Showing papers by "Satoshi Nishio published in 1994"

Magnetic field analysis during breakdown phase in the low loop resistance tokamak HT-2

Abstract: The magnetic analysis code SHP was improved in order to understand the poloidal magnetic field during the breakdown phase of the Hitachi tokamak HT-2, which had its loop resistance modified to a very low value. The SHP code uses a model with filamental loop currents in the plasma area. Its improvements are the following. (1) The eddy currents on the vacuum vessel, which are assumed to be uniform in the toroidal direction, are expanded by distribution functions obtained by a singular value decomposition of a projection matrix from the eddy currents to the flux distribution on the plasma surface area. (2) The magnetic field due to the iron core biasing current and the stray horizontal field of the toroidal field coils are compensated. After improvements, it was confirmed that the poloidal field null point was generated before breakdown and the SHP results were consistent with discharge photographs taken by a high speed camera. (author).

Blanket vessel for nuclear fusion device

Abstract: PURPOSE:To provide a blanket vessel for a nuclear fusion device having a structure with sufficient reliablity against vacuum leakage and with a favourable manufacturing property. CONSTITUTION:A first wall 2 facing plasma in a blanket vessel 1 is constituted of a plural number of cooling tubes and a pair of a front face plate 2a and a back face plate 2b sandwiching the cooling tubes 3 by way of separately receiving each of the cooling tubes 3 respectively and cooperating with each other. An integrated joint block 6 is interposed between a container bottom plate 1a on which a cooling water passage 1b is formed and the first wall 2, and the cooling tubes 3 are inserted into through holes 6a of the joint block 6. The first wall 2 is welded and connected on to the bottom plate 1a of the blanket container 1 through the joint block 6. The connected part is separated from cooling water by the joint block 6 and formed on a part facing an external space, has sufficient resistance against vacuum leakage and secures weldability.

Vacuum vessel for fusion reactor

Abstract: PURPOSE:To facilitate the cooling while satisfying the mechanical rigidity and the shielding performance without lowering the perimetral electric resistance in the troidal direction by filling a space, defined by the inner/outer walls of vacuum vessel and each rib, with a large number of neutron shielding elements. CONSTITUTION:The vacuum vessel has double wall structure of inner and outer walls 10, 11 with a plurality of troidal ribs 12 being arranged therebetween and the spaces thus defined are filled with a large number of spherical neutron shielding elements 14. Since a thin plate can be employed for the walls 10, 11 without sacrifice of the total mechanical rigidity, the perimetral electric resistance of the vessel wall itself can be increased in the troidal direction. Furthermore, since the diameter of the element 14 is shorter than the peripheral length of the vessel in the troidal direction and an insulation layer is formed on the outer surface of each shield, the perimetral electric resistance at the shielding layer part filled with the elements 14 can also be increased in the troidal direction. This structure facilitate the cooling by increasing the perimetral electric resistance in the troidal direction without sacrifice of mechanical rigidity and shielding performance.