Beam-Photoelectron Interactions in Positron Storage Rings

The possibility of a coupled-bunch instability caused by beam-photoelectron interactions is discussed. Very many photoelectrons are produced in a storage ring when photons emitted by synchrotron radiation hit the beam chamber. Since electrons are not trapped by a positron beam in ion-trapping theory, they are not considered to affect the beam. However, it is possible that an enormous number of photoelectrons would have sufficient density to cause a coupled-bunch instability. A simulation has shown that such an instability may be serious for positron storage rings with high current and multibunches.