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The disposal of 2011 Japan earthquake waste has become an important issue in Japan and it is not realistic or economical to send all of these wastes to landfill sites, due to limited space, high costs, and related environmental issues. In sustainable geotechnical applications, mixing of the separated soils from disaster wastes with additives (e.g., cement and fiber) is required to improve their strength and stiffness characteristics. In this study, monotonic triaxial drained compression tests are performed on medium dense specimens of Toyoura sand-cement-fiber mixtures with different percentages of fiber and cement (e.g., 0&ndash, 3%) additives. The experimental results indicate that behavior of the mixtures is significantly affected by the concentration of fiber and cement additives. Based on a comprehensive set of test results, modifications to the series of equations were developed that can be used to evaluate the shear modulus and mobilized stress curves at small-strain levels. The experimental results and model comparison show that the elastic threshold strain (&gamma, e), reference strain (&gamma, r), increases with fiber and cement additives. In addition, the range of curvature parameter, from 0.88 to 1.0, provides a good comparison with the results of small-strain measurements. Overall, the comparison of the results and model shows that the small-strain measurements obtained using local strain transducers fall within the range of model upper and lower bound curves. The results of the unreinforced, fiber, and cemented sand shows a close agreement with the model mean curve, but fiber-reinforced cemented sand shows a good comparison with model upper bound.

We have investigated the influence of self-field on the critical current density distribution in a Bi-2223 tape and its effect on the current capacity of an assembled conductor. Critical current of a tape is usually measured by four-probe transport method under self-field. On the other hand, the critical current of an assembled conductor cannot be simply summed because the tape experiences different condition of magnetic field due to the interaction among the tapes. To quantify the situation, it is necessary to clarify first how the critical current of a tape is determined at the self-field and then to consider the interaction among the tapes. In this study, it was found that the distribution of critical current density was largely influenced by local magnetic field inside the tape. The results were quantitatively described by a model considering the position dependence and magnetic field dependence of local critical current density. Using such a quantitative model, we numerically investigated the current capacities of assembled conductors with different arrangements of the tapes.

This study aims at investigating the impact of recycling by-product plasterboard wastes (gypsum and bassanite) with asphalt mixtures by replacing partly the filler portion of the asphalt mixtures with pulverised plasterboard wastes in order to contribute to non-toxic and good urban environment on one hand and improve, or at least retain, the design mechanical properties of the resulting asphalt concrete mixture on the other. The study was based on series of wheel tracking tests which successfully proved the possibility of mixing recycled plasterboard wastes with asphalt mixtures. The tests results showed that asphalt samples of 40% gypsum-filler ratio and asphalt samples of 40% bassanite-filler ratio as well gave the maximum resistance to plastic deformations and hence maximum dynamic stabilities. As a result, this research has shown that mixing of plasterboard wastes with asphalt concrete mixtures in specific quantities is promising.

We have designed and fabricated a 3-T Magnetic Resonance Imaging (MRI) magnet system for the human brain, which was wound with Bi-2223 tape conductors. The magnet was successfully energized to 1.5 T and then up to 3.0 T. The magnet experienced more than 60 ramp-up and down processes to 1.5 T with no trouble. A magnetic field of 3.0 T (184.8 A) could be maintained for longer than 3 h without any problems. However, abnormal voltage behavior was observed during the ramp down for the third trial to 3.0 T, and the temperature rapidly increased with a ramping rate of 1.7 K/min. To investigate the cause, we opened the cryostat and inspected the inside of the magnet. In addition, we have analyzed the details of this event using the recorded current, voltage, and temperature data. The purpose of this paper is to report the investigation of this abnormal event in the magnet.

