Classification of beam breakup instabilities in linear accelerators

With the use of a standard model, beam breakup growths in all types of linacs are shown to be classified by only two dimensionless parameters which depend on the beam current, beam energy, pulse length, machine length, breakup mode frequency, focal strength, and transverse shunt impedance. This classification suggests that rf cure plays a more important role in the control of beam breakup than focusing in a long pulse beam. The converse holds for a short pulse beam