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Journal Articles

Development of Terminal Joint and Lead Extension for JT-60SA Central Solenoid

Murakami, Haruyuki; Kizu, Kaname; Ichige, Toshikatsu; Furukawa, Masato; Natsume, Kyohei; Tsuchiya, Katsuhiko; Kamiya, Koji; Koide, Yoshihiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4201305_1 - 4201305_5, 2015/06

 Times Cited Count:6 Percentile:54.89(Engineering, Electrical & Electronic)

JT-60U magnet system will be upgraded to the superconducting coils in the JT-60SA programme of the Broader Approach activities. Terminal joint of Central Solenoid (CS) is wrap type Nb$$_{3}$$Sn-NbTi joint used for connecting CS (Nb$$_{3}$$Sn) and current feeder (NbTi). The terminal joints are placed at the top and the bottom of the CS systems. CS modules located at middle position of CS system need the lead extension from the modules to the terminal joint. The joint resistance measurement of terminal joint was performed in the test facility of National Institute for Fusion Science. The joint resistance was evaluated by the operating current and the voltage between both ends of the terminal joint part. Test results met the requirement of JT-60SA magnet system. The structural analysis of the lead extension and its support structure was conducted to confirm the support design. In this paper, the results of resistance test of joint and the structural analysis results of lead extension are reported.

Journal Articles

Design of JT-60SA thermal shield and cryodistribution

Kamiya, Koji; Onishi, Yoshihiro; Ichige, Toshikatsu; Furukawa, Masato; Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Mizumaki, Shoichi*

Proceedings of 24th International Cryogenic Engineering Conference (ICEC 24) and International Cryogenic Materials Conference 2012 (ICMC 2012) (CD-ROM), p.587 - 590, 2012/05

The JT-60 plans to be upgraded to a full-superconducting tokamak referred as the JT-60 Super Advance (JT-60SA) as one of the JA-EU broader approach projects. In the JT-60SA, the superconducting magnets are surrounded by thermal shield cooled at 80 K, which is categorized into 3 groups; the vacuum vessel thermal shield (VVTS), the port thermal shield (PTS) and the cryostat thermal shield (CTS). In this study, seismic analysis was conducted for the thermal shield to confirm the soundness of the latest design, taking the dynamical analysis into account. Trial manufacturing of a 10 degree outer VVTS was also conducted. The outer VVTS was subsequently assembled with already existing inner VVTS to measure the total tolerance (manufacturing plus assembly). It was found that the total tolerance was 5.2 mm which is less than the target tolerance of 10 mm. Finally, concept and the current status of the JT-60SA cryodistribution design are reported.

Journal Articles

Current sharing temperature of central solenoid conductor for JT-60SA under repetition excitation

Murakami, Haruyuki; Kizu, Kaname; Ichige, Toshikatsu; Kamiya, Koji; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Hamaguchi, Shinji*; Takahata, Kazuya*; Yanagi, Nagato*; et al.

Proceedings of 24th International Cryogenic Engineering Conference (ICEC 24) and International Cryogenic Materials Conference 2012 (ICMC 2012) (CD-ROM), p.575 - 578, 2012/05

The JT-60U magnet system will be upgraded to the superconducting coils (JT-60SA) in the Broader Approach (BA) project. The JT-60SA magnet system has 18 Toroidal Field (TF) coils, a Central Solenoid (CS) with 4 modules and 6 Equilibrium Field (EF) coils. The CS conductors are designed with Nb$$_{3}$$Sn cable in conduit (CIC) conductor because the magnetic field of CS is up to 8.9 T. The short CS conductor was manufactured and processed into the performance verification test sample. The Tcs test results indicate that the initial Tcs of the CS conductor is about 2 K higher than the minimum requirement of the conductor design. In addition the Tcs after the repetition excitation is more important issues for the CS conductor because the CS conductor is made of Nb$$_{3}$$Sn strand. The Tcs changes with the repetition excitation and the influence of the warm up and cool down process on the Tcs were measured. The test results show that there is no degradation while the repetition excitation tests. The AC loss test of the CS conductor was also performed for precise estimation of the conductor heat loads. The Tcs margin analysis of the CS conductor was conducted based on the latest conductor heat loads. The analysis results show that the CS conductor has enough Tcs margin during the JT-60SA operation. These results show that the design and the manufacturing process of the CS conductor satisfy its requirements. Thus CS conductors for the CS1 module have been manufactured on the mass production process. In this paper, the Tcs test, the repetition excitation test, the AC loss test and the Tcs margin analysis of the CS conductor are described.

