Detuning Properties of RF Phase Modulation in the Electron Storage Ring KARA

In electron storage rings, it is possible to increase the electron bunch length by applying a phase modulation on the radio frequency accelerating field by choosing appropriate parameters for the modulation. Such a bunch lengthening effect improves beam parameters such as the beam lifetime, which can help us to get better beam stability. The dependence of the bunch lengthening on the modulation frequency, the so-called detuning property, tends to have a peak with asymmetric slopes around it. The modulation amplitude and the beam current also affect the properties of the detuning condition of such bunch lengthening. We have investigated the detuning property with systematic measurements at the electron storage ring KARA. The experimental results agree with the theoretical model and the simulation results.