Variation of the Number of Field Periods for Symmetric Stellarators

Numerical optimization of the design of stellarator fusion reactors is ongoing. These devices have many symmetries, including a symmetry of the geometry defined by the number of field periods and often an underlying quasi-symmetry of the magnetic geometry. There are many numerical codes that are used in this effort, including the SIMSOPT code [1]. These codes allow for the variation of the shape of the geometry of the device and often target a particular quasi-symmetry. These codes do not vary the number of field periods during the optimization process. In this work, a study is done varying the number of field periods and optimizing for each value of the number of field periods. The impact on the optimization, the quasi-symmetry, transport and stability of the configurations is explored.

[1] M. Landreman, B Medasani, F Wechsung, A Giuliani, R Jorge, and C Zhu, J. Open Source Software 6, 3525 (2021)