LEIR LONGITUDINAL STUDIES

S. Albright et al.

Abstract


Towards the end of 2015 and during 2016 there were extensive studies of longitudinal beam dynamics in LEIR aimed at improving extracted intensities. As the driving source of losses early in the ramp was shown to be transverse space charge tune spread a significant improvement came from flattening the beam profile to increase the bunching factor by offsetting the RF frequency from the beam revolution frequency. Further benefits were provided by modulating the RF frequency during capture, leading to emittance blow-up and improved reproducibility. The use of two RF cavities during operation was studied to try and further increase the captured emittance, however after careful alignment of the RF it was found that a hard limit in the bunch heigh of approximately 7 MeV exists. Due to the acceptance limit there was no operational benefit to using both cavities simultaneously.

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DOI: http://dx.doi.org/10.23727/CERN-Proceedings-2017-002.123

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