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Nine toroidal field (TF) coils have been developed in Japan for the international thermonuclear experimental reactor (ITER). The joint resistance of TF coil should satisfy the requirement of smaller than 3 nano-ohm at 2 T of external magnetic field and 68 kA of transport current. Full-size joint sample (FSJS) tests were performed for joint development and for TF coil manufacture, as part of the process control. 11 FSJS tests are conducted in total. FSJS tests were conducted with assistance from a test faculty in the National Institute for Fusion Science as reported in a previous paper. All FSJS tests successfully satisfied the requirement of resistance less than 3 nΩ at 2 T. Additionally, the TF coil joints are subjected to cyclic electromagnetic force and warm-up/cool-down during the ITER operation. The authors investigated the joint performance for the abovementioned influence. The results showed no degradation in the joint resistance. Thus, the TF joint developed in Japan was qualified successfully. [ABSTRACT FROM AUTHOR]

The Broader Approach agreement between Europe and Japan includes the construction of a fully superconducting tokamak, the JT-60 Super Advanced (JT-60SA), as a satellite experiment to ITER. In particular, the whole Toroidal Field magnet system, described in this paper, will be provided to Japan by the EU. All the TF coil main constituents, i.e. conductor, winding pack, joints, casing, current leads, are here presented and discussed as well as the design criteria adopted to fulfil the machine requirements. The results of the analyses performed by the EU and JA to define and assess the TF magnet system conceptual design are reported and commented. Future work plan is also discussed. [ABSTRACT FROM AUTHOR]

The upgrade of JT-60U to JT-60 Super Advanced (JT-60SA), a fully superconducting tokamak, will be performed in the framework of the Broader Approach (BA) agreement between Europe (EU) and Japan. In particular, the Toroidal Field (TF) system, which includes 18 coils, is foreseen to be procured by France, Italy and Germany. This work covers activities from design and manufacturing to shipping to Japan. The present paper is mainly devoted to the analyses that lead to the conductor design and to the technical specifications of the joints for the JT-60SA TF coils. The conductor geometry is described, which is derived from Cable-In-Conduit concept and adapted to the actual JT-60SA tokamak operating conditions, principally the ITER-like scenario. The reported simulations and calculations are particularly dealing with the stability analysis and the power deposition during normal and off-normal conditions (AC losses, nuclear heating). The final conductor solution was selected through a trade-off between scientific approach and industrial technical orientation. Besides, the TF system connections layout is shown, derived from the industrially assessed twin-box concept, together with the associated thermo-hydraulic calculations ensuring a proper temperature margin. [ABSTRACT FROM AUTHOR]

JAEA has conducted qualification and rationalization activities in Japan since March 2009 in order to rationalize manufacturing procedure of ITER toroidal field coil (TFC) structures. These following activities has been performed: qualification of structural materials and qualification and development of welding procedure according to the JSME code constituted for fusion devices, demonstration of the manufacturing method and procedures through manufacture of 1 m mock-ups and full-scale segments of TFC structure. From results of these activities, JAEA confirmed quality of materials and weld joints of gas tungsten arc welding and gas metal arc welding. In addition, JAEA obtained knowledge of welding deformation of actual TFC structures. This paper describes results of these qualification and development activities for ITER TFC structure. [ABSTRACT FROM PUBLISHER]

HTS cable demonstration project supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO) has started in Japan. The target of this project is to operate a 66 kV, 200 MVA HTS cable in the live network of Tokyo Electric Power Company in order to demonstrate its reliability and stable operation. The design of the HTS cable with DI-BSCCO has been completed as well as those of a termination and a joint. A 30-meter HTS cable system with terminations, a joint and a cooling system was installed in SEI facility to confirm their design and performance. Various tests as voltage tests, nominal and over current tests, heat cycle tests, heat loss measurements and so on were conducted and it is verified that the cable has good performances as design. This paper describes the design and test results of a 30-meter HTS cable, and discusses required test items of HTS cables. [ABSTRACT FROM AUTHOR]

