Comment on “Adiabatic excitation of longitudinal bunch shape oscillations”

This comment takes up the suggestion of the authors that it could be informative to model the excitation of the bunch shape oscillations using multiparticle tracking. The experiment they report employs an 80% modulation of the rf amplitude at approximately twice the synchrotron frequency; the first-order perturbation analysis given in the paper is not suitable for quantitative comparison to the experimental observations. The tracking code esme is used to model the conditions of the experiment. The potential well distortion arising from image charge and current and a broadband longitudinal impedance of Z_∥/n  =  6 Ω was considered as an additional perturbation which also varies at the modulating frequency.