| AVS 55th International Symposium & Exhibition | |
| Applied Surface Science | Tuesday Sessions |
| Session AS-TuP |
| Session: | Aspects of Surface Analysis Poster Session |
| Presenter: | M.J. Kelley, College of William & Mary |
| Authors: | H. Tian, College of William & Mary G. Ribeill, North Carolina State University C.E. Reece, Thomas Jefferson National Accelerator Facility M.J. Kelley, College of William & Mary |
| Correspondent: | Click to Email |
An unprecedented number and scale of particle accelerator projects are getting underway, most notably the 30-km plus long International Linear Collider. The dominant technology is based on superconducting niobium radio-frequency (SRF) cavities, powered to ever-increasing acceleration gradients. The rf energy’s shallow penetration depth – few tens of nm – lends great importance to cavity interior surfaces. Interior surface etching to remove mechanical damage leaves surface topography, including 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. We introduce a Power Spectral Density (PSD) approach based on Fourier analysis of surface topography data acquired by both stylus profilometry and atomic force microscopy (AFM). We report the evolution of the Nb surface PSD as a function of applied etching and polishing steps, resulting in a novel quantitative description of roughness. An important aspect of the impact of processing on SRF performance is made significantly clearer.