[en] A method is presented for computing the class of axisymmetric current distributions flowing in a torus whose peripheral surface is a flux surface for the magnetic field produced by the current itself. The method allows the correct calculation of the 'self-induced' magnetic forces arising from the interaction between these currents and their own field. The general expression for the self-induced force is given and an approximate formula is presented in the large aspect-ratio limit. (author)

[en] The eddy current density induced by the poloidal magnetic field vacuum vessel of a high field compact experiment is calculated, taking into account the non uniform resistivity due to the bellows sectors. To this purpose, a simple method for making this computation is described. Finally, some preliminary results are presented together with the temperature profiles on the vessel wall due to the heating by plasma losses. (author)

[en] In this paper the design of a poloidal air core field system to produce plasma current in a large RFP experiment is presented. The electromagnetic system consists of two independent windings; the field shaping winding and the magnetizing winding. The first one is designed to provide a magnetic field distribution around the outer surface of the metal shell equal to the field distribution produced by the plasma current on the inner surface; if this condition is fulfilled any field mismatch on the shell surface at the minor gap is avoided. The magnetizing winding consists of a number of coils arranged out-side the shell in order to obtain a flux swing of 12.5 Wb, in unipolar operation, with stray fields in the plasma region not exceeding 10^-₂ T to give a maximum flux line deviation at the edge of the plasma not exceeding 10 mm. For a proper operation of the two windings; further bonds must be verified by their parameters and by their connections to the power supplies. The results obtained by numerical computations show that the above conditions can be achieved. In the paper the main concepts followed in the design and the main features and parameters of the electromagnetic system are presented and discussed. (author)

[en] An integral formulation for eddy-current problems in nonmagnetic structures is presented. The solenoidality of the current density is assured by introducing a current vector potential T. This potential possesses only two scalar components, as the gauge chosen to ensure its uniqueness is T·u = O, where u is a prescribed vector field. The discrete analogue of this gauge and the boundary conditions are directly imposed by the shape functions. In massive structures, the two degrees of freedom are to be compared to four of the usual integral methods which exploit the presence of a scalar potential to ensure solenoidality. On the other hand, the procedure naturally reduces to the stream function approach when applied to thin shells. Finally, an integration procedure which guarantees symmetry and positive-definiteness of the inductance matrix is proposed. (author)

[en] In this paper the computation of the eddy currents in thin non-magnetic conductors is discussed, with a specific reference to the vacuum vessel of a Tokamak fusion device. In particular, the problem is stated in terms of the surface current density vector and of the scalar electric potential. The resulting mathematical model is described in detail, together with the numerical formulation based on the finite elements method. Results are given with reference to the vacuum vessel of the Intor reactor and of the Ignitor experiment

[en] The structural behavior of a compact toroidal ignition experiment of very high magnetic field has been analyzed. Several steel structures have been designed, and stress analysis has been carried out using several numerical codes. 10 refs

[en] A three-dimensional stress analysis of the shaped magnet coils carried out by means of a numerical code is described. The results of the two-dimensional stress analysis and of the three-dimensional stress analysis are given

[en] In this paper the nonlinear problem of the free boundary equilibrium of a plasma inside a conducting circular shell has been solved analytically in the high beta limit. The unknown function describing the plasma shape has been expanded in a Volterra functional series, the functional analogous to the Taylor series. The hierarchy of the linear integral equations obtained from the expansion is, at least in principle, analytically solvable, so that the solution of each equation can be given in a closed form. The analytical computations have been carried out up to the fourth order and the results compared with numerical computations

[en] Until recently the realization of a D-³ He or a D-D burning reactor had been considered a goal to be achieved in the next century, since a near-term experiment to test the possibility of igniting these kinds of plasmas could not be foreseen. However, recent experimental observations, as well as new theoretical developments, have led to the identification of a class of experiments that can lead to the realization of ignition conditions for a D-³ He system on the basis of present-day technology. This paper discusses how this goal may be achieved by specifying the requisite plasma confinement configuration, which can be achieved in an axisymmetric toroidal configuration, embodied in a device identified previously as ''Katharsor'' or ''candor''. The technological feasibility of these experimental reactors are discussed as is a description of the main parameters of two reference devices. In addition, the perspective characteristics of high-field, high particle-density D-³ He power producing reactors are examined

[en] The Ignitor experiment consists of a compact high field device for the confinement and heating of plasmas close to thermonuclear conditions. The electromagnetic and 3-D stress analysis of its vacuum vessel subjected to a plasma disruptive instability has been performed. A new design-concept, which realizes bearing of the vessel against the coils, is analyzed. The numerical simulation of the static and dynamic response of this interaction between the vessel and the magnet leads to a non-linear set of equations, which has been solved by means of a special purpose F.E. program. The NASTRAN code has also been used for the static and eigenvalue analysis. The maximum static and dynamic stresses found on the vessel appear to satisfy the design criteria with an adequate safety factor. (author)