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Persistent URL http://purl.org/net/epubs/work/12213723
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Record Id 12213723
Title Precise Instruments for Bunch Charge Measurement
Abstract For the pulse charge q injected into a capacitor of a parallel resonating circuit, the oscillation voltage V on a series resistor R is V=qwRexp(–wt/2Q)sin(wt–1/2Q), t>?, where w is the resonance frequency, Q>>1 is the quality factor and ?<<1/w is the pulse length. Of the two main parameters, R is known, and w can be found directly from the signal above. The quality factor contribution is low, and its rough estimation is sufficient to retain voltage accuracy. The observations above open a possibility of precise bunch charge measurement. We describe a bunch charge monitor that is a cavity with a lump capacitor as a low impedance coaxial line connected to a gap in the vacuum pipe. An LC electronic circuit is also presented. It integrates the single bunch current delivered by a Faraday Cup, or a Wall Current Monitor, or a Fast Current Transformer. The circuit has w~30MHz, Q~20, and with a Faraday Cup, the lower range is 10pC/V and the noise floor is about 20fC. Several such circuits are in use on the VELA injector in Daresbury Laboratory.
Organisation ASTeC , STFC , ASTeC-DL
Keywords ASTeC 2014-2015 , 06 Instrumentation, Controls, Feedback & Operational Aspects , T03 Beam Diagnostics and Instrumentation
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Language English (EN)
Type Details URI(s) Local file(s) Year
Paper In Conference Proceedings In 5th International Particle Accelerator Conference (IPAC14), Dresden, Germany, 15-20th June, 2014, (2014). http://jacow.org/…/papers/thpme182.pdf 2014