Observations of the coherent beam-ion interaction in the CESR storage ring

Abstract

The coherent interaction between the electron beam and trapped ions in the Cornell Electron/positron Storage Ring (CESR) has been seen by shaking the beam and observing the resulting beam oscillation amplitude. A linear theory is developed which enables the calculation of ion densities from the experimental measurements. Nonlinearities in the beam-ion force are shown to be important in understanding the ion trapping effects including frequency shifts of the betatron sideband resonances.