We present the design and performance of a highresolution, high charge sensitivity imaging camera system for the APS linac beam profile measurement. Electron beam distribution is converted to light intensity distribution using standard YAG or optical transition radiation (OTR) screens. Two CCD cameras share the light through a beam splitter, each with its own imaging optics. One camera is normally set to a low magnification to give a full view of the converter screen (20 mm × 15 mm), and the other is set to a high magnification for measuring small beam. The overall dimension of the camera system is 400 mm × 165 mm × 110 mm. The focus and irises are driven by stepper motors and are remotely controlled. The fixed magnification and remotely controlled focus enable high reproducibility during beam-based setup of the optics. On bench test, the camera gave better then 10-µm resolution and better that 1% reproducibility of the magnification.
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.
We discuss wake field excitation and propagation in dielectric structures, particularly concentrating on the case of multiple drive beam excitation in multimode structures. We emphasize calculations of the energy loss of the drive bunch train, the amplitude of the wakefield, and the relation between power flow and stored energy in the dielectric wakefield device. We show that for a collinear multimode structure the amplitude of the wakefield generated by a bunch train is less than or equal to the wakefield generated by a single bunch of the same total charge. Furthermore, the transformer ratio, R, is shown to be always less than 2, even in the multiple drive beam case. Plans for an experiment to measure wakes in a multimode structure at AWA are presented.
The Advanced Photon Source (APS) is a third-generation 7-GeV synchrotron radiation source. The precision measurement of beam current is a challenging task in high energy accelerators, such as the APS, with a wide range of beam parameters and complicated noise, radiation, and thermal environments. The beam pukes in the APS injector and storage ring have charge ranging from 5OpC to 25nC with pulse durations varying from 30ps to 3011s. A total of nine non-intercepting beam current monitors have been installed in the APS facility (excluding those in the linac) for general current measurement. In addition, several independent current monitors with specially designed redundant interlock electronics are installed for personnel safety and machine protection. This paper documents the design and development of current monitors in the APS, discusses the commissioning experience in the past year, and presents the results of recent operations.
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