Linac Coherent Light Source (LCLS) Design Study Report

Abstract

The concept and the feasibility of an x-ray FEL is based on the theoretical and experimental work of many people. We are indebted to those scientists and engineers who prepared the ground for this Design Study. A special thanks is due to the LCLS Study Group, led by Herman Winick, that conducted the first exploratory and design studies of an x-ray FEL based on the SLAC linac following the 1992 SLAC Workshop on Fourth-Generation Sources, where the concept was introduced by Claudio Pellegrini.The Design Study has benefited greatly from comments and suggestions made during reviews. We are grateful to the members of the LCLS Design Review Committee whose members were: Joe Bisognano (Chairman), Ilan Ben-Zvi, Alex Chao, Bill Colson, Gary Deis, Efim Gluskin, Hank Hsieh, Gerd Materlik, Joachim Pflueger, Marc Ross, and Ross Schlueter. Previous reviews included an early LCLS review chaired by Ilan Ben-Zvi and an undulator review chaired by Efim Gluskin. Their comments and suggestions proved to be very useful, and some of them are incorporated in the Design.We thank Terry Anderson (cover design), Frank Cebulski (technical editing), Ruth McDunn (production), Berah McSwain (project administration), and Thelma Walker (administration) for their valuable contribution to this report. 3UHIDFHThe Stanford Linear Accelerator Center (SLAC), in collaboration with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of California at Los Angeles, is proposing to build a Free-Electron-Laser (FEL) R&D facility operating in the self-amplified spontaneous emission (SASE) mode in the wavelength range 1.5-15 Å. This FEL, called "Linac Coherent Light Source" (LCLS), utilizes the SLAC linac and produces sub-picosecond pulses of short wavelength x-rays with very high peak brightness and full transverse coherence.Until about the 1960s x-rays were obtained from Roentgen tubes. After the first observation of synchrotron radiation [1] and the evolution of cyclic electron synchrotrons and then storage rings for high energy physics applications, it was realized that these accelerators could be exploited as much more intense x-ray sources. Storage ring synchrotron light sources have now evolved through three generations. The first-generation sources utilized radiation from storage rings built for high-energy physics purposes. These included Tantalus at the University of Wisconsin, ACO and DCI at LURE, SPEAR and PEP at SLAC, DORIS and PETRA at DESY, Adone at Frascati, VEPP-2M and VEPP-3 in Novosibirsk, and CESR at Cornell. Initially only bending magnet radiation was used and experiments were carried out parasitically during high-energy physics runs. The second-generation machines were purpose built, but still initially used bending magnet radiation. The first round of second-generation sources included the SOR-ring in Tokyo, the SRS at Daresbury, Aladdin in Wisconsin, the Photon Factory at KEK, and the NSLS at Brookhaven. Eventually, insertion devices were added to these facilities, but only in limited number becau...

The history of X-ray free-electron lasers

“…22. The intensity and temporal structure evolution of a SASE radiation pulse for the LCLS case [Cornacchia 1998]. The random intensity fluctuation for a short undulator is that of the spontaneous radiation, changing on the scale of the radiation wavelength.…”

“…The interest moved back 42 from the water window FEL to shorter wavelength, about 1.5Å, that attracted more 43 support from X-ray scientists. The study group was followed near the end of 1995 by 44 a design group, under the direction of Cornacchia, that produced a full conceptual 45 design report of the system [Cornacchia 1998], and extended the operating wavelength 46 to 0.15-1.5 nm.…”

The FEL Program at DESY: From First Results at 100 nm Wavelength to a True 1 Å X-ray Laser

“…The radiation pulses have been characterized with respect to pulse energy, statistical fluctuations, angular divergence and spectral distribution, both in the linear gain and in the saturation regime of the FEL [1]. The results are in good agreement with theoretical simulations, providing a solid basis for other projects aiming at still shorter wavelengths down to the 0.1 nm range [2,3]. The GW level VUV pulses have been used for first exploratory experiments on gases and solids demonstrating the unique properties of the new source [4].…”

Characterization of an 800 nm SASE FEL at Saturation

“…The proposal for a SASE FEL to generate hard Xrays was made several years ago [1], and recently experiments have confirmed high gain, short wavelength SASE FEL theory [2,3,4,5,6]. X-ray SASE FEL devices have been proposed [7,8], and recent experimental success shows the feasibility of building such facilities.…”