Online bunch-by-bunch position monitoring and analysis at the Taiwan Photon Source

Abstract

The online bunch-by-bunch position monitor has been established through the utilization of a high-speed analog-to-digital converter, synchronized meticulously with the accelerator's radio frequency. This implementation serves the purpose of refining the alignment of the four injection kickers. A substantial volume of data needs to be managed when dealing with the motion of the bunches. To untangle the intricacies of bunch motion, an independent component analysis has been employed. This method efficiently segregates the bunch motion into discrete sources. The resulting bunch motion is a direct outcome of the linear combination of these distinct sources. Consequently, this approach significantly simplifies the overarching data analysis procedure. Throughout the injection phase, the predominant factors influencing the oscillation of filled bunches originate from three distinct sources. Firstly, there is a contribution arising from the mismatch among the four kickers during their activation period. Additionally, the damped betatron oscillation and the oscillation generated by wake fields constitute the other sources of bunch motion. To comprehend the tune variation in these sources, an examination is conducted through a numerical analysis of fundamental frequencies. Specifically, the tune associated with the betatron oscillation is contingent upon the amplitude of said oscillation. In contrast, the tune corresponding to the wake-field oscillation displays comparably minor fluctuations during both the growing and damping phases.