NOVEL INSTRUMENTS AND TECHNIQUES FOR DETECTION AND REMOVAL OF CONTAMINATION PARTICULATES IN HIGH-POWER PROTON SUPERCONDUCTING LINAC RADIO FREQUENCY CAVITIES

This topic seeks the development of diagnostic instruments and surface cleaning techniques for understanding, predicting, controlling, and possibly reversing particulate contamination in superconducting radio frequency (SRF) cavities operated in high-power proton linear accelerators. Particulate contamination introduced onto the surface of an operational SRF cavity is a source of unwanted field emission. Consequently, it causes degradation of the cavity operational gradient and radiation damage to linac components. These in turn lead to a loss in the linac energy output, availability, and maintainability. Novel instruments and techniques are required to understand the source of particulates in the beamline of operational SRF linacs, the movement of pre-existing and newly generated particulates over the entire length of the beamline envelope, the stopping of particulate transportation onto the SRF cavity surfaces, and the removal of accumulated particulates from the surfaces of cavities installed in the accelerator tunnel without taking apart cryomodules. Such instruments and techniques are lacking. The applicant must propose solutions applicable for operational SRF linacs and associated cryomodule and cavity components, subjected to radiation fields and sometimes residual activation. Grant applications are sought in the following subtopics: a. Non-Invasive Instruments for Detecting Particulate Movement in SRF Linac Beamlines and Tools and Processes for In-Situ Removal of Particulates from SRF Cavity Surfaces of a Cryomodule Without Taking Apart Cryomodule Components In this subtopic applications are sought for the development of non-invasive diagnostic instrument systems for detecting particulate movement in the SRF linac beamlines. The system must not interrupt the normal accelerator operation. The detection method must be compatible with the ultra-high vacuum condition within the beamline envelope. The system must be capable of resisting damage against the ionization radiation environment often found in the vicinity of the accelerator beamline. The detection technique should be sensitive to organic, inorganic, metallic, and semiconducting particulates of sizes in the range of 1-100 micron, moving at a speed in the range of 1-10 m/s. The data acquisition system should be capable and flexible in dealing effectively with different scenarios in particulate flux down to one per day. The data analysis algorithm should be able to report at minimum: the particle size and movement speed. Capabilities in discerning the type of materials of the moving particulates are highly desired. Applications are also sought for the development of new tools and processes capable of removing particulates deposited on the surface of SRF cavities in a cryomodule without taking apart cryomodule components. The new techniques must transport the removed particulates from the inner space enclosed by the surface of a string of cavities embedded in a cryomodule. Discharged particulates must be captured to prevent release of activated particulate matter. Particulates down to 1 micron in size should be effectively dislodged and transported over a length of a multi-cell elliptical cavity (with a length on the order of 1 meter) and the entire cavity string as well (on the order of 10 meters). No scratching of the cavity iris is permitted. The design of the tool and process must be flexible to allow turning the cleaning medium on and off at demand so as to protect sensitive cryomodule components such as coupler tips and copper plating from being compromised and damaged. Questions - Contact: Eliane Lessner, eliane.lessner@science.doe.gov b. Other In addition to the specific subtopic listed above, the Department invites grant applications in other areas that fall within the scope of the topic description above.