HTS MMIC circuit simulation containing the HTS passive circuit models. Impedance matching optimization between the junction and passive devices is investigated. Junction DC I-V characteristics, current and local oscillator bias conditions and mixing performance are simulated and compared with the experimental results. Good agreement is obtained between the simulation and measurement results.

  3. Long Term Operation of Cooling System for the Kepco Hts Power Cable

    NASA Astrophysics Data System (ADS)

    Yang, H. S.; Kim, D. L.; Sohn, S. H.; Lim, J. H.; Choi, Y. S.; Hwang, S. D.

    2010-04-01

    HTS power cable systems of to several hundred meters in length are presently being developed and evaluated for practical use in real power grids. Since 2006, a cooling system for the 3-phase, 100-m HTS power cable with 22.9 kV/1.25 kA has been installed and tested at the KEPCO's Gochang power-testing center. Performance reliability through several demonstration tests of over 9,000 hours was demonstrated. This paper mainly describes the cooling performance test results of the HTS power cable system obtained during the long-term performance tests.

  4. The electrical characteristics of solid insulators for 154 kV class HTS transformer

    NASA Astrophysics Data System (ADS)

    Cheon, H. G.; Choi, J. H.; Pang, M. S.; Kim, W. J.; Kim, S. H.

    2011-11-01

    HTS transformer, without any loss of insulation lifetime due to the reduction in terms of size and weight, can increase the overload capacity, and have some benefits such as the improvement in efficiency, minimization of environmental pollution, and convenient spatial arrangement, which contribute a lot to electric power system operation. However, for practical insulation design of the HTS transformer, it is necessary to establish the research on electrical properties LN2 as well as solid insulators. These solid insulators have been used as main insulations for HTS transformer. In this paper, we discussed breakdown and V-t characteristics of glass fiber reinforced plastics (GFRP) and pressboard in LN2.

  5. Design of Current Leads for the MICE Coupling Magnet

    SciTech Connect

    Wang, Li; Li, L.K.; Wu, Hong; Xu, Feng Yu; Liu, X.K.; Jia, Lin X.; Green, Michael A.

    2008-04-02

    A pair of superconducting coupling magnets will be part of the Muon Ionization Cooling Experiment (MICE). They were designed and will be constructed by the Institute of Cryogenics and Superconductivity Technology, Harbin Institute of Technology, in collaboration with Lawrence Berkeley National Laboratory. The coupling magnet is to be cooled by using cryocoolers at 4.2K. In order to reduce the heat leak to the 4.2K cold mass from 300 K, a pair of current leads composed of conventional copper leads and high temperature superconductor (HTS) leads will be used to supply current to the magnet. This paper presents the optimization of the conventional conduction-cooled metal leads for the coupling magnet. Analyses on heat transfer down the leads using theoretical method and numerical simulation were carried out. The stray magnetic field around the HTS leads has been calculated and effects of the magnetic field on the performance of the HTS leads has also been analyzed.

  6. Effect of size and geometry on levitation force measurements between permanent magnets and high-temperature superconductors

    SciTech Connect

    Cha, Y.S.; Hull, J.R.; Mulcahy, T.M.; Rossing, T.D. )

    1991-11-15

    A series of experiments measuring the levitation force between a permanent magnet (PM) and a high-temperature superconductor (HTS) and between pairs of PMs, coupled with finite-element calculations of the forces and fields, has identified factors that influence the levitation force. The self-demagnetizing factor within the HTS and, to some extent, within the PM has a profound effect on magnetic pressure. For large HTSs with strong flux-pinning, the demagnetizing effect of the diamagnetic image of the PM is substantial. For short distances between the HTS and PM, compression of magnetic flux produces a dependence on PM diameter.

  7. Effect of size and geometry on levitation force measurements between permanent magnets and high-temperature superconductors

    SciTech Connect

    Cha, Y.S.; Hull, J.R.; Mulcahy, T.M.; Rossing, T.D. Northern Illinois Univ., De Kalb, IL . Dept. of Physics)

    1991-01-01

    A series of experiments measuring the levitation force between a permanent magnet (PM) and a high temperature superconductor (HTS) and between pairs of PMs, coupled with finite-element analysis of the experiments, has identified factors that influence the levitation force. The self demagnetizing factor within the HTS and, to some extent, within the PM has a profound effect on magnetic pressure. For large HTSs with strong flux-pinning, the demagnetizing effect of the diamagnetic image of the PM is substantial. For short distances between the HTS and PM, compression of magnetic flux produces a dependence on PM diameter. 8 refs.

  8. Performance of HTS SQUID using resonant coupling of cooled Cu pickup coil

    NASA Astrophysics Data System (ADS)

    Enpuku, K.; Hirakawa, S.; Momotomi, R.; Matsuo, M.; Yoshida, T.

    2011-11-01

    We designed and tested an HTS SQUID magnetometer using resonant coupling of a copper pickup coil cooled at T = 77 K. The pickup coil was made of a twisted multi-filamentary wire, the so-called Litz wire, to prevent the increase in coil resistance at high frequencies. First, we measured the coil characteristics in the frequency range from DC to 100 kHz when the diameter df of the elementary filament of the Litz wire was varied between 0.04 and 0.2 mm. We showed that the coil characteristics at high frequencies can be improved when the diameter df is reduced. Next, we constructed a magnetometer using a pickup coil with an average diameter D = 45 mm and number of turns N = 150. The measured magnetic field noise of the magnetometer was 3.3 fT/Hz1/2 at a resonant frequency of fr = 10.15 kHz. The Q value of the resonant circuit was Q = 153. The experimental results agreed well with the designed value. The obtained high sensitivity of the magnetometer is expected to be useful for its application to low-field NMR.

  9. Foetal magnetocardiography with a multi-channel HTS rf SQUID gradiometer

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Wolters, N.; Lomparski, D.; Zander, W.; Banzet, M.; Schubert, J.; Krause, H.-J.; Geue, D.; van Leeuwen, P.

    2006-05-01

    Foetal magnetocardiography (fMCG) is a promising technique for prenatal cardiac diagnosis. In this paper, we discuss the special requirements of a system for fMCG measurements. A SQUID system incorporating five HTS rf SQUID magnetometers has been developed and constructed. Four magnetometers are arranged at the bottom of the cryostat in a 4 cm × 4 cm square configuration. One reference magnetometer is located 20 cm above the plane to form four first-order axial gradiometers with the four bottom magnetometers. The magnetometer with a 18 mm diameter flux focuser, which reaches a field sensitivity of 20-30 fT Hz-1/2, proved sufficient for recording foetal magnetocardiograms in a magnetically shielded room. The cardiac activities of two foetuses (31st and 33rd weeks of gestation) were recorded in 90 Hz bandwidth. The foetal QRS peak signals ranged from 4 to 7 pT and could easily be identified in the real-time gradiometer outputs with a signal-to-noise ratio of up to five. Furthermore, the averaged fMCG data enabled the determination of de- and repolarization time intervals. Overall, the fMCG signals proved of sufficient quality to perform foetal heart diagnostics.

  10. Permanent magnets composed of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Weinstein, Roy; Chen, In-Gann; Liu, Jay; Lau, Kwong

    1991-01-01

    A study of persistent, trapped magnetic field has been pursued with high-temperature superconducting (HTS) materials. The main effort is to study the feasibility of utilization of HTS to fabricate magnets for various devices. The trapped field, when not in saturation, is proportional to the applied field. Thus, it should be possible to replicate complicated field configurations with melt-textured YBa2Cu3O7 (MT-Y123) material, bypassing the need for HTS wires. Presently, materials have been developed from which magnets of 1.5 T, at 77 K, can be fabricated. Much higher field is available at lower operating temperature. Stability of a few percent per year is readily attainable. Results of studies on prototype motors and minimagnets are reported.

  11. Transient analysis of an HTS DC power cable with an HVDC system

    NASA Astrophysics Data System (ADS)

    Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun; Yang, Byeongmo

    2013-11-01

    The operational characteristics of a superconducting DC power cable connected to a highvoltage direct current (HVDC) system are mainly concerned with the HVDC control and protection system. To confirm how the cable operates with the HVDC system, verifications using simulation tools are needed. This paper presents a transient analysis of a high temperature superconducting (HTS) DC power cable in connection with an HVDC system. The study was conducted via the simulation of the HVDC system and a developed model of the HTS DC power cable using a real time digital simulator (RTDS). The simulation was performed with some cases of short circuits that may have caused system damage. The simulation results show that during the faults, the quench did not happen with the HTS DC power cable because the HVDC controller reduced some degree of the fault current. These results could provide useful data for the protection design of a practical HVDC and HTS DC power cable system.

  12. Design, development and calibration of HTS wire based LOX level sensor probe

    NASA Astrophysics Data System (ADS)

    Karunanithi, R.; Jacob, S.; Nadig, D. S.; Prasad, M. V. N.; Gour, A. S.; Gowthaman, M.; Deekshith, P.; Shrivastava, V.

    2014-01-01

    For space applications, the weight of the liquid level sensors are of major concern as they affect the payload fraction and hence the cost. An attempt is made to design and test a light weight High Temperature Superconductor (HTS) wire based liquid level sensor for Liquid Oxygen (LOX) tank used in the cryostage of the spacecraft. The total resistance value measured of the HTS wire is inversely proportional to the liquid level. A HTS wire (SF12100) of 12mm width and 2.76m length without copper stabilizer has been used in the level sensor. The developed HTS wire based LOX level sensor is calibrated against a discrete diode array type level sensor. Liquid Nitrogen (LN2) and LOX has been used as cryogenic fluid for the calibration purpose. The automatic data logging for the system has been done using LabVIEW11. The net weight of the developed sensor is less than 1 kg.

  13. Current leads and magnetic bearings

    NASA Astrophysics Data System (ADS)

    Hull, J. R.

    1993-10-01

    Since the discovery of high temperature superconductors (HTS's), Argonne National Laboratory (ANL) has been active in a broad spectrum of activities in developing these materials for applications. Work at every stage of development has involved industrial collaboration in order to accelerate commercialization. While most of the development work has been devoted to improving the properties of current-carrying wires, some effort has been devoted to applications that can utilize HTS's with properties available now or in the near future. In this paper, advances made in the area of current leads and magnetic bearings are discussed.

  14. High Temperature Superconductivity Space Experiment (HTSSE). Hybrid HTS/Dielectric Resonator Bandpass Filter

    DTIC Science & Technology

    1992-04-02

    enlarged ( limited by waveguide moding) or the metal walls replaced by HTS material . HTS walls are particularly attractive since they can be placed...an order of magnitude the resistive losses of filters, waveguide feeds, and transmission lines. Significant reduction in size and weight of these...suspending a dielectric resonator inside a waveguide cavity below cutoff. One of the basic advantages of a dielectric resonator as compared to a

  15. Optimization of parameters for the synthesis of Y2Cu2O5 nanoparticles by Taguchi method and comparison of their magnetic and optical properties with their bulk counterpart

    NASA Astrophysics Data System (ADS)

    Farbod, Mansoor; Rafati, Zahra; Shoushtari, Morteza Zargar

    2016-06-01

    Y2Cu2O5 nanoparticles were synthesized by sol-gel combustion method and effects of different factors on the size of nanoparticles were investigated. In order to reduce the experimental stages, Taguchi robust design method was employed. Acid citric:Cu+2 M ratio, pH, sintering temperature and time were chosen as the parameters for optimization. Among these factors the solution pH had the most influence and the others had nearly the same influence on the nanoparticles sizes. Based on the predicted conditions by Taguchi design, the sample with a minimum particle size of 47 nm was prepared. The magnetic behavior of Y2Cu2O5 nanoparticles were measured and found that at low fields they are soft ferromagnetic but at high fields they behave paramagnetically. The magnetic behavior of nanoparticles were compared to their bulk counterparts and found that the Mr of the samples was slightly different, but the Hc of the nanoparticles was 76% of the bulk sample. The maximum absorbance peak of UV-vis spectrum showed a blue shift for the smaller particles.

  16. Development and construction of an HTS rotor for ship propulsion application

    NASA Astrophysics Data System (ADS)

    Nick, W.; Frank, M.; Kummeth, P.; Rabbers, J. J.; Wilke, M.; Schleicher, K.

    2010-06-01

    A low-speed high-torque HTS machine is being developed at Siemens on the basis of previous steps (400kW demonstrator, 4MVA generator). The goal of the programme is to utilize the characteristic advantages offered by electrical machines with HTS-excited rotor, such as efficiency, compact size, and dynamic performance. To be able to address future markets, requirements from ship classification as well as potential customers have to be met. Electromagnetic design cannot be focused on nominal operation only, but has to deal with failure modes like short circuit too. Utilization of superconductor requires to consider margins taking into account that the windings have to operate reliably not only in "clean" laboratory conditions, but in rough environment with the stator connected to a power converter. Extensive quality control is needed to ensure homogenous performance (current capacity, electrical insulation, dimensions) for the large quantity of HTS (45 km). The next step was to set up and operate a small-scale "industrial" manufacturing process to produce HTS windings in a reproducible way, including tests at operating conditions. A HTS rotor includes many more components compared to a conventional one, so tough geometric tolerances must be met to ensure robust performance of the system. All this gives a challenging task, which will be concluded by cold testing of the rotor in a test facility. Then the rotor will be delivered for assembly to the stator. In following machine tests the performance of the innovative HTS drive system will be demonstrated.

  17. Operation and design selection of high temperature superconducting magnetic bearings

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Floegel-Delor, U.; Riedel, T.; Rothfeld, R.; Wippich, D.; Goebel, B.

    2004-10-01

    Axial and radial high temperature superconducting (HTS) magnetic bearings are evaluated by their parameters. Journal bearings possess advantages over thrust bearings. High magnetic gradients in a multi-pole permanent magnet (PM) configuration, the surrounding melt textured YBCO stator and adequate designs are the key features for increasing the overall bearing stiffness. The gap distance between rotor and stator determines the specific forces and has a strong impact on the PM rotor design. We report on the designing, building and measuring of a 200 mm prototype 100 kg HTS bearing with an encapsulated and thermally insulated melt textured YBCO ring stator. The encapsulation requires a magnetically large-gap (4-5 mm) operation but reduces the cryogenic effort substantially. The bearing requires 3 l of LN2 for cooling down, and about 0.2 l LN2 h-1 under operation. This is a dramatic improvement of the efficiency and in the practical usage of HTS magnetic bearings.

