発表論文 1996年

[1996_01]

Concept definition of vacuum system for loop operation of large helical device.

A. Miyaharaa, N. Nodab, K. Akaishib, T. Kawamurab, K.-N. Satob, Y. Murakamic, K. Watanabed, G. Horikoshie, G. Tominagaf

a School of Economics, Teikyo University, Hachioji 192-03, Japan

b National Institute for Fusion Science, Nagoya 464-01, Japan

c Naka Fusion Research Establishment, JAERI, Ibaraki 311-01, Japan

d Hydrogen Isotope Research Center, Toyama University, Toyama 930, Japan

e National Laboratory for High Energy Physics, Tukuba 305, Japan

f Faculty of Science, Toho University, Funahashi 274, Japan

Abstract

    As the Large Helical Device (LHD), which is under construction at the National Institute for Fusion Science, is installed in a super conducting magnet as confinement magnetic field, it is capable of operating in a steady state loop operation, if proper particle controls of both upstream (plasma region) and downstream (exhaust, impurity removal, H-isotope separation and refueling) are achieved. In the following, not only is the concept of the steady state loop operation described but also several hardware developments to meet this requirement are discussed.

Keywords: Fusion research; helical device; particle balance; loop operation; vacuum system

[1996_02]

Structure and mechanical properties of internally hydrided Mg-3a transition metal alloys.

S. Morozumia, H. Saikawab, T. Minegishib, M. Matsuyamac, K.Watanabec, M.Iijimad, M. Ohtsukid

a Magnesium Research Center, Chiba Institute of Technology, Narashino 275, Japan

b Department of Metallurgical Engineering, Chiba Institute of Technology, Narashino 275, Japan

c Hydrogen Isotope Research Center, Toyama University, Toyama 930, Japan

d Mitsubishi Materials Corp., Ohtemachi, Chiyoda-ku, Tokyo 100, Japan

Abstract

    Magnesium alloys containing 3a transition metals, such as Sc, Y and Ho, respectively were hydrogenated at 773 K and examined for microstructure, X-ray diffraction pattern, micro-Vickers hardness, and tensile properties at room and high temperatures.

Results obtained are as follows:
  1. The alloys, respectively, have been internally hydrided and have precipitated hydrides of the 3a transition metals as small flake-like particles in the matrix and at grain boundaries, as well as twin boundaries
  2. The dispersed hydride particles do not necessarily contribute to further hardening of the alloys at room temperature and up to near 673 K.
  3. However, the dispersed particles are very stable and seem to improve mechanical properties of the alloys above 673 K.
  4. Presumed relationships of crystallographic coincidence between the matrix and hydrides have been obtained.

[1996_03]

An electrical analog model of hydrogen permeation through single laminate.

W.M. Shua, Y. Hayashia, M. Sugisakib

a Department of Materials Science and Engineering and

b Department of Nuclear Engineering, Kyusyu University, Fukuoka 812, Japan

Abstract

    A simple analog has been developed to simulate the effects of bulk diffusion and surface recombination upon hydrogen permeation through a single laminate. The analog is based on the similarity between the resistance to electrical current density and the resistance to hydrogen permeation flux. Permeation potential and permeation resistance are defined for both diffusion in the bulk and recombination on the surface. General formulate have been developed to analyze the gas-driven permeation (GDP) and the plasma-driven permeation (PDP). The relationships between the permeation flux and the gas pressure in GDP or the incident flux in PDP derived under specific conditions agree well with the former models.

[1996_04]

Hydrogen isotope separation by advanced gas chromatography and fractionation.

Kuniaki Watanabe, Masao Matsuyama

Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan

Abstract

    A new kind of gas chromatography and a tritium counting device were developed for the separation of hydrogen isotopes. The active materials examined for chromatography were Pd/Al2O3, Pd and Pd-Pt (8 at%) alloy powders. The Pd-Pt alloy showed the best separation efficiency among the three materials. It could separate a 50%H2-50%D2 mixture to H2 and D2 of 97.5% purity with 80% recovery at 274K without using any replacement gas. The bremsstrahlung X-ray counting device developed for measuring high concentration tritium showed a good linearity between the counting rate and the tritium pressure, the specific counting rate being evaluated as 70.8 cps/Pa. The combined use of these two devices is expected to be applicable to the recovery of tritium from the flow of fuel gas in thermonuclear fusion reactor.