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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:38.57(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

From CS and TF model coils to ITER; Lessons learnt and further progress

Okuno, Kiyoshi; Nakajima, Hideo; Koizumi, Norikiyo

IEEE Transactions on Applied Superconductivity, 16(2), p.880 - 885, 2006/06

 Times Cited Count:10 Percentile:50.7(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

A New model to simulate critical current degradation of a large CICC by taking into account strand bending

Koizumi, Norikiyo; Nunoya, Yoshihiko; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 16(2), p.831 - 834, 2006/06

 Times Cited Count:24 Percentile:72.52(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Manufacturing study and trial fabrication of radial plate for ITER toroidal field coil

Abe, Kanako*; Nakajima, Hideo; Hamada, Kazuya; Okuno, Kiyoshi; Kakui, Hideo*; Yamaoka, Hiroto*; Maruyama, Naoyuki*

IEEE Transactions on Applied Superconductivity, 16(2), p.807 - 810, 2006/06

 Times Cited Count:11 Percentile:53.12(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Stress analyses of the support structure and winding pack of the superconducting TF coil in National Centralized Tokamak

Tsuchiya, Katsuhiko; Kizu, Kaname; Takahashi, Hiroyuki*; Ando, Toshinari*; Matsukawa, Makoto; Tamai, Hiroshi

IEEE Transactions on Applied Superconductivity, 16(2), p.922 - 925, 2006/06

 Times Cited Count:1 Percentile:12.39(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Control and instrumentation for the ITER magnet system

Yoshida, Kiyoshi; Takahashi, Yoshikazu; Iida, Hiromasa

IEEE Transactions on Applied Superconductivity, 16(2), p.775 - 778, 2006/06

 Times Cited Count:1 Percentile:12.39(Engineering, Electrical & Electronic)

The ITER superconducting coil system consists of 18 TF coils, 6 PF coils, 6 CS modules, 18 Correction Coils and their feeders. An extensive measurement and control system is required to monitor and to control these coils and feeders for safety and optimal operational availability. For each coil, both current and helium are supplied from external systems and are controlled from a central control system that manages flow distribution at each cooling pass to smooth the cryoplant loads by a virtual model of the coil thermo-hydraulic system. Quench detection is provided as stand alone system. Monitoring of the electric insulation system inside the coils is performed to detect incipient problems before serious damage. The ITER will procure directly all sensors, wires, electrical insulation breaks and cryogenic components for all the coils and feeders to a common specification. This will avoid duplication of qualification work and guarantee a common interface. This paper introduces the requirements and specifications of the control and instrumentation for the ITER magnet system.

Journal Articles

Effects of tensile and compressive strain on critical currents of Nb$$_{3}$$Al strand and cable-in-conduit conductor

Kizu, Kaname; Tsuchiya, Katsuhiko; Shimada, Katsuhiro; Ando, Toshinari*; Hishinuma, Yoshimitsu*; Koizumi, Norikiyo; Matsukawa, Makoto; Miura, Yushi*; Nishimura, Arata*; Okuno, Kiyoshi; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.872 - 875, 2006/06

 Times Cited Count:1 Percentile:12.39(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Simulation of quench tests of the central solenoid insert coil in the ITER central solenoid model coil

Takahashi, Yoshikazu; Yoshida, Kiyoshi; Nabara, Yoshihiro; Edaya, Masahiro*; Mitchell, N.*

IEEE Transactions on Applied Superconductivity, 16(2), p.783 - 786, 2006/06

 Times Cited Count:9 Percentile:48.15(Engineering, Electrical & Electronic)

To investigate the conductor behavior during a quench, quench tests of Center Solenoid (CS) insert coils were carried out with various initial conditions in DC and pulse modes. The conductor has very similar configuration and parameters. The inductive heater, attached at the center of the length, initiated an artificial quench in DC mode. A quench has also occurred during the pulse operation with the ramping rate of 0.4-2 T/s. Simulations of electric, thermal and hydraulic behaviors of the conductor during the quench tests in both modes were carried out by using the thermohydraulic simulation code. The experimental results were compared with the simulation and good agreement was obtained. These results are described and the implication for quench detection in ITER is discussed in this paper. The voltage tap method will be used for the quench detection for the CS, and the sensitivity of the detection and the maximum temperature of the conductor during a quench are described. It is shown that the detection system could be designed with high enough detection sensitivity.