  18. Feasibility study of contaminant detection for food with ULF-NMR/MRI system using HTS-SQUID

    NASA Astrophysics Data System (ADS)

    Hatsukade, Yoshimi; Tsunaki, Shingo; Yamamoto, Masaaki; Abe, Takayuki; Hatta, Junichi; Tanaka, Saburo

    2013-11-01

    We have developed an ultra-low frequency (ULF) nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) system utilizing an HTS-SQUID for an application of contaminant detection in food and drink. In the system, a permanent magnet of 1.1 T was used to pre-polarize protons in a water sample. We measured NMR signals from water samples with or without various contaminants, such as stainless steel (SUS304), aluminum, and glass balls using the system. In the case that the contaminant was the SUS304 ball, the NMR signal intensity was reduced compared to that from the sample without the contaminant due to the remnant field of the contaminant. One-dimensional (1D) MRIs of the samples were also acquired to detect non-magnetic contaminants. In the 1D MRIs, changes of the MRI spectra were detected, corresponding to positions of the contaminants. These results show that the feasibility of the system to detect various contaminants in foods.

  19. Properties of II-VI Semiconductors: Bulk Crystals, Epitaxial Films, Quantum Well Structures, and Dilute Magnetic Systems. Materials Research Society Symposium Proceedings. Volume 161

    DTIC Science & Technology

    1990-11-21

    BULK CdTe P.M. AMIRTHARAJ AND N.K. DHAR U.S. Army Center for Night Vision and Electro-Optics Fort Belvoir, VA-22060 ABSTRACT The native defects...those that contain exposed surfaces. ACKNOWLEDGEMENT The authors wish to acknowledge Mr. Philip R. Boyd of the U.S. Army Center for Night Vision and...del IPN. Apdo. Postal 14-740, 07000 Mexico, D. F. +Departamento de Fisica del Instituto de Ciencias, Universidad Aut6noma de Puebla , Apdo. Postal J-48

  20. First order sigma-delta modulator in HTS bicrystal technology

    NASA Astrophysics Data System (ADS)

    Ruck, B.; Chong, Y.; Dittmann, R.; Siegel, M.

    1999-11-01

    We have designed, fabricated and successfully tested a first-order sigma-delta modulator using a High-Temperature Superconducting (HTS) multi-layer technology with bicrystal Josephson junctions. The circuit has been fabricated on an SrTiO 3 bicrystal substrate. The trilayer was fabricated by laser deposition and high-pressure sputtering. The bottom layer served as a superconducting groundplane. The Josephson junctions were formed at the bicrystal line in the upper layer. The integrator resistance has been made from a Pd/Au thin film. The circuit consists of a Single Flux Quantum (SFQ) pulse generator, a Josephson transmission line (JTL), a comparator, an integrator and an output stage. The correct operation of the modulator has been tested using dc and low frequency ac measurements. The linearity of the modulator was studied by measuring the harmonic distortions of a 19.5 kHz sine wave input signal. From the recorded spectrum, a minimum resolution of at least 6 bits can be estimated. This accuracy was limited by the noise of the preamplifier. The correct operation of the current feedback loop was demonstrated by cutting the feedback inductance.

  1. Large Coaxial Coldfinger Ptc for Process Liquefaction and Hts Applications

    NASA Astrophysics Data System (ADS)

    Spoor, P. S.; Corey, J. A.

    2010-04-01

    Large (>100 W cooling capacity at 80 K) `pulse-tube' coolers are ideal candidates for emerging applications such as HTS transmission lines, transformers, and motor windings, meso-scale oxygen liquefaction on-demand, cryopumping, and cryogen boiloff recovery. A number of successful large `in-line' pulse-tube coolers have been built, but these require embedded shell-and-tube process heat exchangers, hence transport of the process fluid/gas to and from the coldhead, and often a high degree of process fluid purity, to avoid clogging in the narrow inlets and outlets of these heat exchangers. It is far preferable in most circumstances to have a coldfinger design that presents a salient cold tip, with the coldhead at the end of a flexible transfer line, as is done with Gifford-McMahon or Joule-Thomson coolers. This paper presents some design details and data from the development of our first high-capacity coldfinger, as well as the results of its application to a 55 gallon/day oxygen liquefier for the Navy.

  2. No-insulation multi-width winding technique for high temperature superconducting magnet

    PubMed Central

    Hahn, Seungyong; Kim, Youngjae; Keun Park, Dong; Kim, Kwangmin; Voccio, John P.; Bascuñán, Juan; Iwasa, Yukikazu

    2013-01-01

    We present a No-Insulation (NI) Multi-Width (MW) winding technique for an HTS (high temperature superconductor) magnet consisting of double-pancake (DP) coils. The NI enables an HTS magnet self-protecting and the MW minimizes the detrimental anisotropy in current-carrying capacity of HTS tape by assigning tapes of multiple widths to DP coils within a stack, widest tape to the top and bottom sections and the narrowest in the midplane section. This paper presents fabrication and test results of an NI-MW HTS magnet and demonstrates the unique features of the NI-MW technique: self-protecting and enhanced field performance, unattainable with the conventional technique. PMID:24255549

  3. Test results from Siemens low-speed, high-torque HTS machine and description of further steps towards commercialisation of HTS machines

    NASA Astrophysics Data System (ADS)

    Nick, Wolfgang; Grundmann, Joern; Frauenhofer, Joachim

    2012-11-01

    With extensive testing of the 4 MW 120 rpm HTS machine connected to a standard Siemens converter this first development stage for a basically new technology is concluded. The most innovative part of the machine, the HTS excited rotor, outperformed our expectations and demonstrated our capability to design, develop and build successfully such a technically challenging component. This could only be achieved on the base of a thorough understanding of the innovative material and its behaviour including practical handling experience, the ability to simulate 3D electromagnetics including transients, and finally transfer of the scientists' knowledge to a qualified manufacturing process. Equally important are the improved capabilities of critical component suppliers, e.g. for superconducting tapes and compact cryo-refrigerators. However, the transition of a technology into highly reliable industrial products does require more than technical mastering of the machine. Based on outstanding technical test results as presented above, the next step in future can be addressed: product development. Some thoughts will be presented regarding the needs of application fields and market oriented development, as the market is not "waiting for HTS". If HTS technology is seen as one key technology for a sustainable, material saving and energy efficient future, it certainly needs more effort, even at the 100th anniversary of superconductivity.

  4. Vortex flux dynamics and harmonic ac magnetic response of Ba(Fe0.94Ni0.06)2As2 bulk superconductor

    SciTech Connect

    Nikolo, Martin; Zapf, Vivien S.; Singleton, John; Jiang, Jianyi; Weiss, Jeremy D.; Hellstrom, Eric E.

    2016-07-22

    Vortex dynamics and nonlinear ac response are studied in a Ba(Fe0.94Ni0.06)2As2(Tc= 18.5 K) bulk superconductor in magnetic fields up to 12 T via ac susceptibility measurements of the first ten harmonics. A comprehensive study of the ac magnetic susceptibility and its first ten harmonics finds shifts to higher temperatures with increasing ac measurement frequencies (10 to 10,000 Hz) for a wide range of ac (1, 5, and 10 Oe) and dc fields (0 to 12 T). The characteristic measurement time constant t1 is extracted from the exponential fit of the data and linked to vortex relaxation. The Anderson-Kim Arrhenius law is applied to determine flux activation energy Ea/k as a function dc magnetic field. The de-pinning, or irreversibility lines, were determined by a variety of methods and extensively mapped. The ac response shows surprisingly weak higher harmonic components, suggesting weak nonlinear behavior. Lastly, our data does not support the Fisher model; we do not see an abrupt vortex glass to vortex liquid transition and the resistivity does not drop to zero, although it appears to approach zero exponentially.

  5. Large magnetic entropy change and adiabatic temperature rise of a Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} bulk metallic glass

    SciTech Connect

    Xia, L.; Tang, M. B.; Chan, K. C.; Dong, Y. D.

    2014-06-14

    Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} bulk metallic glass (BMG) was synthesized by minor Ni substitution for Co in the Gd{sub 55}Al{sub 20}Co{sub 25} BMG in which excellent glass forming ability (GFA) and magneto-caloric effect were reported previously. The Gd{sub 55}Al{sub 20}Ni{sub 20}Co{sub 5} amorphous rod has a similar GFA to the Gd{sub 55}Al{sub 20}Co{sub 25} BMG but exhibits better magnetic properties. The peak value of magnetic entropy change (−ΔS{sub m}{sup peak}) of the Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} BMG is 9.8 Jkg{sup −1} K{sup −1}. The field dependence of −ΔS{sub m}{sup peak} follows a −ΔS{sub m}{sup peak}∝H{sup 0.85} relationship. The adiabatic temperature rise of the rod is 4.74 K under 5 T and is larger than of other BMGs previously reported. The improved magnetic properties were supposed to be induced by the enhanced interaction between 4f electron in the rare-earth and 3d electron in the transition metal elements by means of a minor Ni substitution for Co.

  6. A study on accumulation of magnetic drug in the capillary vessel of target organ using superconducting MDDS

    NASA Astrophysics Data System (ADS)

    Mishima, F.; Akiyama, Y.; Nishijima, S.

    2010-11-01

    Magnetic Drug Delivery System (MDDS) is one of the drug therapy technologies to accumulate the drug at the targeted part efficiently. The ferromagnetic particle is attached to the medicine, antibody, hormones and so on. The magnetic seeded drug is injected into the blood vessel, and then is accumulated in capillary vessel of target organ by magnetic field generated by the superconducting magnet placed outside of the body. The technology is great prospective for not only human medical treatment but also stockbreeding field. Treatment for cow ovarian diseases (decay of ovarian hormone secretion) requires an improvement in suppression of the drug diffusion to non-diseased part by the blood flow. In order to solve the problem, the applicability of the MDDS was examined. The behavior of the magnetic drug under the magnetic field generated by high temperature superconducting (HTS) bulk magnet were studied by the model experiment and computer simulation with the capillary model of the corpus luteum. As a result, it was shown that MDDS is able to apply to the capillaries of the corpus luteum (yellow body).

  7. Rotary bulk solids divider

    DOEpatents

    Maronde, Carl P.; Killmeyer, Jr., Richard P.

    1992-01-01

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  8. ROTARY BULK SOLIDS DIVIDER

    DOEpatents

    Maronde, Carl P.; Killmeyer JR., Richard P.

    1992-03-03

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  9. (Ba1-xKx)(Cu2-xMnx)Se2: A copper-based bulk form diluted magnetic semiconductor with orthorhombic BaCu2S2-type structure

    NASA Astrophysics Data System (ADS)

    Guo, Shengli; Man, Huiyuan; Gong, Xin; Ding, Cui; Zhao, Yao; Chen, Bin; Guo, Yang; Wang, Hangdong; Ning, F. L.

    2016-02-01

    A new copper-based bulk form diluted magnetic semiconductor (DMS) (Ba1-xKx)(Cu2-xMnx)Se2 (x=0.075, 0.10, 0.125, and 0.15) with TC ∼18 K has been synthesized. K substitution for Ba introduces hole-type carriers, while Mn substitution for Cu provides local spins. Different from previous reported DMSs, this material crystallizes into orthorhombic BaCu2S2-type crystal structure. No ferromagnetism is observed when only doping Mn, and clear ferromagnetic transition and hysteresis loop have been observed as K and Mn are codoped into the parent compound BaCu2Se2.

  10. Performance test of a 1 MW class HTS synchronous motor for industrial application

    NASA Astrophysics Data System (ADS)

    Kwon, Y. K.; Kim, H. M.; Baik, S. K.; Lee, E. Y.; Lee, J. D.; Kim, Y. C.; Lee, S. H.; Hong, J. P.; Jo, Y. S.; Ryu, K. S.

    2008-09-01

    This paper deals with development activities of high temperature superconducting (HTS) synchronous motor at DOOSAN heavy industry and Korea Electrotechnology Research Institute (KERI) in Korea, and is sponsored by DAPAS program which is supported by Korean government. The final aim of the project is realization of HTS motor in the field of industry such as large driving pumps, fans and compressors for utility and industrial environments. At present time, 1 MW HTS motor is developed for the purpose to fully represent the design and manufacturing issues for the larger capacity machine. The number of pole and rotating speed of machine are 2 pole and 3600 rpm. The HTS field coil of the developed motor is cooled by way of neon thermosyphon mechanism and the stator coil is cooled by water through hollow copper conductor. This paper describes status of 1 MW HTS motor development, such as design, fabrication and performance test results, which was conducted at steady state in generator mode and motor mode.

  11. Progress in American Superconductor's HTS wire and optimization for fault current limiting systems

    NASA Astrophysics Data System (ADS)

    Malozemoff, Alexis P.

    2016-11-01

    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 decreasing its critical J. This conflicts with other desirable wire characteristics. Optimization of these conflicting requirements is discussed.

  12. AC HTS Transmission Cable for Integration into the Future EHV Grid of the Netherlands

    NASA Astrophysics Data System (ADS)

    Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Aanhaanen, G.; Melnik, I.; Geschiere, A.

    Due to increasing power demand, the electricity grid of the Netherlands is changing. The future grid must be capable to transmit all the connected power. Power generation will be more decentralized like for instance wind parks connected to the grid. Furthermore, future large scale production units are expected to be installed near coastal regions. This creates some potential grid issues, such as: large power amounts to be transmitted to consumers from west to east and grid stability. High temperature superconductors (HTS) can help solving these grid problems. Advantages to integrate HTS components at Extra High Voltage (EHV) and High Voltage (HV) levels are numerous: more power with less losses and less emissions, intrinsic fault current limiting capability, better control of power flow, reduced footprint, etc. Today's main obstacle is the relatively high price of HTS. Nevertheless, as the price goes down, initial market penetration for several HTS components is expected by year 2015 (e.g.: cables, fault current limiters). In this paper we present a design of intrinsically compensated EHV HTS cable for future grid integration. Discussed are the parameters of such cable providing an optimal power transmission in the future network.

  13. Race-track coils for a 3 MW HTS ship motor

    NASA Astrophysics Data System (ADS)

    Ueno, E.; Kato, T.; Hayashi, K.

    2014-09-01

    Since the discovery of high-temperature superconductivity (HTS), Sumitomo Electric has been developing silver-sheathed Bi2223 superconducting wire and products. Ship propulsion motors are one of the most promising applications of HTS. Sumitomo Electric Industries, Ltd. (SEI) has recently manufactured 24 large racetrack coils, using 70 km long DI-BSCCO wires, for use in a 3 MW HTS motor developed by Kawasaki Heavy Industries, Ltd. (KHI). The 3 MW HTS motor, using our newly developed racetrack coils, has successfully passed the loading test. It is particularly important that the HTS field coils used in ship propulsion motors can withstand the expansive forces repeatedly applied to them. As racetrack type coils have straight sections, the support mechanism they require to withstand expansive forces is very different from that of circular coils. Therefore, we ran tests and obtained the basic data to evaluate the 20-year durability of racetrack coils against the repeatedly applied expansive forces expected in domestic ship propulsion motors.