The mission of the JT-60SA Tokamak, which will be built in Japan, is to contribute to the early realization of fusion energy in support and supplement of the ITER program. The JT-60SA project is part of the broader approach for fusion energy. In 2008, due to a design change of the TF cross section, and following the redefinition of the global JT-60SA features, mechanical analyses were redone. The first 2D and 3D mechanical analyses were performed on the current TF design, providing useful information on the pros and cons of the new design. For the 2D analysis, the critical area of the inner leg cross section in the location of the equatorial plane was meshed to study the effect of in plane loads. The analysis includes checking the peak field applied to the conductors and the stress on each of the components of the winding pack cross section, in particular in the insulation which is a critical component. The stress in winding pack cross section is due to the accumulation of cool down strain, "in plane" Lorentz forces and to the quench pressure. Both magnetic and mechanical analyses are performed with the ANSYS V11.0 code. In this paper, we present the main steps of the 2D and 3D FEM calculations which were developed by CEA and used in the following analyses. Associated statements concerning possible TF design optimization with respect to cost, feasibility or risk are also presented. [ABSTRACT FROM AUTHOR]

As an intense neutron source for the boron neutron capture therapy system, a FFAG storage ring with Energy/emittance Recovery Internal Target (ERIT) has been developed in the Kyoto University Research Reactor Institute (KURRI). In order to develop storage ring for ERIT scheme, the spiral sector and radial sector FFAG rings were designed and compared about performance in ERIT system. The 3-dimensional magnetic fields of these magnets were calculated with the field analysis code, TOSCA. The pole shape of magnet was carefully optimized checking the betatron tune. Tunes were computed by means of tracking simulations in field maps based on TOSCA models. In this paper, the FFAG magnet design for ERIT system and the construction of FFAG ring in KURRI are described. [ABSTRACT FROM AUTHOR]

We analyse the issues of quench propagation in the NbTi Poloidal Field Conductor Insert (PFCI), recently tested at JAEA Naka, Japan. The simulation tools Mithrandir, already validated against data from previous Nb3Sn Insert Coils, and M3, implementing a more detailed thermal-hydraulic description of the CICC cross section, are used. The results of the analysis are reported in the paper and compared with experimental data, with particular attention to NbTi versus Nb3Sn features and to the effects of different model assumptions. [ABSTRACT FROM AUTHOR]

ITER PFCI has been manufactured in the Europe and installed into the ITER Test Facility in Naka, Japan. The conductor is NbTi cable-in-conduit conductor with thick square stainless steel jacket and almost identical with the design of the ITER PF coils. The main objective of this test is the characterization of the conductor and joints at the conditions relevant to the ITER PF coil operation. Intermediate joint is located in the winding at relatively high field to examine its performance. The main items in the PFCI test program are thermo-hydraulic test, DC mode test, cyclic test and pulse mode test. The PFCI and CSMC were successfully cooled down to cryogenic temperature within 450 hours. The test of the PFCI was performed from May to August 2008. The key technology of the installation, the test methods and procedures, and some preliminary results of cool-down are described in this paper. [ABSTRACT FROM AUTHOR]

Since 2003, three years of the current 5-year national project for development of coated conductors using Y-system superconductors have passed and remarkable results have been achieved. In this paper, the current status and future prospects are reviewed. The group of Fujikura and SRL has worked on a long tape with high performance in the PLD-YBCO supercon- ducting tapes on the IBAD-GZO buffered substrates. The highest Ic × L value of the tape is over 50 k Am which is 212 m in length and 245 A of critical current (Ic). Additionally, a 500 m long IBAD-buffered tape with a reasonable in-plane texture was produced using a large scale IBAD apparatus by Fujikura. In the other group, long tape processing has been developed focusing on lowering production cost. An extremely high Ic value of 692 A was obtained in a short sample by the advanced TFA-MOD method on a CeO2 (PLD)/GZO(IBAD)/Hastelloy substrate. In the efforts for the long tape processing, a 25 m long tape with the Ic value of 100 A by a continuous reel-to-reel system and a 40 m long tape with 155 A by a batch system were realized. 100 m class long tapes were also obtained with the MOCVD and PLD-HoBCO processes. Both groups are aiming for 500 m long tapes with the high Ic value of 300 A/cm-w with a production rate of 5 m/h. Furthermore, feasibility studies for applications using coated conductors have already began due to the above mentioned success of long tape production. Several kinds of coils using the long coated conductors such as solenoid and pancake types and spiral shaped conductors for the cable were made. Reasonable high performance results were confirmed in the trials. New approaches on the preliminary studies for the applications of cables, transformers, motors and current limiters etc. are planned in this project. [ABSTRACT FROM AUTHOR]

