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Sugihara, Masayoshi; Lukash, V.*; Kawano, Yasunori; Yoshino, Ryuji; Gribov, Y.*; Khayrutdinov, R.*; Miki, Nobuharu*; Omori, Junji*; Shimada, Michiya
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
We examine plasma behaviours during plasma disruptions in detail in JT-60U and other tokamaks to derive appropriate physics guidelines for the behaviours. Their interpretations and their extrapolations to ITER are incorporated into the DINA code, which solves plasma transport and 2D free boundary plasma equilibrium simultaneously with circuit equations for the vacuum vessel and the PF coils. Sensitivity of the plasma behaviours and their impact on the EM force during disruptions due to the range of variation and uncertainty of the experimental data are examined.
Sugie, Tatsuo; Costley, A. E.*; Malaquias, A.*; Medvedev, A.*; Walker, C.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
The main functions of the Divertor Impurity Monitor are to measure the parameters of impurities and isotopes of hydrogen in the divertor plasmas by using spectroscopic techniques in the wavelength range of 200-1000 nm. This system will have three different types of spectrometers; a) Visible survey spectrometers for impurity species monitoring. b) Filter spectrometers for two-dimensional measurements of particle influxes. c) High dispersion spectrometers for measuring the ion temperature and the particle energy distribution. The divertor region will be observed from the divertor-, the equatorial- and the upper-port. Optical components, such as mirrors, windows etc, mounted close to the plasma will experience higher levels of radiation due to neutron, gamma ray and/or particle irradiations than in present devices. Therefore, the materials of the components have to be carefully selected and mitigating methods adopted where possible. In addition, in-situ and remote calibration methods for diagnostic systems, which will be installed in the strong radiation field, are absolutely essential.
-particle diagnostics by CO
laser collective Thomson scattering in ITERKondoh, Takashi; Richards, R. K.*; Hutchinson, D. P.*; Sugie, Tatsuo; Costley, A. E.*; Miura, Yukitoshi; Lee, S.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
In order to understand the behavior of alpha-particles which are the dominant heat source in a burning plasma, it is necessary to measure the spatial distribution of the number of the alpha-particles and their energy spectrum. A collective Thomson scattering (CTS) system based on a pulsed CO laser is being developed and is under consideration for alpha-particle measurements on ITER. Heating beam ions (E = 1 MeV) are normally co-injected and have a similar velocity with alpha-particles in ITER. The CTS measurement can not, in general, distinguish beam ions and alpha-particles which have the same velocity. A vertical scattering geometry to distinguish between beam ions and alpha-particles is proposed. Calculations have shown that the vertically viewing CTS can resolve counter-travelling alphas without being masked by beam ions. Preliminary design of a beam line and a receiver system with the vertical scattering geometry has been developed. A proof-of-principle test on the CTS system using the JT-60U plasma is being conducted.
Kondoh, Takashi; Kawano, Yasunori; Costley, A. E.*; Malaquias, A.*; Sugie, Tatsuo; Walker, C.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
In order to measure line average electron density for long pulse operation on ITER, a CO laser interferometer/polarimeter system has being selected. High reliability is necessary because the measurements will be used as a reference signal for real time control of the density during long plasma pulses. The design of the interferometer/polarimeter is improved from the previous design because of an input from experiences gained on JT-60U. A dual CO laser interferometer/polarimeter was chosen in order to improve reliability. The proof-of-principle test of the dual CO laser interferometer/polarimeter has been demonstrated and the system is operating routinely on JT-60U. Five tangential sight lines are designed near the midplane of ITER. The laser beams will be transmitted to the plasma through shielding labyrinths in an equatorial port and reflected by retroreflectors. Position of the laser beams will be remotely controlled by steering mirrors outside the port plug because the vacuum vessel of ITER will move due to change in temperature during long plasma pulses.
Mironov, M. I.*; Khudoleev, A. V.*; Kusama, Yoshinori
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
no abstracts in English
Nakamura, Yukiharu; Tsutsui, Hiroaki*; Takei, Nahoko*; Sakamoto, Yoshiteru; Fujita, Takaaki; Sugihara, Masayoshi; Ozeki, Takahisa; Tobita, Kenji; Konishi, Satoshi; Iio, Shunji*; et al.
Europhysics Conference Abstracts, 27A, 4 Pages, 2003/00
no abstracts in English
Fujita, Takaaki; Aniel, T.*; Barbato, E.*; Behn, R.*; Bell, R. E.*; Field, A. R.*; Fukuda, Takeshi*; Gohil, P.*; Ida, Katsumi*; Imbeaux, F.*; et al.
Europhysics Conference Abstracts, 27A, 4 Pages, 2003/00
no abstracts in English
Hobirk, J.*; Oikawa, Toshihiro; Fujita, Takaaki; Fukuda, Takeshi; G
nter, S.*; Gruber, O.*; Isayama, Akihiko; Kamada, Yutaka; Kikuchi, Mitsuru; Maraschek, M.*; et al.