  14. Use of in Vitro HTS-Derived Concentration-Response Data as ...

    EPA Pesticide Factsheets

    Background: Quantitative high-throughput screening (qHTS) assays are increasingly being employed to inform chemical hazard identification. Hundreds of chemicals have been tested in dozens of cell lines across extensive concentration ranges by the National Toxicology Program in collaboration with the NIH Chemical Genomics Center. Objectives: To test a hypothesis that dose-response data points of the qHTS assays can serve as biological descriptors of assayed chemicals and, when combined with conventional chemical descriptors, may improve the accuracy of Quantitative Structure-Activity Relationship (QSAR) models applied to prediction of in vivo toxicity endpoints. Methods and Results: The cell viability qHTS concentration-response data for 1,408 substances assayed in 13 cell lines were obtained from PubChem; for a subset of these compounds rodent acute toxicity LD50 data were also available. The classification k Nearest Neighbor and Random Forest QSAR methods were employed for modeling LD50 data using either chemical descriptors alone (conventional models) or in combination with biological descriptors derived from the concentration-response qHTS data (hybrid models). Critical to our approach was the use of a novel noise-filtering algorithm to treat qHTS data. We show that both the external classification accuracy and coverage (i.e., fraction of compounds in the external set that fall within the applicability domain) of the hybrid QSAR models was superior to convent

  15. The Mechanical Design Optimization of a High Field HTS Solenoid

    SciTech Connect

    Lalitha, SL; Gupta, RC

    2015-06-01

    This paper describes the conceptual design optimization of a large aperture, high field (24 T at 4 K) solenoid for a 1.7 MJ superconducting magnetic energy storage device. The magnet is designed to be built entirely of second generation (2G) high temperature superconductor tape with excellent electrical and mechanical properties at the cryogenic temperatures. The critical parameters that govern the magnet performance are examined in detail through a multiphysics approach using ANSYS software. The analysis results formed the basis for the performance specification as well as the construction of the magnet.

  16. Functional cell-based uHTS in chemical genomic drug discovery.

    PubMed

    Croston, Glenn E

    2002-03-01

    The availability of genomic information significantly increases the number of potential targets available for drug discovery, although the function of many targets and their relationship to disease is unknown. In a chemical genomic research approach, ultra-high throughput screening (uHTS) of genomic targets takes place early in the drug discovery process, before target validation. Target-selective modulators then provide drug leads and pharmacological research tools to validate target function. Effective implementation of a chemical genomic strategy requires assays that can perform uHTS for large numbers of genomic targets. Cell-based functional assays are capable of the uHTS throughput required for chemical genomic research, and their functional nature provides distinct advantages over ligand-binding assays in the identification of target-selective modulators.

  17. The Role of HTS in Drug Discovery at the University of Michigan

    PubMed Central

    Larsen, Martha J.; Larsen, Scott D.; Fribley, Andrew; Grembecka, Jolanta; Homan, Kristoff; Mapp, Anna; Haak, Andrew; Nikolovska-Coleska, Zaneta; Stuckey, Jeanne A.; Sun, Duxin

    2014-01-01

    High throughput screening (HTS) is an integral part of a highly collaborative approach to drug discovery at the University of Michigan. The HTS lab is one of four core centers that provide services to identify, produce, screen and follow-up on biomedical targets for faculty. Key features of this system are: protein cloning and purification, protein crystallography, small molecule and siRNA HTS, medicinal chemistry and pharmacokinetics. Therapeutic areas that have been targeted include anti-bacterial, metabolic, neurodegenerative, cardiovascular, anti-cancer and anti-viral. The centers work in a coordinated, interactive environment to affordably provide academic investigators with the technology, informatics and expertise necessary for successful drug discovery. This review provides an overview of these centers at the University of Michigan, along with case examples of successful collaborations with faculty. PMID:24409957

  18. Cancer and virus leads by HTS, chemical design and SEA data mining.

    PubMed

    Thepchatri, Pahk; Min, Jaeki; Ganesh, Thota; Du, Yuhong; Lewis, Iestyn; Kurtkaya, Serdar; Prussia, Andrew; Li, Lian; Sneed, Blossom; Plemper, Richard K; Fu, Haian; Liotta, Dennis C; Snyder, James P; Dingledine, Raymond; Sun, Aiming

    2009-01-01

    A variety of medicinal chemistry approaches can be used for the identification of hits, generation of leads and to accelerate the development of drug candidates. The Emory Chemical and Biology Discovery Center (ECBDC) has been an active participant in the NIH's high-throughput screening (HTS) endeavor to identify potent small molecule probes for poorly studied proteins. Several of Emory's projects relate to cancer or virus infection. We have chosen three successful examples including discovery of potent measles virus RNA-dependent RNA polymerase inhibitors, development of Heat Shock Protein 90 (Hsp90) blockers and identification of angiogenesis inhibitors using transgenic Zebrafish as a HTS model. In parallel with HTS, a unique component of the Emory virtual screening (VS) effort, namely, substructure enrichment analysis (SEA) program has been utilized in several cases.

  19. Cycle Design of Reverse Brayton Cryocooler for HTS Cable Cooling Using Exergy Analysis

    NASA Astrophysics Data System (ADS)

    Gupta, Sudeep Kumar; Ghosh, Parthasarathi

    2017-02-01

    The reliability and price of cryogenic refrigeration play an important role in the successful commercialization of High Temperature Superconducting (HTS) cables. For cooling HTS cable, sub-cooled liquid nitrogen (LN2) circulation system is used. One of the options to maintain LN2 in its sub-cooled state is by providing refrigeration with the help of Reverse Brayton Cryo-cooler (RBC). The refrigeration requirement is 10 kW for continuously sub-cooling LN2 from 72 K to 65 K for cooling 1 km length of HTS cable [1]. In this paper, a parametric evaluation of RBC for sub-cooling LN2 has been performed using helium as a process fluid. Exergy approach has been adopted for this analysis. A commercial process simulator, Aspen HYSYS® V8.6 has been used for this purpose. The critical components have been identified and their exergy destruction and exergy efficiency have been obtained for a given heat load condition.

  20. Reliability Test of a 1-kW Pulse Tube Cryocooler for Hts Cable Application

    NASA Astrophysics Data System (ADS)

    Chen, R.-L.; Henzler, G. W.; Royal, J. H.; Billingham, J. F.

    2010-04-01

    The recent progress of a large Stirling-type pulse tube cryocooler is reported based on 24/7 operation since August 2008 in a high temperature superconducting (HTS) cable application at American Electric Power's (AEP) Bixby Road substation in Columbus, OH. The 20-kW pressure wave generator (PWG) has been upgraded to a second generation design. The in-line configured pulse tube coldhead, rated at 1 kW at 77 K, was developed by Praxair. The objective of the continued testing at the HTS cable demonstration facility is to accumulate cryocooler operating hours and demonstrate system reliability. The cryocooler uses a parallel flow from the main vacuum subcooling refrigerator then both flows are supplied to the HTS cable inlet. The cryocooler operation has shown consistent results with satisfactory cooling performance. The field demonstrated thermodynamic efficiency is 15% of Carnot at 72 K.

  1. Cancer and Virus Leads by HTS, Chemical Design and SEA Data Mining

    PubMed Central

    Thepchatri, Pahk; Min, Jaeki; Ganesh, Thota; Du, Yuhong; Lewis, Iestyn; Kurtkaya, Serdar; Prussia, Andrew; Li, Lian; Plemper, Richard K.; Fu, Haian; Liotta, Dennis C.; Snyder, James P.; Dingledine, Raymond; Sun, Aiming

    2015-01-01

    A variety of medicinal chemistry approaches can be used for the identification of hits, generation of leads and to accelerate the development of drug candidates. The Emory Chemical and Biology Discovery Center (ECBDC) has been an active participant in the NIH’s high-throughput screening (HTS) endeavor to identify potent small molecule probes for poorly studied proteins. Several of Emory’s projects relate to cancer or virus infection. We have chosen three successful examples including discovery of potent measles virus RNA-dependent RNA polymerase inhibitors, development of Heat Shock Protein 90 (Hsp90) blockers and identification of angiogenesis inhibitors using transgenic Zebrafish as a HTS model. In parallel with HTS, a unique component of the Emory virtual screening (VS) effort, namely, substructure enrichment analysis (SEA) program has been utilized in several cases. PMID:19807668

  2. Ion composition of the bulk ring current during a magnetic storm - Observations with the CHEM-instrument on AMPTE-CCE

    NASA Technical Reports Server (NTRS)

    Stuedemann, W.; Wilken, B.; Kremser, G.; Gloeckler, G.; Ipavich, F. M.

    1986-01-01

    Ion composition measurements in the entire energy range of the ring current population, obtained with the Charge-, Energy-, Mass-spectrometer instrument on the Charge Composition Explorer in September 1984, are reported. From the energy spectra obtained for all major constituents during the main phase of a magnetic storm, the number densities, energy densities, and mean energies are calculated and displayed as radial profiles. The mean energies of He(2+) are found to be about twice that of H(+) and He(+) throughout this storm, and the time profiles for the mean energies of all major ions are seen to bunch together (when normalizing mean energies by the ionic charge), with the largest variations of the energy densities and mean energies occurring for O(+) ions.

  3. Performance of the BG1Luc ER TA method in a qHTS format.

    PubMed

    Ceger, Patricia; Allen, David; Huang, Ruili; Xia, Menghang; Casey, Warren

    2015-01-01

    In 2012, the BG1Luc4E2 estrogen receptor (ER) transactivation (TA) method (BG1Luc ER TA) was accepted by U.S. regulatory agencies and the Organisation for Economic Co-operation and Development to detect substances with ER agonist activity. The method is now part of the Tier 1 testing battery in the Environmental Protection Agency's Endocrine Disruptor Screening Program. The BG1Luc ER TA method uses the BG1 ovarian cell line that endogenously expresses full-length ER (α and β) and is stably transfected with a plasmid containing four estrogen responsive elements upstream of a luciferase reporter gene. To allow increased throughput and testing efficiency, the BG1Luc ER TA ("BG1 manual") method was adapted for quantitative high-throughput screening (BG1 qHTS) in the U.S. Tox21 testing program. The BG1 qHTS test method was used to test approximately 10,000 chemicals three times each, and concentration-response data (n=15) were analyzed to evaluate test method performance. The balanced accuracy of the BG1 qHTS test method (97% [32/33]) was determined by comparing results to ER TA performance standards for the BG1 manual method. Concordance between the BG1 manual and qHTS methods was 92% (57/62) when calculated for a larger set of non-reference chemicals tested in both methods. These data demonstrate that the performance of the BG1 qHTS is similar to the currently accepted BG1 manual method, thereby establishing the utility of the BG1 qHTS method for identifying ER active environmental chemicals.

  4. The Development and Demonstration of a 360m/10 kA HTS DC Power Cable

    NASA Astrophysics Data System (ADS)

    Xiao, Liye

    With the quick development of renewable energy, it is expected that the electric power from renewable energy would be the dominant one for the future power grid. Due to the specialty of the renewable energy, the HVDC power transmission would be very useful for the transmission of electric power from renewable energy. DC power cable made of High Tc Superconductor (HTS) would be a possible alternative for the construction of HVDC power transmission system. In this chapter, we report the development and demonstration of a 360 m/10 kA HTS DC power cable and the test results.

  5. A Study on the Body Insulators for the Bushing for HTS Devices at Cryogenic Temperature

    NASA Astrophysics Data System (ADS)

    Kim, W. J.; Shin, H. S.; Kim, S. H.

    A bushing for high temperature superconducting devices (HTS bushing) is important because of applying high voltage to the cable or the winding of the transformer. It is cooled with liquid nitrogen (LN2) and is insulated with various insulators. For the development of the HTS bushing, it is necessary to know the fundamental characteristics of various insulators at cryogenic temperature. The electrical characteristics of the breakdown were studied under AC and impulse voltages. Also, the mechanical characteristics such as tensile strength in air and LN2 were studied. It was confirmed that GFRP is excellent not only electrical characteristics but also mechanical characteristics in LN2.

  6. Progress in research, development, and pre-commercial deployment of second generation HTS wires in the USA

    NASA Astrophysics Data System (ADS)

    Hawsey, Robert A.; Christen, David K.

    2006-10-01

    US efforts to develop and deploy "second generation" (2G) high-temperature superconducting (HTS) wires that use the compound Y1Ba2Cu3Ox (YBCO) or other rare-earth (RE) superconducting materials are described. Wires have been demonstrated in 20 to >200-m lengths with the YBCO deposited using vapor deposition or wet chemical processes in ultra-thin layers onto textured, buffered metallic templates, which forces the grains of the RE-BCO into near perfect alignment. Critical currents for these pre-commercial wires are now within striking distance of those achieved for commercial BSSCO wires. One expected advantage of 2G wire is a 5-fold decrease in the price of wire compared with first generation wires. Another advantage of 2G wire is the intrinsic behavior of YBCO in the presence of a strong magnetic field. Enhancements in flux pinning of at least a factor of two have been demonstrated for MOCVD and MOD deposited YBCO films. US progress towards meeting the challenging goals for the year 2006, including current exceeding 300 A/cm width (77 K, self-field) in 100-m lengths and engineering current density exceeding 10,000 A/cm2 (65 K, 3-T) is reported. In addition, initial efforts toward engineering the conductor for the mechanical and electrical properties needed for strong magnetic field applications are described.

  7. Comparative study of ¹³C composition in ethanol and bulk dry wine using isotope ratio monitoring by mass spectrometry and by nuclear magnetic resonance as an indicator of vine water status.

    PubMed

    Guyon, Francois; van Leeuwen, Cornelis; Gaillard, Laetitia; Grand, Mathilde; Akoka, Serge; Remaud, Gérald S; Sabathié, Nathalie; Salagoïty, Marie-Hélène

    2015-12-01

    The potential of wine (13)C isotope composition (δ(13)C) is presented to assess vine water status during grape ripening. Measurements of δ(13)C have been performed on a set of 32 authentic wines and their ethanol recovered after distillation. The data, obtained by isotope ratio monitoring by mass spectrometry coupled to an elemental analyser (irm-EA/MS), show a high correlation between δ(13)C of the bulk wine and its ethanol, indicating that the distillation step is not necessary when the wine has not been submitted to any oenological treatment. Therefore, the ethanol/wine δ(13)C correlation can be used as an indicator of possible enrichment of the grape must or the wine with exogenous organic compounds. Wine ethanol δ(13)C is correlated to predawn leaf water potential (R(2) = 0.69), indicating that this parameter can be used as an indicator of vine water status. Position-specific (13)C analysis (PSIA) of ethanol extracted from wine, performed by isotope ratio monitoring by nuclear magnetic resonance (irm-(13)C NMR), confirmed the non-homogenous repartition of (13)C on ethanol skeleton. It is the δ(13)C of the methylene group of ethanol, compared to the methyl moiety, which is the most correlated to predawn leaf water potential, indicating that a phase of photorespiration of the vine during water stress period is most probably occurring due to stomata closure. However, position-specific (13)C analysis by irm-(13)C NMR does not offer a greater precision in the assessment of vine water status compared to direct measurement of δ(13)C on bulk wine by irm-EA/MS.