We have proposed a transformer-type SFCL of a re-wound structure, which can produce a limiting reactance (L-limiting) for smaller fault current and, for larger one, additively give a limiting resistance (L + R limiting). The single-phase proposed model SFCL had been tested and shown good limiting characteristics and excellent recovery performance. A 3-phase tri-axial SFCL of the proposed type had been designed and made using BSCCO2223. This paper describes demonstration tests of the model SFCL carried out using a lab-scale one-machine infinite bus transmission model system. The experimental results on the current limiting performance of the SFCL at the 3-line-to-ground (3LG) fault were shown and discussed. The peak fault current 560 A without SFCL was reduced to 230 A with SFCL immediately. The 3-phase SFCL successfully worked without large inter-phase interaction. The SFCL recovered to the stand-by mode under a typical Circuit Breaker (CB) operation sequence.

Sumitomo Electric has been developing the silver-sheathed Bi2223 multi-filamentary wires since the discovery of Bi-based superconductors. DI-BSCCO (Dynamically-Innovative BSCCO) is the high performance wires produced with the controlled-overpressure (CT-OP) sintering technique. The recent R&D activities have enabled to produce the 1000 m-long wires with I c of 200 A and the maximum I c reached 250 A at 77 K by short sample. Besides, the fine control of the carrier density with the non-stoichiometric oxygen enhanced the in-field I c performances at lower temperature. At a magnetic field of 3 T applied normal to wire surface, the I c of 280 A at 30 K, and 420 A at 20 K were successfully achieved. To meet the growing needs for various high temperature superconducting applications, Type HT wire with high mechanical strength and Type G wire with low thermal conductivity have been developed.

The design and safety analysis for miniature heat exchangers, the cooling system of high performance microelectronics, research nuclear reactors, fusion reactors and the cooling system of the spallation neutron source targets requires the knowledge of the gas–liquid two-phase flow in a narrow rectangular channel. In this study, flow measurements of vertical upward air–water flows in a narrow rectangular channel with the gap of 0.993 mm and the width of 40.0 mm were performed at seven axial locations by using the imaging processing technique. The local frictional pressure loss gradients were also measured by a differential pressure cell. In the experiment, the superficial liquid velocity and the void fraction ranged from 0.214 m/s to 2.08 m/s and from 3.92% to 42.6%, respectively. The developing two-phase flow was characterized by the significant axial changes of the local flow parameters due to the bubble coalescence and breakup in the tested flow conditions. The existing two-phase frictional multiplier correlations such as Chisholm (1967), Mishima et al. (1993) and Lee and Lee (2001) were verified to give a good prediction for the measured two-phase frictional multiplier. The predictions of the drift-flux model with the rectangular channel distribution parameter correlation of Ishii (1977) and several existing drift velocity correlations of Ishii (1977), Hibiki and Ishii (2003) and Jones and Zuber (1979) agreed well with the measured void fractions and gas velocities. The interfacial area concentration (IAC) model of Hibiki and Ishii (2002) was modified by taking the channel width as the system length scale and the modified IAC model could predict the IAC and Sauter mean diameter acceptably.

In this paper, we simulate the effects of eddy currents induced by switched gradient coils in the cylindrical cryostat structures of a high-temperature superconducting (HTS) magnetic resonance imaging magnet. A novel network method was used with spectral decomposition of the current density in the φ- and z-directions to simulate the effects of X-gradient coils. Two types of active magnetic shielding were simulated, and it was found that one type is able to reduce the power of the eddy currents in the cryostat to a greater extent than the other. These results will inform the design of gradient coils that protect the HTS magnet from eddy-current-induced heating and vibrations.

