The development of technologies for the additive manufacturing, in particular of metallic materials, is offering the possibility of producing parts with complex geometries. This opens up to the possibility of using topological optimization methods for the design of electromagnetic devices. Hence, a wide variety of approaches, originally developed for solid mechanics, have recently become attractive also in the field of electromagnetics. The general distinction between gradient-based and gradient-free methods drives the structure of the paper, with the latter becoming particularly attractive in the last years due to the concepts of artificial neural networks. The aim of this paper is twofold. On one hand, the paper aims at summarizing and describing the state-of-art on topology optimization techniques while on the other it aims at showing how the latter methodologies developed in non-electromagnetic framework (e.g., solid mechanics field) can be applied for the optimization of electromagnetic devices. Discussions and comparisons are both supported by theoretical aspects and numerical results.

The main purpose of the Divertor Tokamak Test facility (DTT) [1], whose construction is starting in Frascati, Italy, is to study solutions to mitigate the issue of power exhaust in conditions relevant for ITER and DEMO. DTT will be equipped with a significant amount of auxiliary heating power (45 MW) to reach P SEP /R = 15 MW m −1 required to be DEMO-relevant [2]. DDT is characterized by high flexibility for the assembling and testing of divertor components and for the different magnetic configurations to address the integrated physics and technology problems. The current conceptual design of the beamline for the DTT Neutral Beam Heating system is here presented, with a particular focus on the effect on the DTT plasma and on the technical solutions adopted to maximize the RAMI indexes (Reliability, Availability, Maintainability and Inspectability) and minimize complexity and costs. Various design options were considered, and a comprehensive set of simulations was carried out using several physics and engineering codes to drive the choice of the most suitable design options and optimize them, aiming at finding a good compromise among different requirements. This paper describes the design of the main components of the DTT NBI beamline, explaining the motivations for the main design choices.

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A fast and general Partial Element Equivalent Circuit (PEEC) method based on the Fast-Fourier-Transform (FFT) is proposed for the first time. The numerical tool only requires common CAD data input files (e.g. .stl format), then the discretization process is performed automatically by means of a fast voxelization technique based on ray intersection, thus drastically reducing the human effort required to setup the model. The method allows for considering at the same time inductive and capacitive effects, and is focused on power electronics applications where propagation effects can be neglected, whereas all the other electromagnetic phenomena are considered. Specifically, the proposed method is particularly suited for problems where both electric and magnetic fields are equally important and therefore quasistatic approximations do not apply. An ad-hoc preconditioner which significantly speeds-up the solver is also proposed and, thanks to the FFT, both memory and computation time are significantly reduced, without the need of applying data compression. Both linear and non-linear materials are considered by the proposed FFT-PEEC method. Sample implementation of the method is made publicly available.