Journal Articles

Poloidal field coil configuration and plasma shaping capability in NCT

Matsukawa, Makoto; Tamai, Hiroshi; Fujita, Takaaki; Kizu, Kaname; Sakurai, Shinji; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; Ando, Toshinari; Miura, Yushi

IEEE Transactions on Applied Superconductivity, 16(2), p.914 - 917, 2006/06

 Times Cited Count:4 Percentile:30.34(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Magnetic field measurements, 3D field calculation and heat measurements of a prototype thick septum magnet for 3 GeV rapid cycling synchrotron of J-PARC

Watanabe, Masao; Irie, Yoshiro; Kamiya, Junichiro; Shimada, Taihei; Takayanagi, Tomohiro; Suzuki, Hiromitsu; Watanabe, Yasuhiro; Kawakubo, Toshimichi*

IEEE Transactions on Applied Superconductivity, 16(2), p.1354 - 1357, 2006/06

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

Septum magnets used in the injection and extraction section of the 3 GeV rapid cycling synchrotron of the J-PARC require large aperture for low-loss operations of high intensity beam, protection against the high radiation and the high durability to avoid the maintenance after the high activation. A prototype septum magnet was constructed. Magnetic fields in the gap of the core and leakage field outside of the magnetic shield were measured by a Hall device probe. The experimental results were compared with the 3D calculation by TOSCA. The leakage field of the measurements is larger than the one of the model. After we made a more detailed model, it cleared that many bolt holes which fasten a return yoke narrow the effective sectional area and thus reduce the permeability at the return yoke, making the leakage field larger. Because the thickness of the return yoke is not sufficient, magnetic flux density approaches saturation easily. Moreover, we discuss about the results of heat measurements of the magnet and efficiency of water cooling.

Journal Articles

Design of thick septa magnets based on 3D field calculation for the 3 GeV rapid cycling synchrotron of J-PARC

Watanabe, Masao; Irie, Yoshiro; Kamiya, Junichiro; Shimada, Taihei; Takayanagi, Tomohiro; Fujimori, Hiroshi*; Igarashi, Susumu*; Kawakubo, Toshimichi*; Nakayama, Hisayoshi*

IEEE Transactions on Applied Superconductivity, 16(2), p.1350 - 1353, 2006/06

 Times Cited Count:2 Percentile:19.62(Engineering, Electrical & Electronic)

Thick septa are used in the injection and extraction section of the 3 GeV rapid cycling synchrotron of the J-PARC. We have been designing seven thick septum magnets, two for injection, two for beam dump and three for extraction, respectively. These septa require low-loss operations. For the mechanical stability they are operated by direct current. The yoke is made of the soft-iron block. We have been designing them by using the three-dimensional magnet static field calculation code, TOSCA. In this presentation, we discuss about magnetic field flatness in the gap and effects of the leakage fields in the synchrotron.

Journal Articles

Kicker magnet system of the RCS in J-PARC

Kamiya, Junichiro; Takayanagi, Tomohiro; Kawakubo, Toshimichi*; Murasugi, Shigeru*; Nakamura, Eiji*

IEEE Transactions on Applied Superconductivity, 16(2), p.168 - 171, 2006/06

 Times Cited Count:3 Percentile:25.39(Engineering, Electrical & Electronic)

The kicker magnets are installed in the extraction section of the RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex) facility. They extract the 3GeV proton beam to a downstream beam transport line. In order to achieve 1MW beam power, kicker is required to have a wide aperture, UHV (ultra-high vacuum) in its chamber, and uniformity of magnetic field. In this paper, we will introduce the specification of the extraction kicker system in the RCS, and report countermeasure against the technical challenge described above.

