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Journal Articles

Demonstration of JK2LB jacket fabrication for ITER central solenoid

Hamada, Kazuya; Nakajima, Hideo; Kawano, Katsumi; Takano, Katsutoshi*; Tsutsumi, Fumiaki*; Seki, Shuichi*; Okuno, Kiyoshi; Fujitsuna, Nobuyuki*; Mizoguchi, Mitsuru*

IEEE Transactions on Applied Superconductivity, 16(2), p.787 - 790, 2006/06

 Times Cited Count:6 Percentile:37.47(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Rapid normal zone propagation observed in a 13 T-46 kA Nb$$_{3}$$Al cable-in-conduit conductor

Koizumi, Norikiyo; Matsui, Kunihiro; Kume, Etsuo; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 15(2), p.1363 - 1366, 2005/06

 Times Cited Count:0 Percentile:0(Engineering, Electrical & Electronic)

The Nb$$_{3}$$Al Insert was developed by JAERI aiming at the demonstration of a Nb$$_{3}$$Al conductor to fusion reactor magnets. A quench test was performed on the Nb$$_{3}$$Al Insert at 13 T with various temperature margins, which are defined as a difference between current sharing temperature and operating temperature. The initial normalcy was initiated by using an inductive heater and a coil current was kept for several seconds. The normal zone propagation velocity was accelerated after 3 s from the onset of heating in case that the temperature margin was set at 0.5 K. A simulation using one-dimensional stability and quench simulation code was performed. The calculation results indicate that such rapid propagation occurred due to a temperature rise beyond a current sharing temperature because of a large pressure increase even at the location where the normal front did not reach yet. This large pressure rise was caused since the coolant was contained in the closed circulation circuit of the cooling system, which is usually applied to a large magnet cooling system.

Journal Articles

Experimental investigation on the effect of transverse electromagnetic force on the V-T curve of the CIC conductor

Nunoya, Yoshihiko; Isono, Takaaki; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 14(2), p.1468 - 1472, 2004/06

 Times Cited Count:45 Percentile:83.58(Engineering, Electrical & Electronic)

The voltage temperature characteristic curve (V-T curve) observed in the large-current Nb$$_{3}$$Sn CIC conductor, which was used in the ITER CS Insert, showed a gradual take-off toward normal state as compared with the V-T curve of an individual strand composing the conductor. The gradual take-off corresponds to the reduction in so-called "n-value." In addition, the take-off shifted to lower temperature than that of the strand, namely lower current sharing temperature (Tcs) or lower critical current (Ic). These behaviors cannot be explained by non-uniform magnetic field accompanying enlargement of the conductor, or by non-uniform contact resistance of the conductor terminals. Investigation is therefore required to clarify the condition of each strand in such large CIC conductor, especially in terms of the strain state under large electromagnetic force. In a CIC conductor, since strands are twisted to form a cable, each strand is mechanically supported by a nearby strand at an interval related to the twist pitch. Between two supporting points, the strand is fee to move under transverse force and a cyclic deformation will occur along the strand length. We designed the apparatus to simulate this cyclic deformation and measured the V-T characteristic of the strand. When the strand received the transverse force of about 500 N/m, n-value reduced to one-fifth (about 6) of the original value, which corresponds to that observed in the CS Insert. The level of the force agreed to the electromagnetic force when the CS Insert was energized to 46 kA at 13 T (about 40 A each strand $$times$$ 13 T = 520 N/m). This suggests that the transverse force acting on each strand can explain the behavior of the V-T curve of the large-current CIC conductor.

Journal Articles

Performance of joints in the CS model coil and application to the full size ITER coils

Takahashi, Yoshikazu; Yoshida, Kiyoshi; Mitchell, N.*; Bessette, D.*; Nunoya, Yoshihiko; Matsui, Kunihiro; Koizumi, Norikiyo; Isono, Takaaki; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 14(2), p.1410 - 1413, 2004/06

 Times Cited Count:10 Percentile:48.33(Engineering, Electrical & Electronic)