Development of the SMES using high temperature superconducting (HTS) coil has progressed as a Japanese national project since FY 2004. The objective of the project is to obtain around twice the normal energy density via an HTS-LTS ‘hybrid’ coil system compared to an LTS coil system. The HTS coil is composed of sixteen double-pancake coils and the double-pancake coil is wound with a Bi2212 Rutherford-type cable. The HTS coil is operated at 4.2 K in liquid helium bath with the LTS coil, and operated at maximum field of 8.9 T. Before we made a hybrid coil system, we verified the design issues using HTS experimental coils. In this paper mechanical compression tests, DC operation tests and thermal runaway tests using the experimental coils are discussed. [ABSTRACT FROM AUTHOR]

A high-temperature superconducting dipole floating in the magnetic field of a normal conducting coil has been developed for the Ring Trap (RT)-1 plasma confinement apparatus at the University of Tokyo. The RT-1 device consists of the floating superconducting dipole, a levitation coil made of normal conductor, a vacuum vessel for plasma confinement and detachable services for the floating dipole. This paper describes the design concept and operating scenario of the floating dipole as well as the required services such as a HTS persistent current switch necessary to realize this scenario. [ABSTRACT FROM AUTHOR]

R&D of fundamental technologies for superconducting AC Power equipment (Super-ACE project) started as a national project, for a five-year plan since fiscal 2000 by MIT and NEDO. This project is to research and develop the basic technology of super-conductive cable, fault current limiter and transformer. This paper summarizes the research and development of following 2 types FCL. The R&D of the SN transition resistive type superconducting thin film fault current limiter aims to establish large-current/high-voltage technology by arranging films in multi-parallel/series, and increasing the current-carrying capacity through widening the area of the thin film of the current limiting element. The R&D of the reactor for a rectifier-type fault current limiter using coils of superconducting wire of the Ag sheath Bi2223 tape, aiming to apply it to high-voltage systems. [ABSTRACT FROM AUTHOR]

Railway transportation is of safety, convenience, economy, and environmental friendliness. However, with energy issues becoming increasingly important in this century, it is important to assess the situation in the transportation sector. When the superconducting cable is used as a feeder of the railway electrification system, the voltage drop can be significantly reduced. Therefore, the superconducting feeder has many effects, for example, the reduction transmission losses, the improvement of the regeneration factor, and the reduction of substations. We designed superconducting feeder and introduced to the Izuhakone Railway Sunzu line in Japan. After the system was checked from the aspect of cooling and current properties, the train running test was conducted. From the result of switching notch tests, it was found that the current flows continuously via the superconducting cable according to the notch operation. Furthermore, to inspect the influence of superconducting material, a large pulse current test was performed using the transmission equipment of a railway. It can be confirmed that superconductor can be used as railway feeder because the materials can cope with the current change peculiar to railway required for practical use. [ABSTRACT FROM AUTHOR]

Japan Atomic Energy Agency (JAEA) started sub- and full-scale trials to qualify and optimize manufacturing procedure of ITER TF coil from March 2009 under the contract with Toshiba. As major outcome of these trials, feasibility of high accuracy of winding, prediction of the conductor elongation due to heat treatment and radial plate manufacture is confirmed. Therefore, JAEA can mostly establish manufacturing plan for the TF coil and then, start the first TF coil procurement from 2013, following to full demonstration through manufacturing a dummy double-pancake in 2012. [ABSTRACT FROM PUBLISHER]

The HTS cable demonstration project, called the Yokohama Project, supported by Ministry of Economy, Trade and Industry and the New Energy and Industrial Technology Development Organization, was initiated in Japan in 2007. The aim of this project is to operate a 66 kV, 200 MVA high-temperature superconducting (HTS) cable in a network of the Tokyo Electric Power Company to demonstrate cable reliability and stable operation. Total project period was changed from 5 years to 6 years. Chosen as the demonstration site was the Asahi substation in Yokohama. Based on the analysis of the network conditions of the demonstration site, specifications of the HTS cable system were determined. Element technologies were developed and various preliminary tests using short core samples were conducted to confirm the HTS cable design. A 30-meter HTS cable system was manufactured and tested prior to initial demonstration tests. Long-term demonstration tests of the HTS cable system in an actual grid at the Asahi substation are scheduled to be started in 2011. [ABSTRACT FROM AUTHOR]

