Development of a system for coating SRF cavities using Remote Plasma CVD (Chemical Vapor Deposition) Gabriel Gaitan, Zeming Sun, Adam Holic, Gregory Kulina, Matthias Liepe, James Sears, Paul Bishop (CLASSE)

Setup Background • Samples are loaded on Moly boats and • Thin-film surfaces employing Nb3Sn, NbN, NbTiN, and introduced in the system for other compound superconductors are destined to annealing/CVD Clean Room allow reaching superior RF performance levels in SRF • Fused Quartz tube suitable to 1100C Turbopump cavities • An RF source will create plasma from the & VQM • Optimized, advanced deposition processes are precursors and this will reduce processing Quartz tube required to enable high-quality films of such materials temperature and promote precursor on large and complex shaped cavities. In doing this, decomposition Cornell University is developing a remote plasma- • Clean room is used for minimizing enhanced chemical vapor deposition (CVD) system contaminants in the furnace Furnace Furnace that facilitates coating on complicated geometries • Heat shields protect the O-rings on the controls with a high deposition rate. end flanges from overheating. Plasma source Cold trap

Furnace offers independent control of heating for all 3 • Loading and unloading system is being designed to allow processing of small VQM is important for monitoring carbon and hydrogen zones of the furnace. Maximum furnace temperature samples and cavities of 2.6GHz and 3.9GHz. contamination that might affect cavity performance 1500C.

Moly boats Maximum safe temperature 1100C. 3 zones with separate control VQM is used for detecting contaminants and has Tube furnace in operation the advantage of not overrepresenting hydrogen

Loading system

Commissioning stage

• Pressure of 7.8 ∙10-7 Torr obtained on the system-> The goal is 5 ∙ 10-7 Torr • Target temperature of 1100C was reached->Very good temperature control for all 3 zones • Will start with annealing Nb-> continue with Nb3Sn CVD studies • Will add a spectrometer to characterize the the ions present in the plasma

This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.