Cable-in-conduit conductors that consist of about 1,000 Nb$$_{3}$$Sn strands with an outer diameter of about 0.8mm, have been designed for the TF and CS coils of the ITER. The rated current of these coils is 40 -68kA. Two joint types (Butt and Lap) were developed during the CS Model Coil project. The performance of these joints was evaluated during the operating tests and the satisfied results were obtained. The joints of the TF coils are located outside of the winding in a region where the magnetic field is about 2.1T, a very low value as compared to the maximum field of 11.8T at the winding. The CS joints are located at the coil outer diameter and embedded within the winding pack due to the lack of the space. The maximum fields at the CS joint and winding are 3.5 and 13T, respectively. For the TF coils and the CS, the joints are cooled in series with the conductor at the outlet. The maximum temperature increase due to the joule heating in the joints is set at 0.15K to limit the heat load on the refrigerator. It is shown that both joint types are applicable to the ITER coils.

Journal Articles

Quench analysis of an ITER 13T-40kA Nb$$_{3}$$Sn coil (CS insert)

Inaguchi, Takashi*; Hasegawa, Mitsuru*; Koizumi, Norikiyo; Isono, Takaaki; Hamada, Kazuya; Sugimoto, Makoto; Takahashi, Yoshikazu

Cryogenics, 44(2), p.121 - 130, 2004/02

 Times Cited Count:6 Percentile:27.96(Thermodynamics)

In order to analyze the quench characteristic of a cable-in-conduit (CIC) conductor that has a sub-cooling channel at the center of conductor cross section, an axisymmetrical two-dimensional calculation model was developed. The test and calculation results of the CS insert were compared regarding the pressure drop and the behavior of the total voltage, temperature and normal zone propagation in the quench. They show good agreement. Therefore, the effectiveness of the calculation model is verified. It was also found that there is coolant convection between the central channel and bundle region even in a steady state. This makes the pressure drop in the central channel larger than that in a cylindrical pipe which has a smooth surface. In addition, it was found that the higher temperature of the coolant flowing through the central channel heats the coolant and the cable in the bundle region. It can be said that the hot coolant flowing through the central channel accelerates normal zone propagation.

Journal Articles

Effect of electromagnetic force on the pressure drop and coupling loss of cable-in-conduit conductor

Hamada, Kazuya; Takahashi, Yoshikazu; Matsui, Kunihiro; Kato, Takashi; Okuno, Kiyoshi

Cryogenics, 44(1), p.45 - 52, 2004/01

 Times Cited Count:21 Percentile:61.28(Thermodynamics)

In the ITER Central Solenoid Model Coil (CSMC) and a CS Insert Coil (CSIC) experiment, a pressure drop of the CSIC decreased by about 12% at 40 kA, 10 T and coupling losses indicated an transport current dependence. As a result of pressure drop analysis, an electromagnetic force causes a compressive deformation of cable in a jacket and a new flow passage was generated as a gap between cable and jacket. The cable deformation causes a decrease of a contact electrical resistance between strands and an increase of coupling losses. Taking account of the electromagnetic force dependency of a coupling time constant, calculated coupling losses show a good agreement with measured coupling losses at a pulsed operation of CSMC and CSIC.

Journal Articles

Evaluation of strain applied to strands in a 13T-46kA Nb$$_{3}$$Al cable-in-conduit conductor

Koizumi, Norikiyo; Nunoya, Yoshihiko; Matsui, Kunihiro; Nakajima, Hideo; Ando, Toshinari*; Okuno, Kiyoshi

Superconductor Science and Technology, 16(9), p.1092 - 1096, 2003/09

 Times Cited Count:9 Percentile:46.14(Physics, Applied)

A 13T-46kA Nb$$_{3}$$Al insert (ALI) has been developed in the ITER-EDA to demonstrate the applicability of react-and-wind technique to TF coil fabrication. Since it is estimated that a conductor is subjected to 0.4% bending strain after heat treatment when the react-and-wind method is applied, 0.4% bending strain was artificially applied to the ALI conductor. Thus, the conductor is subjected to the thermal and bending strains. The strains due to thermal stress and conductor bending are estimated from the critical current test results of the ALI to be 0.4% and 0%, respectively. The thermal strain showed good agreement with the prediction but the axial strain was not applied to the strand by the 0.4% bending. In addition, the evaluated strain of the Nb$$_{3}$$Al conductor is compared with those of Nb$$_{3}$$Sn conductors. There was an unexpected strain in the Nb$$_{3}$$Sn conductors but the one was not observed in the Nb$$_{3}$$Al conductor. One of the explanations is higher rigidity of the Nb$$_{3}$$Al strand. This shows that an Nb$$_{3}$$Al conductor is suitable to the application to large magnets.

