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Journal Articles

Development of a high power wideband polarizer for electron cyclotron current drive system in JT-60SA

Saigusa, Mikio*; Oyama, Gaku*; Matsubara, Fumiaki*; Takii, Keita*; Sai, Takuma*; Kobayashi, Takayuki; Moriyama, Shinichi

Fusion Engineering and Design, 96-97, p.577 - 582, 2015/10

 Times Cited Count:4 Percentile:32.14(Nuclear Science & Technology)

A wideband polarizer has been developed for an ECCD system in JT-60SA. The groove depth of the mirrors installed in miter bends were optimized for two frequencies (110 GHz and 138 GHz) by numerical simulations. All surfaces of Poincare spheres were covered at both of the frequencies in low power test. The thermal stress of polarizer were estimated by the numerical simulations. The twister polarizer has been tested up to 0.24 MW during 3 s at 110 GHz.

Journal Articles

Upgrade of control signal distribution system at J-PARC Linac

Futatsukawa, Kenta*; Ito, Yuichi; Kikuzawa, Nobuhiro; Kobayashi, Tetsuya*; Sato, Fumiaki; Shinozaki, Shinichi; Suzuki, Takahiro*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1126 - 1129, 2014/06

no abstracts in English

Journal Articles

Precise measurement of the installed cable attenuation

Futatsukawa, Kenta*; Anami, Shozo*; Kobayashi, Tetsuya*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*; Sato, Fumiaki; Shinozaki, Shinichi

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.765 - 768, 2013/08

no abstracts in English

Journal Articles

Status of J-PARC linac LLRF after the Tohoku Earthquake

Futatsukawa, Kenta*; Anami, Shozo*; Kobayashi, Tetsuya*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*; Kawamura, Masato*; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.769 - 773, 2013/08

no abstracts in English

Journal Articles

RF control system for the RFQ test station at J-PARC linac

Fukui, Yuji*; Kawamura, Masato*; Kobayashi, Tetsuya*; Fang, Z.*; Futatsukawa, Kenta*; Sato, Fumiaki; Shinozaki, Shinichi; Suzuki, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.762 - 764, 2013/08

no abstracts in English

Journal Articles

Application of the small OSL elements to the ring type dosemeter

Miyauchi, Hideaki; Yoshitomi, Hiroshi; Sato, Yoshitaka; Takahashi, Fumiaki; Tachibana, Haruo; Kobayashi, Ikuo*; Suzuki, Akifumi*

Nihon Hoshasen Anzen Kanri Gakkai-Shi, 12(1), p.41 - 45, 2013/07

In the Japan Atomic Energy Agency (JAEA), exposures to fingertips can be significant in radiological decontamination at the facilities with mixture fields of beta and $$gamma$$ (X) rays. The radiation doses to fingertips have been measured by ring type dosemeters equipped with thermoluminescence dosemeters (TLD) in JAEA. We applied small Optically Stimulated Luminescence (OSL) elements to the ring type dosemeter, which has the advantages in the use for long term and repeating in dose measurements comparing to the TLDs. In this report, we introduce the outline and the dose evaluation method of the new ring type dosimeter which we applied.

Journal Articles

Progress in ECRF antenna development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Hasegawa, Koichi; Suzuki, Sadaaki; Hiranai, Shinichi; Sato, Fumiaki; Wada, Kenji; Yokokura, Kenji; Shimono, Mitsugu; Sawahata, Masayuki; et al.

Fusion Engineering and Design, 86(6-8), p.763 - 767, 2011/10

 Times Cited Count:6 Percentile:48.42(Nuclear Science & Technology)

Progress of antenna development of the Electron Cyclotron Range of Frequency system for JT-60 SA is presented. Capability of pulse length of 100 s, which requires active cooling for mirrors, and flexibility of beam injection angles in both poloidal and toroidal directions are required for the antenna with high reliability. Mechanical and structural design works of the launcher (antenna and its support with steering structure) based on a linear motion antenna concept are in progress. The key component is a long-stroke bellows which enables to alter poloidal injection angle and a bellows which enables to alter toroidal injection angle. Using a newly fabricated mock-up of the steering structure, it was confirmed that the antenna was mechanically realized for poloidal and toroidal injection angle ranges of -10 to +45$$^{circ}$$ and -15 to +15$$^{circ}$$, respectively. Those angles are consistent with angles required in JT-60SA. The results of thermal and structural analyses are also presented.

Journal Articles

Progress of high-power and long-pulse ECRF system development in JT-60

Kobayashi, Takayuki; Isayama, Akihiko; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Sato, Fumiaki; et al.

