A nonlinear future Measurements and corrections of nonlinear beam dynamics using forced transverse oscillations

As the design parameters of the LHC are pushed further to more challenging regimes, the control of the beam optics becomes increasingly important. A good control of nonlinear beam dynamics is now becoming more critical to achieve the luminosity targets, and Run II of the LHC has seen a major effort in demonstrating and validating correction strategies.
The work presented in this thesis focuses on the process of measurement and correction of nonlinear errors in the LHC using ac dipoles. This thesis explores a new theoretical parametrization of forced oscillations in synchrotrons. It further presents the first measurements and corrections of skew octupolar nonlinear magnetic errors. This forms a milestone achievement for the use of resonance driving terms for nonlinear corrections in the LHC. A new observable is proposed, known as the forced dynamic aperture, to study machine nonlinearities. Lastly, the effect of beam-beam interactions on resonance driving terms is studied theoretically, and demonstrated in experiments for the first time.
In all, the achievements presented in this thesis significantly improve the understanding of the nonlinear motion under the influence of ac dipoles both theoretically as well as experimentally. This thesis offers the first demonstration of specific nonlinear correction strategies using the ac dipoles. The validation of these methods now offer new strategies to improve the control of the beams and further push the performance of the LHC as well as future machines as the High Luminosity LHC and the FCC.