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Journal Articles

Gyrotron development for high-power, long-pulse electron cyclotron heating and current drive at two frequencies in JT-60SA and its extension toward operation at three frequencies

Kobayashi, Takayuki; Moriyama, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Hoshino, Katsumichi; et al.

Nuclear Fusion, 55(6), p.063008_1 - 063008_8, 2015/06

 Times Cited Count:15 Percentile:19.21(Physics, Fluids & Plasmas)

A gyrotron enabling high-power, long-pulse oscillations at both 110 GHz and 138 GHz has been developed for electron cyclotron heating (ECH) and current drive (CD) in JT-60SA. Oscillations of 1 MW for 100 s have been demonstrated at both frequencies, for the first time as a gyrotron operating at two frequencies. The optimization of the anode voltage, or the electron pitch factor, using a triode gun was a key to obtain high power and high efficiency at two frequencies. It was also confirmed that the internal losses in the gyrotron were sufficiently low for expected long pulse operation at the higher power level of $$sim$$1.5 MW. Another important result is that an oscillation at 82 GHz, which enables to use fundamental harmonic waves in JT-60SA while the other two frequencies are used as second harmonics waves, was demonstrated up to 0.4 MW for 2 s. These results of the gyrotron development significantly contribute to enhancing operation regime of the ECH/CD system in JT-60SA.

Journal Articles

Development of a dual frequency (110/138 GHz) gyrotron for JT-60SA and its extension to an oscillation at 82 GHz

Kobayashi, Takayuki; Moriyama, Shinichi; Isayama, Akihiko; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.

EPJ Web of Conferences (Internet), 87, p.04008_1 - 04008_5, 2015/03

 Times Cited Count:3 Percentile:16.8

A dual-frequency gyrotron, which can generate 110 GHz and 138 GHz waves independently, is being developed in JAEA to enable electron cyclotron heating (ECH) and current drive (ECCD) in a wider range of plasma discharge conditions of JT-60SA. Operation for the gyrotron conditioning and parameter optimization toward 1 MW for 100 s, which is the target output power and pulse length for JT-60SA, is in progress without problems. Oscillations of 1 MW for 10 s and 0.51 MW for 198 s were obtained, so far, at both frequencies. In addition, an oscillation (0.3 MW for 20 ms) at 82 GHz was demonstrated as an additional frequency of the dual-frequency gyrotron which shows a possibility of the use of fundamental harmonic wave in JT-60SA.

JAEA Reports

Development of instrument to measure transmission power density distribution using dielectric disk in millimeter waveguide

Yokokura, Kenji; Moriyama, Shinichi; Kobayashi, Takayuki; Hiranai, Shinichi; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; Wada, Kenji; Sato, Yoshikatsu; Hoshino, Katsumichi; et al.

JAEA-Technology 2014-002, 64 Pages, 2014/03

JAEA-Technology-2014-002.pdf:6.83MB

A new instrument has been developed to measure spatial distribution of power density and total power of the millimeter wave, by measuring temperature rise of dielectric material inserted in the waveguide. For a measurement, a dielectric disk with thermally insulated support is inserted into the few millimeters gap in the waveguide. The disk is heated by the millimeter wave pulse for 0.1$$sim$$0.2 s, and immediately after the pulse, it is pulled up and its temperature distribution is measured by an infrared camera to estimate the spatial power density distribution of the millimeter wave. In the other hand, total transmission power is estimated by the disk temperature reached equilibrium. In the measurement test, deformation of the power density distribution was successfully detected when the mirror angle was intentionally changed in the matching optics unit (MOU) at the waveguide input from the gyrotron. The test result shows that the instrument is effective for both adjustment of MOU without opening the vacuum boundary and to detect any abnormal transmission during operation of the ECH system. The test also shows high reliability of the instrument which stands with 1 MW high power transmission without any arcing or pressure rise in vacuum region. The instrument will be contributed to keep good condition of high power long pulse ECH system by detecting abnormal transmission in the waveguide in operation without open vacuum boundary.

Journal Articles

Development of a linear motion antenna for the JT-60SA ECRF system

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Suzuki, Sadaaki; Hiranai, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; et al.

