Title: Optimal shape design for divertors

Authors: Wouter Dekeyser; Detlev Reiter; Martine Baelmans

Addresses: Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300A, 3001 Leuven, Belgium ' IEK-4 Plasma Physics, Forschungszentrum Jülich GmbH, EURATOM Association, Trilateral Euregio Cluster, D-52425 Jülich, Germany ' Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300A, 3001 Leuven, Belgium

Abstract: Owing to the complex physics of the plasma edge, numerical simulation tools are indispensable for the evaluation of novel divertor concepts. Simulation-based divertor design is computationally extremely expensive, however, not in the least due to the large number of design variables. In this work, we show how shape optimisation methods can prove very valuable in partially automating the design process. We apply the continuous adjoint method to design divertor targets for maximum power load spreading. Shape sensitivities are derived using the material derivative approach. The resulting sensitivities depend on boundary data only, and can be computed very efficiently. Through numerical tests, we also prove that their accuracy is good. Next, the performance of two gradient-based optimisation algorithms and a so-called one-shot method is compared. Using the latter method, optimal solutions are obtained in a computational effort less than five times the time needed for a single analysis simulation.

Keywords: divertor design; plasma edge; optimal design; shape design; shape optimisation; shape sensitivity analysis; continuous adjoint method; one-shot method; numerical simulation.

DOI: 10.1504/IJCSE.2014.064525

International Journal of Computational Science and Engineering, 2014 Vol.9 No.5/6, pp.397 - 407

Received: 19 Dec 2011
Accepted: 29 Jun 2012
Published online: 22 Sep 2014 *

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