ANALYSIS OF THE VERTICAL BEAM INSTABILITY IN CTF3 COMBINER RING AND NEW RF DEFLECTOR DESIGN

摘要

In the last CTF3 run (November 2007) a vertical beam instability has been found in the Combiner Ring during operation. Possible sources of the instability are the vertical deflecting modes excited by the beam in the RF deflectors. In the first part of the paper we illustrate the results of the beam dynamics analysis obtained by a dedicated tracking code that allows including the induced transverse wake field and the multi-bunch multi-passage effects. To reduce the effects of such vertical trapped modes, two new deflectors have been designed. In the new devices special antennas absorb the power released by the beam to the modes. The structures will be made in aluminium to reduce the costs and delivery time.