Designing a buildable optimised stellarator to confine electron–positron plasmas

Abstract

In this paper, the design of the plasma equilibrium and superconducting coils for the electrons and positrons in an optimised stellarator electrons and positrons in an optimized stellarator (EPOS), experiment is presented. With newly developed stellarator optimisation tools, including single-stage and stochastic optimisation, as well as high-temperature superconductor strain, this work demonstrates that it is possible to achieve key metrics for the buildability and confinement properties of the device. In particular, satisfactory quality of quasisymmetry and stellarator robustness is designed, and engineering requirements are met for eight different candidates. A feasibility study is presented that optimises multiple candidates for different plasma major radii and coil currents, as well as the best EPOS candidate to date, named C4_R19.