Europhysics Conference Abstracts (CD-ROM), 27A, 4 Pages, 2003/00
no abstracts in English
Peterson, B. J.*; Ashikawa, Naoko*; Konoshima, Shigeru; Ingesson, L. C.*; Walker, C. I.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
Research and development of imaging bolometers has progressed from the Segmented Mask IR Imaging Bolometer to the IR Imaging Video Bolometer (IRVB). Meanwhile tests of conventional resistive bolometers have shown their weakness to the high neutron flux. In this paper we compare the IRVBs currently installed in the Large Helical Device with a conceptual design for the JT-60U tokamak and a feasibility study for the International Thermonuclear Experimental Reactor. Comparisons are made with conventional resistive bolometers in terms of sensitivity, spatial and time resolution, port access requirements, steady-state operation, long term durability and shielding of stray ECH power.
Kusama, Yoshinori; JFT-2M Group
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
no abstracts in English
Asakura, Nobuyuki; Shimizu, Katsuhiro; Nakano, Tomohide; Higashijima, Satoru; Kubo, Hirotaka; Takenaga, Hidenobu
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
The measurements of the parallel SOL flow (Mach number, M) and electric field (Er) both at the high-field-side (HFS) and low-field-side (LFS) have been accomplished using Mach probes in JT-60U. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow (niMCs) and ErxB drift flow (niEr/B) were evaluated. For the case of intense gas puffing from the plasma top (puff and pump), Zeff was reduced largely to 1.3, comparing to 1.42 for the divertor gas puff. It was found that both M and ni in niMCs were enhanced, in particular, at HFS. On the other hand, niEr/B for the two cases were comparable since ni increased and Er decreased for the puff and pump. Friction force and thermal force on impurity ions were estimated from the measured M, ne, Te and Ti, and ratios of Ffric/Fi-therm at HFS increased to 3-4 compared to 1.5-1.8 for the divertor gas puff. This result was consistent with a conventional model of reduction in Zeff. Two-dimensional transport of the carbon impurity at the HFS and LFS divertors was discussed using IMPMC (Impurity Monte-Carlo) code.
Chankin, A. V.; Stangeby, P. C.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
no abstracts in English
Higashijima, Satoru; Nakamura, Hirofumi; Horikawa, Toyohiko*; Kaminaga, Atsushi; Seki, Masami; Kubo, Hirotaka; Konishi, Satoshi; Tanabe, Tetsuo*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
no abstracts in English
Tokuda, Shinji
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
When we solve the eigenvalue problem associated with the two-dimensional Newcomb equation, we can identify the stability of a tokamak plasma against ideal MHD perturbations. The eigenvalue problem does not give the physical growth rate when the plasma is unstable. However, we can determine the growth rate by constructing a dispersion relation that gives the relation between the growth rate and the eigenvalue. It is expected that the dispersion relation provides an effective and fast method of stability analysis of MHD modes close to the marginal stability against ideal MHD perturbations, and the relation can be extended for non-ideal MHD modes close to the marginal stability.
Takenaga, Hidenobu; JT-60 Team
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
no abstracts in English
Kawano, Yasunori; Sugihara, Masayoshi; Ozeki, Takahisa; Shimada, Michiya
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
Since the major disruption determines key designing conditions of a vacuum vessel and plasma facing components of the tokamak fusion reactor, it is essential to understand the characteristics of major disruption. For this purpose, a disruption database has been constructed covering most of high performance discharges in JT-60U. By database analysis, for disruptions during the reverse shear discharges, we have found that fast current quench tends to occur at the regime of surface safety factor of just around 4 and internal inductance of around 0.5. This knowledge will provide basis to investigate the physics of current quench in the reverse shear discharges.
Kawano, Yasunori; Chiba, Shinichi; Inoue, Akira*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
It has been successful to apply CVD diamond plate as the vacuum window for infrared CO laser interferometry and polarimetry for electron density measurement in the JT-60U tokamak. In comparison with using the conventional zinc-selenide windows, the Faraday rotation component at diamond windows was small as negligible. This resulted in the improvement of the Faraday rotation measurement for a tokamak plasma by polarimetry.
Kawano, Yasunori; JT-60 Team
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
Diagnostics play essential roles both in understanding of the plasma physics and in control of the plasma itself. JT-60U has plenty of developments and thus experiences in concepts of the real-time feedback control. The parameters concerned are averaged electron density, neutron emission rate, plasma stored energy, central electron temperature, temperature gradient, temperature fluctuations, current density profile, plasma radiation, outer gap distance, neutral gas pressure, etc., and those combinations. In JT-60U, production of high-performance fusion plasmas and their sustainment owed to such the real-time feedback control. In this paper, the overview of diagnostics equipped for the real-time feedback control in JT-60U is presented.
