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JAEA Reports

Synthesized research report in the second mid-term research phase; Mizunami Underground Research Laboratory Project, Horonobe Underground Research Laboratory Project and Geo-stability Project

Hama, Katsuhiro; Mizuno, Takashi; Sasao, Eiji; Iwatsuki, Teruki; Saegusa, Hiromitsu; Sato, Toshinori; Fujita, Tomo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Yokota, Hideharu; et al.

JAEA-Research 2015-007, 269 Pages, 2015/08

JAEA-Research-2015-007.pdf:68.65MB
JAEA-Research-2015-007(errata).pdf:0.07MB

We have synthesised the research results from Mizunami/Horonobe URLs and geo-stability projects in the second mid-term research phase. It could be used as technical bases for NUMO/Regulator in each decision point from sitting to beginning of disposal (Principal Investigation to Detailed Investigation Phase). High quality construction techniques and field investigation methods have been developed and implemented and these will be directly applicable to the National Disposal Program (along with general assessments of hazardous natural events and processes). It will be crucial to acquire technical knowledge on decisions of partial backfilling and final closure by actual field experiments in Mizunami/Horonobe URLs as main themes for the next phases.

Journal Articles

Thickness-dependent magnetic properties and strain-induced orbital magnetic moment in SrRuO$$_{3}$$ thin films

Ishigami, Keisuke*; Yoshimatsu, Kohei*; Toyota, Daisuke*; Takizawa, Masaru*; Yoshida, Teppei*; Shibata, Goro*; Harano, Takayuki*; Takahashi, Yukio*; Kadono, Toshiharu*; Verma, V. K.*; et al.

Physical Review B, 92(6), p.064402_1 - 064402_5, 2015/08

 Times Cited Count:36 Percentile:83.24(Materials Science, Multidisciplinary)

Journal Articles

Thickness-dependent ferromagnetic metal to paramagnetic insulator transition in La$$_{0.6}$$Sr$$_{0.4}$$MnO$$_3$$ thin films studied by X-ray magnetic circular dichroism

Shibata, Goro*; Yoshimatsu, Kohei*; Sakai, Enju*; Singh, V. R.*; Verma, V.*; Ishigami, Keisuke*; Harano, Takayuki*; Kadono, Toshiharu*; Takeda, Yukiharu; Okane, Tetsuo; et al.

Physical Review B, 89(23), p.235123_1 - 235123_5, 2014/06

AA2015-0419.pdf:0.33MB

 Times Cited Count:15 Percentile:58.56(Materials Science, Multidisciplinary)

Journal Articles

Spin orientation transition across the single-layer graphene/nickel thin film interface

Matsumoto, Yoshihiro; Entani, Shiro; Koide, Akihiro*; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Amemiya, Kenta*; Fujikawa, Takashi*; Sakai, Seiji

Journal of Materials Chemistry C, 1(35), p.5533 - 5537, 2013/09

 Times Cited Count:28 Percentile:73.27(Materials Science, Multidisciplinary)

Journal Articles

Effect of proton irradiation on AlGaN/GaN micro-Hall sensors

Abderrahmane, A.*; Koide, Shota*; Okada, Hiroshi*; Takahashi, Hiroki*; Sato, Shinichiro; Oshima, Takeshi; Sandhu, A.*

Applied Physics Letters, 102(19), p.193510_1 - 193510_4, 2013/05

 Times Cited Count:7 Percentile:33.17(Physics, Applied)

The magnetoelectric properties of AlGaN/GaN micro-Hall effect sensors were studied after 380 keV proton irradiation. After irradiation the current-voltage measurements, stability of the magnetic sensitivity of the sensors, and the sheet electron density were degraded with a dramatic decrease of the electron mobility at high temperatures. Raman spectroscopy showed a degradation in the crystalline quality of GaN crystal, but there was no change in the strain.

Journal Articles

Effect of Proton Irradiation on 2DEG in AlGaN/GaN Heterostructures

Abderrahmane, A.*; Koide, Shota*; Tahara, Tomoyuki*; Sato, Shinichiro; Oshima, Takeshi; Okada, Hiroshi*; Sandhu, A.*

Journal of Physics; Conference Series, 433, p.012011_1 - 012011_8, 2013/04

 Times Cited Count:5 Percentile:82.58

We investigated the effect of high energy and high fluence proton irradiation on magnetoelectric properties of AlGaN/GaN micro-Hall sensors from 5.4 K to room temperature. The sensors show good resistance versus the irradiation translated by the stability of the sheet density therefore the stability of the absolute sensitivity of the sensor. However, the proton irradiation damaged the electrical properties of the sensor indicated by the dramatically decrease of the mobility at low temperature by rate of about 81% at 5.4 K. The existing of the 2DEG system either after irradiation with high energy was confirmed by investigation the magnetotransport measurements at low temperature and which show Shubnikov de Haas oscillations at high magnetic field. Damping of the Shubnikov de Haas oscillations and disappearance of Landau plateaus after irradiation were related to the degradation in the mobility causing by increasing the scattering at the interface.

