TUIYSP3
SLAC, Menlo Park, California, USA
SLAC, Menlo Park, California, USA
SLAC, Menlo Park, California, USA
Stanford University, Stanford, California, USA
LBNL, Berkeley, California, USA
ANL, Lemont, Illinois, USA
MAX IV Laboratory, Lund University, Lund, Sweden
UAM, Madrid, Spain
X-ray Free-Electron Laser Oscillators (XFELOs) and X-ray Regenerative Amplifier FELs (XRAFELs) are currently in development to improve longitudinal coherence and spectral brightness of XFELs. These schemes lase an electron beam in an undulator within an optical cavity to produce X-rays. X-rays circulate in the cavity and interact with fresh electron bunches to seed the FEL process over multiple passes, producing progressively brighter and more spectrally pure X-rays. Typically, the optical cavities used are composed of Bragg-reflecting mirrors to provide high reflectivity and spectral filtering. This high reflectivity necessitates special techniques to out-couple X-rays from the cavity to deliver them to users. One method involves "Q-switching" the cavity by actively modifying the reflectivity of one Bragg-reflecting crystal. To control the crystal lattice constant and thus reflectivity, we use an infrared laser to heat a buried boron layer in a diamond crystal. Here, we build on earlier work in Krzywinski et al.* and present the current status of our Q-switching diamond, including implantation with 9 MeV boron ions, annealing, characterization and early tests.
*Krzywinski et al., "Q-switching of X-Ray Optical Cavities by using Boron Doped Buried Layer under a Surface of a Diamond Crystal," Proceedings of FEL2019, Hamburg, Germany, TUP033, 2019.
SLAC, Menlo Park, California, USA
Two new undulator lines have been installed as part of the Linac Coherent Light Source upgrade (LCLSII) at SLAC National Accelerator Laboratory. One undulator line, composed of 21 horizontally polarizing undulator segments, is dedicated to producing Soft X-Rays (SXR). The other line, composed of 32 vertically polarizing undulator segments, is dedicated to producing Hard X-Rays (HXR). The devices were installed, and the control system was deployed in 2019. Commissioning culminated with the achievement of first light from the HXR undulator in the Summer of 2020 and from the SXR undulator in the Fall of 2020. Since then, both undulator lines have been successfully providing x-Rays to user experiments with very limited downtime. In this paper, we first describe the strategies utilized to simplify the deployment, commissioning, and maintenance of the control system. Such strategies include scripts for automated components calibration and monitoring, a modular software structure, and debugging manuals for accelerator operators. Then, we discuss lessons learned which could be applicable to similar projects in the future.
SLAC, Menlo Park, California, USA
LBNL, Berkeley, California, USA
In this proceeding we present start-to-end simulations of the LCLS-II-HE free electron laser. The HE project will extend the LCLS-II superconducting radio-frequency (SRF) linac from 4 GeV to 8 GeV in order to produce hard x-rays from the eponymous hard x-ray undulators (26 mm period). At the same time, soft x-ray performance is preserved (and extended into the tender regime) by using longer period undulators (56 mm period) than were originally built for LCLS-II (39 mm period). Here we use high-fidelity numerical particle simulations to study the performance of several SASE beamline configurations, and compare the resulting x-ray energy, power, duration, and transverse properties. Using the LCLS-II normal-conducting gun, we find that the x-ray pulse energy drops off rapidly above ~15 keV, while using the lower emittance beam from a proposed SRF gun, we improve the cutoff to ~20 keV.