High temperature superconducting (HTS) cables achieve large power capacity and low-loss power transmission in a compact package. In a new Japanese national project, Sumitomo Electric Industries, Ltd. is working to develop a 66 kV–5 kArms HTS cable with REBCO wires. One of the important technical targets is to reduce AC loss to less than 2 W/m/ph at 5 kArms. To investigate the effect of wire width on the AC losses in multi-layer cable conductors, 30-mm-wide REBCO tapes were divided into 4-mm-wide or 2-mm-wide strips, and two 4-layer cable conductors were manufactured with these strips. The measured AC loss characteristics of the two cable conductors were comparable. The measured AC loss in the cable conductor with 4-mm-wide wire was in good agreement with numerical calculations. However, the AC loss in the cable conductor with 2-mm-wide wires was larger than the numerical prediction. The difference may be due to the wires' non-uniform Jc distribution in the width direction, because the AC losses in cable conductors with narrow wires are strongly influenced by the Jc profiles of the wires. AC loss simulations assuming that the wire's Ic will be higher show that a 14000 A-Ic class cable with 4-mm-wide wires is expected to achieve the AC loss target. For cables with 2-mm-wide wires, the improvement of Jc distribution in the width direction will reduce the AC loss level, and the goal will be achieved with lower Ic wires. [ABSTRACT FROM AUTHOR]

Japan Atomic Energy Agency has developed Nb3Sn strands for the ITER magnet, whose critical current density is about 1.4 times as large as that of ITER CS Model Coil. The magnetic field, temperature, and strain dependence on the critical current (Ic) of the strands were measured with apparatus that were developed by the authors. The strain properties in particular were investigated in detail, with strain tensor analysis revealing that the upper critical field dependence on strain can be naturally formulated using a high order polynomial terms of strain taking into account residual strain due to thermal contraction difference inside the strand and strain applied externally. A correlation formula for field, temperature, strain and Ic of the strand is discussed and presented. Recent results of fabricating strands for ITER TF coil are then finally provided. [ABSTRACT FROM AUTHOR]

The authors performed trials and studies to solve the remaining technical problems for manufacturing the ITER Toroidal Field (TF) coil. Cover plate (CP) welding deformation of a side double pancake may achieve specified tolerances with correction of a long wave distortion through the use of a small load, although complicated welding operations are required. In addition, JAEA developed a new procedure for manufacturing a CP at a reduced cost. Straight and curved CPs are fabricated by hot-rolling and cold-drawing and bending the straight CP with sufficient accuracy. Applying these results, JAEA has started procurement of the TF coil, beginning with qualification trials. Manufacture of a full-scale regular RP, finalization of a manufacturing plan and drawings and design of tooling will be completed by the middle of 2011. [ABSTRACT FROM AUTHOR]

The target station in the hadron experimental facility at J-PARC consists of a production target and a huge vacuum chamber in which several secondary-beam-line magnets can work. This vacuum chamber system aims to remove the vacuum beam pipe from the magnet gap, because the cooling of the beam pipe is the most serious problem in the high intensity beam facility. We have developed indirectly cooled radiation-resistant magnets for the hadron target station. Their coils are made of solid-conductor type mineral-insulation cables and stainless-steel water pipes. They have the great advantages that electric circuits can be completely independent of water pass. The mechanical strength and the insulation performance of the coil are significantly improved also because the insulation water pipes can be avoided from the water pass. A C-type sector dipole and a figure-8-type quadrupole magnet have been fabricated by using indirectly cooled radiation-resistant magnet technology, and installed in the vacuum chamber. We have succeeded to operate them in vacuum stably with the current of DC 1000 A by improving the end structure of the MIC coils and increasing their emissivity. These magnets have been used for the real beam operation without any serious problems. [ABSTRACT FROM AUTHOR]

