• J.N. Corlett, K.M. Baptiste, J.M. Byrd, P. Denes, R.W. Falcone, J. Feng, J. Kirz, D. Li, H.A. Padmore, C. F. Papadopoulos, G. Penn, J. Qiang, D. Robin, R.D. Ryne, F. Sannibale, R.W. Schoenlein, J.W. Staples, C. Steier, T. Vecchione, M. Venturini, W. Wan, R.P. Wells, R.B. Wilcox, J.S. Wurtele, A. Zholents
  LBNL, Berkeley, California
• A.E. Charman, E. Kur
  UCB, Berkeley, California

Recent reports have identified the scientific requirements for a future soft x-ray light source and a high-repetition-rate FEL facility responsive to them is being studied at LBNL. The facility is based on a CW superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun, and on an array of FELs to which the beam is distributed, each operating at high repetition rate and with even pulse spacing. Dependent on the experimental requirements, the individual FELs may be configured for either SASE, HGHG, EEHG, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format ranging from sub-femtoseconds to hundreds of femtoseconds. We are developing a design concept for a 10‐beamline, coherent, soft x‐ray FEL array powered by a 2.5 GeV superconducting accelerator operating with a 1 MHz bunch repetition rate. Electron bunches are fanned out through a spreader, distributing beams to an array of 10 independently configurable FEL beamlines with nominal bunch rates up to 100 kHz. Additionally, one beamline could be configured to operate at higher repetition rate.