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Journal Articles

A Project focusing on the contamination mechanism of concrete after the accident at Fukushima Daiichi Nuclear Power Plant

Yamada, Kazuo*; Maruyama, Ippei*; Haga, Kazuko*; Igarashi, Go*; Aihara, Haruka; Tomita, Sayuri*; Kiran, R.*; Osawa, Norihisa*; Shibata, Atsuhiro; Shibuya, Kazutoshi*; et al.

Proceedings of International Waste Management Symposia 2021 (WM 2021) (CD-ROM), 10 Pages, 2021/03

Journal Articles

Progress report of Japanese simulation research projects using the high-performance computer system Helios in the International Fusion Energy Research Centre

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.

Journal Articles

Achievement of robust high-efficiency 1 MW oscillation in the hard-self-excitation region by a 170 GHz continuous-wave gyrotron

Sakamoto, Keishi; Kasugai, Atsushi; Takahashi, Koji; Minami, Ryutaro*; Kobayashi, Noriyuki; Kajiwara, Ken

Nature Physics, 3(6), p.411 - 414, 2007/06

 Times Cited Count:191 Percentile:97.53(Physics, Multidisciplinary)

The first 1 MW quasi-continuous wave generation is demonstrated at 170 GHz gyrotron of TE31,8 resonator mode with outstanding efficiency of greater than 55 percent. The robust high efficiency oscillation is obtained in a hard self-excitation region with an active control of gyrotron parameters. Furthermore, a novel nonlinear process is found that the desired TE31,8 mode is excited as a parasitic mode of an adjacent TE30,8 mode and finally the TE31,8 dominates a system. This effect extends a substantial soft self-excitation region of the desired mode significantly.

Journal Articles

Development of the 170GHz gyrotron and equatorial launcher for ITER

Sakamoto, Keishi; Kasugai, Atsushi; Takahashi, Koji; Minami, Ryutaro*; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Kobayashi, Noriyuki

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

no abstracts in English

Journal Articles

High power and high efficiency operation of 170GHz gyrotron

Kasugai, Atsushi; Minami, Ryutaro*; Takahashi, Koji; Kobayashi, Noriyuki; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Sakamoto, Keishi

Fusion Science and Technology, 51(2T), p.213 - 216, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Long pulse operation of 170 GHz ITER gyrotron by beam current control

Kasugai, Atsushi; Minami, Ryutaro; Takahashi, Koji; Kobayashi, Noriyuki; Sakamoto, Keishi

Fusion Engineering and Design, 81(23-24), p.2791 - 2796, 2006/11

 Times Cited Count:9 Percentile:55.03(Nuclear Science & Technology)

In JAEA (Japan Atomic Energy Agency, formerly JAERI), development of 170 GHz, 1 MW, CW gyrotron for ITER has been carried out. Key technologies for ITER gyrotron such as a diamond window, a depressed collector for high efficiency operation and a stable operation at 170 GHz/1 MW with higher mode TE31,8 have been developed. By integration of these key technologies, gyrotron performance of 0.5 MW/ 100 sec and 0.9 MW/ 9.2 sec were demonstrated. Hence, next target is a demonstration of long pulse operation. One of the issues which prevent the pulse extension is large beam current decrease due to so called the emission cooling of a cathode. During the operation, the oscillation mode shift from TE31,8 to TE30,8 was caused by the current decrease. Then, the magnetic field of the cavity should be increased to avoid the downshift of the oscillation mode, however, the efficiency decreases and the parasitic oscillation appears in a quasi-optical mode converter. To suppress the beam current decrease and to demonstrate the long pulse operation of the high power gyrotron, pre-programming control of the cathode heater power was applied and the long pulse experiment was carried out to sustain the beam current. As a result, stable electron beam of 1000 s, which is required for ITER operation, was demonstrated without oscillation, and pre-programming control directed the effectiveness for constant beam current. Moreover, in the experiment of the long pulse oscillation with oscillation, the pre-programming control suppressed the beam current decrease. Up to now, stable long pulse operation of $$sim$$8 minutes with 0.2 MW output power was obtained. The output energy of the oscillation is maximum value in the 170GHz ITER gyrotron. Since overheating due to stray radiation inside the gyrotron limit the pulse extension, long pulse operation with high power output will be achieved by enhancement of the cooling and reduction of stray radiation due to modification of a built-in mode converter.

Journal Articles

Conceptual study of ECH/ECCD system for fusion DEMO plant

Sakamoto, Keishi; Takahashi, Koji; Kasugai, Atsushi; Minami, Ryutaro; Kobayashi, Noriyuki*; Nishio, Satoshi; Sato, Masayasu; Tobita, Kenji

Fusion Engineering and Design, 81(8-14), p.1263 - 1270, 2006/02

 Times Cited Count:5 Percentile:37.87(Nuclear Science & Technology)

no abstracts in English

Journal Articles

The Designs of high efficiency launcher of quasi-optical mode converter for high power gyrotrons

Minami, Ryutaro; Kasugai, Atsushi; Takahashi, Koji; Kobayashi, Noriyuki*; Mitsunaka, Yoshika*; Sakamoto, Keishi

International Journal of Infrared and Millimeter Waves, 27(1), p.13 - 24, 2006/01

 Times Cited Count:11 Percentile:52.53(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Development of high power and long pulse 170GHz gyrotron

Sakamoto, Keishi; Kasugai, Atsushi; Minami, Ryutaro; Takahashi, Koji; Kobayashi, Noriyuki; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*

Proceedings of 14th Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating (EC-14), p.517 - 525, 2006/00

no abstracts in English

Journal Articles

Development of high power gyrotron for CW operation

Minami, Ryutaro; Kasugai, Atsushi; Takahashi, Koji; Kobayashi, Noriyuki; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Hayashi, Kenichi*; Sakamoto, Keishi

