Statistical model for field emitter activation on metallic surfaces used in high-gradient accelerating structures

Lagotzky, Stefan; Müller, Günter

doi:10.1016/j.nima.2015.10.003

Cited by 3 publications

(1 citation statement)

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“…In particular, local surface defects with jagged geometries like holes, pits, bumps, scratches etc. as well as foreign particles exhibit a reduced field emission threshold and lead to a break-down of superconductivity [14,15]. The conventional approach to prepare an accelerator cavity involves numerous process steps, e.g.…”

Section: Introductionmentioning

confidence: 99%

Laser-processing of grinded and mechanically abraded Nb-surfaces

Porshyn

Rothweiler

Lützenkirchen‐Hecht

2020

Journal of Laser Applications

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The effect of pulsed laser polishing on rough niobium surfaces was investigated. We created different well-defined roughness profiles with standard emery papers and subsequently remelted random surface areas with a size of about 2 x 2 mm 2 with ns-laser pulses (wavelength 1064 nm, pulse length 10 ns). Pristine as well as laser-treated surfaces were investigated using optical profilometry and atomic force microscopy, and the surface topography was described by means of correlation functions. Uniformly rough and highly smooth surface geometries were achieved for fractals above and below 7 µm, respectively. Moreover, the behavior of foreign particles during the laser-processing was investigated in detail. The polishing procedure was also monitored point by point by detecting electrical signals, i.e. sample charging, which resulted from the intense laser illumination. The measured electrical charges were found to be correlated with the local surface texture. Thus, regions with initially high roughness profiles and regions with extensive laser-induced defects could be directly identified from the detected electrical signals.

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Section: Introductionmentioning

confidence: 99%