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Otsuki, Daiki*; Ishida, Tatsuhiro*; Tsutsumi, Naoya*; Kobayashi, Masaki*; Inagaki, Kodai*; Yoshida, Teppei*; Takeda, Yukiharu; Fujimori, Shinichi; Yasui, Akira*; Kitagawa, Saiki*; et al.
Physical Review Materials (Internet), 7(12), p.124601_1 - 124601_6, 2023/12
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)Natsume, Kyohei; Murakami, Haruyuki; Kizu, Kaname; Yoshida, Kiyoshi; Koide, Yoshihiko
IOP Conference Series; Materials Science and Engineering, 101(1), p.012113_1 - 012113_8, 2015/12
Times Cited Count：2 Percentile：65.53(Thermodynamics)Kizu, Kaname; Murakami, Haruyuki; Natsume, Kyohei; Tsuchiya, Katsuhiko; Koide, Yoshihiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Hamaguchi, Shinji*; Takahata, Kazuya*
Fusion Engineering and Design, 98-99, p.1094 - 1097, 2015/10
Times Cited Count：6 Percentile：45.66(Nuclear Science & Technology)Current feeder and Coil Terminal Box (CTB) for the superconducting magnets for JT-60SA were designed. Copper busbar from power supply is connected to the High Temperature Superconductor Current Lead (HTS CL), which is installed on the vacuum vessel called CTB. The superconducting current feeder is connected to the cold end of HTS CL, and is led to main cryostat for magnets. Trial manufacturing of crank shaped feeder to reduce the thermal stress was performed. The small tool which can connect soldering joint with vertical direction was developed. Insulation materials made by manufacturing condition showed sufficient shear stress. Since the all manufacturing process concerned was confirmed, the production of current feeder and CTB can be started.
Koide, Yoshihiko; Yoshida, Kiyoshi; Wanner, M.*; Barabaschi, P.*; Cucchiaro, A.*; Davis, S.*; Decool, P.*; Di Pietro, E.*; Disset, G.*; Genini, L.*; et al.
Nuclear Fusion, 55(8), p.086001_1 - 086001_7, 2015/08
Times Cited Count：32 Percentile：83.12(Physics, Fluids & Plasmas)The most distinctive feature of the superconducting magnet system for JT-60SA is the optimized coil structure in terms of the space utilization as well as the highly accurate coil manufacturing, thus meeting the requirements for the steady-state tokamak research: A conceptually new outer inter-coil structure separated from the casing is introduced to the toroidal field coils to realize their slender shape, allowing large-bore diagnostic ports for detailed plasma measurements. A method to minimize the manufacturing error of the equilibrium-field coils has been established, aiming at the precise plasma shape/position control. A compact butt-joint has been successfully developed for the Central Solenoid, which allows an optimized utilization of the limited space for the Central Solenoid to extend the duration of the plasma pulse.
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：34.11(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
Sn-NbTi joint used for connecting CS (NbSn) 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.
Yoshida, Kiyoshi; Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Kamiya, Koji; Koide, Yoshihiko; Phillips, G.*; Zani, L.*; Wanner, M.*; Barabaschi, P.*; et al.
IEEE Transactions on Applied Superconductivity, 24(3), p.4200806_1 - 4200806_6, 2014/06
Times Cited Count：13 Percentile：56.34(Engineering, Electrical & Electronic)The upgrade of the JT-60U magnet system to the superconducting coils (JT-60SA) is progressing as a satellite facility for ITER by Japan and EU in the BA agreement. All components of magnet system are now under manufacturing in mass production. The first superconducting EF conductor was manufactured in 2010 in Japan. First superconducting coil EF4 was manufactured in 2012. Other EF5 and EF6 coils shall be manufactured by 2013 to install temporally on the cryostat base before the assembly of the plasma vacuum vessel. CS model coil is fabricated to qualify all manufacturing process of NbSn conductor. The first TF conductor was manufactured in 2012. The cryogenic requirements for JT-60SA are about 9 kW at 4.5K. Each coil is connected through an in-cryostat feeder to the current leads located outside the cryostat in the CTB. A total of 26 HTS current leads are installed in the CTB. The manufacturing of the magnet system is in progress to provide components to assembly the Tokamak machine.
Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Koide, Yoshihiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Takahata, Kazuya*; Hamaguchi, Shinji*; Chikaraishi, Hirotaka*; Natsume, Kyohei*; et al.
