JLab, Newport News, Virginia, USA
Particles are one possible cause of field emission issues in SRF cavity operations. During clean room cavity preparation, several processes could contribute to the generation of particles. One of them is friction between hardware during assembly and disassembly. It is important to understand the behaviours that generate and propagate particles into cavities. Using a single cell cavity, particle shedding between flanges and other materials have been tested. The number of particles is recorded with an airborne particle counter, and the generated particles are examined with microscope. The migration of particles into a cavity due to different movements is studied. Suggestions are made to reduce particle generation and prevent contamination of the cavity interior area.
JLab, Newport News, Virginia, USA
The Thomas Jefferson National Accelerator Facility is currently engaged, along with several other DOE national laboratories, in the Linac Coherent Light Source II project (LCLS II). The SRF Institute at Jefferson Lab will be building 1 prototype and 17 production cryomodules based on the TESLA / ILC / XFEL design. Each cryomodule will contain eight nine cell cavities with coaxial power couplers operating at 1.3 GHz. New and modified infrastructure and assembly tooling is required to construct cryomodules in accordance with LCLS-II requirements. The approach for modifying assembly infrastructure included evaluating the existing assembly infrastructure implemented at laboratories world-wide in support of ILC and XFEL production activities and considered compatibility with existing infrastructure at JLab employed for previous cryomodule production projects. These modifications include capabilities to test cavities, construct cavity strings in a class 10 cleanroom environment, assemble cavity strings into cryostats, and prepare cryomodules for cryogenic performance testing. This paper will give a detailed description of these modifications.