Investigations of Superconducting Helix Resonators for a Heavy Ion Post Accelerator

As a part of a feasibility study the design and the construction of an accelerator section to be tested at the heavy ion beam of an electrostatic tandem Van de Graaff has been started. This test section consists of a cryostat with two independently phased ¿/2-helix structures at 108 MHz and of a suitable rf-control system. Design criteria and recent results of measurements on a superconducting test cavity with electric surface peak fields up to 29 MV/m are presented.