Journal Articles

Design and trial manufacturing of the thermal shield for JT-60SA

Kamiya, Koji; Ichige, Toshikatsu; Honda, Atsushi; Yoshida, Kiyoshi

Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.797 - 802, 2011/07

The JT-60 is planned to be upgraded to a full-superconducting tokamak referred as the JT-60 Super Advance (JT-60SA) as one of the JA-EU Broader Approach projects. In the JT-60SA, the superconducting magnets are to be surrounded with the thermal shield to reduce the radiation heat from the plasma vacuum vessel and from the ambient temperature. This study describes the design concept and current status of the JT-60SA thermal shield followed by thermal analysis focusing on the vacuum vessel side thermal shield (VVTS). Subsequently, the structural analysis in the plasma operation mode and at assembly was conducted. Finally, the trial model of the 10 degree VVTS and its manufacturing tolerance are presented.

Journal Articles

Stability margin of NbTi CIC conductor for JT-60SA equilibrium field coil

Murakami, Haruyuki; Ichige, Toshikatsu; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Hamaguchi, Shinji*; Takahata, Kazuya*; Yanagi, Nagato*; Mito, Toshiyuki*; et al.

IEEE Transactions on Applied Superconductivity, 21(3), p.1991 - 1994, 2011/06

 Times Cited Count:2 Percentile:79.23(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Heat generation and cooling optimization of the superconducting coils for JT-60SA

Kamiya, Koji; Murakami, Haruyuki; Kizu, Kaname; Ichige, Toshikatsu; Yoshida, Kiyoshi

Teion Kogaku, 46(1), p.10 - 17, 2011/01

JT-60SA project replaces the JT-60U tokamak with a full superconducting tokamak. The helium refrigerator cools the superconducting coils by circulating 4.4 K, 0.6 MPa supercritical helium in the circulation loop at certain mass flow rate. Since the cooling power of the helium refrigerator is determined by the heat load of the superconducting coils, estimation of the heat generation and required mass flow rate to acquire sufficient temperature margin is of crucial importance. In this paper, optimizing the mass flow rate in the superconducting coils was attempted to satisfy 1 K temperature margin. Then, it is shown that the consequent maximum pressure drop in the circulation loop is 81 kPa to result in minimizing the heat load of the supercritical helium circulation pump.

JAEA Reports

Analysis method of AC loss and temperature margin in forced flow cooled superconductors

Ichige, Toshikatsu; Murakami, Haruyuki; Kizu, Kaname; Yoshida, Kiyoshi

JAEA-Data/Code 2010-021, 45 Pages, 2010/12

JAEA-Data-Code-2010-021.pdf:6.52MB

The superconducting coil cannot operate after the quench that its conductor temperature becomes above the critical temperature and normal reason expands explosively. It is important to keep enough temperature margin from the operating temperature to the current sharing temperature. The forced flow conductor is adopted for the Tokamak machine because the mechanical strength and electrical high voltage are required. The performance of its conductor is depended on the magnetic field and temperature. This analysis method is validated by the comparison between experimental data and this analysis. This analysis method can evaluate the temperature margin of the superconducting conductor along its cooling length and during all operation scenarios, in case of the inlet temperature and the mass flow rate for the cooling condition. This analysis method can provide analysis results for selection of conductor parameters and for optimizing of the cooling condition from the cryoplant.

