Development of Vertical Electropolishing Facility for Nb 9-Cell Cavity (3)

Ida, Yoshiaki; Akabori, Takao; Anetai, Yasunori; Chouhan, Vijay; Hayano, H.; Kato, Shigekí; Mitoya, Goh; Miyano, Kenichi; Monjushiro, Hideaki; Nii, Keisuke; Saeki, Takayuki; Sawabe, Motoaki; Takahashi, Fukumi

doi:10.18429/jacow-srf2019-tup028

Cited by 1 publication

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“…Buffered chemical polishing (BCP), which is especially efficacious for large-grain cavities [17][18][19], can also be beneficial for removal of the surface damage layer and surface contamination at much lower cost than EP. Several effective but complex EP facilities have been constructed and applied to cavity surface treatments worldwide [20][21][22][23][24][25][26] because it has been shown that EP can produce cavities with smoother surfaces than BCP, which generally results in better SRF performance. Nevertheless, compared with EP processing, BCP processing is usually quicker and less labor-intensive and requires fewer chemicals, making it more economical and efficient in mass production.…”

Section: Introductionmentioning

confidence: 99%

Surface resistance effects of medium temperature baking of buffered chemical polished 1.3 GHz nine-cell large-grain cavities

Yang¹,

Hao²,

Quan³

et al. 2022

Supercond. Sci. Technol.

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Three 1.3 GHz 9-cell large grain superconducting niobium cavities were experimented with the proposal of medium temperature baking, using buffered chemical polishing to remove the previous heat treatment impurity profiles. 2 K vertical tests of the cavities gave the average intrinsic quality factor of 2.7×1010 at 16 MV/m, as well as the maximum accelerating gradients of 20-22 MV/m. These promising values confirmed the effectiveness of an improved medium temperature baking recipe for niobium cavities which have been benefitting the superconducting radiofrequency community. Furthermore, the resistance analysis demonstrated that medium temperature baking reduced both the BCS resistance and the residual resistance of the cavities. Impurity analysis on niobium samples provided some proof that the former reduction was due to the shortened electron mean free path, while the later reduction was probably correlated with the mitigation of the increased interstitial impurity atoms.

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