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Journal Articles

Progress of JT-60SA Project; EU-JA joint efforts for assembly and fabrication of superconducting tokamak facilities and its research planning

Shirai, Hiroshi; Barabaschi, P.*; Kamada, Yutaka; JT-60SA Team

Fusion Engineering and Design, 109-111(Part.B), p.1701 - 1708, 2016/11

 Times Cited Count:14 Percentile:2.74(Nuclear Science & Technology)

The JT-60SA Project has shown steady progress toward the first plasma in 2019. JT-60SA is a superconducting tokamak designed to operate in the break-even conditions for a long pulse duration with a maximum plasma current of 5.5 MA. Design and fabrication of JT-60SA components shared by EU and Japan started in 2007. Assembly in the torus hall started in January 2013, and welding work of the vacuum vessel sectors is currently on going on the cryostat base. Other components such as TF coils, PF coils, power supplies, cryogenic system, cryostat vessel, thermal shields and so forth were or are being delivered to Naka site for installation, assembly and commissioning. This paper gives technical progress on fabrication, installation and assembly of tokamak components and ancillary systems, as well as progress of JT-60SA Research Plan being developed jointly by EU and Japanese fusion communities.

JAEA Reports

Work and safety managements for on-site installation, commissioning, tests by EU of quench protection circuits for JT-60SA

Yamauchi, Kunihito; Okano, Jun; Shimada, Katsuhiro; Omori, Yoshikazu; Terakado, Tsunehisa; Matsukawa, Makoto; Koide, Yoshihiko; Kobayashi, Kazuhiro; Ikeda, Yoshitaka; Fukumoto, Masahiro; et al.

JAEA-Technology 2015-053, 36 Pages, 2016/03

JAEA-Technology-2015-053.pdf:8.33MB

The superconducting Satellite Tokamak machine "JT-60SA" under construction in Naka Fusion Institute is an international collaborative project between Japan (JA) and Europe (EU). The contributions for this project are based on the supply of components, and thus European manufacturer shall conduct the installation, commissioning and tests on Naka site. This means that Japan Atomic Energy Agency (JAEA) had a quite difficult issue to manage the works by European workers and their safety although there is no direct contract. This report describes the approaches for the work and safety managements, which were agreed with EU after the tough negotiation, and then the completed on-site works for Quench Protection Circuits (QPC) as the first experience for EU in JT-60SA project. With the help of these approaches by JAEA, the EU works for QPC were successfully completed with no accident, and a great achievement was made for both EU and JA.

JAEA Reports

Assessment report of research and development activities in FY2014; Activity "Fusion Research and Development" (In-advance evaluation)

Fusion Research and Development Directorate

JAEA-Evaluation 2016-002, 40 Pages, 2016/03

JAEA-Evaluation-2016-002.pdf:2.66MB

Japan Atomic Energy Agency (hereinafter referred to as "JAEA") asked the assessment committee, "Evaluation Committee of Research and Development Activities for Fusion" (hereinafter referred to as "Committee") for in-advance evaluation of "Research and Development of the technical system for extraction of fusion energy," in accordance with "General Guideline for the Evaluation of Government R&D Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and "Regulation on Conduct for Evaluation of R&D Activities" by JAEA. In response to the JAEA's request, the Committee assessed the research program of the Fusion Research and Development Directorate (hereinafter referred to as "FRDD") during the period from April 2015 to March 2022. The Committee evaluated the management and research activities of the FRDD based on the explanatory documents prepared by the FRDD, the oral presentations with questions-and-answers by the Director General and the Deputy Director Generals.

JAEA Reports

Assessment report of research and development activities in FY2014; Activity "Fusion Research and Development" (Result evaluation)

Fusion Research and Development Directorate

JAEA-Evaluation 2016-001, 128 Pages, 2016/03

JAEA-Evaluation-2016-001.pdf:33.25MB

Japan Atomic Energy Agency (hereinafter referred to as "JAEA") asked the assessment committee, "Evaluation Committee of Research and Development Activities for Fusion" (hereinafter referred to as "Committee") for result evaluation of "Research and Development of the Technical System for Extraction of Fusion Energy," in accordance with "General Guideline for the Evaluation of Government R&D Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology " and "Regulation on Conduct for Evaluation of R&D Activities" by JAEA. In response to the JAEA's request, the Committee assessed the research program of the Fusion Research and Development Directorate (hereinafter referred to as "FRDD") during the period from April 2010 to November 2014. The Committee evaluated the management and research activities of the FRDD based on the explanatory documents prepared by the FRDD, the oral presentations with questions-and-answers by the Director General and the Deputy Director Generals.