Progresses in the development of the TFA-MOD process for the coated conductors in Japan are reviewed. In the fundamental approaches, some important advantages of Ba-poor starting solution were found such as for obtaining higher Jc, shorter reaction time and wider process temperature window. The high Ic value of 735 A/cm-w@77 K was attained. Additionally, introduction of artificial pinning centers by Sm-substitution and Zr-addition to the Ba-poor films was successfully investigated. The films showed a high minimum Ic value of 42 A/cm-w at 77 K, 1 T. Furthermore, isotropic Ic properties in the angular dependence of applied magnetic fields was realized by the uniform distribution of nanoprticles of Zr-compound. On the other hand, two different process of MOD including batch and reel-to-reel (RTR) types have been developed as an engineering process for low cost and long tape production with high superconducting performances at a high rate. In the batch type, long tape synthesis process could be developed by the optimization of the growth conditions in a large furnace. A 500 m long tape was heat-treated and a high Ic value of 310 A/cm-w in a 250 m tape was confirmed. Concerning the RTR type, a high production rate system was developed after confirmation of the ability of the continuous process in a 90 m long tape. A multi-turn with a vertical gas flow system was developed for this purpose. This system was applied to the fabrication of superconducting films on the lower cost buffer layers including a high deposition rate LBAD-MgO layer. Currently, a 5 m long tape with 250 A/cm-w was obtained at the production rate of 3 m/h using a part of the multi-turn system, which is equivalent to 15 m/h in the entire use of the furnace. [ABSTRACT FROM AUTHOR]

A new application of SMES (Superconducting Energy Storage) for on-line grasping of power system stability is proposed. Experiment was carried out on a power system simulator with actual rotating generator models, which is a property of Central Research Institute of Electric Power Industry (CRIEPI), Japan. SMIES system was designed and developed. Small power deviation of known pattern was generated by SMES and, by means of system identification, eigen-value of the power system was analysed from system response due to the power modulation. It was successful in evaluating the stability by eigen-values measured with the proposed method. [ABSTRACT FROM AUTHOR]

A test stand of a DC superconducting power transmission cable was finished to construct in October 2006 in Chubu University, Japan, and three cooling cycles were carried out to measure the properties of the cable. Critical current of HTS tapes in the cable was measured at every cooling cycle and shows the similar temperature dependence; conclusively, the HTS tapes suffered no damage after cooling and heating process between the each cycle. Peltier current leads were partly installed in the test stand, and it was measured that the temperatures of the feed through near to the liquid nitrogen were decreased in spite of a current feeding. [ABSTRACT FROM AUTHOR]

A new HTS cable project supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO) has just started in Japan. Target of this project is to operate a 66 ky, 200 MVA HTS cable in a real grid in order to demonstrate its reliability and stable operation. Tokyo Electric Power Company (TEPCO) provides the real grid and studies the impact of connecting the HTS cable to the existing conventional facilities in Yokohama. Sumitomo Electric Industries, Ltd. (SEI) designs and manufactures the HTS cable, terminations and joint. Mayekawa Mfg. Co. Ltd. provides a cooling system. Total project period is planned to be 5 years. In 2007, components of HIS cable systeni were studied and designed. In 2008 and early 2009, the pre-system with a 30-meter cable will be installed in the factory to demonstrate basic performance of the HTS cable and its accessories. Then the 200 MVA HIS cable will be manufactured in 2009 and installed and operated at the site in 2010 and 2011. One of the technical targets in this project is to reduce the AC loss of HTS cable. For this purpose, a new type DI-BSCCO wire with twisted superconducting filaments is planned to be applied in the cable. A 1-meter cable core manufactured with the new wires shows its AC loss as less than 1 W/m/ph at 2 kArms, which is 1/4 of AC loss with normal DI-BSCCO. [ABSTRACT FROM AUTHOR]

Due to the development of superconducting magnets, the magnetic filtration process is now undergoing its biggest evolution since its conception. In Japan, the first industrial superconducting magnetic filter has been successfully applied for factory wastewater treatment. Much effort in both theory and practice is needed to further contribute to the new developments of this high gradient magnetic filtration process. In this substantial review, we have collected the most important theoretical and practical data about magnetic filtration, its recovery and design to establish a good framework for further development of this amazing technology. [ABSTRACT FROM AUTHOR]

