Compensation of Transient Beam Loading in Ramping Synchrotrons using a Fixed Frequency Processing Clock

Transient beam loading compensation schemes, such as One-Turn-FeedBack (OTFB), require beam synchronous processing (BSP). Swept clocks derived from the RF, and therefore harmonic to the revolution frequency, are widely used in CERN synchrotrons; this simplifies implementation with energy ramping, wh...

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Bibliographic Details
Published in:Journal of physics. Conference series 2018-09, Vol.1067 (7), p.72033
Main Authors: Galindo Guarch, F J, Moreno Aróstegui, J M, Baudrenghien, P
Format: Article
Language:English
Subjects:
Algorithms
Clocks
Clocks & watches
Compensation
Data transmission
Digital data
Física
Low level
Physics
Radio frequency
Synchrotrons
Àrees temàtiques de la UPC
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Summary:Transient beam loading compensation schemes, such as One-Turn-FeedBack (OTFB), require beam synchronous processing (BSP). Swept clocks derived from the RF, and therefore harmonic to the revolution frequency, are widely used in CERN synchrotrons; this simplifies implementation with energy ramping, where the revolution frequency changes. It is however not optimal for state-of-the-art digital hardware that prefers fixed frequency clocks. An alternative to the swept clocking is the use of a deterministic protocol, for example White Rabbit (WR): a fixed reference clock can be extracted from its data stream, while enabling digital distribution of the RF frequency among other data. New algorithms must be developed for BSP using this fixed clock and the digital data transmitted on the WR link. This is the strategy adopted for the SPS Low Level RF (LLRF) upgrade. The paper gives an overview of the technical, technological and historical motivations for such a paradigm evolution. It lists the problems of fixed clock BSP, and presents an innovative solution based on a real-time variable ratio re-sampler for implementing an OTFB with the new fixed clock scheme.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/1067/7/072033