Journal Articles

Development of a Nb$$_{3}$$Al conductor to be applied to a fusion reactor and its application to a large superconducting coil

Koizumi, Norikiyo; Okuno, Kiyoshi; Nakajima, Hideo; Ando, Toshinari*; Tsuji, Hiroshi

Teion Kogaku, 38(8), p.391 - 398, 2003/08

no abstracts in English

Journal Articles

Evaluation of the critical current performance of a Nb$$_{3}$$Al insert

Koizumi, Norikiyo; Nunoya, Yoshihiko; Takayasu, Makoto*; Sugimoto, Makoto; Nabara, Yoshihiro; Oshikiri, Masayuki*; CS Model Coil Test Group

Teion Kogaku, 38(8), p.399 - 409, 2003/08

A Nb$$_{3}$$Al insert was developed to demonstrate the applicability of a Nb$$_{3}$$Al conductor and wind-and-react method to a TF coil of a fusion reactor by artificially applying 0.4% bending strain to the conductor after its heat treatment. The critical current test results show that the effective strains applied to the strands is almost zero. Then, the validity of the react-and-wind method was demonstrated. In addition, while an unexpected strain, which was proportional to electromagnetic force, was observed in the same scale Nb$$_{3}$$Sn conductor, such strain did not exist in the Nb$$_{3}$$Al conductor. This shows a Nb$$_{3}$$Al conductor is suitable to the application to large magnets, such as the TF coil. Furthermore, the effect of the current transfer among the strands on the critical current evaluation is studied by developing a numerical analysis code, KORO. The results figure out that the critical current of a large cable-in-conduit conductor can be easily evaluated assuming the uniform current distribution if the conductance among the strands is 10E5 S/m or less.

Journal Articles

Development of the Nb$$_{3}$$Al D-shaped coil fabricated by react-and-wind method for JT-60 superconducting Tokamak

Kizu, Kaname; Miura, Yushi; Tsuchiya, Katsuhiko; Koizumi, Norikiyo; Matsui, Kunihiro; Ando, Toshinari*; Hamada, Kazuya; Hara, Eiji*; Imahashi, Koichi*; Ishida, Shinichi; et al.

Proceedings of 6th European Conference on Applied Superconductivity (EUCAS 2003), p.400 - 407, 2003/00

Toroidal field coils (TFC) of the JT-60SC consist of 18 D-shape coils. The maximum magnetic field is 7.4 T at an operational current of 19.4 kA. An advanced Nb$$_{3}$$Al superconductor was developed for the TFC conductor material in JAERI. The Nb$$_{3}$$Al has lower strain sensitivity on superconducting performances, and allows us to fabricate the TFC by react-and-wind (R&W) method that makes that the coil fabrication with high reliability becomes easier and the fabrication cost becomes lower. To demonstrate the coil fabrication by R&W method, a two-turn D-shape coil was developed. The D-shape coil was tested at 4.3-4.4K and 7-12T. Measured critical current (Ic) was 30 kA at 7.3 T and 4.4 K. Using the measured conductor and strand Ic values, the strain of the conductor was estimated to be -0.6%. The Ic-B-T characteristic expected by an empirical equation substituting this strain shows that the required temperature margin for TFC is satisfied. Thus, the R&W method was demonstrated to be the applicable fabrication method of the TFC.

Journal Articles

Critical current test results of 13T-46kA Nb$$_{3}$$Al cable-in-conduit conductor

Koizumi, Norikiyo; Takahashi, Yoshikazu; Nunoya, Yoshihiko; Matsui, Kunihiro; Ando, Toshinari; Tsuji, Hiroshi; Okuno, Kiyoshi; Azuma, Katsunori*; Fuchs, A.*; Bruzzone, P.*; et al.