Japan Atomic Energy Agency has developed four types of Nb3Sn strand which can be used in the ITER TF coils. One is a strand made by an internal tin process strand and the others are bronze process strands. The achieved critical current density is more than 790 A/mm2 in the bronze process strands and more than 980 A/mm2 in the internal tin process strand under 4.2 K temperature and 12 T magnetic field and there is hysteresis loss of less than 770 mJ/cc under ± 3 T cycle. Since these strands are utilized with an external strain, it is necessary to evaluate strain dependency to confirm the ITER conductor design. An apparatus to measure the strain dependency was newly developed. It has a horseshoe-shaped ring to produce uniform axial compressive or tensile strain along the strand length, a strand being soldered on the outer surface of the ring. The detailed strand characteristics were investigated subjecting the developed strands to a magnetic field from 10 T to 13 T, a strain from about -0.8% to 0.5%, and a temperature from 4.2 K to the critical temperature. When the critical current is normalized to that under the conditions where strain is intrinsically zero, the bronze process strands exhibit better performance than the internal tin process strand. However, the three bronze process strands do not exhibit the same Ic-strain characteristics. Two types of scaling relations are applied to the data, and good expressions of strand performance were obtained by the least square method within 3 A as RMS. [ABSTRACT FROM AUTHOR]

Power supply for the large-scale accelerator magnets draws a large amount of power from the utility network. For an example, the new proton accelerator complex for high intensity beam (Japan Particle Accelerator Research Complex, J-PARC) is under construction at the Tokai campus of Japan Atomic Energy Agency (JAEA) as a joint project between KEK and JAEA. The J-PARC SO GeV proton synchrotron (50 GeV-PS) magnets power supplies are constructed with IGBT and IEGT, then the power factor is almost 100%. However, the swing of an active power becomes almost 170 MW, although the average power is about 50 MW. Such large pulse power will give un-allowed disturbances to an ac power line. A SMES system will be required for compensating such as pulse electric power and reducing the disturbances. Case study on circuit configuration of the power supply with SMES and present status of the R & D for the SMES system will be discussed. [ABSTRACT FROM AUTHOR]

The toroidal magnetic field of ITER is provided by 18 Nb3 Sn superconducting coils that provide 5.3 Tin the Tokamak magnetic centre thanks to a nominal current of 68 kA. Two major procurement packages will be integrated to accomplish the final assembly of the coils: 1) the winding pack which houses the double pancakes in 7 stacked radial plates (RP) and 2) the TF coil case which houses the winding pack (WP) and is the main structural component of the ITER machine. 19 TF coil cases (18+1 spare) will be entirely procured by Japan, whereas the WP and the TF coil assembly will be shared between Japan (9) and Europe (10). The insertion process of the WP inside the coil case, VPI and final closure welding is presented with an emphasis on the R&D still remaining. An appropriate metrology strategy and correct benchmarking of the WP current center line (CCL) in the coil case external walls is essential to allow the correction of the error fields during operation. The TF coils will be assembled and pre-aligned in pairs together with their corresponding VV sector and craned to the Tokamak hall hanging from 2 independent hooks. The integration of the IF coils in the Tokamak primary datum system will have to bc accomplished within the maximum tolerances defined by the error field analysis. As-built 3D data collected during manufacture will be used to ensure the correct positioning of the CCL against the Tokamak datum system and ease the alignment process. Shimming will be used in the gravity support for vertical alignment and in the upper and lower OIS for toroidal alignment. A subsequent survey of the `as-installed' TF coils will determine the final Tokamak Datum System. [ABSTRACT FROM AUTHOR]

The demonstration and verification tests of a 500 m High-Tc superconducting (HTS) cable were carried out at the CRIEPI laboratory in Yokosuka from March 2004 to March 2005. The HTS cable consisted of a cold dielectric core with nominal capacity of 77 kV and 1 kA that had an HTS shield layer. CRIEPI and Furukawa have conducted tests for investigating the basic properties of the cable and a long-term loading test for confirming 30-year operations. Moreover, we conducted an ‘over-loading test’ and a ‘cooling system fault test’ to investigate the reliability and safety of the cable. After all field tests, the cable was dismantled and taken away from the site to Furukawa's factory for internal inspection. No Ic degradation was found in the HTS conductor, but local degradation was seen in the HTS shield. These degradations might have arisen because protective layer for the shield did not have enough thickness but were within the acceptable range of about 5%. [ABSTRACT FROM AUTHOR]

