Toward the multi-beamline operation of SACLA

In order to increase user time, the operation of plural beamlines in parallel is an important issue for XFEL facilities. At SACLA, this multi-beamline operation using two beamlines, which are BL2 and BL3, has been tested since last year. Although simultaneous lasing has been successfully obtained at the two beamlines, the peak current of the electron bunch need to be decreased to 2 kA, which is about 1/5 compared to that used in the nominal operation of SACLA BL3, due to the CSR effects at a dogleg beam transport. In the current beam optics of the dogleg, a kicker deflection angle is made small as possible to relax the current stability requirement for a pulsed power supply at the expense of the CSR effects. To cancel out the CSR effects between bending magnets, the beam optics of the dogleg will be changed to a DBA based lattice. The simulations show an emittance increase can be significantly suppressed with the new lattice for a 10 kA bunch compared to the current lattice. The replacement of the dogleg lattice is scheduled in January 2017. (author)