Cryogenics, 42(11), p.675 - 690, 2002/11

 Times Cited Count:23 Percentile:64.85(Thermodynamics)

In the framework of ITER-EDA, a 13T-46kA Nb$$_{3}$$Al conductor with stainless steel jacket has been developed to demonstrate applicability of an Nb$$_{3}$$Al conductor with react-and-wind technique to ITER-TF coils. The critical current performances of the Nb$$_{3}$$Al conductors were studied to verify that the conductor achieves the expected performance and 0.4% bending strain does not originate degradation. The critical currents were measured at the background magnetic fields of 7, 9, 10 and 11 T at the temperatures from 6 to 9 K. The expected critical currents is calculated using the developed model and the calculation results indicate that the experimental results showed good agreement with the expected critical currents. Accordingly, we can conclude that the fabrication process of this conductor was appropriate and the applicability of the react-and-wind technique was demonstrated.

Journal Articles

Pulse charge test results of CS model coil and CS insert coil

Koizumi, Norikiyo; Isono, Takaaki; Matsui, Kunihiro; Nunoya, Yoshihiko; Ando, Toshinari; CS Model Coil Test Group

Teion Kogaku, 36(6), p.368 - 372, 2001/06

no abstracts in English

Journal Articles

AC Loss performance of CS insert coil

Matsui, Kunihiro; Nunoya, Yoshihiko; Kawano, Katsumi; Takahashi, Yoshikazu; Nishii, Kenji*; CS Model Coil Test Group

Teion Kogaku, 36(6), p.361 - 367, 2001/06

no abstracts in English

Journal Articles

Cool-down, static heat load and warm-up performance of the central solenoid model coil and the central solenoid insert model coil

Hara, Eiji*; Hamada, Kazuya; Kawano, Katsumi; Kato, Takashi; Shimba, Toru*; CS Model Coil Test Group

Teion Kogaku, 36(6), p.324 - 329, 2001/06

no abstracts in English

JAEA Reports

Study on the flow reduction of forced flow superconducting magnet and its stable operation condition

Sugimoto, Makoto

JAERI-Research 2000-069, 134 Pages, 2001/03


no abstracts in English

Journal Articles

AC loss measurement of 46kA-13T Nb$$_{3}$$Sn conductor for ITER

Takahashi, Yoshikazu; Matsui, Kunihiro; Nishii, Kenji; Koizumi, Norikiyo; Nunoya, Yoshihiko; Isono, Takaaki; Ando, Toshinari; Tsuji, Hiroshi; Murase, Satoru*; Shimamoto, Susumu*

IEEE Transactions on Applied Superconductivity, 11(1), p.1546 - 1549, 2001/03

 Times Cited Count:29 Percentile:77.56(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

AC loss performance of the 100kwh SMES model coil

Hamajima, Takataro*; Hanai, Satoshi*; Wachi, Yoshihiro*; Shimada, Mamoru*; Ono, Michitaka*; Martovetsky, N.*; Zbasnik, J.*; Moller, J.*; Takahashi, Yoshikazu; Matsui, Kunihiro; et al.

IEEE Transactions on Applied Superconductivity, 10(1), p.812 - 815, 2000/03

 Times Cited Count:10 Percentile:53.66(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

An Evaluation of the inlet flow reduction for a cable conduit conductor by rapid heating

Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Nishijima, Gen; Matsui, Kunihiro; Nunoya, Yoshihiko; Takahashi, Yoshikazu; Tsuji, Hiroshi

Cryogenics, 39(11), p.939 - 945, 1999/11

 Times Cited Count:3 Percentile:18.96(Thermodynamics)

no abstracts in English

Journal Articles

Fabrication of ITER central solenoid model coil-outer module

Ando, Toshinari; Hiyama, Tadao; Takahashi, Yoshikazu; Nakajima, Hideo; Kato, Takashi; Sugimoto, Makoto; Isono, Takaaki; Kawano, Katsumi; Koizumi, Norikiyo; Hamada, Kazuya; et al.

IEEE Transactions on Applied Superconductivity, 9(2), p.628 - 631, 1999/06

 Times Cited Count:8 Percentile:51.58(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Quasi-two-dimensional numerical model for stability simulation of a cable-in-conduit conductor

Koizumi, Norikiyo; *; K.Macfall*; Matsui, Kunihiro; Takahashi, Yoshikazu; Tsuji, Hiroshi

Cryogenics, 39(6), p.495 - 507, 1999/00

 Times Cited Count:4 Percentile:23.86(Thermodynamics)

no abstracts in English

41 (Records 1-20 displayed on this page)