  8. Long-term operating characteristics of Japan's first in-grid HTS power cable

    NASA Astrophysics Data System (ADS)

    Nakano, Tetsutaro; Maruyama, Osamu; Honjo, Shoichi; Watanabe, Michihiko; Masuda, Takato; Hirose, Masayuki; Shimoda, Masahiro; Nakamura, Naoko; Yaguchi, Hiroharu; Machida, Akito

    2015-11-01

    Tokyo Electric Power Company, Sumitomo Electric Industries, Ltd and Mayekawa Mfg. Co., Ltd have jointly conducted the first in-grid demonstration test of a high-temperature superconducting (HTS) cable in Japan, from FY2007 to FY2013. The objective of this project is to evaluate the reliability, stability and other characteristics of the system. The cable structure used in this project is the type of three-in-one cable. As a coolant, sub-cooled liquid nitrogen flows through the gap between the corrugated cryostat and the three cable cores. This structure can realize compactness and reduce heat invasion compared with three single-core HTS cables housed in separate cryostats. The cooling system consists of six refrigerators, two circulation pumps and a reservoir tank. Each refrigerator has a cooling power of 1.0 kW at 77 K, 0.8 kW at 67 K. The number of operating refrigerators is controlled so that the coolant temperature at the cable inlet is kept to preset value. The HTS cable was connected to the live electricity grid from October 29, 2012 to December 25, 2013. In-grid operation continued for more than one year without any accidental interruption of operation or other operating issues. During this time, we studied the operating performance of the HTS cable in dependence on the sub-cooled LN2 temperature.

  9. Pathway Profiling and Tissue Modeling Using ToxCast HTS Data

    EPA Science Inventory

    High-throughput screening (HTS) and high-content screening (HCS) assays are providing data-rich studies to probe and profile the direct cellular effects of thousands of chemical compounds in commerce or potentially entering the environment. In vitro profiling may compare unknown ...

  10. Partial Discharge Characteristics in Composite Insulation Systems with PPLP for HTS Cable

    NASA Astrophysics Data System (ADS)

    Kikuchi, Y.; Yamashita, K.; Kumada, A.; Hidaka, K.; Tatamidani, K.; Masuda, T.

    2014-05-01

    The electrical insulation system of high-temperature superconducting (HTS) cable consists of liquid nitrogen (N2(l)) and polypropylene laminated paper (PPLP). Partial discharge (PD) may occur in butt gaps of the insulation layers and its characteristics imply the insulation performance of HTS cables. N2(l) cooling system is installed in the power system and N2(l) will flow through the cables during the system operation. Filling the HTS cable with N2(l) in order to perform pre-shipment inspection is time-consuming and costly for cable manufacturers. Therefore, they are trying to find a cost effective method for pre-shipment inspections. One alternative is to use high pressure gaseous nitrogen (N2(g)) instead of N2(l). This article investigates PD characteristics such as PD inception electric field (PDIE) and PD extinction electric field (PDEE) in butt gaps of HTS cables in 0.1 to 0.3 MPa and 0.1 MPa to 1.0 MPa N2(g) environments. For assessing the surface/volume effects, PD characteristics are measured with changing the size of butt gaps. It turns out that PDIE and PDEE in N2(g) are linearly correlated with those in N2(l) at any gas pressure in our testing, and PDIE in 1.0 MPa N2(g) is almost 30% of that in 0.2 MPa It suggests that PD characteristics in N2(l) can be extrapolated from those in N2(g).

  11. Basic concepts, status, opportunities, and challenges of electrical machines utilizing high-temperature superconducting (HTS) windings

    NASA Astrophysics Data System (ADS)

    Frauenhofer, J.; Grundmann, J.; Klaus, G.; Nick, W.

    2008-02-01

    An overview of the different approaches towards achieving a marketable application of a superconducting electrical machine, either as synchronous motor or generator, will be given. This field ranges from relatively small industrial drives to utility generators with large power ratings, from the low speed and high torque of wind power generators and ship propulsion motors, to high speed generators attached to turbines. Essentially HTS machine technology offers several advantages such as compactness (weight and volume reduction), increased efficiency, and other operational benefits. The machine features have to be optimized with regard to the specific application, and different concepts were developed by internationally competing teams, with Siemens being one of them. The achieved status in these fields will be summarized, pointing to the specific technical challenges to overcome. For this purpose we have not only to consider the technology of manufacturing the HTS rotor winding itself, but also to check requirements and availability of supporting technologies. This ranges from new challenges posed to the non-superconducting ("conventional") components of such innovative HTS machines, manufacturing superconducting material in the coming transition from 1st to 2nd generation HTS tape, cryogenic technology including material behavior, to new and challenging tasks in simulating and predicting the performance of such machines by computational tools. The question of market opportunities for this technology obviously is a function of all these aspects; however, a strong tendency for the near future is seen in the area of high-torque ship propulsion.

  12. Operational experience in the use of 18 kA HTS current leads for Edipo

    NASA Astrophysics Data System (ADS)

    March, S.; Wesche, R.; Bruzzone, P.

    2014-05-01

    In spring 2013, the Edipo facility of CRPP was commissioned. The dipole is powered via two 18 kA HTS current leads, designed and manufactured at CRPP. As part of the Edipo commissioning framework, the operational parameters of the leads were implemented in the control system. The in-situ tests were found to be in good agreement with the tests performed without a background field in 2011. The leads consist of a conduction cooled HTS module, made of AgMgAu/Bi-2223 stacks, and a wire bundle heat exchanger. The heat exchanger is cooled by forced flow helium gas, the inlet temperature of which was measured to vary between 65 K and 85 K. During operation with field, the mass flow rate is a function of current (2.05 g/s per lead at full field, 12.35 T, 17.2 kA). Reduced cooling investigations showed that 0.31 g/s per lead is suitable for overnight standby and 0.2 g/s per lead for longer periods. For detection of and protection against quench in the HTS module, a threshold of 10 mV was found to be appropriate. The heat exchanger has a voltage protection threshold of 120 mV. The temperatures of the heat exchanger, the HTS, and the helium inlet temperature were monitored in order to provide a further layer of protection.

  13. Predictive Signatures of Developmental Toxicity Modeled with HTS Data from ToxCast™ Bioactivity Profiles

    EPA Science Inventory

    The EPA ToxCast™ research program uses a high-throughput screening (HTS) approach for predicting the toxicity of large numbers of chemicals. Phase-I contains 309 well-characterized chemicals which are mostly pesticides tested in over 600 assays of different molecular targets, cel...

  14. Nanomaterial (NM) bioactivity profiling by ToxCast high-throughput screening (HTS)

    EPA Science Inventory

    Rapidly increasing numbers of new NMs and their uses demand efficient tests of NM bioactivity for safety assessment. The EPA’s ToxCast program uses HTS assays to prioritize for targeted testing, identify biological pathways affected, and aid in linking NM properties and potential...

  15. Thermal Insulation Performance of Flexible Piping for Use in HTS Power Cables

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

    2001-01-01

    High-temperature superconducting (HTS) cables that typically operate at temperatures below 80 K are being developed for power transmission. The practical application of HTS power cables will require the use of flexible piping to contain the cable and the liquid nitrogen coolant. A study of thermal performance of multilayer insulation (MLI) was conducted in geometries representing both rigid and flexible piping. This experimental study performed at the Cryogenics Test Laboratory of NASA Kennedy Space Center provides a framework for the development of cost-effective, efficient thermal insulation systems that will support these long-distance flexible lines containing HTS power cables. The overall thermal performance of the insulation system for a rigid configuration and for a flexible configuration, simulating a flexible HTS power cable, was determined by the steady-state liquid nitrogen boiloff method under the full range of vacuum levels. Two different cylindrically rolled material systems were tested: a standard MLI and a layered composite insulation (LCI). Comparisons of ideal MLI, MLI on rigid piping, and MLI between flexible piping are presented.

  16. Assessment of High Temperature Superconducting (HTS) electric motors for rotorcraft propulsion

    NASA Technical Reports Server (NTRS)

    Doernbach, Jay

    1990-01-01

    The successful development of high temperature superconductors (HTS) could have a major impact on future aeronautical propulsion and aeronautical flight vehicle systems. Applications of high temperature superconductors have been envisioned for several classes of aeronautical systems, including subsonic and supersonic transports, hypersonic aircraft, V/STOL aircraft, rotorcraft and solar powered aircraft. The potential of HTS electric motors and generators for providing primary shaft power for rotorcraft propulsion is examined. Three different sized production helicopters were investigated; namely, the Bell Jet Ranger, the Sikorsky Black Hawk and the Sikorsky Super Stallion. These rotorcraft have nominal horsepower ratings of 500, 3600, and 13400 respectively. Preliminary results indicated that an all-electric HTS drive system produces an improvement in rotorcraft Takeoff Gross Weight (TOGW) for those rotorcraft with power ratings above 2000 horsepower. The predicted TOGW improvements are up to 9 percent for the medium-sized Sikorsky Black Hawk and up to 20 percent for the large-sized Sikorsky Super Stallion. The small-sized Bell Jet Ranger, however, experienced a penalty in TOGW with the all-electric HTS drive system.

  17. A miniaturized HTS microwave receiver front-end subsystem for radar and communication applications

    NASA Astrophysics Data System (ADS)

    Bian, Yongbo; Guo, Jin; Gao, Changzheng; Li, Chunguang; Li, Hong; Wang, Jia; Cui, Bin; He, Xiaofeng; Li, Chao; Li, Na; Li, Guoqiang; Zhang, Qiang; Zhang, Xueqiang; Meng, Jibao; He, Yusheng

    2010-08-01

    This paper presents a miniaturized high performance high temperature superconducting (HTS) microwave receiver front-end subsystem, which uses a mini stirling cryocooler to cool a high selective HTS filter and a low noise amplifier (LNA). The HTS filter was miniaturized by using specially designed compact resonators and fabricating with double-sided YBCO films on LAO substrate which has a relatively high permittivity. The LNA was specially designed to work at cryogenic temperature with noise figure of 0.27 dB at 71 K. The mini cryocooler, which is widely used in infrared detectors, has a smaller size (60 mm × 80 mm × 100 mm) and a lighter weight (340 g) than the stirling cryocoolers commonly used in other HTS filter subsystem. The whole front-end subsystem, including a HTS filter, a LNA, a cryocooler and the vacuum chamber, has a size of only φ120 mm × 175 mm and a weight of only 3.3 kg. The microwave devices inside the subsystem are working at 71.8 K with a consumed cooling power of 0.325 W. The center frequency of this subsystem is 925.2 MHz and the bandwidth is 2.7 MHz (which is a fractional bandwidth of 0.2%), with the gain of 19.75 dB at center frequency and the return loss better than -18.11 dB in the pass band. The stop band rejection is more than 60 dB and the skirt slope is exceeding 120 dB MHz -1. The noise figure of this subsystem is less than 0.8 dB. This front-end subsystem can be used in radars and communication systems conveniently due to it’s compact size and light weight.

  18. Large area bulk superconductors

    DOEpatents

    Miller, Dean J.; Field, Michael B.

    2002-01-01

    A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

  19. A Practical HTS SQUID Magnetometer System for NDI of Aircraft

    DTIC Science & Technology

    1994-01-10

    York, 1017 (1993). I Final Report Quantum Magnetics, Inc. 115 Contract No. F49620-93-C-0029I I 18. A. D. Hibbs, R. E. Sager, D. W. Cox, T. H. Aukerman ... Aukerman , and H. M. Schneider, "A SQUID Based AC Suscep-3tometer," to be published in Review of Scientific Instrunents. 38. Superconductivity News

  20. Experimental investigation on ejecting low-temperature cooling superconducting magnets

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Zhang, Qiang; Tong, Ming-wei; Hu, Peng; Wu, Shuang-ying; Cai, Qin; Qin, Zeng-hu

    2013-10-01

    With the development of the high-temperature superconducting (HTS) materials and refrigeration technologies, using ejecting refrigeration to cool the superconducting materials becomes the direction of HTS applications. In this paper, an experimental study has been carried out on the basis of the theory of analyzing the ejecting low-temperature cooling superconducting magnet. The relationship between area ratios and refrigeration performance at different system pressures was derived. In addition, the working fluid flow and suction chamber pressure of the ejector with different area ratios at various inlet pressures have been examined to obtain the performance of ejectors under different working conditions. The result shows that the temperature of liquid nitrogen can be reduced to 70 K by controlling the inlet water pressure when the pressurized water at 20 °C is used to eject the saturated liquid nitrogen, which can provide the stable operational conditions for the HTS magnets cooling.

  1. Magnetic levitation/suspension system by high-temperature superconducting materials

    SciTech Connect

    Chen, I.; Hsu, J.; Jamn, G.; Lin, C.E.; Wu, M.K.

    1997-04-01

    Recently, with the advance of materials processing techniques, such as top-seeding and melt-texturing (TSMT) method, very large single-grained Y-Ba-Cu-O (YBCO) samples up to several centimeters in diameter can be produced. Each sample is capable of levitating over kilograms of weight. A HTS magnetic levitation (MagLev) transportation prototype has been constructed at National Cheng-Kung University (NCKU) to validate the concept of HTS-MagLev system based on Meissner effect. This HTS-MagLev is an inherent stable levitation system, unlike traditional MagLev system that requires sensors and feedback circuits to dynamically adjust its unstable levitation position. In this report, the results of various magnetic levitation parameters, such as different permanent magnet configurations, relative levitation stability, levitation force, etc., as well as magnetic field intensity and distribution will be discussed. {copyright} {ital 1997 American Institute of Physics.}

  2. Al addition effect of bulk MgB 2 superconductor

    NASA Astrophysics Data System (ADS)

    Shinohara, K.; Ikeda, H.; Yoshizaki, R.

    2007-10-01

    The properties of transport and magnetization have been investigated for bulk MgB2Alx superconductor with Al addition (x = 0, 0.5, 1 wt%). MgB2 bulk samples sintered at different temperatures at 650-740 °C were prepared in the undoped state. The temperature and applied field dependencies of resistivity and magnetization were measured for the samples. The sample sintered at 690 °C exhibited the highest critical current density (Jc) and the lowest resistivity. This undoped sample was chosen as a criterion sample, and the effect of Al addition on the MgB2 bulk was studied from the transport and magnetization properties in a magnetic field. For MgB2Alx bulk samples sintered at 690 °C, the resistivity increased and Jc decreased as amount of Al was increased.

