Plasma Treatment of Bulk Niobium Surface for SRF Cavities - Optimization of the Experimental Conditions on Flat Samples
Accelerator performance, in particular the average accelerating field and the cavity quality factor, depends on the physical and chemical characteristics of the superconducting radio-frequency (SRF) cavity surface. Plasma based surface modification provides an excellent opportunity to eliminate non-superconductive pollutants in the penetration depth region and to remove mechanically damaged surface layer improving surface roughness. Here we show that plasma treatment of bulk Nb presents surface preparation method alternative to the commonly used BCP and EP methods. We have optimized the experimental conditions in the microwave glow discharge system and their influence on the Nb removal rate on the flat samples. We have achieved etching rates of 1.5 micro-m/min using only 3% Cl2 in the reactive mixture. Combining fast etching step with the moderate one, we have improved a surface roughness without exposing fresh sample surface to the environment. We will apply optimized experimental conditions to single cell cavities, in pursuing improvement of their RF performance.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1998942
- Report Number(s):
- JLAB-ACC-09-1076; DOE/OR/23177-1110
- Resource Relation:
- Conference: SRF2009, Berlin, Germany, September 20, 2009
- Country of Publication:
- United States
- Language:
- English
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