IEEE Transactions on Applied Superconductivity, 24(3), p.4200205_1 - 4200205_5, 2014/06
Times Cited Count：25 Percentile：73.77(Engineering, Electrical & Electronic)Central Solenoid (CS) of JT-60SA are designed with the NbSn cable in conduit conductor. CS model coil (CSMC) was manufactured by using the real manufacturing jigs and procedure to validate the CS manufacturing processes before starting mass production. The dimensions of the CSMC are the same as real quad-pancake. The cold test of the CSMC was performed and the test results satisfied the design requirements. These results indicate that the manufacturing processes of the JT-60SA CS has been established. In this paper, the development and the validation of the CS manufacturing processes are described.
Tsuchiya, Katsuhiko; Kizu, Kaname; Murakami, Haruyuki; Yoshizawa, Norio; Koide, Yoshihiko; Yoshida, Kiyoshi
IEEE Transactions on Plasma Science, 42(4), p.1042 - 1046, 2014/04
Times Cited Count：9 Percentile：41.54(Physics, Fluids & Plasmas)JT-60SA is full superconducting tokamak that was constructed in JAEA Naka site in corporation with JAEA and F4E. The central solenoid (CS) assembly in JT-60SA consists of 4 modules of superconducting solenoid which has outer diameter of 
2m and height of 1.6m. The currents for each module were independently controlled. CS was designed to produce enough flux to control the plasmas with 5.5 MA during 100 sec. Superconducting conductor for CS consists of NbSn strands. The support structure for CS assembly consists of the tie-plates (inner and outer), buffer zones and key-blocks. CS must be cooled down to 4K before charging, and modules will be shrunk during this process. The support structure made of stainless steel was also shrunk at 4K. Thermal expansion ratio of stainless steel, however, is different from that of modules, which would result in the gap between modules and supports. In order to cancel this gap, pre-compress mechanism needs to be introduced in the support structure for CS assembly. Mechanical pressure for the pre-compress will be controlled by hydraulic rams that are set at the top of each support. During the pre-compress process in which both key-blocks clamp the modules, tension works at the tie plates. The support structure for CS assembly, especially tie plates, should have sufficient mechanical strength to withstand the stress induced by the pre-compress at room temperature, not only to withstand the electro-magnetic force which was produced during the plasma operation. Space for installation of CS assembly is limited by TF coils, so that cross section of tie-plate is also limited. Final structure was successfully designed to adopt the stainless steel with 0.120.17 wt% of nitrogen content (SS316LN) for the material of the main parts of support structure.
Kamiya, Koji; Furukawa, Masato; Hatakenaka, Ryuta*; Miyakita, Takeshi*; Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Koide, Yoshihiko; Yoshida, Kiyoshi
AIP Conference Proceedings 1573, p.455 - 462, 2014/01
Times Cited Count：5 Percentile：90.51(Thermodynamics)The thermal shield of JT-60SA is kept at 80 K and will use the Multi Layered Insulator (MLI) to reduce radiation heat load to the superconducting coils at 4.4 K from the cryostat at 300 K. Due to plasma pulse operation, the MLI is affected by eddy current in toroidal direction. The MLI is designed to suppress the current by electrically insulating every 20 degree in the toroidal direction by covering the MLI with polyimide films. In this paper, two kinds of designs for insulated MLI are proposed focusing on a way to overlap MLI. A boil-off calorimeter method and temperature measurement has been performed to determine the thermal performance of MLI. The design of electrical insulated thermal anchor between the toroidal field (TF) coil and the thermal shield is also explained.
Koizumi, Norikiyo; Nunoya, Yoshihiko; Yoshida, Kiyoshi; Barabaschi, P.*
Physics Procedia, 58, p.232 - 235, 2014/00
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)no abstracts in English
Kamiya, Kensaku; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Yoshida, Maiko; Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; et al.
Nuclear Fusion, 52(11), p.114010_1 - 114010_12, 2012/10
Times Cited Count：10 Percentile：40.68(Physics, Fluids & Plasmas)Depending on the direction of the external tangential momentum input, substantial changes in not only toroidal but also poloidal flows for the carbon impurity ions are observed at around the 
-well region. The shear in the edge becomes wider in the co-NBI case, while the edge -well becomes deeper in the counter-NBI case.
Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Suzuki, Takahiro; Aiba, Nobuyuki; Takenaga, Hidenobu; Isayama, Akihiko; Shinohara, Koji; Yoshida, Maiko; Takechi, Manabu; et al.
Nuclear Fusion, 49(9), p.095017_1 - 095017_8, 2009/09
Times Cited Count：33 Percentile：73.96(Physics, Fluids & Plasmas)This paper reports the recent development of reversed shear plasmas with a high bootstrap current fraction towards reactor relevant regime, especially lower 
regime. By utilizing large volume configuration close to the conductive wall for wall stabilization, the beta limit of the reversed shear plasmas is significantly improved. As a result, high confinement reversed shear plasmas with high bootstrap current fraction exceeding no-wall beta limit are obtained in reactor relevant regime, where 
of 2.7, 
of 2.3 is achieved with reversed profile with 
of 2.3, and then HH
of 1.7, 
/
of 0.87 and 
of 0.9 are also obtained at of 5.3.
