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Urso, L.*; Zohm, H.*; Fischer, R.*; Isayama, Akihiko; Kamada, Yutaka; ASDEX Upgrade Team; JT-60 Team
Europhysics Conference Abstracts (CD-ROM), 32D, 4 Pages, 2008/00
no abstracts in English
Okamoto, Masaaki*; Hiraishi, Takehiro*; Ono, Noriyasu*; Takamura, Shuichi*; Nakano, Tomohide; Kawano, Yasunori; Ozeki, Takahisa; Sugihara, Masayoshi
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
It is of importance to evaluate the decay time of the plasma current for estimation of the electromagnetic force acting on the vacuum vessel during plasma disruptions in tokamak devices. The L/R model predicts that the decay time is proportional to three-haves power of the electron temperature, indicating the importance of the electron temperature for the estimation. However, it is difficult to measure the electron temperature of the disruptive plasma with the Langmuir probe due to the heat flux and due to the significant electromagnetic force. We propose a measurement technique of the electron temperature by using temperature-sensitive He I lines with high time resolution. In this method, the incident light to a spectrometer is divided into three, each of which transmits a bandpass filter, and then is measured with an absolutely calibrated photo-multiplier. The measured intensity ratios are analyzed with a collisional-radiative model. It is confirmed that the electron temperature determined by this technique is in agreement with that measured by a Langmuir probe in some devices. In the present work, the temporal evolution of the electron temperature during the disruptive plasma of JT-60U is measured with this technique.
Koubiti, M.*; Nakano, Tomohide; Capes, H.*; Marandet, Y.*; Mouret, L.*; Rosato, J.*; Stamm, R.*
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
no abstracts in English
Nagashima, Yoshihiko*; Ito, Kimitaka*; Fujisawa, Akihide*; Ito, Sanae*; Yagi, Masatoshi*; Hoshino, Katsumichi; Shinohara, Koji; Ido, Takeshi*; Miura, Yukitoshi; Ejiri, Akira*; et al.
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
The recent results on the identification of the outer most magnetic surface and on the identification of the characteristic of the zonal flow are presented by using the measured data of the zonal flow which is a plasma flow in the tokamak plasma. The positon of the outermost magnetic surface was identified using the characteristic of the oscillating zonal flow called as the geodesic acoutic mode (GAM) that the mode exists only in the closed magnetic surface, and the position of the surface was in agreement with that by the magnetic equilibrium reconstruction. Some coincidence with the drift wave - zonal flow theory was obtained by using the finding that the envelope of the density fluctuation of the background turbulence is modulated by the GAM.
C from methane injection into outer divertor plasma in JT-60UNobuta, Yuji; Masaki, Kei; Arai, Takashi; Sakasai, Akira; Miya, Naoyuki; Tanabe, Tetsuo*
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
no abstracts in English
Asakura, Nobuyuki; Kawashima, Hisato; Shimizu, Katsuhiro; Sakurai, Shinji; Fujita, Takaaki; Takenaga, Hidenobu; Nakano, Tomohide; Kubo, Hirotaka; Higashijima, Satoru; Hayashi, Takao; et al.
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
Divertor design for the JT-60 SA has been progressing in order to handle large heat flux during full pulse duration of 100 s. Divertor should be suitable for single null plasma experiments with the full power injection of 41 MW. The simulation results using 2D fluid (plasma) and Monte-Carlo (neutral) code are summarized. Lower single-null divertor is designed for ITER-like plasma configuration in order to study physics concept of the ITER divertor: control of the plasma detachment. Simulation results for various divertor geometries showed that the vertical target with V-shaped corner can produce plasma detachment near the outer strike-point for medium edge plasma density. It was also demonstrated that the divertor plasma became attached to move the outer strike point above the V-corner, suggesting that recover from sever detachment can be achieved by changing the plasma location. USN divertor will be designed for high-
plasma experiments with the highest shaping plasma of S=6.
5D Vlasov code GT5DIdomura, Yasuhiro; Ida, Masato; Tokuda, Shinji
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
A conservative gyrokinetic toroidal five dimensional Vlasov code GT5D is developed. A conservative finite difference scheme is extended to generalized curvilinear coordinates, and a discretization method is developed so that it exactly satisfies the phase space volume conservation, which is an important feature of the gyrokinetic equaion. In the code, highly accurate and robust long time scale tokamak turbulence simulations in a torus configuration are enabled by these techniques. The code is verified through linear benchmark tests against a toroidal particle code. It is also confirmed that first principles such as the particle number conservation and the energy conservation, which was critical issues in the conventional particle code, are satisfied at high presition.
Takei, Nahoko; Ushigome, Masahiro*; Suzuki, Takahiro; Nakamura, Yukiharu; Takase, Yuichi*
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Yoshida, Maiko; Koide, Yoshihiko; Takenaga, Hidenobu; Urano, Hajime; Oyama, Naoyuki; Kamiya, Kensaku; Sakamoto, Yoshiteru; Kamada, Yutaka; JT-60 Team
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Matsunaga, Go; Takechi, Manabu; Kurita, Genichi; Sakamoto, Yoshiteru; Koide, Yoshihiko; Isayama, Akihiko; Suzuki, Takahiro; Fujita, Takaaki; Aiba, Nobuyuki; Ozeki, Takahisa; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Urano, Hajime; Takizuka, Tomonori; Kamada, Yutaka; Oyama, Naoyuki; Takenaga, Hidenobu; JT-60 Team
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
Conducting the experiments on the H-modes in hydrogen (H) and deuterium (D) discharges, the edge non-dimensional parameter dependence of the H-mode pedestal width has been examined. However, the scalings of the pedestal width vary from machine to machine. This disagreement can be caused by the existing strong co-linearity between 
and 
, which is hard to separate out in the peripheral region. In this study, to distinguish these variables, focusing on the mass dependence of (
), a pair of experiments in H and D plasmas were conducted. If the pedestal width were determined by , it would be impossible to match the pedestal width while keeping the edge pressure gradient fixed between H and D plasmas. However, in the experiment, we obtained the same edge profiles for H and D discharges while the required power in the H plasma was 
times larger than that in D plasma. This result indicates that the H-mode pedestal width does not remarkably depend on the plasma particle species or .
