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Kamiya, Kensaku; Itami, Kiyoshi; Enokuchi, Akito*
no journal, ,
Design study of a wide-angle infrared IR thermography and visible observation diagnostics for JT-60SA are reported. In order to image a large section inside the vacuum vessel of both in poloidal and toroidal directions, the optical system of endoscope is being designed with a field of view of 80 degrees having the spatial resolution better than a few cm. The optics of the system can be divided into three parts. A mirror based optical head (two set of spherical mirrors plus two flat mirrors), creating an intermediate image, a Cassegrain telescope system, and individual lens based imaging optics adapted to the various detectors for IR and visible observations, with their optical light paths being separated by in-vacuum small mirror. It makes possible to provide a optical solution without a blind spot, i.e. no image detection area.
Aiba, Nobuyuki; Cooper, W. A.*; Gruber, R.*
no journal, ,
When linear MHD stability is analyzed numerically, it is well-known that numerical instability called "spectrum pollution" sometimes appears. This numerical instability is usually caused due to inadequate choice of basis functions of finite elements, and the numerical method fixing this problem, named as Hybrid-Element-Method, was developed about 30 years ago. However, we identified that this instability is also caused due to missing to adopt numerical integral method. From both the viewpoint of basis functions and that of numerical integral method, we developed the new numerical method for linear MHD stability with Hybrid-Element-Method in combination with Gauss-Legendre quadrature. This new method realizes to suppress completely numerical instability even when plasma rotates.
Maeyama, Shinya; Watanabe, Tomohiko*; Idomura, Yasuhiro; Nakata, Motoki; Nunami, Masanori*; Ishizawa, Akihiro*
no journal, ,
no abstracts in English
Nakamura, Shigetoshi; Sakurai, Shinji; Ozaki, Hidetsugu; Sakasai, Akira; Seki, Yohji; Yokoyama, Kenji
no journal, ,
CFC (Carbon fiber Composite) Mono-block divertor target is required for power handling of 15 MW/m
in JT-60SA. Inspection method for screening heat removal capability of mono-block divertor target with infrared thermography is presented. The inspection detects a delay in the surface temperature evolution through an abrupt variation of the water temperature flowing in the cooling tube. Heat removal capability of the mono-block divertor target is evaluated with the delay. Results of heat load test and thermography inspection are considered to assess adequacy for the screening of the thermography inspection with finite element method. Dispersion in density and thermal conductivity of CFC block, coefficient of heat transfer of cooling water in screw-tube, emissivity of CFC, atmospheric temperature, corrected value of infrared thermography camera, and temperature of hot water and cool water cause error in the inspection. The effects of these factors are evaluated.
Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori
no journal, ,
no abstracts in English
tokamak plasmasMatsunaga, Go; Okabayashi, Michio*; Aiba, Nobuyuki; Boedo, J. A.*; Ferron, J. R.*; Hanson, J. M.*; Hao, G. Z.*; Heidbrink, W. W.*; Holcomb, C. T.*; In, Y.*; et al.
no journal, ,
no abstracts in English
Okano, Fuminori; Ikeda, Yoshitaka; Sakasai, Akira; Hanada, Masaya; Watanabe, Takashi*; Daigo, Yasuhiko*; Hosogane, Nobuyuki*; Aoto, Mitsuo*
no journal, ,
no abstracts in English
Tojo, Hiroshi; Hatae, Takaki; Itami, Kiyoshi
no journal, ,
no abstracts in English
Honda, Mitsuru; Hayashi, Nobuhiko; Takizuka, Tomonori*; Fujita, Takaaki
no journal, ,
A toroidal momentum solver has been derived for the 1.5D integrated transport code TOPICS from the equation of motion and it calculates the evolution of the toroidal angular momentum density summed over thermal species. A novel scheme that can uniquely determine the radial electric field Er without iterative calculations has been modeled and is also used to compute the parallel and toroidal flows for each species based on the neoclassical transport theory. The combination of TOPICS and OFMC enables us to predict the evolution of not only the density, temperature and safety factor but also the toroidal momentum and Er. The framework developed has been tested against experiments and showed the predictive capability of toroidal rotation.
Oyama, Gaku*; Sugiyama, Naoya*; Matsubara, Fumiaki*; Saigusa, Mikio*; Kobayashi, Takayuki; Isayama, Akihiko; Moriyama, Shinichi
no journal, ,
no abstracts in English
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.