  3. Mechanical reinforcement for RACC cables in high magnetic background fields

    NASA Astrophysics Data System (ADS)

    Bayer, C. M.; Gade, P. V.; Barth, C.; Preuß, A.; Jung, A.; Weiß, K. P.

    2016-02-01

    Operable in liquid helium, liquid hydrogen or liquid nitrogen, high temperature superconductor (HTS) cables are investigated as future alternatives to low temperature superconductor (LTS) cables in magnet applications. Different high current HTS cable concepts have been developed and optimized in the last years—each coming with its own benefits and challenges. As the Roebel assembled coated conductor (RACC) is the only fully transposed HTS cable investigated so far, it is attractive for large scale magnet and accelerator magnet applications when field quality and alternating current (AC) losses are of highest importance. However, due to its filamentary character, the RACC is very sensitive to Lorentz forces. In order to increase the mechanical strength of the RACC, each of the HTS strands was covered by an additional copper tape. After investigating the maximum applicable transverse pressure on the strand composition, the cable was clamped into a stainless steel structure to reinforce it against Lorentz forces. A comprehensive test has been carried out in the FBI facility at 4.2 K in a magnetic field of up to 12 T. This publication discusses the maximum applicable pressure as well as the behaviour of the RACC cable as a function of an external magnetic field.

  4. Characteristics of an electromagnetic levitation system using a bulk superconductor

    SciTech Connect

    Senba, A.; Kitahara, H.; Ohsaki, H.; Masada, E.

    1996-09-01

    It is beneficial to apply a high-Tc bulk superconductor as a large flux source to an electromagnetic levitation system, which needs large amounts of levitation force. The authors made an attractive-type electromagnetic levitation system using a hybrid magnet that mainly consisted of bulk superconductor and control coils to confirm the principle of the levitation, and obtained characteristics of its system by both experiment and numerical analysis with magnetic circuit calculation. This is applicable to maglev transportation systems.

  5. Stability test of conduction-cooled LTS/HTS composite coil

    NASA Astrophysics Data System (ADS)

    Cui, Ying Min; Wang, Yin Shun; Lv, Gang; Pi, Wei

    2016-06-01

    A small LTS/HTS composite coil made of NbTi/Cu and YBCO, with an inner diameter of 80 mm, an outer diameter of 88mm, a height of 50 mm, and an inductance of 5.5 μH, was designed to test its heat disturbance performance in a GM cryocooler. For comparison, a conventional LTS coil of a similar size made of NbTi/Cu wire was also tested. Transport current was applied from 50 A to 700 A at 8 K and 8.5 K, respectively. The two coils’ heat disturbance, minimum quench energy and quench propagation velocity performance were investigated and simulated. The results indicate that the LTS/HTS composite coil shows better thermal stability and is more fit for operation in conductive cryocooler systems compared to LTS coils.

  6. Performance of HTS SQUID coupled to cooled-Cu/superconductor pickup coil

    NASA Astrophysics Data System (ADS)

    Enpuku, K.; Tsuji, Y.; Hirakawa, S.; Matsuo, M.; Yoshida, T.

    2010-11-01

    We studied the performance of a magnetometer composed of a high Tc SQUID and a large pickup coil. For the pickup coil, we consider the coil made of a cooled Cu wire or an HTS superconductor tape. A magnetometer was designed for geophysical measurement using transient electromagnetic method. The theoretical field noise of the magnetometer was 0.2-1 pT/Hz1/2 at f = 10 Hz, and 55 fT/Hz1/2 for f > 200 Hz when the pickup coil of 100 mm in diameter and of N = 50 turns was used. Preliminary experimental results using the pickup coil made of the HTS Bi-tape reasonably agreed with the theoretical prediction.

  7. Feasibility of a short-period superconducting undulator using 2G HTS tapes.

    SciTech Connect

    Kim, S. H.; Doose, C. L.; Jaski, M. S.; Kasa, M. T. )

    2011-06-01

    This paper presents a design concept of a planar-type superconducting undulator (SCU) using YBCO high-temperature superconductor (HTS) tapes. The SCU has a period length of 15 mm, and the tape conductor has dimensions of 4-mm width and 0.1-mm thickness. It has been shown that the conductor transition from one coil groove to the one in the next period is possible by making a semi-circular concave loop of the tape for continuous winding in the same direction. Non-uniform current distribution in the tape may cause field quality degradation. Assuming a uniform current density in the tape, the engineering critical-current density of the HTS in the coil for the design and the corresponding achievable on-axis peak field at 4.2 K were calculated.

  8. Observation of the thermosiphon effect in the circulation of liquid nitrogen in HTS cable cooling system

    NASA Astrophysics Data System (ADS)

    Ivanov, Yury; Watanabe, Hirofumi; Hamabe, Makoto; Kawahara, Toshio; Sun, Jian; Yamaguchi, Satarou

    It is traditionally considered that superconducting technology is just the way that will help to overcome the energy crisis and improve the environmental safety of the electricity production. However, real achievements in this field still insufficient to build commercial long power transmission lines. In particular, cooling systems constructed using expensive coolant circulation pumps have to be improved. Our previous calculations show that the use of a thermosiphon effect may reduce both the heat load and the required coolant circulation pump power and, ideally, would completely abandon the forced circulation. Direct experimental verification of this approach has been carried out at the new 200-meter HTS DC experimental facility of the Chubu University. The thermosiphon effect was clearly observed in satisfactory agreement with theory, although the change in elevation of the cryopipe was small. Our results will be used to design an effective HTS cable cooling system based on natural circulation of the coolant.

  9. Heat loss analysis-based design of a 12 MW wind power generator module having an HTS flux pump exciter

    NASA Astrophysics Data System (ADS)

    Sung, Hae-Jin; Go, Byeong-Soo; Jiang, Zhenan; Park, Minwon; Yu, In-Keun

    2016-11-01

    The development of an effective high-temperature superconducting (HTS) generator is currently a research focus; however, the reduction of heat loss of a large-scale HTS generator is a challenge. This study deals with a heat loss analysis-based design of a 12 MW wind power generator module having an HTS flux pump exciter. The generator module consists of an HTS rotor of the generator and an HTS flux pump exciter. The specifications of the module were described, and the detailed configuration of the module was illustrated. For the heat loss analysis of the module, the excitation loss of the flux pump exciter, eddy current loss of all of the structures in the module, radiation loss, and conduction loss of an HTS coil supporter were assessed using a 3D finite elements method program. In the case of the conduction loss, different types of the supporters were compared to find out the supporter of the lowest conduction loss in the module. The heat loss analysis results of the module were reflected in the design of the generator module and discussed in detail. The results will be applied to the design of large-scale superconducting generators for wind turbines including a cooling system.

  10. An overview of flywheel energy systems with HTS bearings

    NASA Astrophysics Data System (ADS)

    Wolsky, A. M.

    2002-05-01

    Passive magnetic bearings incorporating permanent magnets and ReBaCuO, together with carbon fibre, offer the possibility of increasing the stored, volumetric energy density of FES and unprecedentedly low idling loss of FES. Its stored energy need only satisfy customers' needs for the time it takes to bring on conventional 'back-up'. The FES itself must come up to power quickly enough to avoid any disruption in the customer's operation (e.g., continuous industrial processes involving fragile materials, for example paper forming). Such customers do not care about the price of electricity nearly as much as they care about not ruining their product, damaging their machines or having 'clean ups' that stop or slow output. Firms that engage in electronic commerce and/or telecommunications also value uninterruptible power. Another set of potential customers (construction, electric railroads) may wish to avoid fluctuations in their electrical supply or they may wish to avoid causing harm to others who may hold them liable for poor power quality. Finally, real time prices (e.g., every 15 s) and real time commands, disseminated via internet, and distributed storage might enable reduced system generation costs. Generators and FES makers would have to cooperate to make this feasible. Now, the central techno-economic challenge is to build a high-power, low-loss motor generator that reaches full power in a very short time.

  11. Prospects for Brushless ac Motors with HTS Rotors

    NASA Astrophysics Data System (ADS)

    McCulloch, M. D.; Jim, K.; Kawai, Y.; Dew-Hughes, D.; Morgan, C.; Goringe, M. J.; Grovenor, C. R. M.

    1997-03-01

    There is a superconducting equivalent for every type of brushless ac motor; permanent magnet, reluctance, hysteresis and induction (squirrel cage) motor. The particular advantage of superconducting versions of these machines is that they are expected to provide much higher power densities than their conventional equivalents. The behaviour of superconducting rotors fabricated in the form of (a) squirrell cages from silver coated with melt-processed Bi-2212, (b) tubes cast centifugally from Bi-2212, and (c) small cylinders of melt-processed and seeded YBCO has been studied in rotating magnetic fields provided by conventional motor coils. Measurements of static torque, and values of dynamic torque deduced from angular velocity and acceleration have been used to characterise the potential performance of these embryonic machines. Two broad types of behaviour have been observed. In the Bi-2212 rotors the torque decreases with increasing rotor speed; this behaviour is believed due to flux creep. By contrast the strong-pinning YBCO rotors maintain a constant torque up to synchronous speed. Mathematical modelling of flux penetration and distribution within the rotors is able to reproduce both types of the observed behaviour. Power densities some 5 to 10 times that of conventional machines are predicted to be achievable in optimised prototype machines.

  12. The method of measuring the temperature dependence of the critical current of the HTS-2

    NASA Astrophysics Data System (ADS)

    Yashkin, D. S.; Krasnoperov, E. P.; Brazhnik, P. A.; Kruglov, V. S.

    2016-09-01

    A new method of measurement of Ic(T) dependence for the HTS-2 tape is realized. In this method, the metal substrate of the tape is used as both a heater and a thermometer. Index n(T) was calculated from the measured current-voltage characteristics (CVC). For the tape manufactured by SuperPower Inc. the data of n-index temperature dependence in the range from 77 K up to 90 K are presented.

  13. MAGNETS

    DOEpatents

    Hofacker, H.B.

    1958-09-23

    This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.

  14. Experimental Study of Local Micro-forming for Bi-HTS

    SciTech Connect

    Zeng Pan; Lu Yongjin; Lei Liping; Qu Timing; Fang Gang

    2010-06-15

    The Bi-HTS (BSCCO high temperature superconductor) tape now has become the product in an industrial way, which has been available to apply in electric and electron fields. The main way to manufacture Bi-HTS tape is to use the technique of oxide powder in silver tube (OPIT), which involves the multi-step drawing and rolling with plastic deformation, which obviously belongs to a type of the micro-forming in macro-scale processing. There are two main characteristics founded: (a) contact and friction between silver and BSCCO surfaces, (b) interface between two materials. A series of micro-tensile experiments of silver foil with thicknesses of 0.03, 0.06 and 0.1 mm are designed to investigate the behaviors of silver with various scale of sizes. And the surface topography measurements have been carried out to analyze the changes in surface topography. Based upon experiments, some topics are researched which are referred to inhomogeneous, local effect, size effect, grain and micro-structure affecting, surface roughness, long-distance sausage phenomenon. Further the local breakdown of silver by Bi-HTS powder during process is analyzed through failure criterion. The results of this work will bring out an important exploration value to the theory and computation of micro-forming.

  15. Development of an HTS hydroelectric power generator for the hirschaid power station

    NASA Astrophysics Data System (ADS)

    Fair, Ruben; Lewis, Clive; Eugene, Joseph; Ingles, Martin

    2010-06-01

    This paper describes the development and manufacture of a 1.7MW, 5.25kV, 28pole, 214rpm hydroelectric power generator consisting of superconducting HTS field coils and a conventional stator. The generator is to be installed at a hydro power station in Hirschaid, Germany and is intended to be a technology demonstrator for the practical application of superconducting technology for sustainable and renewable power generation. The generator is intended to replace and uprate an existing conventional generator and will be connected directly to the German grid. The HTS field winding uses Bi-2223 tape conductor cooled to about 30K using high pressure helium gas which is transferred from static cryocoolers to the rotor via a bespoke rotating coupling. The coils are insulated with multi-layer insulation and positioned over laminated iron rotor poles which are at room temperature. The rotor is enclosed within a vacuum chamber and the complete assembly rotates at 214rpm. The challenges have been significant but have allowed Converteam to develop key technology building blocks which can be applied to future HTS related projects. The design challenges, electromagnetic, mechanical and thermal tests and results are presented and discussed together with applied solutions.

  16. Power electronics performance in cryogenic environment: evaluation for use in HTS power devices

    NASA Astrophysics Data System (ADS)

    Pereira, P.; Valtchev, S.; Pina, J.; Gonçalves, A.; Ventim Neves, M.; Rodrigues, A. L.

    2008-02-01

    Power electronics (PE) plays a major role in electrical devices and systems, namely in electromechanical drives, in motor and generator controllers, and in power grids, including high-voltage DC (HVDC) power transmission. PE is also used in devices for the protection against grid disturbances, like voltage sags or power breakdowns. To cope with these disturbances, back-up energy storage devices are used, like uninterruptible power supplies (UPS) and flywheels. Some of these devices may use superconductivity. Commercial PE semiconductor devices (power diodes, power MOSFETs, IGBTs, power Darlington transistors and others) are rarely (or never) experimented for cryogenic temperatures, even when designed for military applications. This means that its integration with HTS power devices is usually done in the hot environment, raising several implementation restrictions. These reasons led to the natural desire of characterising PE under extreme conditions, e. g. at liquid nitrogen temperatures, for use in HTS devices. Some researchers expect that cryogenic temperatures may increase power electronics' performance when compared with room-temperature operation, namely reducing conduction losses and switching time. Also the overall system efficiency may increase due to improved properties of semiconductor materials at low temperatures, reduced losses, and removal of dissipation elements. In this work, steady state operation of commercial PE semiconductors and devices were investigated at liquid nitrogen and room temperatures. Performances in cryogenic and room temperatures are compared. Results help to decide which environment is to be used for different power HTS applications.

  17. Design and development of 500 m long HTS cable system in the KEPCO power grid, Korea

    NASA Astrophysics Data System (ADS)

    Sohn, S. H.; Lim, J. H.; Yang, B. M.; Lee, S. K.; Jang, H. M.; Kim, Y. H.; Yang, H. S.; Kim, D. L.; Kim, H. R.; Yim, S. W.; Won, Y. J.; Hwang, S. D.

    2010-11-01

    In Korea, two long-term field demonstrations for high temperature superconducting (HTS) cable have been carried out for several years; Korea Electric Power Corporation (KEPCO) and LS Cable Ltd. (LSC) independently. Encouraged at the result of the projects performed in parallel, a new project targeting the real grid operation was launched in the fourth quarter of 2008 with the Korean government's financial support. KEPCO and LSC are jointly collaborating in the selection of substation, determination of cable specification, design of cryogenic system, and the scheme of protection coordination. A three phase 500 m long HTS cable at a distribution level voltage of 22.9 kV is to be built at 154/22.9 kV Icheon substation located in near Seoul. A hybrid cryogenic system reflecting the contingency plan is being designed including cryocoolers. The HTS cable system will be installed in the second quarter of 2010, being commissioned by the fall of 2010. This paper describes the objectives of the project and design issues of the cable and cryogenic system in detail.