Fusion Engineering and Design, 88(6-8), p.935 - 939, 2013/10

 Times Cited Count:4 Percentile:56.81(Nuclear Science & Technology)

An antenna having a first mirror driven in the linear motion (LM) and a fixed second mirror was proposed for electron cyclotron range of frequency (ECRF) heating and current drive system, to minimize the risk of cooling-water-leakage. Basic mechanical feasibilities of the bellows covering the movable structures of the antenna were previously investigated using a mock-up. This time, a support structure of the shaft has been designed using a metallic sliding bearing with solid lubricant. The sliding bearing can support combination of linear and rotational motions while a ball bearing supports either linear or rotational motion. We have newly installed the sliding bearing into the mock-up. A vacuum pumping test has been carried out paying attention to the influence of the solid lubricant by mass analysis. To design the LM antenna for JT-60SA in detail, heating and current drive characteristics for typical experimental scenarios of JT-60SA has been investigated by calculation.

Journal Articles

Dual frequency ECRF system development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.

Fusion Science and Technology, 63(1T), p.160 - 163, 2013/05

 Times Cited Count:6 Percentile:43.43(Nuclear Science & Technology)

A dual frequency electron cyclotron range of frequency system has been developed for JT-60SA, by which a second frequency (135 $$sim$$ 140 GHz) is generated in addition to the first frequency of 110 GHz. A development of a dual frequency gyrotron is a key to realize the dual frequency system. The second frequency was chosen to be 138 GHz from the above frequency range from the viewpoint of gyrotron design. In order to realize high-power ($$>$$ 1 MW) and long-pulse operation for both frequencies, we designed main components of the gyrotron (the diamond window, cavity resonator and quasi-optical mode converter). We found the optimum parameter set from the parameters of these components, which has discrete characteristics. It was confirmed that the output power higher than 1 MW is obtained for both frequencies as a result of numerical design. Based on the above design, a dual frequency gyrotron was newly fabricated. In the conditioning operation, an output power was obtained as we expected.

Journal Articles

Dual frequency gyrotron development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.

Proceedings of 37th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2012) (USB Flash Drive), 2 Pages, 2012/09

A new dual frequency (110 GHz and 138 GHz) gyrotron development began for JT-60SA. An output power and efficiency higher than 1 MW and 30% with a peak heat load lower than 1.4 kW/cm$$^{2}$$ were obtained for both frequencies in calculation. High mode conversion efficiencies of the quasioptical mode converter (96.8% for 110 GHz and 98.3% for 138 GHz), which is higher than the previously developed 110 GHz long pulse gyrotron (96.5%), was obtained. The new gyrotron was fabricated and conditioning operation has been started from the middle of June 2012. The gyrotron output power of approximately 200 kW was obtained, so far, as we expected in the design of the gyrotron at low beam current of 10 A and low beam voltage of 75 kV.

Journal Articles

Recent results from the development of the electron cyclotron heating system for JT-60SA toward high-power long-pulse operations

Isayama, Akihiko; Kobayashi, Takayuki; Yokokura, Kenji; Shimono, Mitsugu; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Hinata, Jun; et al.

Plasma and Fusion Research (Internet), 7(Sp.1), p.2405029_1 - 2405029_5, 2012/05

no abstracts in English

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:15 Percentile:35.61(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

Diffusivity Database (DDB) system for major rocks and buffer materials; Released on 2007/specification

Tochigi, Yoshikatsu; Shibata, Masahiro; Sato, Haruo; Kitamura, Akira

JAEA-Data/Code 2007-010, 14 Pages, 2007/03

JAEA-Data-Code-2007-010.pdf:3.32MB

The Diffusivity Database (DDB) System developed on early 2006 was upgraded to apply the data of effective diffusion coefficient of the nuclides in the rock matrix for the "H12: Project to Establish the Scientific and Technical Basis for HLW Disposal in Japan", and the data in the buffer materials from literature survey was newly added. Some functions of data search and selection were reformed to improve the level of convenience. This DDB system (work on MS-AccessTM) is released to the public through Web server managed by JAEA.

JAEA Reports

Diffusivity Database(DDB) system for major rocks; Version of 2006/Specification and CD-ROM

Tochigi, Yoshikatsu; Sasamoto, Hiroshi; Shibata, Masahiro; Sato, Haruo; Yui, Mikazu

JAEA-Data/Code 2006-008, 16 Pages, 2006/03

JAEA-Data-Code-2006-008.pdf:1.15MB

The development of the database system has been started to manage with the generally used. The database system has been constructed based on datasheets of the effective diffusion coefficient of the nuclides in the rock matrix in order to be applied on the "H12: Project to Establish the Scientific and Technical Basis for HLW Disposal in Japan". In this document, the examination and expansion of the datasheet structure and the process of construction of the database system and conversion of all data existing on datasheets are described. As the first step of the development of the database, this database system and its data will continue to be updated and the interface will be revised to improve the availability. The developed database system is attached on the CD-ROM as the file format of Microsoft Access.

