Study of Multipolar RF Kicks from the main deflecting mode in Compact Crab Cavities for LHC

A crab cavity (CC) system is under design in the framework of the High Luminosity LHC project. Due to transverse space constraints on one hand and the RF frequency requirements on the other hand, the design of the crab cavities has to be compact. This results in the crab cavity shape being far from axially symmetric and, as a consequence, higher order multipolar components of the main deflecting mode are non-zero. In this paper, multipolar RF-kicks from the main deflecting mode are calculated in the compact CC for LHC. They are compared to the multipolar error in LHC magnets. The possible influence of the RF-kicks on the beam dynamics has been investigated by means of analytical estimates.