Feasibility study of Cu stabilized Nb3AI strand and Rutherford cable for the application to high field accelerator magnets are being done at Fermilab in collaboration with NIMS. The Nb3A1 strand, which was developed and manufactured at NIMS in Japan, has a non-copper Jc of about 844 A/mm² at 15 Tesla at 4.2 K, a copper content of 50%, and filament size of about 50 microns. Rutherford cables with 27 Nb3Al strands of 1.03 mm diameter were fabricated and tested. Quench tests on a short cable were done to study its stability with only its self field, utilizing a high current transformer. A pair of 2 meter long Nb3Al cables was tested extensively at CERN at 4.3 and 1.9 K up to 11 Tesla including its self field with a high transport current of 20.2 kA. In the low field test we observed instability near splices and in the central region. This is related to the flux-jump like behavior, because of excessive amount of Nb in the Nb3Al strand. There is possibility that the Nb in Nb3Al can cause instability below 2 Tesla field regions. We need further investigation on this problem. Above 8 Tesla, we observed quenches near the critical surface at fast ramp rate from 1000 to 3000 A/sec, with quench velocity over 100 m/sec. A small racetrack magnet was made using a 14 m of Rutherford cable and successfully tested up to 21.8 kA, corresponding to 8.7 T. [ABSTRACT FROM AUTHOR]

Recent progress in single flux quantum (SFQ) device technologies in Japan is described, mainly focusing on those developed in the NEDO ‘Superconductors Network Device Project’ which includes developments of both LTS and HTS devices. The advanced Nb process which consists of a planarized structure with nine Nb layers and 10 kA/cm2 Josephson junctions (JJs) has been developed. This enables fabrication of chips including 100,000 JJs and operating frequency up to 80 GHz. We have also developed the CAD tool by which one can generate SFQ circuit layouts including about 400,000 JJs from logic descriptions. For demonstration of a small-scale switch system, a 4 x 4 switch chip, a 117 Gbps multi- chip-module (MCM) technology, and a packaging technology with 32-ch 10 Gbps I/Os to an MCM have been developed. By using the multilayer process with three HTS epitaxial layers and interface- engineered ramp-edge JJs, we demonstrated operation of SFQ circuits with up to 200 JJs. A variety of elementary SFQ circuits such as a T-FF and a 1:2 switch required for an A/D converter front-end circuit have been designed based on a new layout method, and their operation at 30-50 K has been confirmed. A prototype sampler system is being developed for demonstration of bandwidth over 100 GHz for optical input signals. [ABSTRACT FROM AUTHOR]

The plasma confinement device ‘RT-1’ which had a high temperature superconducting (HTS) floating magnet was constructed for advanced high-beta plasma and fusion research at the University of Tokyo. The high temperature superconducting (HTS) floating magnet is magnetically levitated inside the plasma vacuum vessel. Plasma is confined by a magnetic dipole field around the HTS floating magnet. The HTS floating magnet is operated in persistent-current mode and it consists of an HTS coil, an HTS persistent-current switch (PCS), a pair of demountable joints of current leads, detachable joints of a cooling tube, a thermal shield and a vacuum vessel. The HTS coil and the PCS and the thermal shield are cooled below 20 K by a flow of helium gas through the cooling tube. The floating HTS magnet is designed to operate in the temperature range from 20 K to 30 K without being cooled while it is levitated. We fabricated a persistent-current HTS coil that consists of the HTS coil and the PCS. Persistent-current operations and protection tests were conducted with the persistent-current HTS coil before it was mounted in the floating magnet cryostat. The current-decay rate was 0.9% in an 8 hour operation. The coil energy was safely discharged by inducing PCS quench in a protection test. [ABSTRACT FROM AUTHOR]

Recent progress in the research and development of the TFA-MOD processing for the coated conductors in Japan was reviewed. For the higher Ic performance, the optimizations both in the calcinations and crystallization steps have taken place. Consequently, the extremely high Ic value of 413 A was achieved by the combination of the information from the above investigations and the use of highly textured CeO2 cap layered substrates. Concerning the development of long tapes, a 8.6-m-long tape with its end-to-end Ic value of 119 A was successfully grown by a reel-to-reel system. Additionally, improvement of the production rate in the calcination step was realized by designing a multi-turn system. [ABSTRACT FROM AUTHOR]