Journal Articles

Magnetic field measurement of the extraction kicker magnet in J-PARC RCS

Kamiya, Junichiro; Ueno, Tomoaki*; Takayanagi, Tomohiro

IEEE Transactions on Applied Superconductivity, 16(2), p.1362 - 1365, 2006/06

 Times Cited Count:4 Percentile:30.34(Engineering, Electrical & Electronic)

Kicker magnets in J-PARC RCS are being constructed at JAERI (Japan Atomic Energy Research Institute) as the extraction pulse magnet. It is designed to have a large aperture in order to accept the maximum beam power 1MW. Therefore the impedance mismatch and fringe field have the large effect on distortion of a flatness of the kicker magnetic field. We examined their effect by the simulation and measurement, and contrived to improve the field flatness. In this paper, we present the features of the RCS kicker systems, describe the magnetic field measurement and improvement, and briefly introduce the field mapping which we are performing now.

Journal Articles

Design of the injection bump system of the 3-GeV RCS in J-PARC

Takayanagi, Tomohiro; Kamiya, Junichiro; Watanabe, Masao; Yamazaki, Yoshishige; Irie, Yoshiro; Kishiro, Junichi; Sakai, Izumi*; Kawakubo, Toshimichi*

IEEE Transactions on Applied Superconductivity, 16(2), p.1358 - 1361, 2006/06

 Times Cited Count:14 Percentile:59.24(Engineering, Electrical & Electronic)

The injection bump system of the 3-GeV RCS in J-PARC consists of the pulse bending magnets for the injection bump orbit, which are four horizontal bending magnets (shift bump), four horizontal painting magnets (h-paint bump), and two vertical painting magnets (v-paint bump). In this paper, the design of the magnets and power supply of the injection bump system are reported.

Journal Articles

Design of the shift bump magnets for the beam injection of the 3-GeV RCS in J-PARC

Takayanagi, Tomohiro; Kamiya, Junichiro; Watanabe, Masao; Ueno, Tomoaki*; Yamazaki, Yoshishige; Irie, Yoshiro; Kishiro, Junichi; Sakai, Izumi*; Kawakubo, Toshimichi*; Tounosu, Shigeki*; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.1366 - 1369, 2006/06

 Times Cited Count:7 Percentile:42.11(Engineering, Electrical & Electronic)

The injection system of the 3-GeV RCS in J-PARC is composed of four main orbit bump magnets (shift bump) to merge the injection beam with the circulating beam. The magnetic field design and the structural analysis of the shift bump magnets have been performed using 3D magnetic and mechanical codes. In this paper, the design of the bending magnets is reported.

Journal Articles

Numerical simulation of the critical current and n-value in Nb$$_{3}$$Sn strand subjected to bending strain

Hirohashi, Masayuki*; Murakami, Haruyuki*; Ishiyama, Atsushi*; Ueda, Hiroshi*; Koizumi, Norikiyo; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 16(2), p.1721 - 1724, 2006/06

 Times Cited Count:9 Percentile:48.15(Engineering, Electrical & Electronic)

To demonstrate the applicability of Nb$$_{3}$$Sn CICCs to ITER, four Nb$$_{3}$$Sn model coils have been constructed and tested. The experimental results showed that the measured critical current (Ic) degraded. In addition, the larger is the applied electromagnetic force, the larger the magnitude of the degradation is. The degradation in n-value was also observed. One of the explanations of this degradation is a local strand bending. This consideration has been supported by the test results. However, general dependence of Ic on periodic bending strain has not been clarified in this test since the experiments were carried out at a certain magnetic field, temperature and strain. Therefore, a numerical simulation code was developed to study the general dependence of the Ic and n-value of the Nb$$_{3}$$Sn strand on periodic bending strain. A distributed constant circuit model is applied to simulate current transfer among the filaments in the strand. The simulation results show relatively good agreement with the experiment results but some modification in modeling is required for more accurate simulation.