Journal Articles

Mercury target and its peripheral devices for 1MW spallation neutron source

Haga, Katsuhiro; Kaminaga, Masanori; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Sato, Hiroshi; Ishikura, Shuichi*; Torii, Yoshikatsu; Hino, Ryutaro

Proceedings of 12th International Conference on Nuclear Engineering (ICONE-12) (CD-ROM), 8 Pages, 2004/00

In the Material and Life Science Facility, which will be constructed in the J-PARC project, the spallation mercury target station will be installed. Once the target system operation starts, mercury, the target vessel and the surrounding components are highly irradiated, so that all the replacement and maintenance operations of the target vessel and its peripheral devices have to be done with remote handling. In order to meet the requirements, we designed the target system such that the target vessel and the mercury circulation system are mounted on a target trolley, which is the system carriage. The target vessel is carried with the mercury circulation system together and inserted into the target center by the target trolley during the on-beam operation. During the system maintenance period, the target trolley is withdrawn to the maintenance room of hot cell, and the component exchange or repairing work will be done using a power manipulator and some master-slave manipulators. In this paper, the present design of the mercury target and its peripheral devices for 1MW spallation neutron source including the target vessel, a mercury circulation system, and a target trolley will be reported.

Oral presentation

Study of core and axial blanket mixing effects in the compound process fuel cycle

Ikegami, Tetsuo; Sato, Yoshikatsu*

no journal, , 

Core and axial blanket mixing effects on core nuclear charactarisics are quantitatively studied for a case of the compound process fuel cycle applied for fast reactor mixed oxide spent fuels in which fast reactor spent fuels are re-loaded into the fast reactor core after mixing core and axial blanket.

Oral presentation

Operational experience on ECRF system in JT-60U and development for JT-60SA

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

no journal, , 

As a result of inspection of the ECRF antennas after the JT-60U operation, no large damages were found on them although the color of the mirror surfaces were slightly changed probably due to coating of thin film and some evidences of arcing were found. In the statistical analysis on the 9-year operation of the ECRF system, the success rate, which is defined as the ratio of actual injection time to preprogrammed one was higher than 0.85 in the last 3 years of the operation in average of 4 lines. To meet the long-pulse requirement of JT-60SA, development of long-pulse gyrotron with improved mode converter is on going aiming at 1 MW, 100 s. It was confirmed that the diffraction loss was remarkably decreased and the temperature of the DC break cooling water, which limited the pulse length, was saturated at about half of that before the improvement. As the result, the pulse length reached 17 s at 1 MW, and 30 s at 0.6 MW (18 MJ) recently, and further conditioning will be continued.

Oral presentation

Development of ECRF heating and current drive system for JT-60SA

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

no journal, , 

no abstracts in English

Oral presentation

Design and test of launcher and transmission line for JT-60SA ECRF system

Kobayashi, Takayuki; Isayama, Akihiko; Suzuki, Sadaaki; Hiranai, Shinichi; Wada, Kenji; Hinata, Jun; Sato, Yoshikatsu; Yokokura, Kenji; Hoshino, Katsumichi; Moriyama, Shinichi

no journal, , 

Design and test of launcher and transmission line for JT-60SA electron cyclotron range of frequency (ECRF) system have been carried out. Spatial profile of temperature rise of 31.75 mm waveguide components, which was used in the previous JT-60, was measured for high-power and long-pulse transmission. It was clarified that improvements of cooling efficiency or change in design is required for achieving 1 MW, 100 s transmission, which is required in JT-60SA. Thus 60.3 mm waveguide components was newly installed. In the preliminary test of the new transmission line, unexpected arcing and increase in vacuum pressure was not observed, and the system worked as expected. As for the launcher, a preliminary layout of the launcher and support was improved in order to keep acceptable distance from systems around the ECRF launcher. Moreover, a mock-up of an improved support structure of the driving shaft using solid lubricants was fabricated in order to improve reliability of the structure.

