The clean-room assembly of a 1.3 GHz ILC 9-cell superconducting RF cavity in a test cryomodule was completed at IHEP on May 23rd 2014. The cavity will later be installed into the cryomodule along with the tuner and the warm part of the input coupler, and will undergo horizontal and beam tests when the 2K cryogenic system and RF power source are ready, in the next year or so.

The assembled 9-cell cavity line is 3.5 meters long, including the large-grain, low-loss 9-cell cavity, a helium vessel, the cold part of the double-window input coupler, gate valves and beam tubes. The cavity reached performance of 20 MV/m and Q₀ = 1.4×10¹⁰ without field emission in the vertical test. The input coupler reached 1 MW pulsed traveling wave power in the conditioning test.

Clean-room assembly of superconducting RF cavities is a key technology and a crucial step for the performance of a superconducting accelerator. As the cavity is very sensitive to contamination, it requires extremely high standards for the environment (class 10 to 100), component cleanliness, and vacuum and assembly procedures. To maintain the cavity’s cleanliness and high Q₀ in future operations, the state-of-art clean-room assembly technique developed by ILC/XFEL was used.

The assembled 9-cell cavity line at IHEP （image by IHEP）