Journal Articles

Robust Hall effect magnetic field sensors for operation at high temperatures and in harsh radiation environments

Abderrahmane, A.*; Koide, Shota*; Sato, Shinichiro; Oshima, Takeshi; Sandhu, A.*; Okada, Hiroshi*

IEEE Transactions on Magnetics, 48(11), p.4421 - 4423, 2012/11

 Times Cited Count:17 Percentile:66.44(Engineering, Electrical & Electronic)

Recent industrial trends indicate increasing demand for Hall effect sensors for monitoring magnetic fields under extreme conditions such as high temperatures and under harmful radiation conditions. In this study, robust and high sensitivity Hall effect sensors using AlGaN/GaN heterostructures with a two-dimensional electron gas at the heterointerface were fabricated, and their magnetic properties were investigated. The AlGaN/GaN 2DEG Hall sensors were stable to at least 400 $$^{circ}$$C and even after irradiation of 380 keV protons at the fluence of 1 $$times$$ 10$$^{14}$$ /cm$$^2$$. The results showed that the AlGaN/GaN 2DEG Hall sensors had superior radiation tolerance to AlGaAs/GaAs and AlInSb/InAsSb/AlInSb magnetic sensors.

Journal Articles

Effects of proton irradiation on the magnetoelectric properties of 2DEG AlGaN/GaN micro-hall sensors

Okada, Hiroshi*; Abderrahmane, A.*; Koide, Shota*; Takahashi, Hiroki*; Sato, Shinichiro; Oshima, Takeshi; Sandhu, A.*

Journal of Physics; Conference Series, 352, p.012010_1 - 012010_5, 2012/03

 Times Cited Count:5 Percentile:86.18

Journal Articles

Role of low order rational $$q$$-values in the ITB events in JT-60U reverse shear plasmas

Neudatchin, S. V.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Suzuki, Takahiro

Nuclear Fusion, 44(9), p.945 - 953, 2004/09

The formation of internal transport barriers (ITBs) near q=3 surfaces in normal shear (NrS) discharges of JT-60U is known. In reverse shear (RS) JT-60U plasmas, the role of q minimum (qmin) equal to 3.5,3,2.5,2 was not obvious for ITB formation. ITB-events (non-local confinement bifurcations inside and around ITB) are found in various NrS and RS plasmas. Under sufficient heating power, ITB-events are seen at rational and not rational values of qmin. The space-time evolution of Te and Ti is similar, suggesting the same mechanism of Te and Ti transport. The temporal formation of strong ITB under passing of qmin=3 (after periodical improvements and degradations via ITB-events) in RS mode is presented. Under smaller power, ITB-events are observed only at rational values of qmin. In a weak RS shot, abrupt rise of Te is seen at qmin=3.5, while more cases of Ti rise are observed. The difference of Te and Ti evolutions seen regularly under the low power, suggests decoupling of Te and Ti transport.

Journal Articles

Role of low order rational ${it q}$-values in the ITB events in JT-60U reverse shear plasmas

Neudatchin, S. V.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Suzuki, Takahiro

Nuclear Fusion, 44(9), p.945 - 953, 2004/09

 Times Cited Count:15 Percentile:46.65(Physics, Fluids & Plasmas)

The formation of internal transport barriers (ITBs) near ${it q}$ =2,3 surfaces in normal shear (NrS) discharges of JT-60U and JET is known. In reverse shear (RS) JT-60U plasmas, the role of ${it q}$ minimum (${it q}$$$_{min}$$) equal to 3.5,3,2.5,2 is not obvious for ITB formation. In this paper, the effect of low rational ${it q}$ values on ITB-events in JT-60U NrS and RS plasmas is investigated. Under sufficient neutral beam power (${it P}$$$_{nbi}$$$$>$$8MW for 1.2-1.5MA/3.8T pulses), ITB-events are seen at rational and non-rational values of ${it q}$$$_{min}$$. The space-time evolutions of ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ are similar, suggesting the same mechanism for ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ transports. The temporal formation of stronger ITB under passing ${it q}$$$_{min}$$=3 (after periodical improvements and degradations via ITB-events) in RS H-mode with ${it P}$$$_{nbi}$$=8MW is presented. Under smaller power, ITB-events are observed only at rational ${it q}$$$_{min}$$ values. In a weak RS shot with ${it P}$$$_{nbi}$$=4MW, the abrupt rise of ${it T}$$$_{e}$$ is seen at ${it q}$$$_{min}$$=3.5, while more cases of ${it T}$$$_{i}$$ rise are observed. The difference between the ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ evolutions for the low power suggests the decoupling of ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ transports.