  18. Results of KEPCO HTS cable system tests and design of hybrid cryogenic system

    NASA Astrophysics Data System (ADS)

    Lim, J. H.; Sohn, S. H.; Yang, H. S.; Hwang, S. D.; Kim, D. L.; Ryoo, H. S.; Choi, H. O.

    2010-11-01

    In order to investigate the compatibility as a power utility facility, Korea Electric Power Corporation (KEPCO) had installed a 22.9 kV, 1250 A, 100 m long high temperature superconducting (HTS) power cable system. Using the HTS cable, various tests have been performed to investigate electrical and thermo-mechanical properties. Since 2005, a series of thermal cycle tests between liquid nitrogen (LN2) and ambient temperatures have been conducted using a vacuum-pump driven open-loop cryogenic system with a capacity of 3 kW. In the tests, although the open-loop cryogenic system was reliable to operate the HTS cable system, it was not effective in economic view point because LN2 consumption was larger than expected. In order to secure against unexpected emergencies and solve the problem of LN2 consumption, a hybrid cryogenic system was designed and installed. A stirling cryocooler was employed and combined with the open-loop cryogenic system. Considering the average heat load at rated condition, the cooling capacity of the cryocooler was determined to 4 kW at 77 K. In this paper, results of performance tests and the design of the hybrid cooling system are presented.

  19. [Treating anisometric amblyopia with HTS Amblyopia iNet Software--preliminary results].

    PubMed

    Avram, Elena; Stănilă, Adriana

    2013-01-01

    Amblyopia or "lazy eye" represents a disorder of the visual system characterized by poor vision in an eye that is otherwise physically normal. Anisometropia, the condition in which the two eyes have an unequal refractive error, is considered the second most common cause of amblyopia. The purpose of this study is to determine the efficiency of HTS Amblyopia iNet Software by studying the progress of visual acuity, contrast sensitivity and stereopsis vision in anisometropic amblyopic children. 5 patients (age: 5-13 years), treated with HTS Amblyopia iNet Software at OftaTotal Clinic from Sibiu, between 2010-2013, participated in this clinical trial. Initially, visual acuity ranged from 0.25 to 0.8, contrast sensitivity from 1.35 to 1.65 Log. Unit. and 1 patient presented stereoscopic vision. After treatment, visual acuity ranged from 0.8 to 1, contrast sensitivity from 1.35 to 1.95 Log. Unit., also all patients presented stereoscopic vision. HTS Amblyopia iNet Software represents an effective modern approach in the treatment of anisometropic amblyopia.

  20. ALS superbend magnet system

    SciTech Connect

    Zbasnik, J.; Wang, S.T.; Chen, J.Y.; DeVries, G.J.; DeMarco, R.; Fahmie, M.; Geyer, A.; Green, M.A.; Harkins, J.; Henderson, T.; Hinkson, J.; Hoyer, E.H.; Krupnick, J.; Marks, S.; Ottens, F.; Paterson, J.A.; Pipersky, P.; Portmann, G.; Robin, D.A.; Schlueter, R.D.; Steier, C.; Taylor, C.E.; Wahrer, R.

    2000-09-15

    The Lawrence Berkeley National Laboratory is preparing to upgrade the Advanced Light Source (ALS) with three superconducting dipoles (Superbends). In this paper we present the final magnet system design which incorporates R&D test results and addresses the ALS operational concerns of alignment, availability, and economy. The design incorporates conduction-cooled Nb-Ti windings and HTS current leads, epoxy-glass suspension straps, and a Gifford-McMahon cryocooler to supply steady state refrigeration. We also present the current status of fabrication and testing.

  1. ARQiv-HTS, a versatile whole-organism screening platform enabling in vivo drug discovery at high-throughput rates.

    PubMed

    White, David T; Eroglu, Arife Unal; Wang, Guohua; Zhang, Liyun; Sengupta, Sumitra; Ding, Ding; Rajpurohit, Surendra K; Walker, Steven L; Ji, Hongkai; Qian, Jiang; Mumm, Jeff S

    2016-12-01

    The zebrafish has emerged as an important model for whole-organism small-molecule screening. However, most zebrafish-based chemical screens have achieved only mid-throughput rates. Here we describe a versatile whole-organism drug discovery platform that can achieve true high-throughput screening (HTS) capacities. This system combines our automated reporter quantification in vivo (ARQiv) system with customized robotics, and is termed 'ARQiv-HTS'. We detail the process of establishing and implementing ARQiv-HTS: (i) assay design and optimization, (ii) calculation of sample size and hit criteria, (iii) large-scale egg production, (iv) automated compound titration, (v) dispensing of embryos into microtiter plates, and (vi) reporter quantification. We also outline what we see as best practice strategies for leveraging the power of ARQiv-HTS for zebrafish-based drug discovery, and address technical challenges of applying zebrafish to large-scale chemical screens. Finally, we provide a detailed protocol for a recently completed inaugural ARQiv-HTS effort, which involved the identification of compounds that elevate insulin reporter activity. Compounds that increased the number of insulin-producing pancreatic beta cells represent potential new therapeutics for diabetic patients. For this effort, individual screening sessions took 1 week to conclude, and sessions were performed iteratively approximately every other day to increase throughput. At the conclusion of the screen, more than a half million drug-treated larvae had been evaluated. Beyond this initial example, however, the ARQiv-HTS platform is adaptable to almost any reporter-based assay designed to evaluate the effects of chemical compounds in living small-animal models. ARQiv-HTS thus enables large-scale whole-organism drug discovery for a variety of model species and from numerous disease-oriented perspectives.

  2. The Use of Small Coolers in a Magnetic Field

    SciTech Connect

    Green, Michael A.; Witte, Holger

    2007-07-25

    Small 4 K coolers are used to cool superconducting magnets.These coolers are usually used with high temperature suerconductor (HTS)leads. In most cases, magnet is shielded with iron or active shieldcoils. Thus the field at the cooler is low. There are instances when thecooler must be in a magnetic field. Gifford McMahon (GM) coolers or pulsetube coolers are commercially available to cool the magnets. This paperwill discuss how the two types of coolers are affected by the straymagnetic field. Strategies for using coolers on magnets that generatestray magnetic fields are discussed.

  3. High Radiation Environment Nuclear Fragment Separator Magnet

    SciTech Connect

    Kahn, Stephen; Gupta, Ramesh

    2016-01-31

    Superconducting coils wound with HTS conductor can be used in magnets located in a high radiation environment. NbTi and Nb3Sn superconductors must operate at 4.5 K or below where removal of heat is less efficient. The HTS conductor can carry significant current at higher temperatures where the Carnot efficiency is significantly more favorable and where the coolant heat capacity is much larger. Using the HTS conductor the magnet can be operated at 40 K. This project examines the use of HTS conductor for the Michigan State University Facility For Rare Isotope Beams (FRIB) fragment separator dipole magnet which bends the beam by 30° and is located in a high radiation region that will not be easily accessible. Two of these magnets are needed to select the chosen isotope. There are a number of technical challenges to be addressed in the design of this magnet. The separator dipole is 2 m long and subtends a large angle. The magnet should keep a constant transverse field profile along its beam reference path. Winding coils with a curved inner segment is difficult as the conductor will tend to unwind during the process. In the Phase I project two approaches to winding the conductor were examined. The first was to wind the coils with curved sections on the inner and outer segments with the inner segment wound with negative curvature. The alternate approach was to use a straight segment on the inner segment to avoid negative curvature. In Phase I coils with a limited number of turns were successfully wound and tested at 77 K for both coil configurations. The Phase II program concentrated on the design, coil winding procedures, structural analysis, prototyping and testing of an HTS curved dipole coil at 40 K with a heat load representative of the radiation environment. One of the key criteria of the design of this magnet is to avoid the use of organic materials that would degrade rapidly in radiation. The Lorentz forces expected from the coils interacting with the

  4. Application of high temperature superconductors to high-gradient magnetic separation

    SciTech Connect

    Daugherty, M.A.; Prenger, F.C.; Hill, D.D.; Daney, D.E.; Worl, L.W.; Schake, A.R.; Padilla, D.D.

    1994-06-01

    High Gradient Magnetic Separation (HGMS) is a powerful technique which can be used to separate widely dispersed contaminants from a host material, This technology can separate magnetic solids from other solids, liquids or gases. As the name implies HGMS uses large magnetic field gradients to separate ferromagnetic and paramagnetic particles. HGMS separators usually consist of a high-field solenoid magnet, the bore of which contains a fine-structured, ferromagnetic matrix material. The matrix material locally distorts the magnetic field and creates large field gradients in the vicinity of the matrix elements. These elements then become trapping sites for magnetic particles and are the basis for the magnetic separation. In this paper we discuss the design and construction of a prototype HGMS unit using a magnet made with high temperature superconductors (HTS). The prototype consists of an outer vacuum vessel which contains the HTS solenoid magnet The magnet is surrounded by a thermal radiation shield and multilayer insulation (MLI) blankets. The magnet, thermal shield and current leads all operate in a vacuum and are cooled by a cryocooler. High temperature superconducting current leads are used to reduce the heat leak from the ambient environment to the HTS magnet.

  5. Cryogenic experiences during W7-X HTS-current lead tests

    SciTech Connect

    Richter, Thomas; Lietzow, Ralph

    2014-01-29

    The Karlsruhe Institute of Technology (KIT) was responsible for design, production and test of the High Temperature Superconductor (HTS) current leads (CL) for the stellerator Wendelstein 7-X (W7-X). 16 current leads were delivered. Detailed prototype tests as well as the final acceptance tests were performed at KIT, using a dedicated test cryostat assembled beside and connected to the main vacuum vessel of the TOSKA facility. A unique feature is the upside down orientation of the current leads due to the location of the power supplies in the basement of the experimental area of W7-X. The HTS-CL consists of three main parts: the cold end for the connection to the bus bar at 4.5 K, the HTS part operating in the temperature range from 4.5 K to 65 K and a copper heat exchanger (HEX) in the temperature range from 65 K to room temperature, which is cooled with 50 K helium. Therefore in TOSKA it is possible to cool test specimens simultaneously with helium at two different temperature levels. The current lead tests included different scenarios with currents up to 18.2 kA. In total, 10 cryogenic test campaigns with a total time of about 24 weeks were performed till beginning of 2013. The test facility as well as the 2 kW cryogenic plant of ITEP showed a very good reliability. However, during such a long and complex experimental campaign, one has to deal with failures, technical difficulties and incidents. The paper gives a summary of the test performance comprising the test preparation and operation. This includes the performance and reliability of the refrigerator and the test facility with reference to the process measuring and control system, the data acquisition system, as well as the building infrastructure.

  6. Cryogenic experiences during W7-X HTS-current lead tests

    NASA Astrophysics Data System (ADS)

    Richter, Thomas; Lietzow, Ralph

    2014-01-01

    The Karlsruhe Institute of Technology (KIT) was responsible for design, production and test of the High Temperature Superconductor (HTS) current leads (CL) for the stellerator Wendelstein 7-X (W7-X). 16 current leads were delivered. Detailed prototype tests as well as the final acceptance tests were performed at KIT, using a dedicated test cryostat assembled beside and connected to the main vacuum vessel of the TOSKA facility. A unique feature is the upside down orientation of the current leads due to the location of the power supplies in the basement of the experimental area of W7-X. The HTS-CL consists of three main parts: the cold end for the connection to the bus bar at 4.5 K, the HTS part operating in the temperature range from 4.5 K to 65 K and a copper heat exchanger (HEX) in the temperature range from 65 K to room temperature, which is cooled with 50 K helium. Therefore in TOSKA it is possible to cool test specimens simultaneously with helium at two different temperature levels. The current lead tests included different scenarios with currents up to 18.2 kA. In total, 10 cryogenic test campaigns with a total time of about 24 weeks were performed till beginning of 2013. The test facility as well as the 2 kW cryogenic plant of ITEP showed a very good reliability. However, during such a long and complex experimental campaign, one has to deal with failures, technical difficulties and incidents. The paper gives a summary of the test performance comprising the test preparation and operation. This includes the performance and reliability of the refrigerator and the test facility with reference to the process measuring and control system, the data acquisition system, as well as the building infrastructure.

  7. Characterization of Hybrid Ferroelectric/HTS Thin Films for Tunable Microwave Components

    NASA Technical Reports Server (NTRS)

    Winters, M. D.; Mueller, C. H.; Bhasin, K. B.; Miranda, F. A.

    1996-01-01

    Since the discovery of High-Temperature-Superconductors (HTS) in 1986, a diversity of HTS-based microwave components has been demonstrated. Because of their low conductor losses, HTS-based components are very attractive for integration into microwave circuits for space communication systems. Recent advancements have made deposition of ferroelectric thin films onto HTS thin films possible. Due to the sensitivity of the ferroelectric's dielectric constant (epsilon(sub r)) to an externally applied electric field (E), ferroelectric/superconducting structures could be used in the fabrication of low loss, tunable microwave components. In this paper, we report on our study of Ba(0.5)Sr(0.5)TiO3/YBa2Cu3O(7-delta) and Ba(0.08)Sr(0.92)TiO3/YBa2Cu3O(7-delta) ferroelectric/superconducting thin films on lanthanum aluminate (LaAlO3) substrates. For the (Ba:Sr, 0.50:0.50) epitaxial sample, a epsilon(sub r) of 425 and a loss tangent (tan delta) of 0.040 were measured at 298 K, 1.0 MHz, and zero applied E. For the same sample, a epsilon(sub r) of 360 and tan delta of 0.036 were obtained at 77 K, 1.0 MHz, and zero applied E. Variations in epsilon(sub r) from 180 to 360 were observed over an applied E range of 0V/cm less than or equal to E less than or equal to 5.62 x 10(exp 4) V/cm with little change in tan delta. However, the range of epsilon(sub r) variation for the polycrystalline (Ba:Sr, 0.08:0.92) sample over 0V/cm less than or equal to E less than or equal to 4.00 x 10(exp 4) V/cm was only 3.6 percent while tan delta increased markedly. These results indicate that a lack of epitaxy between the ferroelectric and superconducting layers decreases tuning and increases microwave losses.

  8. Magnetization loss for stacks of ReBCO tapes

    NASA Astrophysics Data System (ADS)

    Bykovsky, N.; De Marzi, G.; Uglietti, D.; Bruzzone, P.; Muzzi, L.

