Longitudinal beam dynamics and collective effects at the STCF collider rings

The Super Tau-Charm Facility (STCF) proposed in China is a new-generation high-luminosity [Formula: see text] collider in the low-energy region, with the beam energy of 1–3.5[Formula: see text]GeV and a target luminosity of larger than [Formula: see text] at the optimized beam energy of 2[Formula: see text]GeV. Due to the limitations posed by the coherent X-Z instability and significant beam collective effects, the longitudinal beam dynamics are crucial for the STCF. This paper aims to introduce an iterative optimization model for the design of longitudinal beam dynamics in STCF. The model takes into account factors such as lattice design, coherent X-Z instability, and single-bunch collective effects. The analysis includes an estimation of the main collective instabilities and proposes corresponding mitigation strategies. This study will contribute to the further design optimization of the STCF collider rings.