Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Maeyama, Shinya*; Watanabe, Tomohiko*; Nakata, Motoki*; Nunami, Masanori*; Asahi, Yuichi; Ishizawa, Akihiro*
Nature Communications (Internet), 13, p.3166_1 - 3166_8, 2022/06
Times Cited Count：19 Percentile：95.69(Multidisciplinary Sciences)Turbulent transport is a key physics process for confining magnetic fusion plasma. Recent theoretical and experimental studies of existing fusion experimental devices revealed the existence of cross-scale interactions between small (electron)-scale and large (ion)-scale turbulence. Since conventional turbulent transport modelling lacks cross-scale interactions, it should be clarified whether cross-scale interactions are needed to be considered in future experiments on burning plasma, whose high electron temperature is sustained with fusion-born alpha particle heating. Here, we present supercomputer simulations showing that electron scale turbulence in high electron temperature plasma can affect the turbulent transport of not only electrons but also fuels and ash. Electron-scale turbulence disturbs the trajectories of resonant electrons responsible for ion-scale micro-instability and suppresses large-scale turbulent fluctuations. Simultaneously, ion-scale turbulent eddies also suppress electron-scale turbulence. These results indicate a mutually exclusive nature of turbulence with disparate scales. We demonstrate the possibility of reduced heat flux via cross-scale interactions.
Fujita, Natsuko; Matsubara, Akihiro; Miyake, Masayasu*; Watanabe, Takahiro; Kokubu, Yoko; Kato, Motohisa*; Okabe, Nobuaki*; Isozaki, Nobuhiro*; Ishizaka, Chika*; Nishio, Tomohiro; et al.
Proceedings of the 8th East Asia Accelerator Mass Spectrometry Symposium and the 22nd Japan Accelerator Mass Spectrometry symposium (EA-AMS 8 & JAMS-22), p.34 - 36, 2020/00
no abstracts in English
Kokubu, Yoko; Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Ishizaka, Chika; Okabe, Nobuaki; Ishimaru, Tsuneari; Matsubara, Akihiro*; Nishizawa, Akimitsu*; Nishio, Tomohiro*; et al.
Nuclear Instruments and Methods in Physics Research B, 456, p.271 - 275, 2019/10
Times Cited Count：5 Percentile：43.78(Instruments & Instrumentation)JAEA-AMS-TONO has been in operation at the Tono Geoscience Center, Japan Atomic Energy Agency since 1998 and 20 years have passed from the beginning of its utilization. The AMS system is a versatile system based on a 5 MV tandem Pelletron type accelerator. The system has been used to measure carbon-14 (
C), beryllium-10 (
Be) and aluminium-26 (
Al). In addition, the development of measurement of iodine-129 (
I) has been started. The main use is measurement of C in geological samples for dating studies in neotectonics and hydrogeology. In order to increase the speed of sample preparation, we introduced the automated graphitization equipment and made a gas-strip line to collect dissolved inorganic carbon in groundwater samples. Measurement of Be and Al has been used for geoscience studies and the detection limit in the measurement of Be was improved by 
Be-counting suppression. Recently tuning of measurement condition of I has been progressed.
Fujita, Natsuko; Matsubara, Akihiro; Miyake, Masayasu*; Watanabe, Takahiro; Kokubu, Yoko; Kato, Motohisa*; Okabe, Nobuaki*; Isozaki, Nobuhiro*; Ishizaka, Chika*; Torazawa, Hitoshi*; et al.
Dai-32-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.57 - 59, 2019/09
no abstracts in English
Watanabe, Takahiro; Kokubu, Yoko; Fujita, Natsuko; Ishizaka, Chika*; Nishio, Tomohiro; Matsubara, Akihiro*; Miyake, Masayasu; Kato, Motohisa*; Isozaki, Nobuhiro*; Torazawa, Hitoshi*; et al.
