Study on beam steering in intermediate-/spl beta/ superconducting quarter wave resonators

Superconducting quarter wave resonators, due their compactness and their convenient shape for tuning and coupling, are very attractive for intermediate-/spl beta/ beam acceleration up to about 100 MeV/u. A drawback of this kind of cavities is the beam steering caused by transverse magnetic and electric field components; this can create emittance growth and beam spill, especially in high intensity proton linacs. We did analytical and numerical studies on beam steering in quarter wave resonators and, in particular, in different 352 MHz quarter wave geometries for beta=0.15-0.45 beams. The results suggest that, in this case, the solution of alternative cavity orientation could nearly cancel the steering.