Journal Articles

Properties of internal transport barrier formation in JT-60U

Sakamoto, Yoshiteru; Suzuki, Takahiro; Ide, Shunsuke; Koide, Yoshihiko; Takenaga, Hidenobu; Kamada, Yutaka; Fujita, Takaaki; Fukuda, Takeshi; Takizuka, Tomonori; Shirai, Hiroshi; et al.

Nuclear Fusion, 44(8), p.876 - 882, 2004/08

 Times Cited Count:29 Percentile:68.6(Physics, Fluids & Plasmas)

Response of the ion thermal diffusivity to the radial electric field Er shear has been investigated in JT-60U and the following results were found. (1) In the case of positive magnetic shear (PS) plasma, the ion thermal diffusivity in the core region shows L mode state, weak internal transport barrier (ITB), and strong ITB depending upon the heating power. In the case of reversed magnetic shear (RS) plasma, however, no power degradation of the ion thermal diffusivity is observed. (2) In the case of weak ITB, the ion thermal diffusivity decreases gradually with increasing the Er shear for both PS and RS plasmas. There exists a threshold of an effective Er shear to change its state from weak to strong ITBs. (3) The threshold of the effective Er shear in the case of RS plasma is small compared with that in the case of PS plasma.

Journal Articles

Instantaneous correlation between ELM-like MHD activity and abrupt non-local reduction of transport at internal transport barrier formation in JT-60U high-$$beta$$$$_{p}$$ plasmas

Neudatchin, S.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Ito, Kimitaka*; Miura, Yukitoshi

Purazuma, Kaku Yugo Gakkai-Shi, 79(12), p.1218 - 1220, 2003/12

New type of edge-core instantaneous interplay in JT-60U high-$$beta$$$$_{p}$$ plasmas is found. Abrupt in time and wide in space reduction of electron heat flux in the core (called ITB-event) is correlated in ms timescale with the start of an ELM. This result gives a hint of the control to form the ITB immedeately and non-locally by inducing the ELM-like MHD activity.

Journal Articles

Relationship between particle and heat transport in JT-60U plasmas with internal transport barrier

Takenaga, Hidenobu; Higashijima, Satoru; Oyama, Naoyuki; Bruskin, L. G.; Koide, Yoshihiko; Ide, Shunsuke; Shirai, Hiroshi; Sakamoto, Yoshiteru; Suzuki, Takahiro; Hill, K. W.*; et al.

Nuclear Fusion, 43(10), p.1235 - 1245, 2003/10

 Times Cited Count:70 Percentile:89.41(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Two-dimensional distribution of divertor radiation in JT-60U

Konoshima, Shigeru; Tamai, Hiroshi; Miura, Yukitoshi; Higashijima, Satoru; Kubo, Hirotaka; Sakurai, Shinji; Shimizu, Katsuhiro; Takizuka, Tomonori; Koide, Yoshihiko; Hatae, Takaki; et al.

Journal of Nuclear Materials, 313-316(1-3), p.888 - 892, 2003/03

 Times Cited Count:20 Percentile:78.45(Materials Science, Multidisciplinary)

The emissivity distribution of the JT-60U divertor plasmas has been studied with the bolometer diagnostics. Line integrated bolometer signals of 48 chords have been successfully mapped onto the JT-60U W-shaped divertor geometry. 2D radiation profiles provide an intuitive understanding of the experiments and comparison of experiment with simulation for divertor characterization. An extended region of the radiation along both divertor legs was found in ELMing H-mode discharges with line-average density of 3.7x10$$^{19}$$m$$^{-3}$$. A highly radiative zone with an emissivity of around 15 MWm$$^{-3}$$ at the inboard side and around 8 MWm$$^{-3}$$ at outboard side has been identified to extend more than 10 cm from each target plate toward the x-point. About 70 % of the input neutral beam power, 11 MW, is dissipated as a divertor radiation in that region.

Journal Articles

Stiff temperature profiles in JT-60U ELMy H-mode plasmas

Mikkelsen, D. R.*; Shirai, Hiroshi; Urano, Hajime*; Takizuka, Tomonori; Kamada, Yutaka; Hatae, Takaki; Koide, Yoshihiko; Asakura, Nobuyuki; Fujita, Takaaki; Fukuda, Takeshi*; et al.

