TY - CONF AU - Lin, C.T. AU - Ohmi, K. AU - Zhang, Y. ED - Schaa, Volker RW ED - Huang, Wenhui ED - Yan, Xueqing ED - Tang, Chuanxiang ED - Li, Lu TI - Beam-Beam Interaction with Longitudinal Impedance and Its Application in TMCI Study J2 - Proc. of SAP2023, Xichang, China, 10-12 July 2023 CY - Xichang, China T2 - Symposium on Accelerator Physics T3 - 14 LA - english AB - Simulations have showed a novel coherent head-tail instability induced by beam-beam interaction with a large Piwinski angle. The localized cross-wake force has been introduced to explain the instability. The longitudinal impedance would cause coherent and incoherent synchrotron tune shift and distort the particle¿s trajectories in longitudinal phase space. Further beam-beam simulation revealed that the longitudinal impedance has strong impacts on the beam stability, squeezing the horizontal stable tune area seriously. The instability has become an important issue during the designs of CEPC and FCC-ee. In this paper, we develop a transverse mode coupling analysis method that could be used to study beam-beam instability with and without longitudinal impedance. This method can also be applied in synchrotron light sources to study transverse mode coupling instability (TMCI) with longitudinal impedance and harmonic cavity. Some preliminary results at Shenzhen Innovation Light Source (SILF) are also shown. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1 EP - 3 KW - impedance KW - coupling KW - synchrotron KW - simulation KW - electron DA - 2024/11 PY - 2024 SN - 978-3-95450-265-3 DO - doi:10.18429/JACoW-SAP2023-MOCXA02 UR - https://jacow.org/sap2023/papers/mocxa02.pdf ER - TY - CONF AU - Xu, J.Y. AU - Lin, C.T. AU - Wang, N. AU - Xu, H.S. AU - Zhang, Y. ED - Schaa, Volker RW ED - Huang, Wenhui ED - Yan, Xueqing ED - Tang, Chuanxiang ED - Li, Lu TI - Development of a Vlasov Solver for Arbitrary Sub-optimal Lengthening Conditions in Double-RF System J2 - Proc. of SAP2023, Xichang, China, 10-12 July 2023 CY - Xichang, China T2 - Symposium on Accelerator Physics T3 - 14 LA - english AB - Solving Vlasov equation is a classic method for analyzing collective beam instabilities. Considering longitudinal impedance and the nonlinear longitudinal potential well, we developed a new Vlasov solver which can be used to study the transverse mode-coupling instability under the arbitrary sub-optimal lengthening and the optimal lengthening conditions in a double-RF system. Several different techniques to deal with the radial direction of longitudinal phase space have been tested. Numerical discretization method is selected in this paper. The development of the solver is presented in details here. Benchmarks and crosscheck of the solver have been made and presented as well. PB - JACoW Publishing CP - Geneva, Switzerland SP - 34 EP - 36 KW - synchrotron KW - coupling KW - impedance KW - betatron KW - cavity DA - 2024/11 PY - 2024 SN - 978-3-95450-265-3 DO - doi:10.18429/JACoW-SAP2023-MOPB014 UR - https://jacow.org/sap2023/papers/mopb014.pdf ER - TY - CONF AU - Wang, X.F. AU - Feng, C. AU - Li, X.M. AU - Liang, Y.F. AU - Sun, J.T. AU - Wang, Z. AU - Yang, X.M. AU - Yi, H. AU - Yu, Y. AU - Zeng, L. AU - Zhang, W.Q. ED - Schaa, Volker RW ED - Huang, Wenhui ED - Yan, Xueqing ED - Tang, Chuanxiang ED - Li, Lu TI - Physical Design for EEHG Beamlines at S3FEL J2 - Proc. of SAP2023, Xichang, China, 10-12 July 2023 CY - Xichang, China T2 - Symposium on Accelerator Physics T3 - 14 LA - english AB - The proposed Shenzhen Superconducting Soft X-Ray Free-electron Laser (S3FEL) aims at generating FEL pulses from 1 nm to 30 nm. At phase-I, two undulator beamlines work at ehco-enable harmonic generation (EEHG) principle. The two undulators will cover the spectral ranges 2.3-15 nm (~83-539 eV) and 5-30 nm (~41-248 eV), respectively, when receiving electrons from 2.5 GeV superconducting linac. However, the generated FEL radiation is sensitive to various electron beam