Evaluation of the diffusion coefficient of fluorine during the electropolishing of niobium
Open Access
- 25 August 2010
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review Special Topics - Accelerators and Beams
Abstract
Future accelerators require unprecedented cavity performance, which is strongly influenced by interior surface nanosmoothness. Electropolishing (EP) is the technique of choice being developed for high-field superconducting radio frequency (SRF) cavities. Previous study has shown that the mechanism of Nb electropolishing proceeds by formation and dissolution of a compact salt film under fluorine diffusion-limited mass transport control. We pursue an improved understanding of the microscopic conditions required for optimum surface finishing. The viscosity of the standard electrolyte has been measured using a commercial viscometer, and the diffusion coefficient of fluorine was derived at a variety of temperatures from 0 to using a Nb rotating disk electrode. In addition, data indicate that electrode kinetics becomes competitive with the mass transfer current limitation and increases dramatically with temperature. These findings are expected to guide the optimization of EP process parameters for achieving controlled, reproducible, and uniform nanosmooth surface finishing of SRF cavities. DOI: http://dx.doi.org/10.1103/PhysRevSTAB.13.083502 This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. © 2010 The American Physical Society
Keywords
This publication has 15 references indexed in Scilit:
- The Mechanism of Electropolishing of Niobium in Hydrofluoric–Sulfuric Acid ElectrolyteJournal of the Electrochemical Society, 2008
- Mechanistic Studies of Cu Electropolishing in Phosphoric Acid ElectrolytesJournal of the Electrochemical Society, 2004
- Nb Electrodissolution in Acid Fluoride MediumJournal of the Electrochemical Society, 2002
- Copper Electropolishing in Concentrated Phosphoric Acid: II . Theoretical InterpretationJournal of the Electrochemical Society, 1995
- Impedance Analysis of a Model Mechanism for Acceptor‐Limited ElectropolishingJournal of the Electrochemical Society, 1994
- Roughness Assessment of Polysilicon Using Power Spectral DensityJapanese Journal of Applied Physics, 1993
- Fundamental aspects of electropolishingElectrochimica Acta, 1987
- Anodic Leveling under Secondary and Tertiary Current Distribution ConditionsJournal of the Electrochemical Society, 1982
- Theoretical and Experimental Modeling of Surface Leveling in ECM under Primary Current Distribution ConditionsJournal of the Electrochemical Society, 1980
- The flow due to a rotating discMathematical Proceedings of the Cambridge Philosophical Society, 1934