Ida, Katsumi*; Sakamoto, Yoshiteru; Yoshinuma, Mikiro*; Takenaga, Hidenobu; Nagaoka, Kenichi*; Hayashi, Nobuhiko; Oyama, Naoyuki; Osakabe, Masaki*; Yokoyama, Masayuki*; Funaba, Hisamichi*; et al.
Nuclear Fusion, 49(9), p.095024_1 - 095024_9, 2009/09
Times Cited Count：31 Percentile：71.94(Physics, Fluids & Plasmas)Dynamics of ion internal transport barrier (ITB) formation and impurity transport both in the Large Helical Device (LHD) heliotron and JT-60U tokamak are described. Significant differences between heliotron and tokamak plasmas are observed. The location of the ITB moves outward during the ITB formation regardless of the sign of magnetic shear in JT-60U and the ITB becomes more localized in the plasma with negative magnetic shear. In LHD, the low Te/Ti ratio (
1) of the target plasma for the high power heating is found to be necessary condition to achieve the ITB plasma and the ITB location tends to expand outward or inward depending on the condition of the target plasmas. Associated with the formation of ITB, the carbon density tends to be peaked due to inward convection in JT-60U, while the carbon density becomes hollow due to outward convection in LHD. The outward convection observed in LHD contradicts the prediction by neoclassical theory.
Kamada, Yutaka; Yoshida, Maiko; Sakamoto, Yoshiteru; Koide, Yoshihiko; Oyama, Naoyuki; Urano, Hajime; Kamiya, Kensaku; Suzuki, Takahiro; Isayama, Akihiko; JT-60 Team
Nuclear Fusion, 49(9), p.095014_1 - 095014_9, 2009/09
Times Cited Count：2 Percentile：8.15(Physics, Fluids & Plasmas)For understanding of the physics processes determining the radial profiles of the kinetic plasma parameters in the advanced tokamak plasmas, correlation between the edge and the internal transport barriers (ETB and ITB) has been studied. We fond that the edge pedestal beta, 
, increases almost linearly with the total 
, over a wide range of the plasma current for the type I ELMing H-mode, and the dependence becomes stronger with increasing triangularity. This dependence is not due to the profile stiffness. However, with increasing the stored energy inside the ITB radius (W
), the total thermal stored energy (W
) increases and then the pedestal stored energy (W) increases. With increasing W, the ELM penetration depth expands more inward and finally reaches the ITB-foot radius. At this situation, the ITB radius cannot move outward and the ITB strength becomes weak. Then the fractions of W and W to W become almost constant. We also found that the type I ELM expels/decreases edge toroidal momentum larger than ion thermal energy. The ELM penetration radius for toroidal rotation tends to be deeper than that for ion temperature, and can exceeds the ITB radius. The ELM affected area is deeper for CO rotating plasmas than CTR rotating ones. The ELM affected area is deeper in the order of the toroidal rotation (V
), the ion temperature (T
) and then the electron temperature (Te). The L-H transition also changes the V-profile more significantly than the Ti-profile. After the L-H transition, in the ELM-free phase, the pedestal V sifts into the CTR direction deeply and suddenly, and after that the pedestal V and T evolves in the similar timescale. The change in V by ELM and L-H transition may affect degradation / evolution of ITBs.
Kizu, Kaname; Tsuchiya, Katsuhiko; Obana, Tetsuhiro*; Takahata, Kazuya*; Hoshi, Ryo; Hamaguchi, Shinji*; Nunoya, Yoshihiko; Yoshida, Kiyoshi; Matsukawa, Makoto; Yanagi, Nagato*; et al.
Fusion Engineering and Design, 84(2-6), p.1058 - 1062, 2009/06
Times Cited Count：12 Percentile：62.2(Nuclear Science & Technology)The maximum magnetic field and maximum current of EF coils for JT-60SA is 6.2T, 20 kA, respectively. The EF coil conductors are NbTi cable-in-conduit (CIC) conductor with SS316L conduit. In order to confirm the performance of current sharing temperature (
) tests under coil operational condition was performed. As a results, the degradation of was 0.01-0.08 K indicating that the conductor design and its fabrication method is appropriate. Experimental results were compared with the 
and by standard plasma operation scenario. It was confirmed that the conductor has margin of 
1K.
