Single and multibunch beam dynamics in the DAΦNE main rings

We describe the results of single bunch measurements and observations of the multibunch beam behavior in the DAΦNE electron-positron collider main rings. In single bunch mode the nominal current of 44 mA has been exceeded, reaching 110 mA in both electron and positron rings without any harmful single bunch instability. We have measured the bunch length as a function of the bunch current at different RF voltages. According to the data the longitudinal normalized impedance is lower than 0.6 Ohm. The estimated transverse broad band impedance is small. This is confirmed by the fact that the head-tail instability threshold without sextupoles is as high as 13 mA. The measured transverse tune shift at the nominal current is a small fraction of the synchrotron tune. The longitudinal feedback systems have been successfully commissioned in both main rings allowing to store routinely high multibunch currents and observed the beam behavior for different multibunch fills. In particular, such observations have helped us to identify same parasitic High Order Modes trapped within vacuum chamber elements and capable to drive rather fast multibunch instabilities, both longitudinal and transverse