Nuclear Fusion, 51(10), p.103037_1 - 103037_10, 2011/10

 Times Cited Count:18 Percentile:63.67(Physics, Fluids & Plasmas)

A new gyrotron operation technique to increase oscillation efficiency was developed on the JT 60 ECRF system. The electron pitch factor was optimized by controlling anode voltage within 0.1 s after the start of the operation. By applying this technique, the gyrotron output power of 1.5 MW for 4 s was recorded, for the first time. The reduced collector heat load at 1.5 MW operations was reduced by 20% and it will be acceptable for longer pulse operation. A new gyrotron with an improved mode converter was developed in order to demonstrate reduction of the stray radiation which had limited the pulse length. The stray radiation was reduced to 1/3 of that of the original gyrotron. A conditioning operation of the improved gyrotron is proceeding up to 31 s at 1 MW. These progresses significantly contribute to enhancing the high power and long pulse capability of the ECRF system toward JT 60SA.

JAEA Reports

Measures of the trouble on the long pulse in JT-60U electron cyclotron heating system

Hiranai, Shinichi; Suzuki, Sadaaki; Sato, Fumiaki; Kobayashi, Takayuki; Hasegawa, Koichi; Yokokura, Kenji; Moriyama, Shinichi

JAEA-Technology 2010-031, 24 Pages, 2010/09

JAEA-Technology-2010-031.pdf:1.71MB

The JT-60U electron cyclotron heating (ECH) system injects a millimeter wave at 110 GHz into the JT-60U plasma, and heats the plasma or drives a current locally to enhance the confinement performance of the JT-60U plasma. The ECH system of high power gyrotrons, transmission lines and antenna that launch millimeter wave beams toward the plasma. On the long pulse injection, one of the most important purposes is to prevent arcing in the transmission lines and to transmit millimeter wave beams efficiently. This report describes the problems occurred in a long pulse injection test (0.5 MW, 30 s), e.g., increase in released gas, temperature rise of the transmission line and an arcing at the vacuum window during the conditioning process. It also describes measures for the problems, e.g., improvements in vacuum pumping system, cooling system, and arc detector and introduction of the new dummy road system.

Journal Articles

Development of the long-pulse ECRF system for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Fasel, D.*; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.363 - 368, 2010/08

Improvements are required for expanding the pulse length of the JT-60 ECRF system (5s) for JT-60SA (100s). Newly developed power supplies will be fabricated and installed by EU. The conditioning operation of an improved gyrotron equipping a newly designed mode convertor has been started. The mode convertor will reduce heat flux on the internal components and therefore expected to enable long pulse operation at 1 MW. Pre-programmed and/or feedback control of the heater current and anode voltage, which was successfully demonstrated in JT-60U, will be key techniques because the beam current decreases during a shot. The evacuated transmission lines have a capability of 1 MW per line. Since maintenance of the components in the vacuum vessel is difficult, a linear motion antenna concept was proposed to reduce risks of water leakage and fault of the driving mechanism in the vacuum vessel. The detailed design and the low power test of a mock-up antenna have been started.

Journal Articles

Developments of high power gyrotron and power modulation technique using the JT-60U ECRF system

Kobayashi, Takayuki; Terakado, Masayuki; Sato, Fumiaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Hiranai, Shinichi; Igarashi, Koichi; et al.

Plasma and Fusion Research (Internet), 4, p.037_1 - 037_10, 2009/08

Electron cyclotron (EC) heating and current drive (CD) are key tools to control fusion plasma especially for effective electron heating and for suppression of neoclassical tearing mode (NTM). Recently, developments of a high power gyrotron and a power modulation technique have been successfully achieved on JT-60U ECRF system in order to enhance the system performance. Stable gyrotron oscillation with oscillation power of 1.5 MW for 1 s was demonstrated in 2007, for the first time. Then temperature rise of cavity and collector has been investigated. It has been shown that the longer pulse operation with 1.5 MW by an improved 110 GHz gyrotron is possible. In addition, modulated ECCD in synchronized with NTM rotation has been performed with the oscillation power of 0.8 MW and the frequency around 5 kHz. The synchronizing system has worked very well and it has played an essential role in NTM suppression experiments on JT-60U.

Journal Articles

Development and achievements on the high power ECRF system in JT-60U

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Terakado, Masayuki; Sawahata, Masayuki; Suzuki, Sadaaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Hiranai, Shinichi; et al.

Nuclear Fusion, 49(8), p.085001_1 - 085001_7, 2009/07

 Times Cited Count:16 Percentile:56.57(Physics, Fluids & Plasmas)

In the gyrotron development in JT-60U ECRF system, output power of 1.5 MW for 1 s has been achieved at 110 GHz. It is the world highest power oscillation $$>$$ 1 s. In addition to the carefully designed cavity and collector in view of thermal stress, an RF shield for the adjustment bellows, and a low-dielectric-loss DC break enabled this achievement. Power modulation technique by anode voltage control was improved to obtain high modulation frequency and 5 kHz has been achieved for NTM stabilizing experiments. Long pulse demonstration of 0.4 MW, 30 s injection to the plasma has been achieved with real time control of anode/cathode-heater. It has been confirmed that the temperature of cooled components were saturated and no evidence of damage were found. An innovative antenna having wide range of beam steering capability with linearly-moving-mirror concept has been designed for long pulse. Beam profile and mechanical strength analyses shows the feasibility of the antenna.

