New superconducting heavy ion accelerating structure using chemically polished lead surfaces

A new heavy ion accelerating structure was developed which, together with a parallel development in chemical polishing techniques, makes possible very high accelerating fields for a wide range of particle velocities using inexpensive and easily handled materials. This ''Split Ring'' accelerating structure has a peak magnetic field approximately one third that of other inductively loaded accelerating structures (less than 100G at 1MeV/m accelerating field) and a peak electric field less than 6 times the effective accelerating field. In addition, a chemical polishing technique appropriate for use on electroplated lead surfaces was developed which greatly reduces the electric field emission of electrons from the surface. Surface fields greater than 25MV/m were obtained in superconducting resonators with polished lead surfaces with no detectable loss due to field emission. An accelerating field greater than 4 MV/m in a superconducting structure was achieved, and long term tests were begun. Preliminary results indicate no surface degradation at high fields (greater than 3MV/m) for relatively long times (14 hours). (auth)