Recent RF experiments and application of RF waves to real-time control of safety factor profile in JT-60U

Suzuki, Takahiro; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki; Oikawa, Toshihiro; Sakata, Shinya; Sueoka, Michiharu; Hosoyama, Hiroki*; Seki, Masami; JT-60 Team

AIP Conference Proceedings 787, p.279 - 286, 2005/09

https://doi.org/10.1063/1.2098241

A real-time control system of safety factor (q) profile was developed in JT-60. This system, for the first time, enables 1) real time evaluation of q profile using local magnetic pitch angle measurement by motional Stark effect (MSE) diagnostic and 2) control of current drive (CD) location (rhoCD) by adjusting the parallel refractive index of lower-hybrid (LH) waves through the change of phase difference (dphi) of LH waves between multi-junction launcher modules. The method for q profile evaluation was newly developed, without time-consuming reconstruction of equilibrium, so that the method requires less computational time. The system evaluates q profile within every 10ms, which is much faster than current relaxation time, typically order of 1s. Safety factor profile by the real-time calculation agreed well with that by equilibrium reconstruction with MSE. From temporal evolution of q (or current) profile, we evaluate CD location in real-time, too. The control system controls rhoCD through (or directly dphi) in such a way to minimize difference between the real-time evaluated q profile and its reference profile. The real-time control system was applied to positive shear plasmas (), having plasma current of 0.6MA, toroidal field of 2.3T, and electron density of . In order to keep good coupling of LH waves to the plasma, gap between the launcher and the plasma surface was controlled to about 0.1m. The reference q profile was set to q(0)=1.3. The real-time q profile approached to the reference after application of real-time control; the controlled q profile was sustained for 3s, which was limited by injected LH power. RF experiments in JT-60U, such as stabilization of neo-classical tearing modes, plasma startup experiments, etc., are also presented.

Real-time monitoring of oxidation processes on the Si(001) surface using O gas under 1000 K by synchrotron radiation photoemission spectroscopy

Yoshigoe, Akitaka; Moritani, Kosuke; Teraoka, Yuden

Surface Science, 566-568(Part.2), p.1124 - 1129, 2004/09

https://doi.org/10.1016/j.susc.2004.06.069

The Si(001) oxidaion is an important reaction for not only semiconductor technology but also surface science. It is known that the growth mode forming oxide-layers is divided into two regions depending on surface temperature conditions. One is passive oxidation and the other is two dimensional island growth including SiO desorption. Since the oxygen uptake measurements have been measured in many reported studies, Si oxidatuion states related to the growth of oxide-layers have not been clarified yet. In order to measure the time evolution of Si oxidation states depending on the surface temperature, we have performed the real-time photoemission measurements using synchrotron radiation at SUREAC2000 in SPring-8 . We found that the Si states was formed at the early oxidation stage in the two dimiensional island regions.

Development of a faulty reactivity detection system appling a digital H estimator

Suzuki, Katsuo; Suzudo, Tomoaki; Nabeshima, Kunihiko

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.24 - 33, 2004/03

https://doi.org/10.3327/taesj2002.3.24

This paper concerns an application of digital optimal H estimator to the detection of faulty reactivity in real-time. The detection system, fundamentally based on the reactivity balance method, is composed of three modules, i.e. the net reactivity estimator, the feedback reactivity estimator and the reactivity balance circuit. H optimal filters are used for these two reactivity estimators, and the nonlinear neutronics are taken into consideration especially for the design of the net reactivity estimator. A series of performance tests of the detection system are conducted by using numerical simulations of reactor dynamics with the insertion of a faulty reactivity for an experimental fast breeder reactor JOYO. The system detects the typical artificial reactivity insertions of 1￠ within a few seconds with the accuracy of 0.1￠, and is satisfactory for its practical use.

Real-time monitoring of oxidation on the Ti(0001) surface by synchrotron radiation photoelectron spectroscopy and RHEED-AES

Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Yamauchi, Yasuhiro*; Mizuno, Yoshiyuki*; Tonda, Hideki*; Homma, Teiichi*

Applied Surface Science, 216(1-4), p.395 - 401, 2003/06

https://doi.org/10.1016/S0169-4332(03)00453-7

Real-time in-situ observation using photoelectron spectroscopy for elementary processes of Ti(0001) oxidation by O molecules has been performed at the surface reaction analysis apparatus installed at the BL23SU in the SPring-8. And the real-time observation has been also performed by RHEED-AES methods at Tohoku University. The partial pressure region of oxygen was from 2x10 Torr to 8x10 Torr. The surface temperature was 473 K and 673 K. The variation from clean Ti surface toward TiO was comfirmed by observation of Ti-2p and O-1s photoelectron spectra. Reflected electron intensity and O-KLL Auger electron intensity oscillated in the RHEED-AES measurements. These facts revealed that the surface morphological change of the oxidized Ti(0001) surface was associated not only with a disappearance of the surface metallic layer but also with a change of the oxidation state.

