A bstrcctWe report the status of the diagnostics undulator beamline for the Advanced Photon Source (APS) storage ring. The beamline was designed for the characterization of the 7-GeV, low-emittance positron k a m at high resolution. The special diagnostics undulator has been manufactured by STI Optronics. The device exhibits very low magnetic field errors at closed gap of 10.5 mm: first field integral less than 15 gauss.cm, and optical phase error less than 1.5". The front end of the beamline and a monochromator are installed and tested for use on divergence and directional stability measurements with a target resolution of 3 p a d utilizing the first harmonic radiation of 25 keV. Initiai results for the divergence measurement show that the storage ring is operating well within its design goals.

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,

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At the Advanced Photon Source (APS) at Argonne National Laboratory (ANL), a free-electron laser (FEL) based on the self-amplified spontaneous emission (SASE) process is nearing completion. Recently, an rf photoinjector gun system was made available to the APS by Brookhaven National Laboratory/Accelerator Test Facility (BNL/ATF). It will be used to provide the highbrightness, low-emittance, and low-energy spread electron beam required by the SASE FEL theory. A Nd:Glass laser system, capable of producing a maximum of 500 µJ of UV in a 1-10 ps pulse at up to a 10-Hz repetition rate, serves as the photoinjector's drive laser. Here, the design, commissioning, and integration of this gun with the APS will be discussed.

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.