Sumitomo Electric has been developing the silver-sheathed Bi2223 multi-filamentary wires since the discovery of Bi-based superconductors. DI-BSCCO is the high performance wires produced with the controlled-overpressure (CT-OP) sintering technique. The present commercial DI-BSCCO can provide the uniform high critical current, I c , up to 180 A over 2000 m, and recently 200 A were succeeded to obtain with the same kind of 1000 m-long wires, resulting from the improvement and control of the microstructure in Bi2223 multi-filaments. The short trial wires of several meter have exhibited over 240 A as the highest I c at 77 K, self-field (corresponding to 580 A per 1 cm-width) according with high T c over 112 K. Besides, the optimization of carrier density after CT-OP led to further enhancement of I c , reaching 250 A. All the derivative products have also uniform critical current property over the entire length even after lamination with the reinforcements. The performances of DI-BSCCO can meet the growing needs for various high temperature superconducting applications involving high in-field properties, such as magnets and motors. The recent progress on I c including in-field properties along with the remarkable findings on the performances of DI-BSCCO will be shown.

Recently, we have updated the highest J c and I c at 77 K, self-field, for our R&D short length tapes and I c × L at 77 K, self-field, for our kilometer-length manufacturing product. For our short length R&D tapes, we have updated the I c to 236 A. The highest J c has reached 663 A/mm 2 . Furthermore, we have broken our own world record performance of I c × L with the production of a 4.2 mm wide, 2084 m long Bi wire that carries an average current of 176 A. This has resulted in a new record—high wire performance of 367 k Am.

The critical current property of Bi 2 Sr 2 Ca 2 Cu 3 O x (Bi-2223) silver-sheathed tape has been remarkably improved by application of ConTrolled Over Pressure (CT-OP) process with adjusting temperature and oxygen partial pressure. For further improvement of the property of Bi-2223 tapes, the effect of number of filaments on the critical current density Jc was investigated. It was found that Jc was higher and its decrease with increasing magnetic field was weaker in the tape with larger number of filaments. In addition, the irreversibility field Bi increased with increasing filament number. The field-angle anisotropy Jc(0°)/Jc(90°) of the tape with the largest filament number was smallest, where the field-angle was measured from the a–b plane. However, the out-of-plane misorientation angle is fairly small in this tape. Hence, the low field-angle anisotropy in this tape seems to be attributed to improved superconductivity in the block layers in the superconducting region near the interface with silver matrix.

We are developing a cryogen-free high temperature superconducting (HTS) magnet system for a compact 3T MRI system for human brains. In the conceptual design, the magnet system consists of 5 main coils that are layer windings of Bi-2223 tapes. The magnet system will have 500 mm room temperature bore and be operated at 20 K using G-M cryocoolers. The target field is 3 T ±5 ppm for 250 mm (dia,) and 200 mm (length) volume. All the coils will be connected in series and operated in driven mode. Controlled overpressure (CT-OP) processed Bi-2223/Ag tapes which are reinforced with Cu-alloy laminations are to be used for these coils. We investigated Ic-B-T performance in detail for short samples of the tape. We fabricated and tested five small layer-wound coils using the tape (38.4 ~ 46.2 m piece for each coil). Each small coil could be energized up to its expected current that was calculated using the short sample performance and the coil parameters. The maximum electromagnetic force (hoop stress) reached 137 MPa, and caused no degradation in the coil performance. These results show that our layer-winding techniques and the conductor performance (Ic-B-T and homogeneity along length) can be applicable and suitable for our 3T MRI magnet.

The DI (dynamically innovative)-BSCCO-Bi2223 tapes achieved high critical current as well as high modulus of elasticity. Further the reversible strain limit and the corresponding stress for critical current have been remarkably increased by means of lamination technique. During the course of development, their optimized architecture has been designed based on the principle of the rule of mixture for maximizing the force free strain exerted on the superconducting component. The reversible strain/stress limit (A rev/R rev) was defined as a strain, at which the critical current recovers to the level of 99% I co. Selecting several kinds of laminating materials and changing condition of the fabrication, the excellent Cu alloy-3ply tape with I co of 311 A/cm was realized of which A rev and R rev reached 0.42% and 300 MPa, respectively. Further during the theoretical analysis, the increase of reversible strain limit were made clear to be attributed to the increase of thermally induced residual strain as well as the compensation effect of laminated layers against a local fracture mode.

