Prototype of a superconducting RFQ for a heavy ion injector linac

Two superconducting radiofrequency quadrupoles, SRFQ1 and SRFQ2, resonating at 80 MHz, will provide acceleration from beta=v/c=0.009 to 0.035 in PIAVE, the new injector for the superconducting linac ALPI at INFN - Laboratori Nazionali di Legnaro [1]. The construction of the full niobium structures was preceded by the development of a full size stainless steer prototype of SRFQ2 (fig.1), through which most of the construction techniques also applying to the niobium cavities, electromagnetic characterization of the resonator and its mechanical vibration spectrum can be investigated. This paper presents the most relevant design issues of the superconducting RFQ resonators and the construction techniques adopted.