Superconducting low-velocity linac for the Argonne positive-ion injector

A low-velocity superconducting linac has been developed as part of a positive-ion injector system, which is replacing a 9-MV tandem as the injector for the ATLAS accelerator. The linac consists of an independently phased array of resonators and is designed to accelerate various ions over a velocity range 0.008<v/c<0.06. The resonator array is formed by four different types of superconducting interdigital structures. The linac is being constructed in three phases, each of which will cover the full velocity range. Successive phases will increase the total accelerating potential and permit heavier ions to be accelerated. Assembly of the first phase was completed in early 1989. In initial tests with beam, a five-resonator array provided approximately 3.5 MV of accelerating potential and operated without difficulty for several hundred hours. The second phase is scheduled for completion in late 1989 and will increase the accelerating potential to more than 8 MV