Electrical and mechanical characteristics of Type HT tape, which is standard 4.2 mm wide DI-BSCCO tape reinforced with metallic tapes, have been evaluated. Longitudinal distributions of critical current and n-index in kilometer long Type HT tape has proved uniform from end to end just like the original insert tape, which is Type H tape. Type HT-CA reinforced with 50 mum thick heat-resistant copper alloy is highly balanced tape with high mechanical properties and low splice resistance. Type HT-SS reinforced with 20 mum thick stainless steel has the best mechanical properties, which has been demonstrated under the actual environment in high field magnet, namely the hoop stress load test energizing a one-turn coil in external high magnetic field and liquid helium.

The critical current property of Bi-2223 silver sheathed tape has been significantly improved by application of ConTrolled Over Pressure (CT-OP) process with adjusting temperature and oxygen partial pressure at the final heat treatment. In this paper, the field-angle dependence of the critical current density was measured at 77.3 K and the crystalline misorientation angle was estimated for four specimens with different critical current densities. It is found that in a parallel magnetic field, the critical current density of the latest Bi-2223 tape of 190 A class is remarkably higher than the other specimens over a wide region of magnetic field. On the other hand, although the critical current density of the latest tape in a normal magnetic field is higher than the other specimens, the difference is relatively small especially at high magnetic fields. Thus, the field-angle anisotropy of the latest tape is higher than the other specimen. The observed results can be explained by the improved condensation energy density and the better c-axis alignment in the latest tape.

DI-BSCCO, the commercial BSCCO tapes produced by Sumitomo Electric with the controlled-overpressure sintering technique, has been progressing in the performance for increasing expansion of high temperature superconducting applications. Type H as the most common product has recorded 218 A as the highest critical current in 77 K, self-field, which is corresponding to 500 A per 1 cm width. Now it can provide both long-length and uniform high critical current up to 180 A as commercial products. Type S offers high overall critical current density similar to Type H and half cross-sectional area and the narrower width around 2.5 mm. It gives low price and compact size as a benefit to the applications operated with the relatively smaller current. Type AC offers low AC loss which is produced by application of the narrow width similar to Type S and twisted multi-filaments. All the products have achieved long-length more than 1 km and uniform critical currents over the entire length of the tapes. Mechanical toughness comes from metallic tape lamination technique applicable to all DI-BSCCO family as an optional extra. A 3-ply tape of one Type H and two thin stainless steel tapes provides high rated tensile stress more than 300 MPa and high current density more than 13 kA/cm2 in 77 K. Alternative brass or copper laminated tape brings about lower electric resistance under overload current. It is possible to produce an order-made tape under consultation, which exhibits excellent manifold abilities on critical current, AC property as well as mechanical properties.

Performance of the high temperature superconductor (HTS) is rapidly progressing and applications of the HTS are also improving. Significant enhancements in Jc in Bi2223 long wires have been achieved. The wires produced by Sumitomo Electric Ind., are named DI-BSCCO (Dynamically Innovative bismuth-based HTS wire). A cryo-cooled high-field high-temperature superconducting (HTS) magnet, which is made of this DI-BSCCO and has a room-temperature bore of 200 mm in diameter, has been developed and tested up to 8.1 T. The design study of the magnet using the latest DI-BSCCO shows that the higher magnetic field can be produced with almost the same size of the magnet. This magnet can also be used in various industries such as bio-medicine, semiconductor and environmental industries.

Recently, due to the controlled overpressure (CT-OP) sintering technique, performances such as critical current, n-value, unit-length and mechanical strength of Ag sheathed (Bi, Pb)2Sr2Ca2Cu3Ox (Bi2223) tapes were significantly enhanced. In order to investigate the origin of these improvements, we evaluated the distribution of the superconducting properties inside the tape along the width. We selected several kinds of CT-OP processed Bi2223 tapes and each tape was divided into three parts (one central part and two edge parts). We performed transport (critical current Ic) and magnetic (susceptibility) measurements. We found that a slight inhomogeneity in superconducting properties still remains even in the highest performance tape, whose Ic is about 200 A at 77 K. Critical current densities Jc are lower at the edge part than those of the central parts. These results indicate that we can expect and achieve further improvements of CT-OP processed Bi2223 tape by enhancing the performance of the edge parts of the tape.

