High-power beyond extreme ultraviolet FEL radiation with flexible polarization at SHINEHanxiang Yang, Zhangfeng Gao, Bingyang Yan, Wencai Cheng, Nanshun Huang and Haixiao DengEur. Phys. J. D, 80 5 (2026) 48DOI: https://doi.org/10.1140/epjd/s10053-026-01162-7