Oral presentation

Development on ECRF system for JT-60SA

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

no journal, , 

Development and design of ECRF system are being carried on toward JT-60SA. In spite of the huge earthquake on March 11th, damage on the system was small, and we restart the gyrotron operation after 2 months of careful inspection and test. The diffraction loss in the gyrotron was kept low and the temperature of the DC break cooling water, which limited the pulse length, was saturated at about half of that before the improvement of the mode convertor. The pulse length reached 31 s at 1 MW and 99 s at 0.3 MW. In JT-60SA, ECRF of about 130-140 GHz would make possible central heating/current drive at BT = 2.25 T. From this point of view, development of dual frequency gyrotron was started. In calculation, oscillation conditions with efficiency of 0.4 were obtained for TE22,8 mode (110 GHz) and TE27,10 mode (137.6 GHz). Fabrication of the gyrotron has just been started. The high power test will be started in the next fiscal year.

Oral presentation

Design and development of electron cyclotron heating and current drive system for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Yokokura, Kenji; Shimono, Mitsugu; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; et al.

no journal, , 

Design and development of high-power long-pulse electron cyclotron heating and current drive system for JT-60SA have been progressed. High power transmission test using newly developed components with a waveguide inner diameter of 60.3 mm was carried out. A conditioning operation was progressed to 5 s with an output power of 0.5 MW, so far, within a few weeks without significant trouble. The other progress was made to develop the dual frequency system with an additional frequency of 137.6 GHz in order to enhance operation regime. Output power higher than 1 MW with oscillation efficiency much higher than 30% was obtained for the design of a dual frequency gyrotron for both 110 GHz and 137.6 GHz.

Oral presentation

Progress on electron cyclotron heating antenna design for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Suzuki, Sadaaki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; Hoshino, Katsumichi; Moriyama, Shinichi; et al.

no journal, , 

Capabilities of the transmission power of 0.8 MW and pulse duration of 100 s, and two dimensional beam steering both in poloidal and toroidal directions are required for electron cyclotron (EC) heating antenna in JT-60SA. An antenna based on a linear-motion concept has been designed. Recently, rf profiles for various poloidal/toroidal beam angles were measured using mock-up mirrors and a low power millimeter wave source. It was confirmed that the beam direction and profile of the antenna were agree with the numerical design. Moreover, some candidates of the support structure of the steering shaft were considered and one of them, which used a small sliding bearing, was tested by a mock-up. In this test, smooth movement in vacuum condition was confirmed. An extention of the operation regime of the system by means of dual frequency EC waves has been studied. Results of evaluation of the antenna steering range for this purpose is also presented.

Oral presentation

Development of linear motion ECRF antenna for JT-60SA

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; et al.

no journal, , 

Development of an antenna featuring linear motion (LM) concept for electron cyclotron range of frequency (ECRF) heating and current drive in JT-60SA is in progress. It will handle the injection power of 1MW for 100s. Combination of a linearly movable first mirror and a fixed curved second mirror realizes control of the injection beam angle. A support structure of the shaft using a metallic sliding bearing with solid lubricant was designed and tested. It showed smooth movement in vacuum. Heating and current drive characteristics with the LM antenna for typical experimental scenarios of JT-60SA have been investigated by calculation. As a result, it was confirmed by ECCD calculation that the range of toroidal injection angle, from -15 deg to +15 deg is appropriate at 110 GHz. On the contrary, at 138GHz for experiment scenario at 2.3T of full toroidal field of JT-60SA, the angle in the positive direction of IP, may be larger, e.g., +20 deg, for higher ECCD efficiency.

Oral presentation

Recent progress in gyrotron development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Yokokura, Kenji; Hoshino, Katsumichi; et al.

no journal, , 

Gyrotron developments for JT-60SA electron cyclotron range of frequency heating system have been carried out. A dual frequency gyrotron was developed for extending operation region of the system. A dual frequency gyrotron for 110 GHz and 138 GHz was designed and fabricated. Oscillations of 1 MW and 0.5 MW were obtained at 110 GHz and 138 GHz, respectively, for 0.1 s, so far. The oscillation efficiencies were consistent with the design. Experiments of a gyrotron equipping an improved mode convertor for reducing temperature increase of internal components due to stray radiation were also carried out toward long pulse operations of 100 s required in JT-60SA. Since an increase of waveguide temperature had been limited the pulse length, waveguide components with wider diameter, which is suitable for long pulse operation, were installed. An oscillation of 70 s at 1 MW, which is twice longer than the previous record, was obtained. A high power oscillation of 1.4 MW for 9 s was also obtained.

32 (Records 1-20 displayed on this page)