The Linac Coherent Light Source (LCLS) has demonstrated FEL operations over the energy range 280 eV to 11.2 keV using the fundamental with pulse energies of at least 1-3 mJ depending on the pulse duration and photon energy (please note that operation above 10 keV requires special accelerator conditions that may not be available at all times). Third harmonic radiation is available up to 25 keV at about 1% of the fundamental pulse energy. The pulse length can be varied from 40 fs to 300 fs for hard X-rays, while for soft X-rays the range is extended to 500 fs. Shorter pulses, <10 fs, with a reduced number of photons per pulse can also be provided. The maximum repetition rate of the LCLS is 120 Hz (please note that this may be reduced to 115 Hz at certain time periods).
For users who require a monochromator, seeded beams can provide 2 to 4 times more photons per pulse than SASE beams, and with similar pulse durations and shot-to-shot intensity fluctuations. The narrow seeded line, 0.4 to 1.1 eV FWHM, for 50 fs pulse duration typically contains an average pulse energy of 0.3 mJ, with occasional shots up to 1 mJ. It is accompanied by a relatively broadband SASE background of comparable total energy. Seeded beams are available from 5.5 keV to 9.5 keV and can be tuned up from a SASE beam in about 30 minutes.
We are continuing to upgrade the soft X-ray source parameters of LCLS. Soft X-ray self-seeding has been demonstrated across the range of 500-1000 eV and the Delta Undualtor provides variable polarization, including left/right circular.
LCLS is currently developing "two color" operating modes, where pairs of FEL pulses are produced with about 1% photon energy separation, in both the hard and soft X-ray regimes. LCLS plans to install a polarization control undulator to provide arbitrarily polarized radiation with limited intensity in the soft X-ray regime.
Users are encouraged to review LCLS instrument descriptions and contact LCLS instrument scientists to discuss technical capabilities and proposed experiments.