After a brief review on advanced applications of magnetic fields generated by high-Ta bulk superconductors in Japan, the outline and present status of the CREATE (Collaboration of Regional Entities for the Advancement of Technological Excellence) Iwate Project "Advanced Application of Magnetic Fields-The creation of industries based on magnetic fields application-" will be described. [ABSTRACT FROM AUTHOR]

The ITER TFIC (Toroidal Field Insert Coil), consisting of a titanium jacketed, 40 m long superconducting CICC (Cable-in-Conduit Conductor) wound on a steel mandrel, was tested at the JAERI facility, Naka Japan in 2001. The tested coil is fully equipped with voltage taps and thermometers distributed in the high field region. As the thermometer responses showed some inconsistency, a re-assessment of the performance of the ITER TFIC CICC has been carried out based on a new thermo-hydratitic model allowing the reconstruction of the cable temperature during T cs (current sharing temperature) tests. This model is a time dependent model using pressure, temperature and helium mass flow rates measured by reliable sensors attached to the facility. It includes special features such as heat exchange to the cold busbars at the electrical joints and heat exchange to the steel mandrel. A detailed description of the model is given together with the results of the conductor performance analysis carried out on TCS runs. The impact of the TFIC conductor performance assessment on the ITER TF conductor design is then derived. [ABSTRACT FROM AUTHOR]

Second generation superconducting tape made of an REBa[sub 2]Cu[sub 3]O[sub 7-δ] (RE-Ba-Cu-O) is expected to show improved magnetic field dependence and more economical production cost than that shown by the first generation one of Bi-compound tape. It consists of at least three layers: a metal layer, a buffer layer of some oxide, and a superconducting layer of RE-Ba-Cu-O. Therefore, it is called a "coated conductor." There are several choices of materials and processes when making a metal-buffer layer structure and the processing of the RE-Ba-Cu-O layer. The main difficulties in producing a long superconducting tape are that the RE-Ba-Cu-O layer grains must be in-plane aligned and any defects must not exist throughout the whole length of the tape. Several different processes to obtain the biaxially textured buffer layers or metal substrates, as well as nonvacuum process for deposition of superconducting layers and buffer layers, have been developed. At present, we have developed a coated conductor tape, 30 m in length and about 0.1 mm in thickness, by means of ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD), with J[sub c] of 0.79 MA/cm² at 77 K. This presentation will review the current status of R & D on coated conductors in Japan, which includes developments of textured metal substrates including surface-oxidation epitaxy, IBAD and inclined substrate deposition for a buffer layer, and PLD and metal organic deposition for the superconducting layer. [ABSTRACT FROM AUTHOR]

Introduces the magnet research activity and capacity of the Tsukuba Magnet Laboratory in Japan. History; Affiliations with research organizations; In-house research activities; Superconducting magnet and pulsed magnet development; Cryogenic technology; User facility.

Discusses the activities in High Field Laboratory for Superconducting Materials (HFLSM) at the Tohoku University in Sendai, Japan. High field magnets operated in HFLSM; Principal achievements and research planning; Research on magnetism, optical properties and high field physical properties.

Describes the design and test results of a cryocooled 10 T split-pair superconducting magnet with horizontal and vertical accesses for neutron scattering experiments. Magnet system; Use of the magnet at the research reactor JRR-3M of the Japan Atomic Energy Research Institute.

Japan Atomic Energy Agency has successfully developed Nb3Sn strand which fulfills ITER requirements. Because Nb3Sn is very susceptible to external strain which reduces critical current, critical temperature, and critical field, it is necessary to evaluate strain dependency of these Nb3Sn strands to confirm an ITER conductor design. An apparatus to measure the strain dependency was newly developed. It has a horseshoe-shaped ring and a strand is soldered on its outer surface. This shape produces uniform axial compressive or tensile strain along strand length by expanding or closing the opening of the ring. Critical current can be measured by the apparatus under a magnetic field up to 1ST, a temperature range of 4.2K to 15K, and strains. The maximum allowable current is about 300A. The details of the apparatus and results of strand characterization are presented. [ABSTRACT FROM AUTHOR]