Finite-Beta Optimization of a Quasi-Helically Symmetric Stellarator

An effort is underway to develop stellarator configurations that have good confinement of bulk ions and have good confinement of energetic particles. Optimization of quasi-helical symmetry and minimization of the radial drift velocity can lead to configurations with improved neoclassical confinement and improved confinement of energetic particles [A. Bader, et al.,  J. Plasma Physics 85, 905850508 (2019)]. In this work, finite-β effects such as Ideal MHD stability and self-consistent bootstrap current in these configurations are analyzed. A comparison of the self-consistent bootstrap current predicted by the BOOTSJ code [K.C. Shaing, et al., Phys. Fluids B1, 1663 (1989)] and that predicted by the SFINCS code [M. Landreman, et al., Phys. Plasmas 21, 042503 (2014)] will be undertaken. The Ideal MHD ballooning stability is examined using the COBRAVMEC code [R. Sanchez, et al., Comp. Phys. Comm. 135, 82 (2001)]. Configurations with different rotational transform profiles are explored to obtain configurations that are able to withstand the addition of bootstrap current at higher β. Full results and analysis will be presented.