SLAC, Menlo Park, California
ANL, Argonne
Funding: Work supported by U.S. Department of Energy under Contract Nos. DE-AC02-06CH11357 and DE-AC02-76SF00515.
We present the performance of the cavity beam position monitor (BPM) system for the LCLS undulator. The construction and installation phase of 34 BPMs for the undulator and 2 for the transport line have been completed. The X-band cavity BPM employs a TM010 monopole reference cavity and a TM110 dipole cavity designed to operate at a center frequency of 11.384 GHz. The signal processing electronics features a low-noise single-stage three-channel heterodyne receiver that has selectable gain and a phase locking local oscillator. The approximately 40 MHz IF is digitized by a 120M sample/second four-channel 16-bit digitizer. System requirements include sub-micron position resolution for a single-bunch beam charge of 200 pC. We discuss the system specifications and commissioning results.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS), a third-generation synchrotron light source, has been in operation for eleven years. The monopulse radio frequency (rf) beam position monitor (BPM) is one of three BPM types now employed in the storage ring at the APS. It is a broadband (10 MHz) system designed to measure single-turn and multi-turn beam positions, but it suffers from an aging data acquisition system. The replacement BPM system retains the existing monopulse receivers and replaces the data acquisition system with high-speed analog-to-digital converters (ADCs) and a field-programmable gate array (FPGA) that performs the signal processing. The new system has been installed and commissioned in a full sector of the APS. This paper presents the results of testing of the beam position monitor which is now fully integrated into the storage ring orbit control and fast feedback systems.