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- T. Hara, T. Inagaki, C. Kondo, H. Maesaka, Y. Otake, H. Tanaka, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
- K. Fukami
JASRI/SPring-8, Hyogo, Japan
- T. Hasegawa, O. Morimoto, S. Nakazawa, M. Yoshioka
SES, Hyogo-pref., Japan
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Multi-beamline, multi-user operation is an important issue of linac-based XFELs to improve usability and efficiency of facilities. At SACLA, the multi-beamline operation had been tested since 2015 using two beamlines (BL2 and BL3). But the CSR effects at a 3-degree dogleg beam transport of BL2 caused a projected emittance growth and instability of the beam orbit due to a high peak current of 10 kA and a short bunch duration of SACLA. Consequently, stable lasing was obtained only for elongated electron bunches with low peak currents below 3 kA. To mitigate the CSR effects, the beam optics of the dogleg was rearranged. The new beam optics are based on two DBA (double bend achromatic) structures and the transverse effects of CSR are cancelled between four bending magnets. To avoid the bunch length change, the electron beam passes an off-center orbit at the quadrupole magnets of DBA. Under the new beam optics, stable lasing has been successfully obtained with 10 kA electron bunches, and the parallel operation of the two beamlines will be started in September 2017 for user experiments.
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