Smooth Nb surfaces fabricated by buffered electropolishing

Wu, Andy; Mammosser, J.; Phillips, L.; Delayen, Jean; Reece, Charles; Wilkerson, Amy; Smith, David R.; Ike, Robert

doi:10.1016/j.apsusc.2006.06.060

Cited by 16 publications

(26 citation statements)

References 7 publications

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“…The difference between the two pictures could be visualized easily. Actually, the rms roughness of the niobium surface treated by BEP will be about 20 times better than those treated by BCP [6]. In addition, in the process of taking pictures of them with MOM, sometimes it is much harder to focus on the BEP treated surface since it is so smooth as compared with that on BCP treated one.…”

Section: Effect Of Removed Thickness On Surface Roughness In Bepmentioning

confidence: 99%

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Buffered electropolishing parameters on niobium sheet

Jin

Lin

et al. 2010

Phys. Rev. ST Accel. Beams

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In this paper, studies on applying a new electrolyte to treat the surfaces of Nb sheets, which was called buffered electropolishing (BEP), were reported. Through studies of the BEP I-V characteristic and optimization of main parameters such as acid agitation, temperature, etc., much faster Nb polishing rate and smoother surface finish were achieved in comparison with those obtained from the conventional electropolishing (EP). The average polishing rate could reach around 2:5 m= min . It was over 7 times faster than that of the traditional EP. Meanwhile, the average surface mean square root roughness was around 50 nm over an area of ð200 Â 200Þ m 2 . This study shows BEP has a great potential to replace the traditional EP process and becomes a new generation of technology for treating Nb superconducting radio frequency cavities.

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Section: Effect Of Removed Thickness On Surface Roughness In Bepmentioning

confidence: 99%

“…On the other hand, the polishing rate of the traditional EP was another problem. It was only about 0:38 m= min [6]. So if a cavity is treated by the conventional EP, more than 6 hours is needed in order to remove the so-called surface damage layer of Nb.…”

Section: Introductionmentioning

confidence: 99%

Buffered electropolishing parameters on niobium sheet

Jin

Lin

et al. 2010

Phys. Rev. ST Accel. Beams

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“…So, it was essential to study the oxide layer in detail. Slow sputtering using static SIMS approach [33,36,42] was adopted for such analysis. Using the above approach the intensity of various niobium oxide fragments of P78C (CS polished), P78B (CS+BCP treated), P78H…”

Section: Oxide Depth Profilementioning

confidence: 99%

Study of impurity distribution in mechanically polished, chemically treated and high vacuum degassed pure niobium samples using the TOFSIMS technique

Bose

Joshi

2015

Supercond. Sci. Technol.

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The performance of Superconducting radio frequency cavities (SRF) is strongly influenced by various impurities within the penetration depth (~50nm) of Nb, which in turn depends on the applied surface treatments. The effect of these surface treatments on the impurities of Nb has been explored using various surface analytical treatments.But, the results are still inadequate in many aspects and the effect of sequential SRF treatments on the impurity distribution has not been explored. The present study analyses various impurities within the penetration depth of Nb samples, treated by SRF cavity processing techniques like colloidal silica polishing (simulating centrifugal barrel polishing), buffer chemical polishing (BCP), high pressure rinsing (HPR) and degassing under high vacuum (HV) condition at 600°C for 10hrs. Static, dynamic and slow sputtering modes of Time of flight secondary ion mass spectrometry (TOFSIMS) technique was employed to study the effect of the above treatments on interstitial impurities, hydrocarbons, oxides, acidic residuals, reaction products and metallic contaminations. The study confirms that the impurity distribution in Nb is not only sensitive to the surface treatment, but also to their sequence. Varying the treatment sequence prior to HV degassing treatments affected the final impurity levels in HV degassed bulk Nb samples. BCP treated samples, exhibited minimum hydrocarbon and metallic contamination but, led to extensive contamination of the oxide layer with residuals and reaction products of acids used in BCP solution. HPR treatment, on the other hand was effective in reducing the acidic impurities on the top surface. The study also establishes the application of TOFSIMS technique to analyze and evolve SRF treatments.

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“…We used to believe that the thickness of the oxide layer was approximately 6 nm. However, the latest atomically resolved TEM cross-section images [10] show that the oxide layer is much thinner for BCP and buffered electropolishing [11] treated Nb samples. Most of the oxides in this top layer are Nb pentoxides that are dielectric and are generally believed to have no negative effects on the performance of Nb SRF cavities.…”

Section: Modifications Of Nb Surface Oxide Layer Structure By Gcibmentioning

confidence: 99%

Modification on surface oxide layer structure and surface morphology of niobium by gas cluster ion beam treatments

Swenson

Insepov

2010

Phys. Rev. ST Accel. Beams

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Recently, it was demonstrated that significant reductions in field emission on Nb surfaces could be achieved by means of a new surface treatment technique called gas cluster ion beam (GCIB). Further study as shown in this paper revealed that GCIB treatments could modify surface irregularities and remove surface asperities leading to a smoother surface finish as demonstrated through measurements using a 3D profilometer, an atomic force microscope, and a scanning electron microscope. These experimental observations were supported by computer simulation via atomistic molecular dynamics and a phenomenological surface dynamics. Measurements employing a secondary ion mass spectrometry found that GCIB could also alter Nb surface oxide layer structure. Possible implications of the experimental results on the performance of Nb superconducting radio frequency cavities treated by GCIB will be discussed. First experimental results on Nb single cell superconducting radio frequency cavities treated by GCIB will be reported.

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Smooth Nb surfaces fabricated by buffered electropolishing

Cited by 16 publications

References 7 publications

Buffered electropolishing parameters on niobium sheet

Buffered electropolishing parameters on niobium sheet

Study of impurity distribution in mechanically polished, chemically treated and high vacuum degassed pure niobium samples using the TOFSIMS technique

Modification on surface oxide layer structure and surface morphology of niobium by gas cluster ion beam treatments

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