LCLS-II will be the first XFEL to be based on continuous-wave superconducting accelerator technology (CW-SCRF). The linac energy of 4 GeV will drive two tunable-gap undulators (SXU, HXU), LCLS-II will generate soft X-ray pulses from 0.25 to 5 keV (2.5 Å) at repetition rates up to 1 MHz. The energy upgrade (LCLS-II-HE) will take advantage of infrastructure already being installed as part of the ongoing LCLS-II construction project.
LCLS-II is based on new accelerator cryomodules to be installed in the first 750 m of the 3 km SLAC linac tunnel (L1, L2, L3). By adding additional cryomodules in the final 250 m of the refurbished tunnel (L4), LCLS-II-HE will double the electron beam energy to 8 GeV and thus increase the spectral reach of the hard X-ray undulator (HXU) to more than 12 keV at repetition rates up to 1 MHz. Anticipated improvements in electron beam emittance will extend the energy reach of LCLS-II-HE to 20 keV at high repetition rates. At the same time, the existing Cu-linac and new tunable-gap hard X-ray undulator (HXU) will provide photon energies up to 25 keV, and multi-mJ pulses from the soft X-ray undulator (SXU) at 120 Hz. Both accelerators (Cu-linac and CW-SCRF) can operate simultaneously, driving either SXU, or HXU, or both simultaneously (e.g. by time-multiplexing pulses from a single linac).
Instrument Names and Defining Capabilities
Dynamic X-ray Scattering (DXS) is a new instrument development effort within the high-energy and high-rep-rate upgrade project, LCLS-II-HE.