Two superconducting split-ring accelerating resonators for ions of velocity 0.045 c and 0.055 c

Two superconducting split-ring resonators using the Cu/Pb technology have been built. Previous structures of the same frequency and velocity had their achievable gradient limited by insufficient mechanical stability, and the power dissipation was dominated by losses in the demountable joint between the split-ring and the outer can. These new structures have the split-rings electron-beam welded in the outer can. They also incorporate a new feature: the use of loading arm of non-constant cross section; their diameter being larger at the voltage node than at the drift tube. The increase in mechanical stability should allow them to be operated at accelerating fields limited by the properties of the superconducting surface and not by the mechanical properties of the structure