Sincrotrón ALBA
Defense of the PhD thesis by Michele Carla
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Gabriele Benedetti
The purpose of the thesis was testing and validating the turn-by-turn (TBT) beam position measurement technique applied to the study of the linear and non-linear beam dynamics of synchrotron light sources.
The research started by developing a representation of the beam dynamics derived from a perturbative approach, which agreed with numerical simulations (tracking) within a 0.1%. Moreover, in order to obtain experimental data, the beam position monitor electronics firmware was replaced with a new one (Moving Average Filter, MAF) designed ad-hoc for TBT applications, and next, a novel optimized spectral analysis procedure was developed to properly treat the BPM data. The linear beam dynamics studies achieved a level of agreement comparable to the standard techniques (i.e. based on orbit response matrix). The experiments showed how the TBT technique shines in sensitivity, enabling the detection of very small variations of the optics function. This allowed to apply the TBT technique, for the first time in a light source, to the measurement of localized transverse impedance sources. Finally, the thesis shows how tiny impedance sources can still be properly characterized by manipulating the machine optics. This method has been used to characterize impedances as small as the ALBA IVUs' one.