Oyama, Naoyuki; Urano, Hajime; Yoshida, Maiko; Takenaga, Hidenobu; Shinohara, Koji; Sakurai, Shinji; Masaki, Kei; Kamiya, Kensaku; Isayama, Akihiko; Suzuki, Takahiro; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Kawano, Yasunori; Kondoh, Takashi; Hatae, Takaki
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Takenaga, Hidenobu; Oyama, Naoyuki; Urano, Hajime; Kamiya, Kensaku; Miyo, Yasuhiko; Nishiyama, Tomokazu; Sasajima, Tadayuki; Masaki, Kei; Hiratsuka, Hajime; Ichige, Hisashi; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Nagashima, Yoshihiko*; Ito, Kimitaka*; Ito, Sanae*; Fujisawa, Akihide*; Hoshino, Katsumichi; Nagaoka, Kenichi*; Ejiri, Akira*; Takase, Yuichi*; Yagi, Masatoshi*; Shinohara, Koji; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
The results of the analyses of nonlinear processes in the plasma in JFT-2M tokamak and CHS machine are reported. In both machines, the measurements of the fluctuations were done by electrostatic probes. The obtained bicoherence and biphase from the potential data in JFT-2M were found to be close to the values obtained from a theoretical model of the interaction of the zonal flow and the drift wave turbulence. Therefore the experimentally obtained nonlinear interaction is considered to be that interaction of the zonal flow and the drift wave turbulence. By the analysis of the CHS H-mode plasma, a marked nonlinear interaction was found between a characteristic MHD magnetic fluctuation and density turbulence. By analysing the cross bispectrum of the density fluctuation and the potential fluctuation, it was found that the fluctuating particle flux is affected by the MHD oscillation. As stated above, we progressed in the investigation of the nonlinear processes of the edge plasmas.
Idomura, Yasuhiro; Ida, Masato; Tokuda, Shinji; Villard, L.*
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
A gyrokinetic simulation is an essential tool to study turbulent anomalous transport in tokamak plasmas, and a long time global simulation of driven turbulence in open system is highly desirable towards estimation and prediction of turbulent transport. However, poor conservation properties in conventional gyrokinetic simulations were problematic in such a long time simulation. To overcome this difficulty, a new conservative gyrokinetic code is developed using Morinishi scheme, which was originally developed for conservative simulations of neutral fluid turbulence. In the new code, in addition to the exact particle number conservation, the energy conservation is dramatically improved, and the scheme is robust in a long time simulation. In slab ion temperature gradient driven turbulence simulations, comparisons of the new code and a conventional particle code are presented.
Konoshima, Shigeru; Peterson, B. J.*; Ashikawa, Naoko*; Miura, Yukitoshi; JT-60 Team
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
An IR imaging bolometer with semi-tangential views of the diverted tokamak has been designed and installed in JT-60U in 2003-2004. A 2.5 microns gold absorber foil of 9 cm 
7 cm was shown to be durable during two years of operation with 1800 tokamak discharges including disruptions. Some unique analog video data from the IR camera characterizing diverted tokamak discharges have been obtained during test operation. A radiating toroidal ring has been mapped and recorded onto the foil as a clear high temperature zone at the disruption, consistent with huge core radiation measured by the resistive bolometers. Divertor radiation near the W-shaped divertor tiles of JT-60U could be identified also in the foil image as a thick line having toroidal curvature.
Owaki, Hirokazu; Sugihara, Masayoshi; Kawano, Yasunori; Lukash, V. V.*; Khayrutdinov, R. R.*; Zhogolev, V.*; Ozeki, Takahisa; Hatayama, Akiyoshi*
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
no abstracts in English
Sato, Masayasu; Isayama, Akihiko; Inagaki, Shigeru*; Nagayama, Yoshio*; Kawahata, Kazuo*; Iwama, Naofumi*
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
no abstracts in English
spectral bands for hydrocarbon-loss-events measured in JT-60U divertor plasmasNakano, Tomohide; Tsuzuki, Kazuhiro; Higashijima, Satoru; Kubo, Hirotaka; Asakura, Nobuyuki
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
Emission rates of CH and C
spectral bands for CH
, CD
_2
loss events due to dissociation, ionization and transport were measured in JT-60U divertor plasmas. The obtained data were used for estimating the chemical sputtering yields by a spectroscopic technique. The CH loss events over one CH photon emission was about 200 at electron temperatures between 30 eV and 70 eV. These values fell within the confidential band of the CD one. The CH
loss events over one CH and one C photon emission were, respectively, between 200 - 300 and between 600 - 1800, and their ratio between 3 - 6. On the assumption that only CH among hydrocarbons generated by chemical sputtering emits the C spectral bands, the intensity of the CH spectral bands originating from CH is inferred from the intensity of C spectral bands multiplied by the obtained ratio, resulting in higher than the measured CH intensity. This result indicates that dominant hydrocarbons generated by the chemical sputtering is not CH but CH.
