Interface and requirements analysis on the DEMO Heating and Current Drive system using Systems Engineering methodologies

In this paper we present the methodology implemented for analyzing System Requirements and Interfaces of the Heating and Current Drive (HCD) system of the European Demonstration Fusion Power Reactor DEMO. The work consisted in updating the preliminary framework of the Model-Based Systems Engineering model of the HCD System Architecture. This is now containing an ontology, a set of 6 perspectives and a defined set of viewpoints for each Perspective, for refining the HCD System Architecture. The scope of the work is to manage the interdependencies of HCD system elements and their integration into DEMO, for a given set of system functions. On the one hand, this means to address the identification and definition of the interfaces occurring, both internally in the HCD system, and between the HCD system and neighboring systems. On the other hand, this implies studying the impact of requirements coming from the ongoing physics studies. The rationale is to provide the technical foreground for supporting the decision-making processes related to the HCD system which is planned to be carried out during the forthcoming Conceptual Design Phase. The results we show in this paper are part of the design and integration activities consisting of both systems engineering methodologies and design analysis, all aiming at ensuring consistency in the overall EU DEMO plant design. In this framework the DEMO Heating and Current Drive system has been selected as pilot project for the application of Systems Engineering methodologies

Nonspecular astigmatic reflection of a 3D gaussian beam on an interface

International audienceWe extend a recently proposed approach of the study of nonspecular effects to 3D finite beams. It is shown that a new nonspecular effect appears in 3D: the two beam waist in the two transverse directions across the beam are different and their longitudinal positions are different. In other words a plane interface is an astigmatic system for a finite beam. The effect is illustrated by studying the nonspecular effects for the zero order diffracted beam by a grating. It is shown that this system produces strong nonspecular effects due to the efficient coupling of leaky waves near the total absorption regime

Nonspecular reflection from a lossy dielectric

International audienceNonspecular effects for reflection from a lossy dielectric are studied under the paraxial approximation. It is shown that lateral shifts larger than 100 wavelengths are obtained for an angle of incidence close to the Brewster angle. Furthermore, it is shown that a three-dimensional Gaussian beam with a circular cross section becomes on reflection near the Brewster angle a Gaussian beam with an elliptical cross section. In addition, an evaluation of the accuracy of the paraxial approximation is done by comparison with an exact calculation. Nonspecular reflection effects have been studied for total reflection after the pioneering work of Goos and Hanchen. Experimental evidence of a lateral shift of a finite beam was first reported in the context of acoustic waves. Many theoretical approaches have been developed; among them, the use of an angular spectral approach has proved to be useful in showing that a variety of nonspecular effects may be defined. 3 These effects are easily understood in the context of an angular spectrum approach based on the following expansion of the incident monochro-matic p-polarized beam Ej: Ei(xjL,zi) = Wk^ f exp(W 'k 2Si2)u(vi) X exp(ikisi * x 1 ji + ikicizi)dsi (1) in the (xi, yi, zi) coordinate system (see Fig. 1), where the time dependence exp(-iwst) has been omitted. The beam waist is w, ki = wic, v is the unit vector [s, c = (1-S2)v2] of the wave vector, and u is the unit vector specifying the polarization, given by us zAv/IzAvI, (2a) up vAu, (2b) for s and p polarization, respectively. The reflected field is then expressed as w 2 k. 2 (wki 2 s 2 Er(XllrZr) = 8v! R(sr)exp-r IU(Vr) 47T f 4 / x exp[+iki(sr * Xj 1 r + CrZr)]dSr (3) in the (Xr, Yr, Zr) coordinate system, where R(Sr) is the reflection factor for p polarization. It is seen from Eq. (3) that the dependence of the reflection factor R(Sr) on the direction of the wave vector Sr introduces a distortion of the beam compared with the symmetric beam. If we assume that the reflected beam remains Gaussian, the distortion can be accounted for by introducing variations of the parameters of the beam. These modifications, which appear as nonspecular effects, are lateral and focal shifts 8A and 3, of the p

Coherent reflection factor of a random rough surface: applications

International audienceExpressions for the s and p mean reflected amplitudes of light incident onto a two-dimensional random dielec-tric surface are derived. From these expressions the influence of roughness on the specular component of the field was studied. The effect of the transverse structure of the surface and the role of surface plasmon in the decay of the reflectivity are investigated. The shift of the Brewster angle is studied and applications to the determination of surface parameters are discussed. Finally, it is shown that roughness induces nonspecular effects on dielectric surfaces near the Brewster angle