Integrated Surface Topography Characterization of Variously Polished Niobium for Superconducting Particle Accelerators
As superconducting niobium radio-frequency (SRF) cavities approach fundamental material limits, there is increased interest in understanding the details of topographical influences on realized performance limitations. Micro-and nano-roughness are implicated in both direct geometrical field enhancements as well as complications of the composition of the 50 nm surface layer in which the super-currents flow. Interior surface chemical polishing (BCP/EP) to remove mechanical damage leaves surface topography, including pits and protrusions of varying sharpness. These may promote RF magnetic field entry, locally quenching superconductivity, so as to degrade cavity performance. A more incisive analysis of surface topography than the widely-used average roughness is needed. In this study, a power spectral density (PSD) approach based on Fourier analysis of surface topography data acquired by both stylus profilometry and atomic force microscopy (AFM) is being used to distinguish the scale-dependent smoothing effects. The topographical evolution of the Nb surface as a function of different steps of EP is reported, resulting in a novel qualitative and quantitative description of Nb surface topography.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1021840
- Report Number(s):
- JLAB-ACC-09-979; DOE/OR/23177-0732; TRN: US1104062
- Resource Relation:
- Conference: Particle Accelerator Conference (PAC 09), Vancouver, BC, Canada, 4-8 May 2009
- Country of Publication:
- United States
- Language:
- English
Similar Records
Advanced Topographic Characterization of Variously Prepared Niobium Surfaces and Linkage to RF Losses
Analysis of the topographic transformation of Nb surface under controlled EP conditions