Curing coupled-bunch instabilities with uneven fills.
A new, unified theoretical description of coupled-bunch instabilities in unevenly filled storage rings is presented. Uneven-fill longitudinal dynamics are explained in terms of two physical phenomena: fill-induced tune-spread damping and modulation coupling of strong even-fill eigenmodes. The latter is also present in the transverse plane. The analysis yields simple criteria for optimizing fill shapes to reduce the growth rates of the most unstable modes. Experimental results from the ALS and PEP-II are shown to be in good agreement with the theory.
Prabhakar
S
S
Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309, USA.
Fox
J D
JD
Teytelman
D
D