Falkenstern, F. ; Hoffmann, F. ; Kuske, P. ; Kuszynski, J.: "Bunchview" A fast and accurate bunch-by-bunch current monitor. In: 9th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators, DIPAC 2009, May 25 - 27.2009, Basel, Switzerland, 2009, p. 128-130
Abstract:
Bunch View is a system for the direct measurement of the current from each bunch circulating in a storage ring based on the analysis of the RF-signals delivered by a set of striplines. This paper describes the development, achievements, operation, and results of this fast and accurate bunch current monitor built for the BESSY and MLS storage rings. Using a combination of a 14/16Bit analog to digital converter (ADC), a high-speed FIFO, ECL technique, and FPGAs, a real-time measurement of the fill-pattern with high accuracy and bunch-by-bunch resolution was achieved. The results are identical to the fill-pattern determined by time correlated single photon counting based on synchrotron radiation detected with an avalanche photo diode. BunchView is fully integrated into the EPICS control system. The data provided by the BunchView monitor give accurate bucket position in the ring and bunch current over a wide dynamic range. The smallest measured single bunch current is less than 100nA. In the future the system will be used in the top-up mode of operation in order to inject beam into the emptiest buckets and thus keep the fill-pattern stable over longer periods of time.