JT-60 control system

Yonekawa, Izuru; Kawamata, Yoichi; Totsuka, Toshiyuki; Akasaka, Hiromi; Sueoka, Michiharu; Kurihara, Kenichi; Kimura, Toyoaki; JT-60U Team

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.521 - 529, 2002/09

https://doi.org/10.13182/FST02-A244

The present status of JT-60 control system is reported including its original design concept, the progress of the system and various modifications since JT-60 upgrade. This control system has features of a functionally distributed and hierarchical structure, using CAMAC interfaces at the beginning, which are replaced to versatile module Europe (VME)-bus interfaces later, and a protective interlock system composed of both software and hard-wired interlock logics. Plant monitoring and control are performed by efficient data communication through CAMAC highways and Ethernet with TCP/IP protocols. Sequential control of a plasma discharges are executed by a combination of a remodeled VME-bus system and a timing system. At real-time plasma control system and a human interface system have been continuously modified corresponding to the progress of JT-60 experiments.

Real-time simulation and analysis on long-range atmospheric dispersions of volcanic gases discharged from the Miyake Island

Furuno, Akiko; Nagai, Haruyasu; Umeyama, Nobuaki; Chino, Masamichi

Taiki Kankyo Gakkai-Shi, 37(1), p.23 - 34, 2002/01

http://ci.nii.ac.jp/naid/110003840994

The active volcano Oyama in the Miyake Island has been emitting a huge amount of volcanic gases since the first eruption in July 2000. High concentrations of SO2 gas originated in Oyama frequently appear in the wide area from the northeast to the west part of Honshu, Japan. This paper describes real-time prediction of SO2 dispersion covering the Tokai and Kanto District and its verification by comparing with SO2 observation data from October to November 2000. Atmospheric dispersions of SO2 are calculated by using our software system that combines a regional atmospheric dynamic model and a particle random walk model. It was proved that the real-time prediction of our system has adequate precision. The importance of including the effect of wet deposition was also shown. The release amounts estimated from the comparison between the calculation result and the monitoring data are 20,000 - 50,000 ton/day, which is consistent to measured ones at the Miyake Island.

F used as tracer to study water uptake and transport imaging of a cowpea plant

Nakanishi, Tomoko*; Tanoi, Keitaro*; Yokota, Harumi*; Kang, D.-J.*; Ishii, Ryuichi*; Ishioka, Noriko; Watanabe, Satoshi; Osa, Akihiko; Sekine, Toshiaki; Matsuhashi, Shimpei; et al.

Journal of Radioanalytical and Nuclear Chemistry, 249(2), p.503 - 507, 2001/08

https://doi.org/10.1023/A:1013217425209

We present the water uptake ability of cowpea () which has been regarded as one of the most drought resistant species among the pulse crops. It has been suggested that in the lower part of the stem, parenchymatous tissue for storing water had been developed for the function of deought resistance. We confirmed that in this tissue, water amount was high compared to the other stems by neutron radiography. Then the water uptake manner was measured by positron emitting tracer imaging system (PETIS) using F labeled water produced by a cyclotron. Comparing the water uptake manner of cowpea plant with that of common bean, cowpea plant was found to maintain high water uptake activity after drying treatment, suggesting the high drought resistant character.

Comparison of O-labeled and F-labeled water uptake in a soybean plant by PETIS (Positron Emitting Tracer Imaging System)

Nakanishi, Tomoko*; Yokota, Harumi*; Tanoi, Keitaro*; Ikeue, Natsuko*; Okuni, Yoko*; Furukawa, Jun*; Ishioka, Noriko; Watanabe, Satoshi; Osa, Akihiko; Sekine, Toshiaki; et al.

Radioisotopes, 50(6), p.265 - 269, 2001/06

https://doi.org/10.3769/radioisotopes.50.265

O-Labeled and F-Labeled water uptake manner in a soybean plant was compared by PETIS (Positron Emitting Tracer Imaging System). O-Labeled water (half-life: 2 min) and F-Labeled water (half-life: 110 min) were produced by a cyclotron by N(d,n)O and O(,pn)F reactions, respectively. A root of a soybean plant was cut off and each labeled water was supplied from the basal part of the plant. The gamma-rays emitted from the sample was measured by a BGO counter with a detection area of 5 cm15 cm. The radioactivity from each stem was accumlated every 15 s till 20 min. It was found that F-labeled water was taken up much faster than O-labeled water, suggesting that in F-labeled water, fluorine was moved in the form of F-ion. When BAS image of O-labeled water in a plant after 5 min and 10 min of water supply was taken, it was found that the labeled water was observed only in the lowest internode, between a root and the first leaves.

observation of oxidation states on Si(001)-21 during supersonic O molecular beam irradiation

Yoshigoe, Akitaka; Teraoka, Yuden

Atomic Collision Research in Japan, No.27, p.80 - 82, 2001/00

no abstracts in English

Progress of R&D on seismic emergency information system

Seismic Emergency Information System Research Team

JAERI-Tech 2000-063, 143 Pages, 2000/09

JAERI-Tech-2000-063.pdf:7.78MB

no abstracts in English