The Linac Coherent Light Source (LCLS) has previously demonstrated FEL operations over the energy range 280 eV to 11.2 keV in the fundamental. As part of the LCLS-II upgrade, in 2020 we resume operation with an all-new undulator complex, replacing the previous system with a pair of dedicated, variable-gap hard and soft X-ray undulators driven by the 120 Hz LCLS copper linac.
New undulator systems will operate across the wider 200 eV to 25 keV range in the fundamental with expected pulse energies of at least 0.5-2 mJ depending on the pulse duration and photon energy. The SASE pulse length can be varied from 10 fs to 50 fs for hard X-rays, while for soft X-rays the range is extended to 250 fs. Shorter pulses, < 10 fs, with a reduced number of photons per pulse can also be provided.
Prior advanced capability beyond SASE is also planned for recommissioning in the second half of 2020. For users who require a monochromator, seeded hard X-ray beams can provide 2 to 4 times more photons per unit bandwidth than SASE beams with similar pulse durations. Seeded beams will be available from 4.5 keV to 11 keV and 0.4-1.2 keV in the HXR and SXR range, respectively, with tune up from a SASE beam taking about 30 minutes. The LCLS will also again be capable of providing two-color operating modes, where multiple FEL pulses are produced with about 1% photon energy separation, in both the hard and soft X-ray regimes.
Users are encouraged to review LCLS instrument descriptions and contact LCLS instrument scientists to discuss technical capabilities and proposed experiments.