ANL, Argonne
Recent developments at the Advanced Photon Source (APS) in high-resolution beam position monitoring for both the electron and the x-ray beams has provided an opportunity to study beam motion well below the measurement threshold of the standard suite of instrumentation used for orbit control. The APS diagnostics undulator beamline 35-ID has been configured to use a large variety of high-resolution beam position monitor (BPM) technologies. The source-point electron rf BPMs use commercially available Libera Brilliance electronics from Instrumentation Technologies, together with in-house-developed field-programmable gate array-based data acquisition digitizing broadband (10 MHz) amplitude-to-phase monopulse receivers. Photo-emission-based photon BPMs are deployed in the 35-ID front end at distances of 16 and 20 meters from the source, and a prototype x-ray fluorescence-based photon BPM is located at the end of the beamline, approximately 42 meters from the source. Detailed results describing AC noise and long-term drift performance studies will be provided.
BNL, Upton, Long Island, New York
The NSLS-II Light Source is being built at Brookhaven National Laboratory. It will provide users with ultimate brightness beam and the full realization of its capabilities requires corresponding stability of the beam orbit. The small aperture BPMs, located at the ends of a insertion device, will provide better sensitivity to the beam position but also requires thorough design. In this paper we present the results of the optimization including signal power levels and button heating.
BNL, Upton, Long Island, New York
Two most widely used BPM systems (manufactured by Bergoz and Instrumentation Technologies) implement switching technique to eliminate drifts caused by change in a channel gain. High stability is achieved by an alternative routing of signals from all pick-up electrodes through the same chain. In this paper we propose a different approach of separating signals in the frequency domain, which is based on advances of digital signal processing allowing identical gains for the separate frequencies. Experimental set-up and results are presented. Practical realization of the beam position monitors is also discussed.
ANL, Argonne
As the Advanced Photon Source (APS) prepares for a large-scale upgrade, many of the fundamental limitations on beam stability have to be identified. Studies have been conducted to measure thermal mechanical effects of both the water and air handling systems impacting insertion device vacuum chambers (IDVES). Mechanical stability of beam position monitor pickup electrodes mounted on these small-gap IDVES places a fundamental limitation on long-term x-ray beam stability for insertion device beamlines. Experiments have been conducted on an ID vacuum chamber indicating that the BPM blocks are moving with water temperature cycles at the level of 10 microns/degree C. Measurements and potential engineering solutions will be described.