Construction of a single-pass free-electron laser (EEL) based on the self-amplified spontaneous emission (SASE) mode of operation is nearing completion at the Advanced Photon Source (APS) with initial experiments imminent. The Al% SASE FEL is a proof-of-principle fourth-generation light source. As of January 1999 the undulator hall, end-station building, necessary transfer lines, electron and optical diagnostics, injectors, and initial undulatory have been constructed and, with the exception of the undulatory, installed. All preliminary code development and simulations have also been completed. The undulator hall is now ready to accept first beam for characterization of the output radiation. It is the project goal to push towards fill FEL saturation, initially in the visible, but ultimately to W and VUV, wavelengths,
The rf subsystem for the Advanced Photon Source injector test stand is a totally passive system. Waveguide variable power dividers and phase shifters, which are pressurized with SF6, are used to provide three highpower ports that are independently adjustable in phase and amplitude while maintaining negligible differential phase jitter. Either three independent devices or a device requiring three inputs can be tested at any one time.
DThe low-energy undulator test line (LEUTL) is being constructed at the Advanced Photon Source (APS). Its fmt purpose is to fully characterize innovative, future generation undulators, some of which may prove difficult or impossible to measure by traditional techniques. Second, LEUTL will act as a test line to investigate the generation of coherent radiation at wavelengths down to a few tens of nanometers. The line will use a highbrightness rf electron gun as its source and the APS linac to accelerate these electrons up to > 650 MeV. This beam will then be directed into a new enclosure that is nearly 50 m long and will accommodate beamline components, diagnostics, and undulators. This region is wide enough to house two separate beamlines. In addition, there is an external end station appropriate for housing the equipment necessary to directly study the generated light outside of the radiation environment. At present, the new enclosure and building are 1The submitted muscript hasbecn mated by the University of Chicago as Operator of Argonm National la bra to^^ C'Argonne") complete, the new rf electron gun is installed and operational, and a part of the necessary transport line is installed. An undulator cell prototype, suitable for testing the requirements of single-pass free-electron laser operation, is near completion and will be installed during the winter shutdown of 1997. This paper will describe the LEUTL project and its capability for exploring the self-amplified spontaneous emission process. * Budker InstituteKeywords: Free-Electron Laser, Fourth-Generation Light Source IntroductionThe Low-Energy Undulator Test Line (LEUTL), presently under construction at Argonne National Laboratory's Advanced Photon Source (APS), was designed with two purposes in mind. The first is to characterize innovative, future generation undulators, some which may prove difficult or impossible to measure by traditional techniques. The second is to investigate the generation of coherent radiation at wavelengths down to a few tens of nanometers.Lately, there has been tremendous interest in clearly defining what constitutes a fourthgeneration synchrotron light source and also how it should be constructed [l]. One possibility is to use a high-brightness electron beam passing once through a very long undulator and subsequently producing coherent radiation via the self-amplified spontaneous emission (SASE) process. Here, a high-brightness electron beam is characterized by its simultaneous high peak bunch current, low energy spread, and low normalized transverse emittance. The key to the success with this method is in producing and accelerating the high-brightness beam and further guiding it with sufficient accuracy through the length of the long undulator.As the desired wavelength decreases, the requirements on the electron beam quality become more difficult to meet and the length of the undulator grows. As an example, the SLAC linac coherent light source (LCLS) proposal is striving to reach 0.15 nm [2]. In order to achieve this, the be...
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