LBNL, Berkeley, California, USA
SLAC, Menlo Park, California, USA
ANL, Argonne, Illinois, USA
SLAC, Menlo Park, California, USA
Development of superconducting undulator (SCU) technology continues at the Advanced Photon Source (APS). Experience of building and successful operation of the first short-length, 16-mm period length superconducting undulator SCU0 paved a way for the second 1-m long, 18-mm period device, SCU1, which is in operation since May 2015. The APS SCU team has also built and tested a 1.5-m long, 21-mm period undulator as a part of LCLS SCU R&D program aiming at demonstration of SCU technology availability for free electron lasers. This undulator successfully achieved all the requirements including a phase error of 5 degree rms. Our team is currently completing one more 1-m, 18-mm period undulator that will replace the SCU0. We are also working on a helical SCU for the APS. The status of these projects will be presented.
LBNL, Berkeley, California, USA
SLAC, Menlo Park, California, USA
LCLS-II is a high-repetition rate (1 MHz) Free Electron Laser (FEL) X-ray light source now under construction at SLAC National Accelerator Laboratory. During transport to the FEL undulators, the electron beam is subject to a space charge-driven microbunching instability that can degrade the electron beam quality and lower the FEL performance if left uncontrolled. The present LCLS-II design is well-optimized to control the growth of this instability out of the electron beam shot noise. However, the instability may also be seeded by irregularities in the beam current profile at the cathode (due to non-uniformities in the temporal profile of the photogun drive laser pulse). In this paper, we describe the sensitivity of the microbunching instability to small-amplitude temporal modulations on the emitted beam current profile at the cathode, using high-resolution simulations of the LCLS-II beam delivery system.