Shingaku Giho, 105(498), p.39 - 42, 2005/12

no abstracts in English

Journal Articles

Development of long pulse and high power 170 GHz gyrotron

Sakamoto, Keishi; Kasugai, Atsushi; Minami, Ryutaro; Takahashi, Koji; Kobayashi, Noriyuki*

Journal of Physics; Conference Series, 25, p.8 - 12, 2005/00

The present status of ITER gyrotron development of JAERI is reported. Up to now, we demonstrated 100 sec operation at 0.5 MW level power output. On the other hand, some issues were recognized for CW operation, i.e., the beam current decreased as pulse duration expanded. And the large amount of stray RF of 170 GHz exists in the gyrotron. Former, pre-programming control of the heater power of electron gun was introduced to keep the beam current constant. Latter, the inner surface of the radiator was optimized to minimize the diffraction, and loss was reduced by 1/5. Prior to the RF pulse extension, we tried an electron beam test without RF oscillation. As a result, the constant beam current was demonstrated up to 1000 sec.

Journal Articles

Long pulse operation of high power gyrotron with mm-wave range for fusion reactor

Kasugai, Atsushi; Minami, Ryutaro; Takahashi, Koji; Kobayashi, Noriyuki*; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Hayashi, Kenichi*; Sakamoto, Keishi

Shingaku Giho, 104(520), p.37 - 42, 2004/12

no abstracts in English

JAEA Reports

Control of electron beam current of high power gyrotron for CW operation

Minami, Ryutaro; Kobayashi, Noriyuki*; Sakamoto, Keishi; Kasugai, Atsushi; Takahashi, Koji; Imai, Tsuyoshi

JAERI-Research 2004-006, 17 Pages, 2004/03

JAERI-Research-2004-006.pdf:1.37MB

no abstracts in English

Journal Articles

Development of advanced antennas and diamond windows for ECH/CD in fusion reactor

Takahashi, Koji; Kasugai, Atsushi; Minami, Ryutaro; Sakamoto, Keishi; Ikeda, Yukiharu; Kobayashi, Noriyuki*; Imai, Tsuyoshi

Denki Gakkai Genshiryoku Kenkyukai Shiryo (NE-03-1), p.1 - 6, 2003/09

no abstracts in English

JAEA Reports

Investigation of safety concept of spallation neutron source

Kobayashi, Kaoru*; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Aso, Tomokazu; Hino, Ryutaro

JAERI-Review 2002-010, 52 Pages, 2002/05

JAERI-Review-2002-010.pdf:3.38MB

no abstracts in English

JAEA Reports

Estimation of thermochemical behavior of spallation products in mercury target

Kobayashi, Kaoru*; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Aso, Tomokazu; Teshigawara, Makoto; Hino, Ryutaro

JAERI-Tech 2002-005, 118 Pages, 2002/02

JAERI-Tech-2002-005.pdf:9.71MB

In order to examine the radiation safety of a spallation mercury target system, it is necessary to clarify the chemical forms of spallation products generated by spallation reaction with proton beam. As for the chemical forms of spallation products in mercury that involves large amounts of spallation products, these forms were estimated by using the binary phase diagrams and the thermochemical equilibrium calculation based on the amounts of spallation product. Calculation results showed that the mercury would dissolve Al, As, B, Be, Bi, C, Co, Cr, Fe, Ga, Ge, Ir, Mo, Nb, Os, Re, Ru, Sb, Si, Ta, Tc, V and W in the element state, and Ag, Au, Ba, Br, Ca, Cd, Ce, Cl, Cs, Cu, Dy, Er, Eu, F, Gd, Hf, Ho, I, In, K, La, Li, Lu, Mg, Mn, Na, Nd, Ni, O, Pb, Pd, Pr, Pt, Rb, Rh, S, Sc, Se, Sm, Sn, Sr, Tb, Te, Ti, Tl, Tm, Y, Yb, Zn and Zr in the form of inorganic mercury compounds.

Journal Articles

Present status of spallation neutron source development; JAERI/KEK joint project in Japan

Kaminaga, Masanori; Haga, Katsuhiro; Aso, Tomokazu; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Ishikura, Shuichi*; Terada, Atsuhiko*; Kobayashi, Kaoru*; Adachi, Junichi*; Teraoku, Takuji*; et al.

Proceedings of American Nuclear Society Conference "Nuclear Applications in the New Millennium" (AccApp-ADTTA '01) (CD-ROM), 9 Pages, 2002/00

no abstracts in English

JAEA Reports

Physical and thermochemical properties for inorganic mercury compounds

Kobayashi, Kaoru*; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Aso, Tomokazu; Kogawa, Hiroyuki; Hino, Ryutaro

JAERI-Data/Code 2000-037, 69 Pages, 2000/12

JAERI-Data-Code-2000-037.pdf:3.21MB

no abstracts in English

JAEA Reports

Proposal of source term methodologies for mercury target system

Kobayashi, Kaoru*; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Aso, Tomokazu; Kogawa, Hiroyuki; Hino, Ryutaro

JAERI-Tech 2000-050, 43 Pages, 2000/08

JAERI-Tech-2000-050.pdf:2.36MB

no abstracts in English

Journal Articles

Development of fluid-structure interaction code for mercury target, 1

Imai, Ryuta*; Arakawa, Chuichi*; Kobayashi, Kenichi*; Hino, Ryutaro; Ishikura, Shuichi*; Kogawa, Hiroyuki; Terada, Atsuhiko*; Haga, Katsuhiro; Watanabe, Tadashi

Dai-14-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Yoshishu, p.C10_1_1 - C10_1_14, 2000/00

no abstracts in English

39 (Records 1-20 displayed on this page)