In this Letter we report the experimental demonstration of a new temporal shaping technique for x-ray free-electron lasers (FELs). This technique is based on the use of a spectrally shaped infrared (IR) laser and allows optical control of the x-ray generation process. By accurately manipulating the spectral amplitude and phase of the IR laser, we can selectively modify the electron bunch longitudinal emittance thus controlling the duration of the resulting x-ray pulse down to the femtosecond time scale. Unlike other methods currently in use, optical shaping is directly applicable to the next generation of high-average power x-ray FELs such as the Linac Coherent Light Source-II or the European X-FEL, and it enables pulse shaping of FELs at the highest repetition rates. Furthermore, this laser-shaping technique paves the way for flexible tailoring of complex multicolor FEL pulse patterns required for nonlinear multidimensional x-ray spectroscopy as well as novel multicolor diffraction imaging schemes.

The LCLS hard X-ray Free Electron Laser at SLAC reported first lasing in April 2009. Since then two successful user runs have been completed at the two soft X-ray stations. The first hard X-ray station has started commissioning in July 2010. Beam diagnostics play an essential role for tuning the machine and delivering the requested beam properties to the users. An overview of the LCLS photon diagnostics will be presented including some selected commissioning results. Plans for future improvements and upgrades will be briefly discussed.

The recently commissioned Linac Coherent Light Source is an X-ray free-electron laser at the SLAC National Accelerator Laboratory. It produces coherent soft and hard X-rays with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources and a range of pulse durations from 500 to <10 fs (10 −15 s). With these beam characteristics this light source is capable of imaging the structure and dynamics of matter at atomic size and timescales. The facility is now operating at X-ray wavelengths from 22 to 1.2 Å and is presently delivering this high-brilliance beam to a growing array of scientific researchers. We describe the operation and performance of this new ‘fourth-generation light source’.

LCLS capabilities can be significantly extended with a second undulator aiming at the soft X-ray spectrum (1- 5 nm). To allow for simultaneous hard and soft X-ray operations, 13.6 GeV beams at the end of the LCLS accelerator can be intermittently switched into the SLAC A-line (the beam transport line to End Station A) where a second undulator may be located. Recently, a new optics has been designed to transport the LCLS beam through the A-Line while preserving the beam brightness. In this paper, we discuss the A-Line soft X-ray FEL design — parameter selection and performance expectations with an energy-chirped LCLS beam as required by the A-Line optics. Start-to-end simulations using realistic LCLS beams show that it is possible to generate 70 GW FEL power with a pulse duration as short as 2 fs at 20 pC charge.

Science and Technology of Future Light Sources A White Paper Report prepared by scientists from ANL, BNL, LBNL and SLAC. The coordinating team consisted of Uwe Bergmann, John Corlett, Steve Dierker, Roger Falcone, John Galayda, Murray Gibson, Jerry Hastings, Bob Hettel, John Hill, Zahid Hussain, Chi-Chang Kao, Janos Kirz, Gabrielle Long, Bill McCurdy, Tor Raubenheimer, Fernando Sannibale, John Seeman, Z.-X. Shen, Gopal Shenoy, Bob Schoenlein, Qun Shen, Brian Stephenson, Joachim Stohr, and Alexander Zholents. Other contributors are listed at the end of the document. Argonne National Laboratory Brookhaven National Laboratory Lawrence Berkeley National Laboratory SLAC National Accelerator Laboratory December 2008

The Linac Coherent Light Source (LCLS) Project will be an x-ray free-electron laser. It is intended to produce pulses of 800-8,000 eV photons. Each pulse, produced with a repetition frequency of up to 120 Hz, will provide >1012 photons within a duration of less than 200 femtoseconds. The project employs the last kilometer of the SLAC linac to provide a low-emittance electron beam in the energy range 4-14 GeV to a single undulator. Two experiment halls, located 100 m and 350 m from the undulator exit, will house six experiment stations for research in atomic/molecular physics, pump-probe dynamics of materials and chemical processes, x-ray imaging of clusters and complex molecules, and plasma physics. Engineering design activities began in 2003, and the project is to be completed in the middle of 2010. The project design permits straightforward expansion of the LCLS to multiple undulators.

The spectrum of angle-integrated undulator radiation displays a sharp edge at every harmonic photon energy. A technique utilizing this feature to measure minute changes in K-parameters of an undulator in a free-electron laser has been proposed. To date, this technique requires the use of crystal monochromators as bandpass filters whose energy centroid depends on the incident angle of the x-ray beam. In this work we propose to use the absorption edge of an appropriate element as an energy-selective detector whose response is truly independent of the angle of the x-ray beam, and hence independent of electron beam direction and emittance. We will discuss the basic design concept of the detection system and illustrate its projected performance with computer simulations.

Most people think of lasers as small devices that emit red light and are found in laser pointers or barcode scanners. Experimental physicists tend to be familiar with more powerful devices – some of which are big enough to fill a room – that produce light at shorter wavelengths. But one type of laser is in a league of its own when it comes to size and performance: the free electron laser.