JAEA Reports

Study on disassembly work of the radio frequency heating system in the amplifier rooms and heating power supply building

Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Igarashi, Koichi; Sato, Fumiaki; Wada, Kenji; et al.

JAEA-Technology 2008-065, 98 Pages, 2008/10

JAEA-Technology-2008-065.pdf:38.83MB

Construction of the JT-60SA (super advanced) is planned as an upgrade of JT-60U as the satellite tokamak in ITER broader approach and as the national centralized tokamak facility program in Japan. The present JT-60U will be disassembled and the JT-60SA will be constructed at the same location in the JT-60 tours hall. The disassembly work will be planned in the period from 2009 to 2011. In this report, disassembly of the radio frequency heating system of JT-60U in the amplifier rooms and heating power supply building is studied on (1) object for disassembly, (2) work plan, (3) estimation of materials amount, (4) procedure.

Journal Articles

Long pulse/high power ECRF system development in JT-60U

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Terakado, Masayuki; Sawahata, Masayuki; Suzuki, Sadaaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Hiranai, Shinichi; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10

In the gyrotron development in JT-60U ECRF system, output power of 1.5 MW for 1 s has been achieved at 110 GHz. It is the world highest power oscillation $$>$$ 1 s. In addition to the carefully designed cavity and collector in view of thermal stress, an RF shield for the adjustment bellows, and a low-dielectric-loss DC break enabled this achievement. Power modulation technique by anode voltage control was improved to obtain high modulation frequency and 5 kHz has been achieved for NTM stabilizing experiments. Long pulse demonstration of 0.4 MW, 30 s injection to the plasma has been achieved with real time control of anode/cathode-heater. It has been confirmed that the temperature of cooled components were saturated and no evidence of damage were found. An innovative antenna having wide range of beam steering capability with linearly-moving-mirror concept has been designed for long pulse. Beam profile and mechanical strength analyses shows the feasibility of the antenna.

Journal Articles

Dissolution of uranium nitrides in LiCl-KCl eutectic melt

Hayashi, Hirokazu; Kobayashi, Fumiaki; Ogawa, Toru; Minato, Kazuo

Journal of Nuclear Science and Technology, 39(Suppl.3), p.624 - 627, 2002/11

The behavior of the dissolution of uranium nitrides, which is a component of the MA-U mixed nitride fuel, has been investigated. A mixture of uranium nitride, LiCl-KCl and CdCl$$_2$$ was contained in a double walled quartz reaction vessel. During the heating, the carrier gas helium was introduced to a gas chromatography apparatus equipped with an automatic gas sampler. A fraction of the gas was sampled and analyzed by a mass analyzer. Most of nitrogen is recovered as N$$_2$$ gas from uranium nitrides dissolving in the LiCl-KCl eutectic melt reacted with CdCl$$_2$$ above 550 $$^o$$C, which is higher than that for lanthanide nitrides.

Journal Articles

The Standard molar enthalpy of formation of UNCl

Akabori, Mitsuo; Kobayashi, Fumiaki; Hayashi, Hirokazu; Ogawa, Toru; Huntelaar, M. E.*; Booij, A. S.*; Vlaanderen, P. van*

Journal of Chemical Thermodynamics, 34(9), p.1461 - 1466, 2002/09

 Times Cited Count:0 Percentile:0.02(Thermodynamics)

no abstracts in English

Journal Articles

Effect of $$gamma$$-irradiation on microflora and fermentation quality of silages containing tofu cake or brewer's gain

Tanaka, Osamu*; Akiyama, Fumiaki*; Yamada, Akihisa*; Ando, Sada*; Uegaki, Ryuichi*; Kobayashi, Ryoei*; Kume, Tamikazu

Nihon Sochi Gakkai-Shi, 47(3), p.274 - 282, 2001/08

no abstracts in English

Journal Articles

Effect of $$gamma$$ irradiation on microflora and fermentation quality of alfalfa, orchardgrass, maize and sorgum silage

Tanaka, Osamu*; Akiyama, Fumiaki*; Yamada, Akihisa*; Ando, Sada*; Uegaki, Ryuichi*; Kobayashi, Ryoei*; Kume, Tamikazu

Nihon Sochi Gakkai-Shi, 47(1), p.62 - 67, 2001/04

no abstracts in English

JAEA Reports

Journal Articles

Structure and dynamic properties of molten uranium trichloride

Okamoto, Yoshihiro; Kobayashi, Fumiaki; Ogawa, Toru

Journal of Alloys and Compounds, 271-273, p.355 - 358, 1998/00

 Times Cited Count:35 Percentile:84.01(Chemistry, Physical)

no abstracts in English

80 (Records 1-20 displayed on this page)