Speaker: Sophia Henneberg, Max Planck Institute for Plasma Physics
Abstract: Recent improvements in stellarator optimization and new stellarator designs will be presented. Stellarators possess three-dimensional magnetic fields typically solely generated by the coils’ magnetic field. This reduces or even eliminates the need for generating toroidal plasma currents, which can lead to detrimental instabilities such as disruptions. However, the three-dimensionality can in general involve some drawbacks, e.g., more complicated coils are typically needed compared to the axisymmetric case. Nonetheless, with careful exploitation of the large design space via optimization, the apparent disadvantages can be diminished. In stellarator optimization studies, the boundary of the plasma is usually described by Fourier series that are not unique: several sets of Fourier coefficients describe approximately the same boundary shape. A simple method for eliminating this arbitrariness is proposed and shown to work well in practice. Additionally, we investigate the mathematical structure of the various inter-related calculations that underpin the integrated stellarator optimization problem to better understand how the equilibrium calculation, the coil calculation, and the optimization calculation communicate with each other. Furthermore, new exciting stellarator designs with better confinement properties will be presented. Lastly, I will describe ongoing and future work including ideas for a new university experiment and ways forward for generating simpler coils.