Journal Articles

Analysis of maximum voltage transient of JT-60SA toroidal field coils in case of fast discharge

Novello, L.*; Cara, P.*; Coletti, A.*; Gaio, E.*; Maistrello, A.*; Matsukawa, Makoto; Philipps, G.*; Tomarchio, V.*; Yamauchi, Kunihito

IEEE Transactions on Applied Superconductivity, 26(2), p.4700507_1 - 4700507_7, 2016/03

 Times Cited Count:2 Percentile:69.19(Engineering, Electrical & Electronic)

Journal Articles

News from Broader Approach activities, 59

Hoshino, Kazuo; Matsunaga, Go; Okumura, Yoshikazu

Purazuma, Kaku Yugo Gakkai-Shi, 92(2), p.146 - 147, 2016/02

no abstracts in English

Journal Articles

Time evolution of negative ion profile in a large cesiated negative ion source applicable to fusion reactors

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Umeda, Naotaka; Hiratsuka, Junichi; Ichikawa, Masahiro; Watanabe, Kazuhiro; Grisham, L. R.*; Tsumori, Katsuyoshi*; et al.

Review of Scientific Instruments, 87(2), p.02B144_1 - 02B144_4, 2016/02

 Times Cited Count:3 Percentile:73.23(Instruments & Instrumentation)

Time evolution of spatial profile of negative ion production during an initial conditioning phase has been experimentally investigated in the JT-60 negative ion source. Up to 0.4 g Cs injection, there is no enhancement of the negative ion production and no observation of the Cs emission signal in the source, suggesting the injected Cs is mainly deposited on the water-cooled wall near the nozzle. After 0.4 g Cs injection, enhancement of the negative ion production appeared only at the central segment of the PG. The calculation of the Cs neutral/ion trajectories implied that a part of Cs was ionized near the nozzle and was transported to this area. The expansion of the area of the surface production was saturated after ~2 g Cs injection corresponding to 6000 s discharge time. From the results, it is found that Cs ionization and its transport plays an important role for the negative ion production.

Journal Articles

Development of design technique for vacuum insulation in large size multi-aperture multi-grid accelerator for nuclear fusion

Kojima, Atsushi; Hanada, Masaya; Tobari, Hiroyuki; Nishikiori, Ryo; Hiratsuka, Junichi; Kashiwagi, Mieko; Umeda, Naotaka; Yoshida, Masafumi; Ichikawa, Masahiro; Watanabe, Kazuhiro; et al.

Review of Scientific Instruments, 87(2), p.02B304_1 - 02B304_5, 2016/02

 Times Cited Count:3 Percentile:61.24(Instruments & Instrumentation)

Optimization techniques of the vacuum insulation design have been developed in order to realize a reliable voltage holding capability of Multi-Aperture Multi-Grid accelerators for giant negative ion sources for nuclear fusion. In this method, the nested multilayer configuration of each acceleration stage in the MAMuG accelerator can be uniquely designed to satisfy the target voltage within given boundary conditions. The evaluation of the voltage holding capabilities of each acceleration stages were based on the past experimental results of the area effect and the multi-aperture effect on the voltage holding capability. Moreover, total voltage holding capability of multi-stage was estimated by taking the multi-stage effect into account, which was experimentally obtained in this time. In this experiment, the multi-stage effect appeared as the superposition of breakdown probabilities in each acceleration stage, which suggested that multi-stage effect can be considered as the voltage holding capability of the single acceleration gap having the total area and aperture. The analysis on the MAMuG accelerator for JT-60SA agreed with the past gap-scan experiments with an accuracy of less than 10% variation.

