Shinku
Online ISSN : 1880-9413
Print ISSN : 0559-8516
ISSN-L : 0559-8516
Volume 33, Issue 8
Displaying 1-5 of 5 articles from this issue
  • Ryutaro SOUDA
    1990 Volume 33 Issue 8 Pages 657-663
    Published: August 20, 1990
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
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  • Yousuke NAKASHIMA, Kiyoshi YATSU, Makoto ICHIMURA, Katsuhiko TSUCHIYA, ...
    1990 Volume 33 Issue 8 Pages 664-672
    Published: August 20, 1990
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
    A large-scale cryopumping system using low-temperatute (3.5 K) liquid helium (LHe) was installed in an axisymmetrized tandem mirror GAMMA 10 at the Plasma Research Center, University of Tsukuba, in order to obtain a clean vacuum condition with a larger pumping speed. This paper describes the detailed design of the system and the estimation of the improvement of the vacuum state and of the effectiveness on the plasma confinement. Four cryopumps are located in the end-mirror tanks and in the NBI tanks of the anchor regions on both sides. Performance tests of the cryopump with a set of simple pressure-balance equations have confirmed that the measured pumping speed agrees well with the designed value. Use of this pumping system has made it possible to reduce the base pressure in the plug/barrier to below 1×10-6 Pa and upgraded thermal-barrier experiments were succesfully carried out under the improved vacuum condition.
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  • Yuka YAMADA, Katsuhiko MUTOH, Takashi IWABUCHI, Takeo MIYATA
    1990 Volume 33 Issue 8 Pages 673-678
    Published: August 20, 1990
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
    We have studied the characteristics of tungsten and carbon thin films, and tungsten-carbon multilayers prepared by ArF excimer-laser-induced chemical vapor deposition using tungsten hexafluoride and benzene gases. The carbon films deposited at substrate temperatures of 100-300°C are amorphous hydrogenated carbon films with very smooth surfaces. The surface morphology of the tungsten film depends on substrate temperature; at substrate temperatures of 100-200°C, amorphous tungsten films with very smooth surfaces have been obtained. In small-angle X-ray scattering measurement of a W/C multilayer deposited at a substrate temperature of 200°C, a first order of the multilayer reflection was clearly observed. Furthermore, Auger electron spectroscopy showed that W and C layers in the multilayer were periodically deposited.
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  • Shinichiro MICHIZONO, Tatsuya BANNO, Akira KINBARA
    1990 Volume 33 Issue 8 Pages 679-685
    Published: August 20, 1990
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
    This paper describes experimental results on the recycling of hydrogen on the carbonized wall of a vacuum vessel and the interpretation based on Desorbable phase Model for the recycling mechanism, in order to provide a rational view of the wall pumping phenomena observed in tokamaks. The recycling outflux φout of hydrogen from the amorphous hydrogenated carbon layers during glow discharge with hydrogen or helium gas in the vessel is determined from the pressure measurement of hydrogen. Even after the steady state of the hydrogen surface concentration in the film is reached, the recycling behavior of hydrogen as desorption or absorption is responsible for the energy of hydrogen ions im-planted into the film. The typical change of hydrogen concentration for increase or decrease of the ion energy by e.g. 50 eV from a fixed value is, reproducibly, about 1015 atoms/cm2 within discharge time of 20 s.
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  • Seiki INABA, Kazuhiro Hane
    1990 Volume 33 Issue 8 Pages 686-688
    Published: August 20, 1990
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
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