First operation of MACSE, the Saclay pilot superconducting electron linac

Aune, B.; Antoine, C.; Bonin, Bernard; Bosland, P.; Cavedon, J.M.; Chel, S.; Chianelli, C.; Curtoni, A.; Desmons, M.; Fagot, Joël; Gastebois, J.; Godin, Alfred J.; Gougnaud, Francoise; Gournay, J.F.; Gourcy, G.; Guemas, F.; Hanus, Xavier; Henriot, C.; Jablonka, J.; Joly, J.; Juillard, Michel; Klein, Eric E.; Koechlin, F.; Leconte, Pierre; Mosnier, A.; Ngoc, B. Phung; Promé, M.; Safa, H.; Tourrette, T.; Veyssière, A.; Bühler, Simon; Fouaidy, M.; Junquera, T.

doi:10.1109/pac.1991.164977

Cited by 2 publications

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“…The phenomenon of drastic drop of niobium superconducting radio frequency (SRF) cavities quality factor Q 0 at low accelerating fields below 2 MV=m without field emission or multipacting was encountered more than 20 years ago [1][2][3][4]. It was found that a fast cooldown (< 1 hour from room temperature to 4.2 K) could in some cases solve the problem.…”

Section: Introductionmentioning

confidence: 99%

Direct observation of hydrides formation in cavity-grade niobium

Barkov

Romanenko

Grassellino

2012

Phys. Rev. ST Accel. Beams

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Niobium is an important technological superconductor used to make radio frequency cavities for particle accelerators. Using laser confocal microscopy we have directly investigated hydride precipitates formation in cavity-grade niobium at 77 and 140 K. We have found that large hydrides were usually formed after chemical or mechanical treatments, which are known to lead to a strong degradation of the quality factor known as Q disease. From our experiments we can conclude that hydrides causing Q disease are islands with a characteristic thickness of * 100 nm and in-plane dimensions 1-10 m. Our results show that mechanical polishing uploads a lot of hydrogen into bulk niobium while electropolishing leads to a mild contamination. Vacuum treatments at 600-800 C are demonstrated to preclude large hydride formation in line with the absence of Q disease in similarly treated cavities.

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Section: Introductionmentioning

confidence: 99%

Direct observation of hydrides formation in cavity-grade niobium

Barkov

Romanenko

Grassellino

2012

Phys. Rev. ST Accel. Beams

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“…In this paper we propose that the high field Q-slope (HFQS) can be explained by the breakdown of the proximity effect acting on niobium hydrides in the near-surface layer. Furthermore, Q-degradation phenomenon due to large niobium hydrides (Q-disease) [2][3][4][5][6] can be quantitatively described by the same model. Niobium is a material which exhibits high affinity for hydrogen.…”

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Proximity breakdown of hydrides in superconducting niobium cavities

Romanenko¹,

Barkov²,

Cooley³

et al. 2013

Supercond. Sci. Technol.

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Many modern and proposed future particle accelerators rely on superconducting radio frequency cavities made of bulk niobium as primary particle accelerating structures. Such cavities suffer from the anomalous field dependence of their quality factors Q 0 . High field degradation -so-called 'high field Q-slope' -is yet unexplained even though an empirical cure is known. Here we propose a mechanism based on the presence of proximity-coupled niobium hydrides, which can explain this effect. Furthermore, the same mechanism can be present in any surface-sensitive experiments or superconducting devices involving niobium.PACS numbers: 74.25.nn, 74.45.+c, 81.65.-b, 85.25.-j arXiv:1212.3384v3 [cond-mat.supr-con]

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First operation of MACSE, the Saclay pilot superconducting electron linac

Cited by 2 publications

References 0 publications

Direct observation of hydrides formation in cavity-grade niobium

Direct observation of hydrides formation in cavity-grade niobium

Proximity breakdown of hydrides in superconducting niobium cavities

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