Journal Articles

Dependence of pedestal structure on collisionality at fixed beta in JT-60U

Urano, Hajime; Aiba, Nobuyuki; Kamiya, Kensaku; Kamada, Yutaka; JT-60 Team

Nuclear Fusion, 56(1), p.016005_1 - 016005_8, 2016/01

 Times Cited Count:3 Percentile:62.22(Physics, Fluids & Plasmas)

Dependence of pedestal structure on collisionality at fixed beta has been investigated in JT-60U. In the ITER-relevant low collisionality regime, the pedestal width does not change with edge collisionality. In the high collisionality regime, the pedestal width broadens with increased edge collisionality. The pedestal pressure gradient and width are not significantly changed when the pedestal is close to an intermediate $$n$$ peeling-ballooning mode boundary at low collisionality. The experimental result indicates that conventional pedestal models where the pedestal width is independent of collisionality and is determined by $$beta_{rm p}$$ at the pedestal is not a bad assumption in the ITER-relevant low collisionality regime. On the other hand, the pressure gradient decreases and the pedestal width increases at high collisionality. The pedestal broadening becomes significant when the pedestal is marginal to be unstable at high $$n$$ ballooning mode in high collisionality regime.

Journal Articles

Development of remote pipe welding tool for divertor cassettes in JT-60SA

Hayashi, Takao; Sakurai, Shinji; Sakasai, Akira; Shibanuma, Kiyoshi; Kono, Wataru*; Onawa, Toshio*; Matsukage, Takeshi*

Fusion Engineering and Design, 101, p.180 - 185, 2015/12

 Percentile:100(Nuclear Science & Technology)

Remote pipe welding tool accessing from inside pipe has been newly developed for JT-60SA. Remote handling (RH) system is necessary for the maintenance and repair of in-vessel components such as lower divertor cassettes in JT-60SA. Cooling pipes, which connects between the divertor cassette and the vacuum vessel with bellows are required to be cut and welded in the vacuum vessel by RH system. The available space for RH system is very limited inside the vacuum vessel, especially around the divertor cassettes. Thus, the cooling pipes are required to be cut and weld from the inside in the vacuum vessel. The inner diameter, thickness and material of the cooling pipe are 54.2 mm, 2.8 mm and SUS316L, respectively. An upper pipe connected to the divertor cassette has a jut on the edge to fill the gap between pipes. Owing to the jut and two-times welding, the welding tool achieved the maximum allowable gap of 0.7 mm.

Journal Articles

News from Broader Approach activities, 58

Hoshino, Kazuo; Matsunaga, Go; Okumura, Yoshikazu

Purazuma, Kaku Yugo Gakkai-Shi, 91(12), p.802 - 803, 2015/12

Holding of the 17th IFERC Project Committee (PC), the 16th IFMIF/EVEDA-PC and the progress of the JT-60SA were reported. In the IFERC-PC, total 33 participated including Maisonnier chairperson, JA-EU committee, experts and project members. They reported the status of each activity, discussed the planning of project 2016 and revised plan, and concluded technical advice to the BA Steering Committee (SC). In the IFMIF/EVEDA-PC, total 27 participated including Takatsu chairperson, JA-EU committee, experts and project members. They reported the status of each activity, discussed the planning of project 2016 and revised plan, and the BA-SC recommended the endorsement of the new project plan. In the JT-60SA, a rotary crane for assembly of the troidal field coil has been installed. The disassembly of the constraint jigs of the vacuum vessel which completed 340$$^{circ}$$ assembly has been progressed. 6 high temperature superconductor current leads for the troidal field coils had been delivered from EU.

Journal Articles

Development of operation scenarios for plasma breakdown and current ramp-up phases in JT-60SA tokamak

Urano, Hajime; Fujita, Takaaki*; Ide, Shunsuke; Miyata, Yoshiaki; Matsunaga, Go; Matsukawa, Makoto

Fusion Engineering and Design, 100, p.345 - 356, 2015/11

 Times Cited Count:3 Percentile:53.75(Nuclear Science & Technology)

The operation scenarios for plasma breakdown and current ramp-up phases in JT-60SA tokamak have been developed. The induced current in the in-vessel conducting elements such as vacuum vessel and stabilizing plate increases to the comparable level of plasma current of $$sim$$600 kA during the breakdown phase and thus enhances the strength of error field. The optimized scenarios for half and full pre-magnetization cases satisfied the conditions required for the plasma initiation. At the initial plasma, the vertical magnetic field required to sustain the plasma position was controlled by the outer equilibrium field (EF) coil currents which compensate for a vertical field due to a large eddy current. The condition for the formation of divertor configurations given by the combination of the magnetic flux for plasma and the plasma current enables us to develop the operational scenarios with a smooth transition from a limiter to a divertor configuration.