    2017-02-01

    The AC loss measurements of the high temperature superconductor (HTS) cable prototype in the EDIPO test facility motivated detailed investigations of the loss contributions from the tape, strand and cable stages of the HTS fusion conductor design proposed at the Swiss Plasma Center. As an initial step of the task, magnetization tests of soldered stacks of HTS tapes were carried out at temperatures of 5 and 77 {{K}} and magnetic fields up to 12 {{T}} using the vibrating sample magnetometer technique. The influence on the magnetization loss of the number of tapes, width of the tape, field’s orientation and tape’s manufacturer is studied experimentally performing both the major and minor magnetization loops with different ramp rates of the applied magnetic field. In order to validate the test results, a numerical model is developed and presented in this work. From the numerical model we also deduced an analytical approach for the magnetization loss in the stacks of tapes with arbitrary number of tapes in the critical state model. Comparison between the measured and estimated magnetization loss of the cable prototypes is reported as well.

  9. Numerical calculation of primary slot leakage inductance of a Single-sided HTS linear induction motor used for linear metro

    NASA Astrophysics Data System (ADS)

    Li, Dong; Wen, Yinghong; Li, Weili; Fang, Jin; Cao, Junci; Zhang, Xiaochen; Lv, Gang

    2017-03-01

    In the paper, the numerical method calculating asymmetric primary slot leakage inductances of Single-sided High-Temperature Superconducting (HTS) Linear Induction Motor (HTS LIM) is presented. The mathematical and geometric models of three-dimensional nonlinear transient electromagnetic field are established and the boundary conditions are also given. The established model is solved by time-stepping Finite Element Method (FEM). Then, the three-phase asymmetric primary slot leakage inductances under different operation conditions are calculated by using the obtained electromagnetic field distribution. The influences of the special effects such as longitudinal end effects, transversal edge effects, etc. on the primary slot leakage inductance are investigated. The presented numerical method is validated by experiments carried out on a 3.5 kW prototype with copper wires which has the same structures with the HTS LIM.

  10. Characterization of YBa2Cu3O7, including critical current density Jc, by trapped magnetic field

    NASA Technical Reports Server (NTRS)

    Chen, In-Gann; Liu, Jianxiong; Weinstein, Roy; Lau, Kwong

    1992-01-01

    Spatial distributions of persistent magnetic field trapped by sintered and melt-textured ceramic-type high-temperature superconductor (HTS) samples have been studied. The trapped field can be reproduced by a model of the current consisting of two components: (1) a surface current Js and (2) a uniform volume current Jv. This Js + Jv model gives a satisfactory account of the spatial distribution of the magnetic field trapped by different types of HTS samples. The magnetic moment can be calculated, based on the Js + Jv model, and the result agrees well with that measured by standard vibrating sample magnetometer (VSM). As a consequence, Jc predicted by VSM methods agrees with Jc predicted from the Js + Jv model. The field mapping method described is also useful to reveal the granular structure of large HTS samples and regions of weak links.

  11. Probe molecules (PrM) approach in adverse outcome pathway (AOP) based high throughput screening (HTS): in vivo discovery for developing in vitro target methods

    EPA Science Inventory

    Efficient and accurate adverse outcome pathway (AOP) based high-throughput screening (HTS) methods use a systems biology based approach to computationally model in vitro cellular and molecular data for rapid chemical prioritization; however, not all HTS assays are grounded by rel...

  12. 2D analytical modeling of a wholly superconducting synchronous reluctance motor

    NASA Astrophysics Data System (ADS)

    Malé, G.; Lubin, T.; Mezani, S.; Lévêque, J.

    2011-03-01

    An analytical computation of the magnetic field distribution in a wholly superconducting synchronous reluctance motor is proposed. The stator of the studied motor consists of three-phase HTS armature windings fed by AC currents. The rotor is made with HTS bulks which have a nearly diamagnetic behavior under zero field cooling. The electromagnetic torque is obtained by the interaction between the rotating magnetic field created by the HTS windings and the HTS bulks. The proposed analytical model is based on the resolution of Laplace's and Poisson's equations (by the separation-of-variables technique) for each sub-domain, i.e. stator windings, air-gap, holes between HTS bulks and exterior iron shield. For the study, the HTS bulks are considered as perfect diamagnetic materials. The boundary and continuity conditions between the sub-domains yield to the global solution. Magnetic field distributions and electromagnetic torque obtained by the analytical method are compared with those obtained from finite element analyses.

  13. Theoretical screening of intermetallic ThMn12-type phases for new hard-magnetic compounds with low rare earth content

    PubMed Central

    Körner, Wolfgang; Krugel, Georg; Elsässer, Christian

    2016-01-01

    We report on theoretical investigations of intermetallic phases derived from the ThMn12-type crystal structure. Our computational high-throughput screening (HTS) approach is extended to an estimation of the anisotropy constant K1, the anisotropy field Ha and the energy product (BH)max. The calculation of K1 is fast since it is based on the crystal field parameters and avoids expensive total-energy calculations with many k-points. Thus the HTS approach allows a very efficient search for hard-magnetic materials for which the magnetization M and the coercive field Hc connected to Ha represent the key quantities. Besides for NdFe12N which has the highest magnetization we report HTS results for several intermetallic phases based on Cerium which are interesting as alternative hard-magnetic phases because Cerium is a less ressource-critical element than Neodymium. PMID:27098547

  14. Hybrid superconductor magnet bearings

    NASA Astrophysics Data System (ADS)

    Chu, Wei-Kan

    1995-04-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  15. Hybrid superconductor magnet bearings

    NASA Technical Reports Server (NTRS)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  16. Hybrid superconductor magnet bearings

    SciTech Connect

    Chu, W.

    1995-04-01

    Hybrid superconductor magnet bearings (HSMB`s) utilize high temperature superconductors (HTS`s) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS`s, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, the authors present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  17. Electromagnetic vibration process for producing bulk metallic glasses.

    PubMed

    Tamura, Takuya; Amiya, Kenji; Rachmat, Rudi S; Mizutani, Yoshiki; Miwa, Kenji

    2005-04-01

    It is known that the cooling rate from the liquid state is an important factor in the production of bulk metallic glasses. However, the effects of other factors such as electric and magnetic fields have not been thoroughly investigated. Here, we present a new method for producing bulk metallic glasses by using electromagnetic vibrations with simultaneous imposition of an alternating electric current and a magnetic field. This method was found to be effective in enhancing apparent glass-forming ability in Mg65-Cu25-Y10 (atomic percent) alloys. Indeed, larger bulk metallic glasses could be obtained by the electromagnetic vibration process under the same cooling conditions. We presume that disappearance or decrement of clusters by the electromagnetic vibrations applied to the liquid state cause suppression of crystal nucleation. This electromagnetic vibration process should be effective in other bulk metallic glass systems if the clusters in the liquid state cause the crystal nucleation.

  18. Identification of compounds that modulate retinol signaling using a cell-based qHTS assay.

    PubMed

    Chen, Yanling; Sakamuru, Srilatha; Huang, Ruili; Reese, David H; Xia, Menghang

    2016-04-01

    In vertebrates, the retinol (vitamin A) signaling pathway (RSP) controls the biosynthesis and catabolism of all-trans retinoic acid (atRA), which regulates transcription of genes essential for embryonic development. Chemicals that interfere with the RSP to cause abnormal intracellular levels of atRA are potential developmental toxicants. To assess chemicals for the ability to interfere with retinol signaling, we have developed a cell-based RARE (Retinoic Acid Response Element) reporter gene assay to identify RSP disruptors. To validate this assay in a quantitative high-throughput screening (qHTS) platform, we screened the Library of Pharmacologically Active Compounds (LOPAC) in both agonist and antagonist modes. The screens detected known RSP agonists, demonstrating assay reliability, and also identified novel RSP agonists including kenpaullone, niclosamide, PD98059 and SU4312, and RSP antagonists including Bay 11-7085, LY294002, 3,4-Methylenedioxy-β-nitrostyrene, and topoisomerase inhibitors (camptothecin, topotecan, amsacrine hydrochloride, and idarubicin). When evaluated in the P19 pluripotent cell, these compounds were found to affect the expression of the Hoxa1 gene that is essential for embryo body patterning. These results show that the RARE assay is an effective qHTS approach for screening large compound libraries to identify chemicals that have the potential to adversely affect embryonic development through interference with retinol signaling.

  19. Statistical Evaluation of HTS Assays for Enzymatic Hydrolysis of β-Keto Esters

    PubMed Central

    Dold, S. -M.; Zimmermann, S.; Hamacher, K.; Schmitz, K.; Rudat, J.

    2016-01-01

    β-keto esters are used as precursors for the synthesis of β-amino acids, which are building blocks for some classes of pharmaceuticals. Here we describe the comparison of screening procedures for hydrolases to be used for the hydrolysis of β-keto esters, the first step in the preparation of β-amino acids. Two of the tested high throughput screening (HTS) assays depend on coupled enzymatic reactions which detect the alcohol released during ester hydrolysis by luminescence or absorption. The third assay detects the pH shift due to acid formation using an indicator dye. To choose the most efficient approach for screening, we assessed these assays with different statistical methods—namely, the classical Z’-factor, standardized mean difference (SSMD), the Kolmogorov-Smirnov-test, and t-statistics. This revealed that all three assays are suitable for HTS, the pH assay performing best. Based on our data we discuss the explanatory power of different statistical measures. Finally, we successfully employed the pH assay to identify a very fast hydrolase in an enzyme-substrate screening. PMID:26730596

  20. Preparation of novel HTS films and tunnel junctions for advanced C3I sensor applications

    NASA Astrophysics Data System (ADS)

    Taylor, Benjamin J.; Emery, Teresa H.; Berggren, Susan A. E.; Leese de Escobar, Anna M.; Jeon, Inho; Maple, M. B.

    2015-05-01

    Research into the development of advanced RF electronics and devices having high-Temperature Superconducting (HTS) circuitry is being carried out in the Cryogenic Exploitation of RF (CERF) laboratory at SPAWAR Systems Center (SSC) - Pacific. Recently, we have developed a novel annealing process wherein a film of YBa2Cu3Ox is produced having a gradient of oxygen composition along a given direction which we refer to as YBa2Cu3O∇x. Such samples are intended for rapid experimental investigation of the evolution of electronic properties within the compound and in combination with structurally compatible functional oxide materials as integrated sensor devices. We present here an investigation as to the extent to which local oxygen content affects the ion milling process in the formation of Josephson junctions in the HTS compound YBa2Cu3O∇x. We find an abrupt transition in the profile and depth of ion milled trenches at oxygen concentrations at and below the well ordered oxygen level, O6.72. The method described here shows good potential for use in the fabrication of large numbers of uniform Josephson junctions in films of YBa2Cu3Ox, as either a complementary processing tool for grain boundary, step edge, or ion damaged formed JJs, or as a stand alone method for producing nano-bridge JJ's.

  1. Testing of machine wound second generation HTS tape Vacuum Pressure Impregnated coils

    NASA Astrophysics Data System (ADS)

    Swaffield, D.; Lewis, C.; Eugene, J.; Ingles, M.; Peach, D.

    2014-05-01

    Delamination of second generation (2G) High Temperature Superconducting (HTS) tapes has previously been reported when using resin based insulation systems for wound coils. One proposed root cause is the differential thermal contraction between the coil former and the resin encapsulated coil turns resulting in the tape c-axis tensile stress being exceeded. Importantly, delamination results in unacceptable degradation of the superconductor critical current level. To mitigate the delamination risk and prove winding, jointing and Vacuum Pressure Impregnation (VPI) processes in the production of coils for superconducting rotating machines at GE Power Conversion two scaled trial coils have been wound and extensively tested. The coils are wound from 12mm wide 2G HTS tape supplied by AMSC onto stainless steel 'racetrack' coil formers. The coils are wound in two layers which include both in-line and layer-layer joints subject to in-process test. The resin insulation system chosen is VPI and oven cured. Tests included; insulation resistance, repeat quench and recovery of the superconductor, heat runs and measurement of n-value, before and after multiple thermal cycling between ambient and 35 Kelvin. No degradation of coil performance is evidenced.

  2. Development of 1 MW-class HTS motor for podded ship propulsion system

    NASA Astrophysics Data System (ADS)

    Umemoto, K.; Aizawa, K.; Yokoyama, M.; Yoshikawa, K.; Kimura, Y.; Izumi, M.; Ohashi, K.; Numano, M.; Okumura, K.; Yamaguchi, M.; Gocho, Y.; Kosuge, E.

    2010-06-01

    To reduce fuel consumption and lead to a major reduction of pollution from NOx, SOx and CO2, the electric ship propulsion system is one of the most prospective substitutes for conventional ship propulsion systems. In order to spread it, innovative technologies for the improvement of the power transmission are required. The high temperature superconducting technology has the possibility for a drastic reduction of power transmission loss. Recently, electric podded propulsions have become popular for large cruise vessels, icebreakers and chemical tankers because of the flexibility of the equipment arrangement and the stern hull design, and better maneuverability in harbour, etc. In this paper, a 1 MW-class High temperature superconducting (HTS) motor with high efficiency, smaller size and simple structure, which is designed and manufactured for podded propulsion, is reported. For the case of a coastal ship driven by the optimized podded propulsion in which the 1MW HTS motor is equipped, the reductions of fluid dynamic resistance and power transmission losses are demonstrated. The present research & development has been supported by the New Energy and Industrial Technology Development Organization (NEDO).

  3. Electrical transport anisotropy of uniaxial polycrystalline samples and the effective medium approximation: An application to HTS

    NASA Astrophysics Data System (ADS)

    Cruz-García, A.; Muné, P.

    2016-08-01

    In this paper we have applied the effective medium approximation (EMA) to a polycrystalline sample made up of uniaxial crystallites with similar behavior to the high critical temperature superconductors (HTS) at the normal state (σab ≫ σc). As a result the dependence of the anisotropy parameter at the level of the sample, μ =σx /σz , on orientation probability of the grains' a-axes along a certain preferential direction, γxa is obtained. The intrinsic and shape anisotropy parameters of the crystallites constitute input data. In addition, the dependence of the orientation factor, f, which has been introduced in current models on the transport properties of HTS, is calculated as a function of γxa. These results offer a tool to interpret electrical transport measurements at normal state in granular uniaxial superconducting materials with certain texture degree, by means of the correlation between microstructure and electrical transport properties. Moreover, the comparison between the model and some experimental data suggests the presence of intragranular planar defects in the polycrystalline superconductors. They may affect the measurement of paracoherent resistivity and consequently the determination of f mainly in Bi based samples.