properties, e.g., its energy profile influenced by collective effects such as Coherent Synchroton Radiation (CSR), especially at high harmonics. To generate intense full coherent FEL radiation at ultra-short wavelength, a novel technique of EEHG cascaded harmonic lasing method is also considered. Physical design and FEL performance are described in this paper. PB - JACoW Publishing CP - Geneva, Switzerland SP - 55 EP - 58 KW - FEL KW - electron KW - undulator KW - radiation KW - simulation DA - 2024/11 PY - 2024 SN - 978-3-95450-265-3 DO - doi:10.18429/JACoW-SAP2023-MOPB026 UR - https://jacow.org/sap2023/papers/mopb026.pdf ER - TY - CONF AU - Wang, X.F. AU - Li, X.M. AU - Liang, Y.F. AU - Sun, J.T. AU - Yang, X.M. AU - Yi, H. AU - Yu, Y. AU - Zeng, L. AU - Zhang, W.Q. ED - Schaa, Volker RW ED - Huang, Wenhui ED - Yan, Xueqing ED - Tang, Chuanxiang ED - Li, Lu TI - Multi-bunch Operation Mode for Simultaneously Serving SASE and Seeding FEL Beamlines J2 - Proc. of SAP2023, Xichang, China, 10-12 July 2023 CY - Xichang, China T2 - Symposium on Accelerator Physics T3 - 14 LA - english AB - Modern free-electron laser (FEL) facilities are de-signed to simultaneously serve multiple undulator lines to provide x-ray pulses with high peak power and tunable wavelengths. To satisfy different scientific demands, it is preferred to make the separate undulator lines work under different FEL schemes, such as the self-amplified spontaneous emission (SASE) scheme and the echo-enabled harmonic generation (EEHG) scheme. However, different FEL schemes have differ-ent requirements on the beam longitudinal distribu-tion. Here, we propose to use multiple bunches to sim-ultaneously serve the undulator lines and put the bunches at different acceleration phase to change the bunch length with two compressor chicanes. The ac-celeration phase for each bunch is varied by adjusting the time delays of the photocathode drive laser pulses with the accelerator settings unchanged. The start-to-end simulation demonstrates that a fs bunch with high peak current can be produced to serve the SASE line while a bunch with hundred-of-fs length and uniform current distribution can be produced to serve the EEHG line. The FEL performances are simulated and discussed. PB - JACoW Publishing CP - Geneva, Switzerland SP - 66 EP - 69 KW - FEL KW - electron KW - acceleration KW - undulator KW - laser DA - 2024/11 PY - 2024 SN - 978-3-95450-265-3 DO - doi:10.18429/JACoW-SAP2023-MOPB029 UR - https://jacow.org/sap2023/papers/mopb029.pdf ER - TY - CONF AU - Yi, H. AU - Wang, X.F. AU - Yang, X.M. AU - Zhang, W.Q. ED - Schaa, Volker RW ED - Huang, Wenhui ED - Yan, Xueqing ED - Tang, Chuanxiang ED - Li, Lu TI - Heating Estimation of Undulator Vacuum Chamber at S3FEL J2 - Proc. of SAP2023, Xichang, China, 10-12 July 2023 CY - Xichang, China T2 - Symposium on Accelerator Physics T3 - 14 LA - english AB - Heating of the vacuum chambers are unavoidable when electron beams pass through the chamber channels at relativistic speeds. In the undulator vacuum chambers, such effects might lead to temperature increase of the magnets and eventually cause degradations in the FEL lasing process. Thus, in this paper, the heating of the undulator vacuum chambers at S3FEL due to wake field effects and spontaneous synchrotron radiation are estimated using an analytical approach. For the wake field effects, the contribution from finite conductivity of the vacuum chamber material and from the inner surface roughness are considered. A electron beam profile from a start-to-end simulation is used to calculate the total wake field and the induced heat. For the synchrotron radiation, a simple analytical expression is used. PB - JACoW Publishing CP - Geneva, Switzerland SP - 151 EP - 154 KW - electron KW - wakefield KW - vacuum KW - undulator KW - impedance DA - 2024/11 PY - 2024 SN - 978-3-95450-265-3 DO - doi:10.18429/JACoW-SAP2023-TUPB033 UR - https://jacow.org/sap2023/papers/tupb033.pdf ER -