Journal Articles

Stability and quench test for NbTi CIC conductor of JT-60SA equilibrium field coil

Murakami, Haruyuki; Ichige, Toshikatsu; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Hamaguchi, Shinji*; Takahata, Kazuya*; Mito, Toshiyuki*; Imagawa, Shinsaku*

IEEE Transactions on Applied Superconductivity, 20(3), p.512 - 516, 2010/06

 Times Cited Count:8 Percentile:50.14(Engineering, Electrical & Electronic)

JT-60SA magnets system consists of 18 toroidal field (TF) coils, 4 stacks of central solenoid (CS) and 6 plasma equilibrium field (EF) coils. The maximum magnetic field and maximum current of EF coils is 6.2 T and 20 kA, respectively. It has been decided that the NbTi cable-in-conduit (CIC) conductor is applied to EF coil conductors. The performance verification test was conducted by Japan Atomic Energy Agency (JAEA) and National Institute of Fusion Science (NIFS). The critical current measurement of this sample under the condition of coil operation was performed in the previous test. In addition, the quench test is conducted in this time to evaluate the stability margin and the coil behavior during quench. The Minimum Quench Energy of this conductor and the velocity of normal conducting state propagation are described in this paper. We also described the Tcs margin and maximum temperature during the quench evaluated by thermo-fluid analysis based on the quench test.

Journal Articles

Conductor design of CS and EF coils for JT-60SA

Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Edaya, Masahiro; Ichige, Toshikatsu*; Tamai, Hiroshi; Matsukawa, Makoto; della Corte, A.*; Di Zenobio, A.*; Muzzi, L.*; et al.

IEEE Transactions on Applied Superconductivity, 18(2), p.212 - 215, 2008/06

 Times Cited Count:16 Percentile:33.44(Engineering, Electrical & Electronic)

The maximum magnetic field and maximum current of CS and EF coils is 9 T, 20 kA and 6.2 T, 21 kA, respectively. The conductor for CS is Nb$$_{3}$$Sn CIC conductor with JK2LB conduit. On the other hand, EF coil conductors are NbTi CIC conductor with SS316LN conduit. In order to reduce the pressure drop and to raise the temperature margin against large AC loss and nuclear heating, central spiral is introduced inside cable. The Tcs margin and stability analyses of the CS and EF coils are performed by using the one-dimensional fluid analysis code with transient heat loads. These coils have enough high Tcs and stability margin against the operational scenario.

Oral presentation

Crystallization of $$beta$$-lactoglobulin, $$alpha$$-amylase, 2Zn-insulin, cubic-insulin and RNase a for neutron diffraction experiment

Yagi, Daichi*; Ebata, Toshinobu*; Ichige, Toshikatsu*; Kobayashi, Yoichiro*; Ishikawa, Takuya*; Yamashita, Masahiro*; Onishi, Yuki*; Tanaka, Ichiro*; Kurihara, Kazuo; Niimura, Nobuo*

no journal, , 

no abstracts in English

Oral presentation

Evaluation of heat generation caused by plasma disruption in superconductor of JT-60SA

Kizu, Kaname; Yoshida, Kiyoshi; Edaya, Masahiro; Tsuchiya, Katsuhiko; Matsukawa, Makoto; Ichige, Toshikatsu*

no journal, , 

AC losses are generated in the CS and EF coils by the change of magnetic field and operational current caused by plasma disruption. It is required that the temperature margin for current sharing temperature has to be larger than 1 K even though the event of disruption. Thus, the heat evolution by disruption was evaluated as follows. At first, time evolution of current in coil, vacuum vessel, baffle plate, control coil and plasma was investigated by circuit analysis. Then, time evolution of magnetic field in each coil was calculated by the current pattern. Finally, AC losses were evaluated by the field pattern. It was found that the temperature increase of innermost turn in EF 1 coil becomes about 0.5 K. This indicates that the 1 K temperature margin is attained taking into account the temperature increase by standard plasma operational scenario.

Oral presentation

Quench test for NbTi CIC conductor of JT-60SA equilibrium field coil

Murakami, Haruyuki; Ichige, Toshikatsu; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Hamaguchi, Shinji*; Takahata, Kazuya*; Imagawa, Shinsaku*; Mito, Toshiyuki*

no journal, , 

no abstracts in English

Oral presentation

Design and thermal analysis of JT-60SA thermal shield

Kamiya, Koji; Takenouchi, Tadashi; Ichige, Toshikatsu; Yoshida, Kiyoshi

no journal, , 

JT-60SA, which is planned to use superconducting magnets for plasma confinment, will use a thermal shield cooled at 80K as a radiation shield for 4K magnets. Therefore, the shape of the thermal shield strongly depends on the shape of the superconducting magnets. The specification and the shape of the toroidal field coil has been fixed this year, and 110 mm clearance between plasma vacuum vessel and the magnets has been acquired. In the present publication, the thermal shield has been designed in the 110 mm clearance and the thermal analysis has been conducted for a part of it.

