Pumping Scheme for Arc Region Standard Cell of STCF Collider Rings

For the arc region standard cell of the STCF collider rings, under extreme conditions such as small circumference, small aperture, high energy, high beam intensity, and high gas load, the demanding requirements for ultra-high vacuum (static average vacuum degree ≤5×10⁻⁹ Pa, dynamic average vacuum degree ≤5×10⁻⁸ Pa) are addressed. In this paper, based on the test particle Monte Carlo method, the molecular flow module in COMSOL Multiphysics software is used to carry out pressure distribution simulations under different pump layout schemes. The effects of measures such as increasing pumping speed, coating the inner wall surface, and installing getter strips on the static and dynamic vacuum degrees in the arc region standard cell are studied. The simulation results show that: with a centralized pumping scheme, due to the flow conductance limitation of the pump port connection tube, the average vacuum degree fails to meet the design goal; by coating the inner wall of the beam pipe with a getter film, the static average vacuum degree reaches 4.17×10⁻⁹ Pa, but the dynamic vacuum degree still does not meet the design goal; By installing getter strips in the antechamber, the dynamic average vacuum degree reaches 6.09×10⁻⁸ Pa, approaching the design goal; By adding getter pumps at the centralized pumping locations, combined with all the aforementioned measures, the dynamic average vacuum degree reaches 4.33×10⁻⁸ Pa, meeting the design goal. Through the above research, a "centralized + distributed" pumping scheme is proposed, providing a design basis and theoretical support for the vacuum system design of the STCF collider rings arc region standard cell.