A study of the potential for the development of the Linac Coherent Light Source (LCLS) beyond the specifications of the baseline design is presented. These future developments include delivery of X-ray pulses in the 1 fs regime, extension of the spectral range, increase of the FEL power, exploitation of the spontaneous emission, and a more flexible time structure. As this potential is exploited, the LCLS can maintain its role as a world-leading instrument for many years beyond its commissioning in 2008 and initial operation as the world's first X-ray free-electron laser.

An upgrade project to the SLAC linac allows ultra-short electron bunches to be interleaved with the routine high-energy physics program operation, for use with an undulator to produce short-pulse, high-brightness X-rays. The linac upgrade comprises of the installation in the summer of 2002 of a bunch compressor chicane of similar design to the Linac Coherent Light Source (LCLS) project. A final compression stage in the high-energy Final Focus Test Beam (FFTB) line compresses the 28GeV, 3.4nC electron bunch to 80fs FWHM, where a 5m section of undulator (K=4.45) will produce 1.5Å X-rays with 3×107 photons per pulse and a peak brightness of 4×1024 photons mm−2mrad−2s−1 (0.1% BW). The facility will allow us to test the dynamics and associated technology of bunch compression and gain valuable experience for the LCLS using the SLAC linac. New ultra-short electron bunch diagnostic techniques will be developed hand in hand with the same ultra-fast laser technology to be used for LCLS. Issues of high peak power (27GW) X-ray transport and optics can be addressed at this facility as well as pump-probe and ultra-fast laser timing and stability issues.

Exponential growth of self-amplified spontaneous emission at 530nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

A local bump method has been proposed to determine the transverse impedance of narrow-gap insertion-device (ID) vacuum chambers. As a stored bunch passes through an impedance section, the bunch receives a small transverse kick, which depends on the bunch total charge, the bunch length, and the transverse position. The kick can be measured as a function of orbit by applying a four-magnet bump and forcing closure by a running orbit correction. We measured the ID vacuum chambers with apertures of 5 mm and 8 mm, and a straight section with regular 42 mm aperture extrusion. Two types of local bumps are applied: a parallel and an angle bump, each of which emphasizes the impedance of different parts of the straight section

We report on the first lasing of a high-gain harmonic generation (HGHG) free-electron laser (FEL). The experiment was conducted at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL). This is a BNL experiment in collaboration with the Advanced Photon Source (APS) at Argonne National Laboratory. A preliminary measurement gives a high-gain harmonic generation (HGHG) pulse energy that is 2×107 times larger than the spontaneous radiation. In a purely self-amplified spontaneous emission (SASE) mode of operation, the signal was measured as 10 times larger than the spontaneous radiation in the same distance (∼2 m) through the same wiggler. This means the HGHG signal is 2×106 times larger than the SASE signal. To obtain the same saturated output power by the SASE process, the radiator would have to be 3 times longer (6 m).

A high-gain harmonic-generation free-electron laser is demonstrated. Our approach uses a laser-seeded free-electron laser to produce amplified, longitudinally coherent, Fourier transform-limited output at a harmonic of the seed laser. A seed carbon dioxide laser at a wavelength of 10.6 micrometers produced saturated, amplified free-electron laser output at the second-harmonic wavelength, 5.3 micrometers. The experiment verifies the theoretical foundation for the technique and prepares the way for the application of this technique in the vacuum ultraviolet region of the spectrum, with the ultimate goal of extending the approach to provide an intense, highly coherent source of hard x-rays.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation John N. Galayda; Fourth-generation storage rings. AIP Conf. Proc. 26 June 2000; 521 (1): 429–434. https://doi.org/10.1063/1.1291827 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

A Low-Energy Undulator Test Line (LEUTL) is under construction at the Advanced Photon Source (APS). Its purpose is to fully characterize innovative, future-generation undulators, and to act as a test line in pursuit of generating coherent radiation at wavelengths down to a few tens of nanometers. The line will use a high-brightness RF electron gun as its source and the APS linac to accelerate these electrons up to >650MeV. This beam will then be directed through undulators located in a new 50m long enclosure. In addition, there is an end station external to the radiation environment which will house the equipment necessary to directly study the light generated by the beam and undulator system. At present, the new enclosures are complete, the electron rf gun is installed and operational, and a part of the necessary transport line is installed. A prototypical undulator cell, suitable for testing the requirements of single-pass free-electron laser operation, is near completion and will be installed during the winter shutdown of 1998. This paper will describe the LEUTL project and, in particular, its capabilities for exploring the self-amplified spontaneous emission process.

Closed orbit feedback for the Advanced Photon Source (APS) storage ring employs unified global and local feedback systems for stabilization of particle and photon beams based on digital signal processing. Hardware and software aspects of the system will be described. In particular, we will discuss global and local orbit feedback algorithms, PID (proportional, integral, and derivative) control algorithm, application of digital signal processing to compensate for vacuum chamber eddy current effects, resolution of the interaction between global and local systems through decoupling, self-correction of the local bump closure error, user interface through the APS control system, and system performance in the frequency and time domains. The system hardware, including the digital signal processor (DSPs), is distributed in 20 VME crates around the ring, and the entire feedback system runs synchronously at 4-kHz sampling frequency in order to achieve a correction bandwidth exceeding 100 Hz. The required data sharing between the global and local feedback systems is facilitated via the use of fiber-optically networked reflective memories.