Tanimura, Yoshihiko; Birumachi, Atsushi; Yoshida, Makoto; Watanabe, Tamaki*
Radioisotopes, 57(12), p.733 - 738, 2008/12
In order to develop simple but reliable radiation meters for the general public, photon detection performances of radiation sensors have been studied both experimentally in photon calibration fields and by Monte Carlo simulations. A silicon 
photodiode and a CdTe detector were selected for the low-cost sensors. Their energy responses to ambient dose equivalent H
(10) were evaluated over the energy range from 60 keV to 2 MeV. The response of the CdTe decreases markedly with increasing photon energy. On the other hand, the photodiode has the advantage of almost flat response above 150 keV. The sensitivities of these sensors are 4 to 6 cpm for the natural radiation. Detection limits of the radiation level are low enough to know the extreme increase of radiation due to emergency situations of nuclear power plants, fuel treatment facilities and so on.
Urano, Hajime; Takenaga, Hidenobu; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Oyama, Naoyuki; Yoshida, Maiko; JT-60 Team
Nuclear Fusion, 48(8), p.085007_1 - 085007_9, 2008/08
Times Cited Count：9 Percentile：35.29(Physics, Fluids & Plasmas)Relation between heat transport in the plasma core and toroidal rotation profile was examined in conventional ELMy H-mode plasmas in JT-60U. Energy confinement improvement is observed with toroidal rotation which increases in co-direction with respect to the plasma current. Heat transport in the plasma core varies while sustaining self-similar temperature profile in the variation of toroidal rotation profiles. Large increase in heat conduction imposes the resilient profile of ion temperature, under which local effect of toroidal rotation profile on the scale length of ion temperature gradient is very weak. When the pedestal temperature was fixed between the cases of co and counter-NBI by adjusting the plasma density, the identical temperature profiles were obtained in spite of totally different toroidal rotation profiles.
Ida, Katsumi; Sakamoto, Yoshiteru; Takenaga, Hidenobu; Oyama, Naoyuki; Ito, Kimitaka*; Yoshinuma, Mikiro*; Inagaki, Shigeru*; Kobuchi, Takashi*; Isayama, Akihiko; Suzuki, Takahiro; et al.
Physical Review Letters, 101(5), p.055003_1 - 055003_4, 2008/08
Times Cited Count：34 Percentile：79.28(Physics, Multidisciplinary)A spontaneous transition phenomena between two meta-stable states of plasmas with internal transport barrier (ITB), that are characterized by different radial profiles of second derivative of ion temperature inside the ITB region where the ion temperature gradient is large, is observed in the steady-state phase of magnetic shear in the negative magnetic shear plasma in JT-60U tokamak. The curvature asymmetry factor evaluated from the radial profile of second derivative of ion temperature profiles changes from 0.08 (symmetric curvature ITB) to -0.43 (asymmetric curvature ITB) during transition phase.
-radiolysis of aqueous sulfuric acid solutions containing Al
O, SiO, TiO or ZrO fine particlesYamada, Reiji; Nagaishi, Ryuji; Hatano, Yoshihiko; Yoshida, Zenko
International Journal of Hydrogen Energy, 33(3), p.929 - 936, 2008/02
Times Cited Count：17 Percentile：38.68(Chemistry, Physical)Hydrogen production was studied in the -radiolysis of aqueous HSO
solutions containing oxide powder of AlO, SiO, TiO or ZrO. The observed yields of final product H increased with relative amounts of oxide powder in the solutions and exhibited a particular HSO concentration dependence, which was different for each oxide species and its amount. The addition of a small amount of CHOH to a HSO aqueous solution with oxide powder was quite effective for increasing the final product yields of H. The obtained results revealed that heterogeneous systems composed of oxide powder and aqueous HSO solution were more efficient for producing H molecules in -radiolysis than homogeneous systems without oxides.
Kobayashi, Shinji*; Yoshida, Maiko; Takenaga, Hidenobu; Sakata, Shinya; Kamada, Yutaka; Sakamoto, Yoshiteru; Koide, Yoshihiko; JT-60 Team
Plasma and Fusion Research (Internet), 2, p.S1049_1 - S1049_4, 2007/11
Real-time measurement system of the ion temperature profile has been developed for the feedback (FB) control of the ion temperature gradient (grad-
) with the filter charge exchange recombination spectroscopy (CXRS) system in JT-60U. The rapid analytical scheme without non-linear least square fitting enables us to calculate the ion temperature with four spatial points every 10 ms using a real-time processor system. The FB control experiment of grad- has been demonstrated in ELMy H-mode plasmas by use of the neutral beam injectors having different deposition profiles as actuators. Grad- was controlled to the reference value in the ramp-down phase, however, it did not recovered in the ramp-up phase because the internal transport barrier or transport was affected by the ramp-down of grad-. From the transient response analysis of grad-Ti, the increase in the central using the additional heating was required to recover the deteriorated grad-.