Journal Articles

Comparison between simulations using the PHITS code and activated material analysis

Sukegawa, Atsuhiko; Okuno, Koichi*

IEEE Transactions on Plasma Science, 43(11), p.3916 - 3920, 2015/11

 Percentile:100(Physics, Fluids & Plasmas)

In the present study a comparison between simulations using the PHITS code and activated material analysis of JT-60U has been performed. Neutron transport have been simulated using the Monte Carlo methods PHITS to determine the neutron fluency at the irradiation position. The Activated analysis has been complemented by the foil-activation technique. The preliminary result of these PHITS simulations has been confirmed by comparing the reaction rates of gold, cobalt, and nickel foils activation. The simulation results by PHITS consisted with the measured reaction rate of each foils near the device.

Journal Articles

Reference design of the power supply system for the resistive-wall-mode control in JT-60SA

Ferro, A.*; Gaio, E.*; Novello, L.*; Matsukawa, Makoto; Shimada, Katsuhiro; Kawamata, Yoichi; Takechi, Manabu

Fusion Engineering and Design, 98-99, p.1053 - 1057, 2015/10

 Times Cited Count:2 Percentile:66.76(Nuclear Science & Technology)

Journal Articles

First switching network unit for the JT-60SA superconducting central solenoid

Lampasi, A.*; Zito, P.*; Coletti, A.*; Novello, L.*; Matsukawa, Makoto; Shimada, Katsuhiro; Burini, F.*; Kuate-Fone, Y.*; Taddia, G.*; Tenconi, S.*

Fusion Engineering and Design, 98-99, p.1098 - 1102, 2015/10

 Times Cited Count:7 Percentile:22.72(Nuclear Science & Technology)

Journal Articles

Design and realization of JT60-SA Fast Plasma Position Control Coils power supplies

Zito, P.*; Lampasi, A.*; Coletti, A.*; Novello, L.*; Matsukawa, Makoto; Shimada, Katsuhiro; Cinarelli, D.*; Portesine, M.*; Dorronsoro, A.*; Vian, D.*

Fusion Engineering and Design, 98-99, p.1191 - 1196, 2015/10

 Times Cited Count:8 Percentile:18.76(Nuclear Science & Technology)

Journal Articles

Analyses of the impact of connections' layout on the coil transient voltage at the Quench Protection Circuit intervention in JT-60SA

Maistrello, A.*; Gaio, E.*; Novello, L.*; Matsukawa, Makoto; Yamauchi, Kunihito

Fusion Engineering and Design, 98-99, p.1109 - 1112, 2015/10

 Times Cited Count:2 Percentile:66.76(Nuclear Science & Technology)

Journal Articles

Overview of the new magnet power supply systems of JT-60SA procured by EU

Novello, L.*; Baulaigue, O.*; Coletti, A.*; Dumas, N.*; Ferro, A.*; Gaio, E.*; Lampasi, A.*; Maistrello, A.*; Matsukawa, Makoto; Shimada, Katsuhiro; et al.

Fusion Engineering and Design, 98-99, p.1122 - 1126, 2015/10

 Times Cited Count:9 Percentile:15.14(Nuclear Science & Technology)

Journal Articles

Development of a high power wideband polarizer for electron cyclotron current drive system in JT-60SA

Saigusa, Mikio*; Oyama, Gaku*; Matsubara, Fumiaki*; Takii, Keita*; Sai, Takuma*; Kobayashi, Takayuki; Moriyama, Shinichi

Fusion Engineering and Design, 96-97, p.577 - 582, 2015/10

 Times Cited Count:1 Percentile:81.41(Nuclear Science & Technology)

A wideband polarizer has been developed for an ECCD system in JT-60SA. The groove depth of the mirrors installed in miter bends were optimized for two frequencies (110 GHz and 138 GHz) by numerical simulations. All surfaces of Poincare spheres were covered at both of the frequencies in low power test. The thermal stress of polarizer were estimated by the numerical simulations. The twister polarizer has been tested up to 0.24 MW during 3 s at 110 GHz.

Journal Articles

Development of residual thermal stress-relieving structure of CFC monoblock target for JT-60SA divertor

Tsuru, Daigo; Sakurai, Shinji; Nakamura, Shigetoshi; Ozaki, Hidetsugu; Seki, Yohji; Yokoyama, Kenji; Suzuki, Satoshi

Fusion Engineering and Design, 98-99, p.1403 - 1406, 2015/10

 Times Cited Count:1 Percentile:81.41(Nuclear Science & Technology)

1496 (Records 1-20 displayed on this page)