X-ray Laser Physics

The Linac Coherent Light Source (LCLS) is a free electron laser (FEL) designed to produce self-amplified spontaneous emission (SASE) at 1.5 Å, with a pulse length of approximately 230 fs, a peak power of about 10 GW, and full transverse coherence. However, even if the LCLS surpasses third-generation sources by 10 orders of magnitude in peak brightness, it will still not have attained its ultimate capabilities. In fact, the LCLS can be considered as a first step toward a new class of electromagnetic radiation sources, similar to the evolution of the first generation of storage-ring-based synchrotron radiation (SR) sources. For example, we have already begun to study the production of significantly shorter pulses approaching 1 femtosecond, and optical systems to focus the radiation to spot sizes approaching 10 nanometers. To achieve these features and to provide the x-ray optics that preserve these properties are the goals of the proposed experimental program. The experiments will be based on manipulation of both the electron beam and x-ray optical techniques to achieve short pulses. Seeding the FEL with cascaded harmonic generation will be used to produce a pulse with nearly perfect temporal coherence, that might also be of approximately 10 fs duration. A two stage FEL with an inserted monochromator could produce a pulse with perfect temporal coherence, but with 230 fs duration. Efforts toward producing focal spot sizes of order 10 nm will be based on x-ray optical techniques that are beyond the state of the art today. If successful, these results will qualitatively expand the scientific breadth of the LCLS program and form the design basis of future generations of x-ray FEL user sources in the angstrom region.

“Future capabilities of the LCLS”

Adapted from: LCLS: The First Experiments - X-ray Laser Physics(pdf)
J.B. Hastings, Brookhaven National Laboratory, Upton, NY, USA
J. Arthur, Stanford Linear Accelerator Center, Stanford, CA, USA
P. Emma, Stanford Linear Accelerator Center, Stanford, CA, USA
A. Freund, European Synchrotron Radiation Facility, Grenoble, France
D. Mills, Argonne National Laboratory, Argonne, IL, USA
C. Pellegrini, University of California, Los Angeles, CA, USA
D. Peter Siddons, Brookhaven National Laboratory, Upton, NY, USA
R. Tatchyn, Stanford Linear Accelerator Center, Stanford, CA, USA
A. Toor, Lawrence Livermore National Laboratory, Livermore, CA, USA
L.-H. Yu, Brookhaven National Laboratory, Upton, NY, USA