Kojima, Atsushi; Hanada, Masaya; Yoshida, Masafumi; Inoue, Takashi; Kashiwagi, Mieko; NB Heating Technology Group
no journal, ,
In this paper, the recent activities on the new test stand are reported toward demonstration of the long pulse production. As for the improvement of uniform beam current profile, an estimation from trajectory calculations of primary electrons with the symmetric magnetic field configuration showed that the primary electrons were distributed uniformly in a longitudinal direction. As for the temperature control of the plasma grid, a prototype of the grid with cooling/heating by circulating a high-temperature fluorinated fluid has been developed. This grid was found to have a capability to control the temperature with a time constant of 10 s by considering the physical properties of the fluid. In addition, the un-uniform plasma profile has been observed in the preriminary experiments on the new test stand, which agrees with the calculation results.
Yagi, Masatoshi
no journal, ,
no abstracts in English
Takechi, Manabu; Matsunaga, Go; Kurita, Genichi; Sakurai, Shinji; Ide, Shunsuke; Aiba, Nobuyuki; JT-60SA Team
no journal, ,
no abstracts in English
Kajiwara, Ken; Oda, Yasuhisa; Hayashi, Kazuo*; Takahashi, Koji; Sakamoto, Keishi
no journal, ,
no abstracts in English
Yamanishi, Toshihiko; Tanigawa, Hiroyasu; Nozawa, Takashi; Nakamichi, Masaru; Hoshino, Tsuyoshi; Nishitani, Takeo
no journal, ,
The R&D on DEMO blanket related materials and tritium technology has been started by both the EU and Japan. In accordance with the common interest of the EU and Japan, the followings subjects have been applied: reduced activation ferritic martensitic (RAFM) steels; silicon carbide composites (SiCf/SiC): advanced tritium breeders and neutron multiplier; and tritium. The above R&D subjects have been carried out by JAEA with many Japanese Universities. The DEMO R&D building has been constructed on March 2010, and necessary equipment has been installed into the building. The licensing of usage of RI species and the carry of RI species such as tritium has successfully finished. The recent results on the above mentioned R&D activities have been reported.
Arakawa, Hiroyuki; Kawano, Yasunori; Tojo, Hiroshi; Sasao, Hajime; Itami, Kiyoshi
no journal, ,
no abstracts in English
Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Ueda, Yoshio*
no journal, ,
no abstracts in English
Asakura, Nobuyuki; Shinya, Kichiro*; Hoshino, Kazuo; Tobita, Kenji; Shimizu, Katsuhiro; Uto, Hiroyasu; Someya, Yoji; Nakamura, Makoto; Sakamoto, Yoshiteru
no journal, ,
Design study of poloidal field coil (PFC) locations and current distribution for the advanced divertor in the Demo tokamak reactor was presented. Concept of the super-X divertor (SXD) for Demo reactor has an extra magnetic null in the outer divertor leg in order to increase both the target wetted area and connection length to the outer target (
). Equilibrium calculation code, TOSCA, was developed by introducing two parameters, i.e. super-X null location (
, 
) and a ratio of the poloidal flux at the super-X null to that at the separatrix (
). SXD magnetic configurations with minimal number of PFCs located inside and outside toroidal field coil (TFC) were demonstrated. Locations of the divertor target were also investigated. It was found that SXD has an advantage to increase by 40-60% with , while increase in the flux expansion on the target is small (less than 40%). On the other hand, large currents for the divertor PFCs were required for the case of outside TFC, thus inter-TFC design is a practical solution. Magnetic configurations and arrangement of the divertor PFCs for a snowflake divertor were also demonstrated.
Nakano, Tomohide; Murakami, Izumi*; Suzuki, Chihiro*
no journal, ,
The W spectra in the vacuum ultraviolet range were observed in JT-60U peripheral plasmas (
= 2 keV) and LHD core plasmas ( = 3 keV). In order to reproduce these spectra, we have calculated spectra of 
- 
with an atomic structure code, FAC. By summing up each spectra with a weight, or a fractional abundance of a corresponding W ion, a spectra was synthesized and compared with the measured spectra. A spectrum synthesized with a fractional abundance with a center charge state of 
reproduced well the measured spectrum around 4.7 nm but did not around 5.0 nm. In order to reproduce this, it was found that the spectrum was synthesized with a fractional abundance with a center charge state of 
in addition to . This is commonly seen for reproducing the spectra measured both in JT-60U and LHD. The reason is under investigation in terms of W transport in plasmas.