Nuclear Fusion, 43(1), p.30 - 39, 2003/01

 Times Cited Count:25 Percentile:61.31(Physics, Fluids & Plasmas)

The stiffness of thermal transport in ELMy H-modes is explained in a series of carefully chosen JT-60U plasmas, and measured temperature are compared with the predictions of several transport models. A heating power scan with constant Tped, a scan of pedestal temperature Tped with constant heating power, and an on/off-axis heating comparison are presented. Predictions of the RLWB and IFS/PPPL models generally agree with the measured temperature outside $$r$$$$sim$$0.3$$a$$, but the Multimode model uniformly predicts temperatures that are too high except in the central region.

Journal Articles

Advanced real-time feedback control in JT-60U high performance discharges for application to fusion reactor plasmas

Fukuda, Takeshi; Oikawa, Toshihiro; Takeji, Satoru; Isayama, Akihiko; Kawano, Yasunori; Neyatani, Yuzuru; Nagashima, Akira; Nishitani, Takeo; Konoshima, Shigeru; Tamai, Hiroshi; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.357 - 367, 2002/09

 Times Cited Count:7 Percentile:45.43(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Diagnostics system of JT-60U

Sugie, Tatsuo; Hatae, Takaki; Koide, Yoshihiko; Fujita, Takaaki; Kusama, Yoshinori; Nishitani, Takeo; Isayama, Akihiko; Sato, Masayasu; Shinohara, Koji; Asakura, Nobuyuki; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.482 - 511, 2002/09

 Times Cited Count:6 Percentile:3.03(Nuclear Science & Technology)

The diagnostic system of JT-60U (JT-60upgrade) is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters have been improved, so that the internal structure of plasmas has been explored. The understanding of plasma confinement has been enhanced by density and temperature fluctuation measurements using a mm-wave reflectometer and electron cyclotron emission measurements respectively. In addition, the real-time control experiments of electron density, neutron yield, radiated power and electron temperature gradient have been carried out successfully by corresponding diagnostic devices. These measurements and the real time control contribute to improving plasma performance. Diagnostic devices for next generation fusion devices such as a CO2 laser interferometer/polarimeter and a CO2 laser collective Thomson scattering system have been developed.

Journal Articles

Fusion plasma performance and confinement studies on JT-60 and JT-60U

Kamada, Yutaka; Fujita, Takaaki; Ishida, Shinichi; Kikuchi, Mitsuru; Ide, Shunsuke; Takizuka, Tomonori; Shirai, Hiroshi; Koide, Yoshihiko; Fukuda, Takeshi; Hosogane, Nobuyuki; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.185 - 254, 2002/09

 Times Cited Count:30 Percentile:48.48(Nuclear Science & Technology)

With the main aim of providing physics basis for ITER and the steady-state tokamak reactors, JT-60/JT-60U has been developing and optimizing the operational concepts, and extending the discharge regimes toward sustainment of high integrated performance in the reactor relevant parameter regime. In addition to achievement of the equivalent break-even condition (QDTeq up to 1.25) and a high fusion triple product = 1.5E21 m-3skeV, JT-60U has demonstrated the integrated performance of high confinement, high beta-N, full non-inductive current drive with a large fraction of bootstrap current in the reversed magnetic shear and in the high-beta-p ELMy H mode plasmas characterized by both internal and edge transport barriers. The key factors in optimizing these plasmas are profile and shape controls. As represented by discovery of various Internal Transport Barriers, JT-60/JT-60U has been emphasizing freedom and restriction of profiles in various confinement modes. JT-60U has demonstrated applicability of these high confinement modes to ITER and also clarified remaining issues.

Journal Articles

Power dependence of ion thermal diffusivity at the internal transport barrier in JT-60U

Sakamoto, Yoshiteru; Suzuki, Takahiro; Ide, Shunsuke; Koide, Yoshihiko; Takenaga, Hidenobu; Kamada, Yutaka; Fujita, Takaaki; Takizuka, Tomonori; Shirai, Hiroshi; Fukuda, Takeshi

Purazuma, Kaku Yugo Gakkai-Shi, 78(9), p.941 - 948, 2002/09

no abstracts in English

Journal Articles

Formation and sustainment of ITBs under various heating schemes in JT-60U

Ide, Shunsuke; Suzuki, Takahiro; Sakamoto, Yoshiteru; Takenaga, Hidenobu; Koide, Yoshihiko; Fujita, Takaaki; Fukuda, Takeshi; Kamada, Yutaka; Shirai, Hiroshi; Takizuka, Tomonori

Plasma Physics and Controlled Fusion, 44(5A), p.A137 - A142, 2002/05

 Times Cited Count:17 Percentile:50.29(Physics, Fluids & Plasmas)

no abstracts in English

120 (Records 1-20 displayed on this page)