Influence of electropolishing current densities on sulfur generation at niobium surface
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- 作者：P.V. Tyagi ; M. Nishiwaki ; T. Noguchi ; M. Sawabe ; T. Saeki ; H. Hayano ; S. Kato
- 关键词：Nb electropolishing ; Current density ; SRF cavity ; Surface finishing ; Sulfur generation ; Field emissions
- 刊名：Applied Surface Science
- 出版年：15 November, 2013
- 年：2013
- 卷：285
- 期：part_PB
- 页码：778-782
- 全文大小：1914 K
文摘
We report the effect of different current densities on sulfur generation at Nb surface in the electropolishing (EP) with aged electrolyte. In this regard, we conducted a series of electropolishing (EP) experiments in aged EP electrolyte with high (鈮?0 mA/cm<sup>2sup>) and low (鈮?0 mA/cm<sup>2sup>) current densities on Nb surfaces. The experiments were carried out both for laboratory coupons and a real Nb single cell cavity with six witness samples located at three typical positions (equator, iris and beam pipe). Sample's surfaces were investigated by XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscope) and EDX (energy dispersive X-ray spectroscopy). The surface analysis showed that the EP with a high current density produced a huge amount of sulfate/sulfite particles at Nb surface whereas the EP with a low current density was very helpful to mitigate sulfate/sulfite at Nb surface in both the experiments.