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

Statement of the Problem SRF cavities are starting to be recognized as not only research devices but as devices that might be able to step in as an improved alternative to existing non-superconducting accelerator technology. The largest issue in fostering this change in applicable areas is the cost of the infrastructure and cytotechnology required when maintaining cryo-liquids. This cost has become synonymous with the term SRF cavity, limiting people’s perspective expectation from the technology. Further the few small cryomodules that have been developed have not invested in the level of analysis required for field deployment, instead focusing on building these delicate devices at their final test locations. Technical Approach In this project, we are designing and building a cryomodule that operates without any cryo-liquids utilizing cryocoolers and conductive cooling. This will eliminate the large expense of cryo-fluids and further reduce transportation concerns, since the cryomodule becomes just a vacuum device, not a potentially high- pressure vessel. We will also initiate design and fabrication of the other components needed for full demonstration, such as the cavity and RF coupler. Phase II progress to date In Phase II, we completed the deployable conductively cooled cryomodule design and we are well under way in fabrication. The design included consideration for mobility and will utilize a single cell 650 MHz conductively cooled cavity provided by Fermilab. The cryomodule currently supports up to four cryocoolers, but will only use one for a total of 2.5 watts of cooling power at 4.2K. We are assembling the cryomodule for final testing, which will take place at Fermilab. Phase IIA Plans In Phase IIA, the cryomodule will be further upgraded to support a permanent cavity in preparation for in use testing. This includes the initiation of multicell conductively cooled cavity design, with some fabrication process studies to develop the tooling to build the cavity. We will design and fabricate an appropriate RF power coupler to further fill out the cryomodule build. We will also further fill out the coldhead compliment to make this cryostat have a comfortable heat budget implicit with the dynamic loads we expect to see in operation with the new cavity. Commercial Applications and Other Benefits This device would have immediate benefit to existing SRF facilities now as an independent module utilized for capability expansion. This product would also address the desire of fostering compact SRF technology into industry and small laboratories. Some examples of typical areas of interest that would apply are: cargo inspection and security, food irradiation, bulk material treatment, and environmental issues such as waste water treatment.