Oral presentation

Design and trial manufacturing of JT-60SA thermal shield

Kamiya, Koji; Ichige, Toshikatsu; Yoshida, Kiyoshi

no journal, , 

JT-60SA, which plans to replace all coils for the plasma confinement with superconductor, needs to enclose the superconducting coils with the thermal shield in order to reduce the radiation heat load from the ambient temperature. The thermal shield on the plasma vacuum vessel side (VVTS) requires the manufacturing and assembly torelance with high accuracy due to the narrow space between the toroidal field coil and the VVTS. Therefore, it is important to determine the manufacturing torelance from the trial manufacturing for the VVTS design. In this talk, the results including the VVTS manufacturing torelance determined from the trial manufacturing are presented.

Oral presentation

Stability evaluation of superconductors for equilibrium field coil of JT-60SA

Murakami, Haruyuki; Ichige, Toshikatsu; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Takahata, Kazuya*; Hamaguchi, Shinji*; Yanagi, Nagato*; Imagawa, Shinsaku*; et al.

no journal, , 

no abstracts in English

Oral presentation

Detailed support design of thermal shield for JT-60SA

Onishi, Yoshihiro; Asakawa, Shuji; Ichige, Toshikatsu; Hoshi, Ryo; Kamiya, Koji; Yoshida, Kiyoshi

no journal, , 

no abstracts in English

Oral presentation

Transient phenomena of supercritical helium for cooling JT-60SA superconducting coils

Kamiya, Koji; Murakami, Haruyuki; Kizu, Kaname; Ichige, Toshikatsu; Yoshida, Kiyoshi

no journal, , 

JT-60SA, which replaces all plasma confinement copper coils with superconducting coils, cools the coils with force circulating supercritical helium at a temperature of 4.4K and pressure of 0.6MPa. JT-60SA is equipped with 2 supercritical helium loops. A loop 1 and a loop 2 cool toroidal field coils and poroidal coils, that is center solenoid (CS) and equibrium field coils (EFC), respectively. This study reports transient helium temperature and pressure for cooling CS2 with minimum temperature margin in plasma operation and also when quench occurs.

Oral presentation

Speeding up of temperature margin analysis method in forced flow cooled superconductors

Ichige, Toshikatsu; Murakami, Haruyuki; Kizu, Kaname; Yoshida, Kiyoshi

no journal, , 

no abstracts in English

Oral presentation

Structure analysis of thermal shield for JT-60SA

Onishi, Yoshihiro; Ichige, Toshikatsu; Hoshi, Ryo; Kamiya, Koji; Yoshida, Kiyoshi

no journal, , 

no abstracts in English

Oral presentation

Design status of the current feeding system for superconducting coils of JT-60SA

Kizu, Kaname; Komeda, Masao*; Kuramochi, Masaya; Ichige, Toshikatsu; Furukawa, Masato; Yoshida, Kiyoshi

no journal, , 

In JT-60SA, normal bus bar from power supply is connected to the current lead (CL) installed on the coil terminal box (CTB). CL and coil are connected by the current feeder of superconductor. High temperature superconductor (HTS) CL made in Germany was adopted to reduce the heat load of cryoplant. Because the CL for JT-60SA was designed based on that for W7-X, there are several limitations for the design of the current feeding system. The CTB consists of terminal box in which CLs are installed vertically and port of 7 m in length connecting between terminal box and cryostat. It was expected that large load is applied on the CL because of thermal contraction. In order to reduce the load, the feeder in CTB has 3 bending and is supported by fixing supports to prevent the displacement. The flexible supports using the suspended bolt were also designed. The load under this support design was evaluated. It was found that the horizontal and vertical load was smaller than the limitation.

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