Improvement of critical current properties of well-developed Bi(Pb)2223 superconducting tapes has been still important subject for their extensive applications. On the other hand, enhancement of J c up to applicable level at 15–20 K in ∼5 T is crucial for starting full-scale development of MgB 2 materials. In this paper, we propose several effective methods to improve critical current properties of both Bi(Pb)2223 and MgB 2 conductors mainly from chemical viewpoints. In particular, T c of Bi(Pb)2223 was found to be largely enhanced by post-annealing in air. For MgB 2 , a promising guiding principle for improving flux pinning properties has been just established through various systematic studies.

The hot topics of the critical current properties in YBCO coated conductors and Bi-2223 silver-sheathed tapes are discussed. The dependence of the critical current density in YBCO coated conductors on the superconducting layer thickness is partly associated with the defects nucleated in thicker films and is also caused by the thickness dependent influence of the flux creep. Experimental results on PLD processed conductors with different thicknesses are compared with the theoretical analysis based on the flux creep-flow model. A discussion will also be given for the optimum layer thickness for applications. In Bi-2223 tapes introduction of CT-OP (ConTrolled Over Pressure) process has significantly improved the critical current properties. This progress can be attributed to the improvement of the mean value of the flux pinning strength and the decrease in its distribution width. The possibility of further improvement of the critical current properties is discussed using the flux creep-flow model.

Investigation is done on the effect of ConTrolled Over Pressure (CT-OP) processes on the critical current properties in multifilamentary Bi-2223 tapes. It is found that the critical current density at low magnetic fields is remarkably improved by the new CT-OP process. This result with those on irreversibility field and n-value are compared with the numerical calculation based on the flux creep and flow model. The analysis reveals that the most probable value is increased, although the statistical distribution width is increased for the flux pinning strength. This result indicates that the critical current density at high magnetic fields is deteriorated by the widened distribution. If such an inhomogeneity can be reduced to the level of previous tapes by improving the CT-OP process, the high field performance is shown to be significantly improved.

We have developed high performance silver sheathed Bi2223 wire. The progress in three years is especially remarkable. This dramatic development has been made with the controlled overpressure (CT-OP) sintering technique. The CT-OP sintering technique improves not only the critical current but also other performances such as n-value and mechanical strength, because of the improvement of the relative density up to almost 100%, the homogenization of the Bi2223 phase and the stronger connectivity between the Bi2223 grains. The dense Bi2223 wire prevents the ballooning phenomenon which is caused by the gasification of the trapped liquid nitrogen during warming up to room temperature. Present critical current has reached as about twice high as that in those days and shows over 200 A (77 K, self-field), which showed an excellent critical current property in a magnetic field.

Silver-sheathed Bi-2223 multi-filamentary tapes using controlled-overpressure sintering have attained the highest critical current of 200 A-class at 77 K, self field. The 200 A-class Bi-2223 tape has been evaluated on the critical currents at various temperatures from 4.2 K to 90 K and magnetic fields up to 12 T applied perpendicularly to the tape plane. The critical currents are 500 A at 4.2 K, 5 T, 370 A at 20 K, 3 T and 200 A at 20 K, 10 T typically. This is an improvement by a factor of 1.3-1.5 compared to current commercial tapes produced using controlled-overpressure sintering.

