Performance Simulation for a Prototype 1.5 GHz Superconducting Harmonic Cavity

Superconducting radio frequency cavities are used as main accelerating cavities and harmonic cavities in modern light sources. The addition of a harmonic cavity provides the possibility to increase the electron bunch length and therefore to improve the beam life time. The effects on instabilities and the bunch lengthening factor by harmonic cavities can be obtained from theoretical calculations. However, these calculations ignore phase transient effects and may overestimate the desired performance of the harmonic cavities. A multibunch multiparticle tracking method was developed to simulate the performance of harmonic cavities for non-uniform filling patterns, which take into account phase transient effects. Performance simulations using this tracking method for a prototype 1.5-GHz superconducting harmonic cavity for the Taiwan photon source are presented here.