Review of instabilities with ions or/and electrons and possible mitigations

The presence of ions and electrons from gas ionization, photoemission or secondary emission is unavoidable in the vacuum chambers of high intensity accelerators and storage rings. Under suitable conditions, these ions and electrons can accumulate and drive the beams unstable. In this contribution, the mechanisms behind and the main conditions for ion and electron accumulation in the bunched beams are summarized. The characteristics of the induced instabilities, as well as common modelling techniques and mitigation strategies are reviewed. The possible interplays between ions and electrons are also discussed.