A Robotic Inspection and Assembly Workcell for SRF Cavities

The production of high-Q superconducting radio frequency (SRF) cavities involves a complex chain of fabrication and inspection operations. Currently, much of this demanding work is performed manually within the tightly controlled environment of a production cleanroom. However, as the design precision and cleanliness requirements of modern SRF cavities have increased, this “human factor” has emerged as the biggest contributor to sub-optimal cavity performance. To address this problem, a robotic assembly Workcell is proposed. This Workcell is predicated on a pair of six-axis articulating arm robots, active registration/positioning fixtures and a collection of non-contact metrology tools. Automated end effector exchange allows the robots to select the appropriate tool for each specific tasks. The Workcell is thus able to determine the topography of an incoming cavity, inspect its welds, clean its critical surfaces, and align/attach external flanges. The Workcell is fully compatible with Class 10 cleanrooms and its modular design allows it to be rapidly reconfigured to accommodate different cavity geometries and/or reprogrammed to perform new tasks. Under Phase I, a prototype Workcell utilizing a single six-axis robot was designed and built. This prototype successfully executed a full suite of representative cavity inspection, cleaning and assembly tasks thus demonstrating the feasibility of the concept. Under Phase II, the Workcell’s design will be expanded, adapted for cleanroom operation and brought to full operational fruition. SRF cavities are essential elements of almost all modern particle accelerators; the proposed automated Workcell will serve as a powerful enabling technology and its inherent operational flexibility will allow its work portfolio to evolve and expand. Eventually, the Workcell can be adapted to perform higher-level operations associated with accelerator cavity string assembly. In the near term, the multi-billion dollar Proton Improvement Plan II (PIP-II) now underway at the Fermi National Accelerator Laboratory will be the Workcell’s primary market. Future accelerators such as the planned International Linear Collider along with private sector manufacturers represent an even larger commercial opportunity.