(Ho1Ba2Cu3Ox) (HoBCO) coated conductors on textured Ni-alloy substrates were developed by using pulsed laser deposition (PLD). Hetero-epitaxial growth of CeO2/YSZ/CeO2 was used to introduce in-plane alignment for buffer layers. CeO2 seed and cap layers were deposited by RF sputtering. YSZ diffusion layer was deposited by PLD. The most advantage of these buffer layers are high growth rate and large deposition area by using textured substrate. As for the HoBCO deposition, a production speed of 20 m/h with growth rate of 2-3 mum per minute was demonstrated in our PLD process. By optimizing the deposition temperature, lc and Jc of the short samples reached 265 A/cm-width and 5.6 MA/cm2 at 77 K, 0 T, respectively. Long length HoBCO conductors over 200 m were performed by using reel to reel tape transfer system of each process.

The Albany project has installed a high temperature superconducting (HTS) cable with a 350 m length in 34.5 kV and 800 Arms in the real power grid of the National Grid Power Company. The type of the cable is a 3 cores in a cryostat. Bi-2223 wires manufactured with SEI new sintering method, CT-OP, is used as both superconducting conductor and shield. The Cable was manufactured and shipped to the Albany test site after passing various tests such as Ic measurement, voltage tests, pressurized tests, and so on. Cable installations into a 320 m long conduits and a 30 m long conduit under ground was completed successfully. The cable was pulled with 2.5 ton tension, which is within its allowable limit. A joint between the 320 m cable and the 30 m cable was assembled in an underground vault. Cable terminations were also assembled at both ends of the cable. After all of the installation, the initial cooling was conducted successfully and then in-grid operation was started on July 20th in 2006 after confirmation of cable performance.

A highly efficient enrichment of thin double-wall carbon nanotubes (DWNTs) having an average outer diameter of ca. 1.4 nm by thermal oxidative purification has been reported. Thin DWNTs of ca. 1% with respect to single-wall carbon nanotubes (SWNTs), which are synthesized by catalyst-supported chemical vapor deposition (CCVD) on zeolite supports, are enriched up to ca. 90% (vs SWNTs) by thermal oxidation in air. The present thin DWNTs grown on zeolite are several hundreds of times as resistant as SWNTs toward the oxidation at 700 °C. When oxidative purification is applied for DWNTs with larger diameters, the amount of DWNTs lost during the purification process is large compared to thinner DWNTs lost. The present oxidative purification is much more effective for thin DWNTs with diameters smaller than 2 nm.

Materials for paving on the pedestrians-friendly pavements, which are constructed as the pavements and the promenade in parks, attracts attention, because it is welcomed as eco friendly method considered recent global warming. On the other hand, under the recent influence of rising crude oil price, the demand of thermal power generated by coal has been growing, causing a large amount of coal fly ash. However as securing the large scale of disposal site has been getting more difficult, widening effective utilization of coal ash has become a fairly critical theme. Considering those conditions, this study concludes the properties of the strength of materials using two types of coal ash, PFBC and FA. And then we tried to improve the vulnerability by adding the wasted bamboo crashed to the chip state as a step against the crack. The main conclusions are summarized as follows: 1) Materials added PFBC ash has prominent congealment effect, compared with material added FA ash. 2) In case of using of FA ash, it is possible for the material to gain the higher strength than the PFBC's at the same level, by mixing cement. 3) Destruction due to vulnerability is restrained by mixing 10 percent bamboo chips.

At the J-PARC, to deliver bunches of protons to both of beam transport lines, 3NBT and 3-50BT, a pulsed bending magnet (PB) [1] is operated. Bunches between K1 and K4 timing are bended to 3-50BT, and the other bunches through the PB to 3NBT after the magnetic field is fallen down. The rise and fall time of the pulsed bending magnet was designed as less than 40msec because the interval time of bunches is 40msec. However the residual magnetic field after K4 has been observed as equal to 0.27mrad kick angle at K5 as shown in Fig1. Therefore, bunches at K5, K6 and K7 have not been filled to avoid time depended beam orbit shift at the target of Material and Life Science Experimental Facility (MLF). If the residual field of PB is corrected, the production beam power for the MLF will be higher with K5, K6 and K7 bunches. To reduce the PB residual field, additional coils have been wound to poles of the PB, and a power supply has been installed. Results of the beam study by using the additional correction coil will be reported in this paper.

