Hitachi, Ltd.

Masato Nagao

Sho Kusumoto

Yoshiaki Kazawa

Takamasa Fujinaga

Keizou Wase

Yoshiyasu Ito

In a nuclear fusion device having a torus type vacuum shell around which toroidal coils and poloidal coils are wound and arranged and whose interior is maintained in a high vacuum state, the bending rigidity of a shell wall in a circular cross section of the vacuum shell is made higher on the outer periphery side than on the inner periphery side of the circular cross section, thereby to prevent any deformation of the vacuum shell due to a magnetic force and any damage of the shell attendant upon the deformation in a process in which the coils are energized to confine a plasma within the vacuum shell. Moreover, without increasing the inner diameter of the circular cross section of the vacuum shell, the coils are located in proximity to the plasma so as to enhance the plasma producing efficiency.

Torus type vacuum shell

An apparatus for measuring mechanical stress in one direction (along the x-axis) in the surface of a sample, using white X-rays, wherein white X-rays are cast onto the surface of the sample from on one side of the plane (z-x plane) containing the white X-rays cast position on the surface of the sample, being perpendicular to the surface (x-y plane) of the sample and extending in the direction (along x-axis) along which the stress is measured; the energy of the X-rays diffracted by the lattice planes parallel to the surface of the sample, is detected at a predetermined Bragg angle while the energy of the X-rays diffracted by the lattice planes whose normals are contained in the z-x plane and which incline at an angle with respect to the surface of the sample, is detected also at the same Bragg angle; and the stress .sigma..sub.x in the x-axis direction in the sample surface is calculated on the basis of the difference between the two energies according to the expression ##EQU1## WHERE E.sub.n1 is the energy of the X-rays diffracted by the lattice planes parallel to the sample surface, E.sub.n2 the energy of the X-rays diffracted by the lattice planes including at an angle to the sample surface, .psi..sub.2 the angle which is made by the normal to the sample plane and the normal to the inclining lattice planes, and K is a constant given by the expression ##EQU2## WHERE E is the Young's modulus, .nu. the Poisson's ratio, and E.sub.n the energy of the X-rays diffracted by the sample when it has no strain therein.

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Hitachi, Japan

Masato Nagao