  4. Dynamic Characteristics of Pressure Build Up Tank for HTS Power Cable Refrigeration System

    NASA Astrophysics Data System (ADS)

    Kim, Dongmin; Park, Heecheol; Kim, Seokho; Jang, Hyunman; Kim, Yanghun

    HTS power cables are cooled by the forced circulation of sub-cooled liquid nitrogen to remove heat loss and maintain a cryogenic temperature. The refrigeration systems used consist of cryocoolers, a pressure build-up tank, heat exchangers, and circulation pumps. Liquid nitrogen expands or shrinks according to the temperature variation inside the fixed volume of the refrigeration system and the cable cryostat. The system pressure also changes depending on the volume change of the liquid nitrogen. The pressure of the liquid nitrogen should be kept above a certain level to ensure its dielectric strength. In addition, the pressure should be kept below the allowable pressure level considering the mechanical strength of the refrigeration system. To enhance the pressure controllability, external heating and cooling should be possible in the pressure build-up tank. For the precise modeling of the pressure build-up tank, thermal stratification and axial thermal conduction are considered. An analysis of such a refrigeration system is performed using the commercial code 'Sinda/fluint', a comprehensive finite-difference, one-dimensional, lumped parameter tool. This paper presents the transient thermo-hydraulic characteristics and the design directions of an HTS cable refrigeration system according to a variable heat load including pressure build-up tank.

  5. AC loss measurements in HTS coil assemblies with hybrid coil structures

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenan; Long, Nicholas J.; Staines, Mike; Badcock, Rodney A.; Bumby, Chris W.; Buckley, Robert G.; Amemiya, Naoyuki

    2016-09-01

    Both AC loss and wire cost in coil windings are critical factors for high temperature superconductor (HTS) AC machinery applications. We present AC loss measurement results in three HTS coil assemblies at 77 K and 65 K which have a hybrid coil structure comprising one central winding (CW) and two end windings (EWs) wound with ReBCO and BSCCO wires with different self-field I c values at 77 K. All AC loss results in the coil assemblies are hysteretic and the normalized AC losses in the coil assemblies at different temperatures can be scaled with the I c value of the coil assemblies. The normalised results show that AC loss in a coil assembly with BSCCO CW can be reduced by using EWs wound with high I c ReBCO wires, whilst further AC loss reduction can be achieved by replacing the BSCCO CW with ReBCO CW. The results imply that a flexible hybrid coil structure is possible which considers both AC loss and wire cost in coil assemblies.

  6. Recovery time analysis in a tri-axial HTS cable after an over-current fault

    NASA Astrophysics Data System (ADS)

    Hu, N.; Toda, M.; Watanabe, T.; Tsuda, M.; Hamajima, T.

    2011-11-01

    A tri-axial HTS cable with the advantage of compact structure, low heat loss, and low cost is a perfect solution for future distribution power network demand. In our previous research, a typical single line to ground (SLG) fault simulation was carried out in an adiabatic condition. A stabilizer layer thickness design of the tri-axial HTS cable based on a calculation of maximum temperature rise in the worst condition was proposed. However, in practical application, after the quenched cable is removed from the network by a breaker, a recovery time is also a very important parameter to decide if the cable is allowed to reconnect to the power network. In this paper, a one-dimensional computational fluid dynamics (CFD) analysis is carried out to simulate the transient thermal behavior of the cable. The result shows that it takes time to recover the cable temperature to the steady-state operation level due to a low thermal conductivity of the insulation layer. Since the cable is cooled by forced liquid nitrogen (LN2) flow, there is a temperature gradient along the cable. The temperature of LN2 gradually rises after the fault until the warmed coolant runs out of the cable.

  7. Integrated design of cryogenic refrigerator and liquid-nitrogen circulation loop for HTS cable

    NASA Astrophysics Data System (ADS)

    Chang, Ho-Myung; Ryu, Ki Nam; Yang, Hyung Suk

    2016-12-01

    A new concept of cryogenic cooling system is proposed and investigated for application to long-length HTS cables. One of major obstacles to the cable length of 1 km or longer is the difficulty in circulating liquid nitrogen (LN) along the cables, since the temperature rise and pressure drop of LN flow could be excessively large. This study attempts a breakthrough by integrating the refrigerator with the LN circulation loop in order to eliminate the cryogenic LN pumps, and generate a large LN flow with the power of compressors at ambient temperature. A variety of thermodynamic structures are investigated on standard and modified Claude cycles, where nitrogen is used as refrigerant and the LN circulation loop is included as part of the closed cycle. Four proposed cycles are fully analyzed and optimized with a process simulator (Aspen HYSYS) to evaluate the FOM (figure of merit) and examine the feasibility. The modified dual-pressure cycle cooled with expander stream is recommended for long HTS cables.

  8. Identification of compounds that modulate retinol signaling using a cell-based qHTS assay

    PubMed Central

    Chen, Yanling; Sakamuru, Srilatha; Huang, Ruili; Reese, David H.; Xia, Menghang

    2016-01-01

    In vertebrates, the retinol (vitamin A) signaling pathway (RSP) controls the biosynthesis and catabolism of all-trans retinoic acid (atRA), which regulates transcription of genes essential for embryonic development. Chemicals that interfere with the RSP to cause abnormal intracellular levels of atRA are potential developmental toxicants. To assess chemicals for the ability to interfere with retinol signaling, we have developed a cell-based RARE (Retinoic Acid Response Element) reporter gene assay to identify RSP disruptors. To validate this assay in a quantitative high-throughput screening (qHTS) platform, we screened the Library of Pharmacologically Active Compounds (LOPAC) in both agonist and antagonist modes. The screens detected known RSP agonists, demonstrating assay reliability, and also identified novel RSP agonists including kenpaullone, niclosamide, PD98059 and SU4312, and RSP antagonists including Bay 11-7085, LY294002, 3,4-Methylenedioxy-β-nitrostyrene, and topoisomerase inhibitors (camptothecin, topotecan, amsacrine hydrochloride, and idarubicin). When evaluated in the P19 pluripotent cell, these compounds were found to affect the expression of the Hoxa1 gene that is essential for embryo body patterning. These results show that the RARE assay is an effective qHTS approach for screening large compound libraries to identify chemicals that have the potential to adversely affect embryonic development through interference with retinol signaling. PMID:26820057

  9. Consideration of sub-cooled LN2 circulation system for HTS power machines

    NASA Astrophysics Data System (ADS)

    Yoshida, Shigeru; Hirai, Hirokazu; Nara, N.; Nagasaka, T.; Hirokawa, M.; Okamoto, H.; Hayashi, H.; Shiohara, Y.

    2012-06-01

    We consider a sub-cooled liquid nitrogen (LN) circulation system for HTS power equipment. The planned circulation system consists of a sub-cool heat exchanger (subcooler) and a circulation pump. The sub-cooler will be connected to a neon turbo- Brayton cycle refrigerator with a cooling power of 2 kW at 65 K. Sub-cooled LN will be delivered into the sub-cooler by the pump and cooled within it. Sub-cooled LN is adequate fluid for cooling HTS power equipment, because its dielectric strength is high and it supports a large critical current. However, a possibility of LN solidification in the sub-cooler is a considerable issue. The refrigerator will produce cold neon gas of about 60 K, which is lower than the nitrogen freezing temperature of 63 K. Therefore, we designed two-stage heat exchangers which are based on a plate-fin type and a tube-intube type. Process simulations of those heat exchangers indicate that sub-cooled LN is not frozen in either sub-cooler. The plate-fin type sub-cooler is consequently adopted for its reliability and compactness. Furthermore, we found that a cooling system with a Brayton refrigerator has the same total cooling efficiency as a cooling system with a Stirling refrigerator.

  10. Analysis of transient state in HTS tapes under ripple DC load current

    NASA Astrophysics Data System (ADS)

    Stepien, M.; Grzesik, B.

    2014-05-01

    The paper concerns the analysis of transient state (quench transition) in HTS tapes loaded with the current having DC component together with a ripple component. Two shapes of the ripple were taken into account: sinusoidal and triangular. Very often HTS tape connected to a power electronic current supply (i.e. superconducting coil for SMES) that delivers DC current with ripples and it needs to be examined under such conditions. Additionally, measurements of electrical (and thermal) parameters under such ripple excitation is useful to tape characterization in broad range of load currents. The results presented in the paper were obtained using test bench which contains programmable DC supply and National Instruments data acquisition system. Voltage drops and load currents were measured vs. time. Analysis of measured parameters as a function of the current was used to tape description with quench dynamics taken into account. Results of measurements were also used to comparison with the results of numerical modelling based on FEM. Presented provisional results show possibility to use results of measurements in transient state to prepare inverse models of superconductors and their detailed numerical modelling.

  11. Factors affecting characterization of bulk high-temperature superconductors

    SciTech Connect

    Hull, J.R.

    1997-11-01

    Three major factors affect the characterization of bulk high-temperature superconductors in terms of their levitation properties during interaction with permanent magnets. First, the appropriate parameter for the permanent magnet is internal magnetization, not the value of the magnetic field measured at the magnet`s surface. Second, although levitation force grows with superconductor thickness and surface area, for a given permanent magnet size, comparison of levitation force between samples is meaningful when minimum values are assigned to the superconductor size parameters. Finally, the effect of force creep must be considered when time-averaging the force measurements. In addition to levitational force, the coefficient of friction of a levitated rotating permanent magnet may be used to characterize the superconductor.

  12. Bulk Site Reference Materials

    SciTech Connect

    Barich, J.J. III; Jones, R.R. Sr.

    1996-12-31

    The selection, manufacture and use of Bulk Site Reference Materials (BSRMs) at hazardous waste sites is discussed. BSRMs are useful in preparing stabilization/solidification (S/S) formulations for soils, ranking competing S/S processes, comparing S/S alternatives to other technologies, and in interpreting data from different test types. BSRMs are large volume samples that are representative of the physical and chemical characteristics of a site soil, and that contain contaminants at reasonably high levels. A successful BSRM is extremely homogeneous and well-characterized. While not representative of any point on the site, they contain the contaminants of the site in the matrices of the site. Design objectives for a BSRM are to produce a material that (1) maintains good fidelity to site matrices and contaminants, and (2) exhibits the lowest possible relative standard deviation.

  13. Bulk material handling system

    DOEpatents

    Kleysteuber, William K.; Mayercheck, William D.

    1979-01-01

    This disclosure relates to a bulk material handling system particularly adapted for underground mining and includes a monorail supported overhead and carrying a plurality of conveyors each having input and output end portions with the output end portion of a first of the conveyors positioned above an input end portion of a second of the conveyors, a device for imparting motion to the conveyors to move the material from the input end portions toward the output end portions thereof, a device for supporting at least one of the input and output end portions of the first and second conveyors from the monorail, and the supporting device including a plurality of trolleys rollingly supported by the monorail whereby the conveyors can be readily moved therealong.

  14. Explosive bulk charge

    DOEpatents

    Miller, Jacob Lee

    2015-04-21

    An explosive bulk charge, including: a first contact surface configured to be selectively disposed substantially adjacent to a structure or material; a second end surface configured to selectively receive a detonator; and a curvilinear side surface joining the first contact surface and the second end surface. The first contact surface, the second end surface, and the curvilinear side surface form a bi-truncated hemispherical structure. The first contact surface, the second end surface, and the curvilinear side surface are formed from an explosive material. Optionally, the first contact surface and the second end surface each have a substantially circular shape. Optionally, the first contact surface and the second end surface consist of planar structures that are aligned substantially parallel or slightly tilted with respect to one another. The curvilinear side surface has one of a smooth curved geometry, an elliptical geometry, and a parabolic geometry.

  15. Bulk muscles, loose cables

    PubMed Central

    Liyanage, Chamari R D G; Kodali, Venkata

    2014-01-01

    The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. PMID:25326558

  16. Creating bulk nanocrystalline metal.

    SciTech Connect

    Fredenburg, D. Anthony; Saldana, Christopher J.; Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John; Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  17. Bulk amorphous materials

    SciTech Connect

    Schwarz, R.B.; Archuleta, J.I.; Sickafus, K.E.

    1998-12-01

    This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this work was to develop the competency for the synthesis of novel bulk amorphous alloys. The authors researched their synthesis methods and alloy properties, including thermal stability, mechanical, and transport properties. The project also addressed the development of vanadium-spinel alloys for structural applications in hostile environments, the measurement of elastic constants and thermal expansion in single-crystal TiAl from 300 to 750 K, the measurement of elastic constants in gallium nitride, and a study of the shock-induced martensitic transformations in NiTi alloys.

  18. A new numerical approach to find current distribution and AC losses in coaxial assembly of twisted HTS tapes in single layer arrangement

    NASA Astrophysics Data System (ADS)

    Siahrang, Majid; Sirois, Frédéric; Grilli, Francesco; Babic, Slobodan; Brault, Simon

    2010-06-01

    This paper presents a novel technique for evaluating AC losses and current distribution in single layer assemblies of coaxially wound thin conductors, such as YBCO coated conductors. The proposed approach takes into account the twisted geometry of the individual superconducting tapes by considering the integral relation between the magnetic vector potential and the current density in the tapes (Biot-Savart formula). The integrals are solved numerically and semi-analytically, and the results are used to generate a discretized system of equations based on the magnetic flux diffusion equation (eddy current problem). The latter is solved using an efficient time transient solver (DASPK). It is assumed that, due to the helical symmetry of the problem, it is sufficient to solve for the current distribution in half of a single tape cross-section, even if many tapes are present, which allows a drastic reduction of the 3-D problem to a simple 1-D domain. The method was used to evaluate the AC losses of a HTS cable made of coated conductors, and it was observed that for a given radius of the former and number of tapes, twisted tapes with smaller pitch have lower AC losses.

  19. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: A Peak in Density Dependence of Electron Spin Relaxation Time in n-Type Bulk GaAs in the Metallic Regime

    NASA Astrophysics Data System (ADS)

    Shen, Ka

    2009-06-01

    We demonstrate that the peak in the density dependence of electron spin relaxation time in n-type bulk GaAs in the metallic regime predicted by Jiang and Wu [Phys. Rev. B 79 (2009) 125206] has been realized experimentally in the latest work [arXiv:0902.0270] by Krauß et al.

  20. Induction detection of concealed bulk banknotes

    NASA Astrophysics Data System (ADS)

    Fuller, Christopher; Chen, Antao

    2012-06-01

    The smuggling of bulk cash across borders is a serious issue that has increased in recent years. In an effort to curb the illegal transport of large numbers of paper bills, a detection scheme has been developed, based on the magnetic characteristics of bank notes. The results show that volumes of paper currency can be detected through common concealing materials such as plastics, cardboard, and fabrics making it a possible potential addition to border security methods. The detection scheme holds the potential of also reducing or eliminating false positives caused by metallic materials found in the vicinity, by observing the stark difference in received signals caused by metal and currency. The detection scheme holds the potential to detect for both the presence and number of concealed bulk notes, while maintaining the ability to reduce false positives caused by metal objects.