Wan, X.M. Li, Z. Liao, W.L. Lin, P.T. Luo, X.B. Pu, X.J. Ren, Z.Q. Yang, Y.F. JACoW Publishing Geneva, Switzerland 978-3-95450-265-3 10.18429/JACoW-SAP2023-TUPB019 English 126-128 focusing quadrupole simulation acceleration resonance Contribution to a conference proceedings 2024 2024-11 https://doi.org/10.18429/JACoW-SAP2023-TUPB019 https://jacow.org/sap2023/papers/tupb019.pdf Beam loss control is a crucial research direction in high-current superconducting linear accelerators (SCL). The research findings include firstly, for continuous beams, when tune depression eta > 0.7, zero current periodic phase advance (σ0t) can partially exceed 90° during transport in solenoid and quadrupole doublet periodic focusing channels. Different results occur when eta < 0.7. Secondly, in the solenoid system, σ0t can partially exceed 90° without significant impact on beam quality. In the quadrupole doublet focusing system, the partial breakdown of 90° affects beam quality. Thirdly, Similar conclusions hold for acceleration effects. Fourthly, numerical analysis shows that double-period structures have more stringent design criteria than fully period structures. The double-period structure can cause envelope instability even if σ0t < 90°. Fifthly, the primary factor causing halo is the 2:1 resonance. Additionally, when eta is small, higher-order resonances can also cause halo.