JAEA-Conf 2018-002, p.116 - 119, 2019/02
AMS is widely used for radiocarbon dating of geological samples. However, improvement in efficiency of sample preparation techniques are needed for high-time resolution dataset. In 2016, automated graphitization equipment (AGE3, IonPlus AG) has been installed in Toki Research Institute of Isotope Geology and Geochronology, Tono Geoscience Center, JAEA. Background values and carbon recovery rates during preparation process of AGE3 should be estimated before application in radiocarbon dating. In this study, the AGE3 system was evaluated using the international standard materials (IAEA-C1, C4, C5, C6, C7, C9 and NIST-SRM4990C) at JAEA-AMS-TONO. Graphite samples was prepared by the AGE3 system and radiocarbon concentration of these standards was measured by AMS. The results were agreement with the consensus values. Background values were 0.15
0.01 pMC (IAEA-C1) using the AGE3 system. Therefore, we concluded that the system can be adapted for radiocarbon dating of geological samples.
Kokubu, Yoko; Fujita, Natsuko; Matsubara, Akihiro*; Nishizawa, Akimitsu*; Nishio, Tomohiro; Miyake, Masayasu; Ishimaru, Tsuneari; Watanabe, Takahiro; Ogata, Nobuhisa; Shimada, Akiomi; et al.
JAEA-Conf 2018-002, p.5 - 8, 2019/02
no abstracts in English
I/
I ratio at JAEA-AMS-TONOOkabe, Nobuaki; Fujita, Natsuko; Matsubara, Akihiro*; Miyake, Masayasu; Nishio, Tomohiro*; Nishizawa, Akimitsu*; Isozaki, Nobuhiro*; Watanabe, Takahiro; Kokubu, Yoko
JAEA-Conf 2018-002, p.51 - 54, 2019/02
no abstracts in English
Matsubara, Akihiro*; Fujita, Natsuko; Miyake, Masayasu; Isozaki, Nobuhiro*; Nishizawa, Akimitsu*
JAEA-Conf 2018-013, p.135 - 139, 2019/02
no abstracts in English
Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Kokubu, Yoko; Ishimaru, Tsuneari; Matsubara, Akihiro*; Nishio, Tomohiro*; Kato, Motohisa*; Isozaki, Nobuhiro*; Torazawa, Hitoshi*; et al.
JAEA-Conf 2018-013, p.96 - 99, 2019/02
no abstracts in English
Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Kokubu, Yoko; Matsubara, Akihiro*; Kato, Motohisa*; Okabe, Nobuaki; Isozaki, Nobuhiro*; Ishizaka, Chika*; Torazawa, Hitoshi*; et al.
Dai-31-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.92 - 95, 2018/12
no abstracts in English
Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Kokubu, Yoko; Ishimaru, Tsuneari; Matsubara, Akihiro*; Isozaki, Nobuhiro*; Nishio, Tomohiro*; Kato, Motohisa*; Torazawa, Hitoshi*; et al.
Dai-19-Kai AMS Shimpojiumu, 2016-Nendo "Jumoku Nenrin" Kenkyukai Kyodo Kaisai Shimpojiumu Hokokushu, p.68 - 71, 2017/06
no abstracts in English
Matsubara, Akihiro*; Miyake, Masayasu; Fujita, Natsuko; Isozaki, Nobuhiro*; Nishizawa, Akimitsu*; Kokubu, Yoko
Dai-19-Kai AMS Shimpojiumu, 2016-Nendo "Jumoku Nenrin" Kenkyukai Kyodo Kaisai Shimpojiumu Hokokushu, p.118 - 121, 2017/06
no abstracts in English
Maeyama, Shinya*; Watanabe, Tomohiko*; Idomura, Yasuhiro; Nakata, Motoki*; Ishizawa, Akihiro*; Nunami, Masanori*
Nuclear Fusion, 57(6), p.066036_1 - 066036_10, 2017/05
Times Cited Count：17 Percentile：66.93(Physics, Fluids & Plasmas)Multi-scale plasma turbulence including electron and ion temperature gradient (ETG/ITG) modes has been investigated by means of electromagnetic gyrokinetic simulations. Triad transfer analyses on nonlinear mode coupling reveal cross-scale interactions between electron and ion scales. One of the interactions is suppression of electron-scale turbulence by ion- scale turbulence, where ITG-driven short-wavelength eddies act like shear flows and suppress ETG turbulence. Another cross-scale interaction is enhancement of ion-scale turbulence in the presence of electron-scale turbulence. This is caused via short-wavelength zonal flows, which are created by the response of passing kinetic electrons in ITG turbulence, suppress ITG turbulence by their shearing, and are damped by ETG turbulence. In both cases, sub-ion-scale structures between electron and ion scales play important roles in the cross-scale interactions.