Carbon nanotubes with 1–6 walls have been grown on cobalt-loaded mesoporous silica (i.e., MCM41) by using acetylene catalytic chemical vapor deposition. It is found that titanium grafting on the MCM41 pore walls prior to cobalt loading promotes the growth of nanotubes with 1–6 walls. As-grown nanotube material is found to be a mixture of single-wall carbon nanotubes (SWNTs), double-wall carbon nanotubes (DWNTs) and thin-multiwall carbon nanotubes (t-MWNTs) with 3–6 walls. Annealing of the as-grown nanotubes has reduced the amount of SWNTs in the nanotube mixture. Several structural deformations of the t-MWNTs are observed during transmission electron microscopy (TEM) analysis. Complete or partial collapse of the t-MWNTs is also found due to these structural deformations. Graphite-like domains developed at the collapsed regions stabilize these structural deformations.

The critical current properties of a superconducting Bi-2223 tape produced by the over pressure processing at the final heat treatment were investigated. The critical current density increased more than the factor of densification of the superconducting region. In addition, the irreversibility field also increased. This means that the quality of flux pinning is improved by the new process. From the numerical calculation based on the flux creep and flow model, it is speculated that the fraction of weakly pinning regions decreases due to the improved connectivity of grains.

Up to this day, Ag-sheathed Bi2223 superconducting wires have been widely investigated and the long wires about 1000 m have been produced by using powder-in-tube (PIT) method on a commercial basis in the various facilities or companies. Although the wires are used for some applications such as HTS cables, magnets, motor and so on, the Bi2223 wires not only require much more improvements of the superconducting properties such as critical current, mechanical properties, but also longer and more uniform wires. Recently, the performances of Bi2223 wires have been drastically improved by using Controlled Over Pressure (CT-OP) sintering process. CT-OP process increased critical current ( I c ) by more than 60% at 77 K and self field and improved the mechanical strength by more than 70%. The maximum I c was increased up to 166 A. These drastic improvements were caused by the higher density of Bi2223 filament up to almost 100% and better connectivity of the Bi2223 grains. The dense structure of the Bi2223 filaments prevents the ballooning phenomenon which is caused by the gasification of the trapped liquid nitrogen during temperature rise. Additionally, higher uniformity and higher production yield of long length wire were also achieved by exterminating defects during sintering. These high performance levels in CT-OP wires have contributed commercial level applications. We call as Drastically Innovative BSCCO (DI-BSCCO).

Critical current properties in Bi-2223 superconductor were investigated in detail for silver-sheathed tapes fabricated by the usual process in a normal pressure, the previous controlled over-pressure (CT-OP) process and the recently improved CT-OP process at the final heat treatment. It was shown that the critical current density, the irreversibility field and the n-value were remarkably improved by application of the CT-OP process. The results were analysed using the flux creep-flow model to seek the reason for the improvements. It was found that the grain connectivity and the flux pinning strength were improved by the previous and recent CT-OP processes, respectively. The possibility of further improvements of the critical current properties in Bi-2223 tapes is discussed.

Experimental conditions that govern the double-wall carbon nanotube (DWNT) growth during alcohol catalytic chemical vapor deposition (CCVD) have been optimized for mesoporous silica (MCM41) support materials. Catalyst pretreatment and preparation methods influence the quality of as-grown carbon nanotubes (CNTs). Catalyst pretreatment at low pressure leads to high-quality CNTs concomitant with an increase in the DWNT yield. Impregnation of metal precursors using methanol as the solvent is found to be more suitable than the aqueous solution. Influence of the precursor anion/metal ion on the DWNT yield is also studied under these optimized conditions. Thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and Raman spectroscopic methods have been employed to estimate the quality of the CNTs. It is observed that the present optimized method yields high-quality DWNTs with low amounts of side-wall defects and other carbon impurities.

