Online optimization of NSLS-II dynamic aperture and injection transient

• Published in: Journal of physics. Conference series 2023-01, Vol.2420 (1), p.12071
• Main Authors: Yang, X, Wang, G, Smaluk, V, Yu, L H, Shaftan, T, Li, Y, Plassard, F, Buda, S, Hidaka, Y, Durfee, D, Tian, Y, Hu, Y, Ha, K, Derbenev, A, Bacha, B, Danneil, C, Padrazo, D
• Format: Article
• Language: English
• Subjects: Algorithms; Amplitudes; Apertures; Chromaticity; Efficiency; Nonlinear dynamics; Optimization; Optimization techniques; Perturbation; Physics; Pulse duration; Waveforms
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/2420/1/012071

The goal of the NSLS-II online optimization project is to improve the beam quality for the user experiments. To increase the beam lifetime and injection efficiency, we have developed a model-independent online optimization of nonlinear beam dynamics using advanced algorithms, such as Robust Conjugate-Gradient Algorithm (RCDS). The optimization objective is the injection efficiency and optimization variables are the sextupole magnet strengths. Using the online optimization technique, we increased the NSLS-II dynamic aperture and reduced the amplitude-dependent tune shift. Recently, the sextupole optimization was successfully applied to double the injection efficiency up to above 90% for the high-chromaticity lattice being developed to improve the beam stability and to increase the single-bunch beam intensity. Minimizing the beam perturbation during injection is the second objective in this project, realized by online optimization of the injection kickers. To optimize the full set of kicker parameters, including the trigger timing, amplitude, and pulse width, we upgraded all kicker power supplies with the capability of tunable waveform width. As a result, we have reduced the injection transient by a factor of 29, down to the limit of 60 μm.