• D.F. Ratner, A. Brachmann, F.-J. Decker, Y.T. Ding, D. Dowell, P. Emma, J.C. Frisch, Z. Huang, R.H. Iverson, J. Krzywinski, H. Loos, M. Messerschmidt, H.-D. Nuhn, T.J. Smith, J.L. Turner, J.J. Welch, W.E. White, J. Wu
  SLAC, Menlo Park, California
• R.M. Bionta
  LLNL, Livermore, California

The Linac Coherent Light Source (LCLS) is a Free Electron Laser (FEL) operating with a fundamental wavelength ranging from 1.5-0.15 nm. Characterization of the higher harmonics present in the beam is important to users, for whom harder X-rays can either extend the useful operating wavelength range or represent a background to measurements. We present here measurements of the power in both the second and third harmonics.

Slides

• F.-J. Decker, R. Akre, A. Brachmann, Y.T. Ding, D. Dowell, P. Emma, A.S. Fisher, J.C. Frisch, A. Gilevich, P. Hering, Z. Huang, R.H. Iverson, H. Loos, M. Messerschmidt, H.-D. Nuhn, D.F. Ratner, W.F. Schlotter, T.J. Smith, J.L. Turner, J.J. Welch, W.E. White, J. Wu
  SLAC, Menlo Park, California

The Linac Coherent Light Source at SLAC is a hard X-ray FEL which was designed for single electron bunch operation. Although most user experiments are not interested in multiple bunches from an S-band linac due to their short (ns) separation, there are some advantages with multi-bunch operation. Starting with two bunches where the delayed light of one bunch is used to seed the light of a second bunch, to many more bunches to increase the likelihood of rare target collisions, multi-bunch operation would open more options for the LCLS. In the past the SLAC Linac has operated with a few dedicated bunches for the SLC (Stanford Linear Collider), and up to 1400 bunches for some fixed target experiments, so a few bunches for the LCLS seems possible even with the original single bunch design. This paper will describe how the current RF implementation supports multi-bunch operation. Initial experimental tests with two bunches are presented.