Impact of the cSTART impedance on beam dynamics

The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (about 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project, which will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a versatile source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector. The large-momentum spread bunches in non-equilibrium and with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the beam dynamics simulations. An understanding of the ultra-short bunch dynamics also requires an impedance model up to high frequencies. Here, we present first results on the impact of the machine impedance to the