Effect of the over pressure processing on the distribution of the critical current density in mono-core tapes was measured in detail using Campbell's method. It was found that the magnetic flux profile is more straight in the over-pressured specimen, suggesting that the critical current density is more uniform. This seems to be partly caused by the improved uniformity of the thickness due to the disappearance of voids and the reduction in sausaging of superconducting layer by application of the over pressure. The possibility of the further improvement of the critical current density is discussed

Double-wall carbon nanotubes (DWNTs) have been selectively synthesized by catalytic chemical vapor deposition of alcohol over Fe/Co loaded mesoporous silica. The as-grown carbon nanotubes are purified using a multi-step process involving heat treatment in air followed by alkali and acid treatments. The nanotubes are characterized as-grown and after each step of the purification stage by thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. It is observed that most of the mesoporous silica and metal particles have been removed from the as-grown nanotubes by these treatments. The carbon content of the nanotube material obtained after the purification is found to be more than 90 wt%.

A three-in-One HTS cable has been developed. Its cable core is composed of a conductor and a shield wound with BSCCO wires and electrical insulation of the PPLP. The three cable cores are covered in thermal insulated stainless corrugated pipes. Recently, BSCCO wires were drastically innovated by virtue of a newly developed process named as Controlled Over-Pressure (CT-OP). As a new cable technology, a 350m thermal insulation pipe was tested for 7 months to find that a life of the vacuum property is more than 10 years. The HTS cable with tension members was designed for installation into an underground duct. In addition, a fault current of 23kA, 0.63sec, was applied to a sample cable with no damage on the BSCCO wires and the cable insulation. These technologies will be applied to Albany project in USA.

We studied the influence of the high isostatic pressure and critical current density in Bi2223 long length wires. Heat treatments of Bi2223 wire were carried out using controlled over-pressure sintering process. The controlled over-pressure sintering process allows Bi2223 wires to have higher Ic by more than 30%, because the process increase the relative density up to almost 100% resulting in higher phase purity, higher grain alignment and better grain connectivity than those made with a conventional normal pressure sintering process. Densification of the Bi2223 wire prevents liquid nitrogen penetration during long term exposure to liquid nitrogen of it for use in power cable applications. The ballooning, which the trapped nitrogen expands and forms after Bi2223 wire was warmed to room temperature, does not occur in the controlled over-pressure sintering processed wire. These high performance levels in long length Bi2223 wires have enabled commercial level products and projects such as power cables, magnets and many others.

The Albany Project plans to install a 350 m High Temperature Superconducting (HTS) cable in the power grid of the Niagara Mohawk Power Company to carry 800 Arms at 34.5 kV. The type of the cable has 3 HTS cores in one cryostat with Bi-2223 used for HTS conductor and shield layers. The three cores are housed within double SUS corrugated pipes which provides thermal insulation. The tapes are manufactured with a new innovative sintering method with controlled over pressure (CT-OP) technology. Polypropylene laminated paper (PPLP) is used as electrical insulation. The cable will be installed in long underground conduit. A cable joint will be made in an underground vault to connect a 30 m length of the cable with the remaining 320 m. The original Bi-2223 30 m cable will be replaced with a 30 m YBCO cable after long-term operation. The terminations at both ends of the cable will have three bushings in a cryogenic vessel. Typical performance evaluation experiments, such as cable bending tests, voltage tests, and fault current tests, have been conducted with sample cables to check the design. Voltage tests for 69 kV AC and 200 kV impulse were successfully applied to a 5 m cable in accordance with the Association of Edison Illuminating Companies (AEIC) code of 35 kV class cable. The cable will be manufactured and installed in 2004 and 2005, then, long-term operation will be started.