Journal Articles

Internally Cu-stabilized RHQT Nb$$_{3}$$Al superconductors with Ta matrix

Takeuchi, Takao*; Tagawa, Kohei*; Noda, Tetsuji*; Banno, Nobuya*; Iijima, Yasuo*; Kikuchi, Akihiro*; Kitaguchi, Hitoshi*; Kosuge, Michio*; Tsuchiya, Kiyosumi*; Koizumi, Norikiyo; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.1257 - 1260, 2006/06

 Times Cited Count:6 Percentile:38.57(Engineering, Electrical & Electronic)

Next generation nuclear fusion magnets would require a high-current conductor in fields more than 16 T. A CIC conductor of the rapid RHQT processed Nb$$_{3}$$Al may be a promising candidate. Good deformability of intermediately-formed bcc supersaturated-solid solution indeed allowed fabricating such a CIC conductor, which would be subsequently transformation annealed. Ag has been internally included as a basic constituent of a round strand so far, because Ag is almost non-reactive with Nb matrix during the RHQ. However, both of Ag and Nb are not suitable nuclei from the viewpoint of radioactivity when irradiated with neutrons. Recently, we have succeeded in replacing the Nb matrix with Ta that has the advantage of shorter half-life of radioactivity. In the present study, an attempt has been made to replace the Ag internal stabilizer with Cu, in the aim of further reducing radioactivity, based on anticipation that Ta would be less reactive with Cu than Nb did.

Journal Articles

Irregular loops with long time constants in CIC conductor

Yagai, Tsuyoshi*; Sato, Hidenari*; Tsuda, Makoto*; Hamajima, Takataro*; Nunoya, Yoshihiko; Takahashi, Yoshikazu; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 16(2), p.835 - 838, 2006/06

 Times Cited Count:6 Percentile:38.57(Engineering, Electrical & Electronic)

AC losses in the CIC conductor consist of both regular loss that are proportional to cable twisting pitch squared and irregular loss that could not be estimated from short conductor sample results. It was explained from our previous works that irregular loops produce the losses with long time constants up to several hundred seconds. The observed long time constant indicates that contact conditions between the two strands forming the loop should be line contact. We traced the sample conductor with 1 m in length. The measured results show that large displacements of strands from their original positions due to compressing the conductor provide many line contacts. It is found that the averaged line contact length reaches about 10 mm that is three orders of magnitude larger than the 0.01 mm of point contact length.

Journal Articles

Implications of NbTi short-sample test results and analysis for the ITER Poloidal Field Conductor Insert (PFCI)

Zanino, R.*; Bagnasco, M.*; Baker, W.*; Bellina, F.*; Bruzzone, P.*; della Corte, A.*; Ilyin, Y.*; Martovetsky, N.*; Mitchell, N.*; Muzzi, L.*; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.886 - 889, 2006/06

 Times Cited Count:7 Percentile:42.11(Engineering, Electrical & Electronic)

As the test of the PFCI is foreseen at JAERI Naka, Japan, it is essential to consider in detail the lessons learned from the short NbTi sample tests, as well as the issues left open after them, in order to develop a suitable test program of the PFCI aimed at bridging the extrapolation gap between measured strand and future PF coil performance. Here we consider in particular the following issues: (1) the actual possibility to quench the PFCI conductor in the TCS tests before quenching the intermediate joint, (2) the question of the so-called sudden or premature quench, based on SULTAN sample results, applying a recently developed multi-solid and multi-channel extension of the Mithrandir code to a short sample analysis; (3) the feasibility of the AC losses calorimetry in the PFCI. These results show that Tcs measurement and the calorimetric measurement of AC losses will be carried out successfully. However, we need further analytic works for the problem of the sudden quench.

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