Fujita, Natsuko; Matsubara, Akihiro*; Watanabe, Takahiro; Kokubu, Yoko; Umeda, Koji*; Ishimaru, Tsuneari; Nishizawa, Akimitsu*; Miyake, Masayasu; Owaki, Yoshio*; Nishio, Tomohiro*; et al.
Dai-29-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.39 - 42, 2017/03
no abstracts in English
Fujita, Natsuko; Matsubara, Akihiro; Watanabe, Takahiro; Kokubu, Yoko; Umeda, Koji; Nishizawa, Akimitsu*; Miyake, Masayasu*; Owaki, Yoshio*; Nishio, Tomohiro*; Kato, Motohisa*
Dai-18-Kai AMS Shimpojiumu Hokokushu, p.85 - 90, 2016/12
no abstracts in English
Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03
The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.
Matsubara, Akihiro; Fujita, Natsuko; Miyake, Masayasu*; Nishizawa, Akimitsu*; Kokubu, Yoko
Dai-17-Kai AMS Shimpojiumu Hokokushu, p.40 - 45, 2015/12
no abstracts in English
Maeyama, Shinya; Watanabe, Tomohiko*; Idomura, Yasuhiro; Nakata, Motoki; Nunami, Masanori*; Ishizawa, Akihiro*
Parallel Computing, 49, p.1 - 12, 2015/11
Times Cited Count：7 Percentile：51.36(Computer Science, Theory & Methods)Kokubu, Yoko; Matsubara, Akihiro; Miyake, Masayasu*; Nishizawa, Akimitsu*; Owaki, Yoshio*; Nishio, Tomohiro*; Sanada, Katsuki*; Hanaki, Tatsumi
Nuclear Instruments and Methods in Physics Research B, 361, p.48 - 53, 2015/10
Times Cited Count：15 Percentile：75.36(Instruments & Instrumentation)The JAEA-AMS-TONO facility was established in 1997 at the Tono Geoscience Center, Japan Atomic Energy Agency. Our AMS system has been made available for C- and Be-AMS. At present, the development of Al-AMS has been conducted to enhance the capability for multi-nuclide AMS. In this presentation, we report the progress on multi nuclide AMS in addition to the status of our facility.
Maeyama, Shinya*; Idomura, Yasuhiro; Watanabe, Tomohiko*; Nakata, Motoki*; Yagi, Masatoshi; Miyato, Naoaki; Ishizawa, Akihiro*; Nunami, Masanori*
Physical Review Letters, 114(25), p.255002_1 - 255002_5, 2015/06
Times Cited Count：98 Percentile：95.25(Physics, Multidisciplinary)Multiscale gyrokinetic turbulence simulations with the real ion-to-electron mass ratio and 
value are realized for the first time, where the value is given by the ratio of plasma pressure to magnetic pressure and characterizes electromagnetic effects on microinstabilities. Numerical analysis at both the electron scale and the ion scale is used to reveal the mechanism of their cross-scale interactions. Even with the real- mass scale separation, ion-scale turbulence eliminates electron-scale streamers and dominates heat transport, not only of ions but also of electrons. When the ion-scale modes are stabilized by finite- effects, the contribution of the electron-scale dynamics to the turbulent transport becomes non-negligible and turns out to enhance ion-scale turbulent transport.
