Stand-alone accelerator system based on SRF quarter-wave resonators

Superconducting accelerators are currently relatively large and complex systems requiring a central refrigeration system and complex piping to distribute liquid helium and nitrogen to the accelerator. Stand-alone systems are of significant interest both to scientific facilities and industrial applications, as they do not require massive and extremely expensive cryogenic facilities and the trained specialists required for their operation. However, the cryomodule for stand-alone system needs to be designed to minimize the heat losses to the liquid helium so that commercially-available self-contained cryocoolers are able to handle thermal load. In response to this problem, we propose to develop a stand-alone cryomodule with liquid based cooling system, based on a commercially available cryocooler, for the dressed 72 MHz quarter- waver resonator (QWR) designed and fabricated at Argonne for the ATLAS intensity upgrade project. In Phase I, we will develop a preliminary cryomodule concept to ensure the compactness, minimize the heat leak to the cryogenic environment, and evaluate available cryocoolers for this project. We will do a survey of available cryocoolers over the next three years, estimate the cost of the cooling systems and the utilities required for these systems. To address the critical part of the cryomodule design, and optimize the main cost-drivers of the system, we will develop low heat leak transitions for beam lines, helium system, 4 kW power coupler, targeting a static heat load of ~5 W. Commercial Applications and Other Benefits: The cryomodule prototype can be immediately used at ATLAS as a re-accelerator in the general purpose beamline, as a de-buncher cavity the Argonne In-flight Rare Isotope Separator (AIRIS), and as a high-performance buncher before the beam switch yard. The technology developed in this project can be further adapted for the other types of cavities and used for industrial (ion implantation), security (cargo-inspection) and medical (ion therapy) applications.