It has been demonstrated recently that local magnetic field enhancement can originate from roughness (e.g. steps at grain boundaries) [1]. We are willing to investigate if the quench observed in superconducting niobium cavities can be related to such morphological defects. We therefore have to develop two kinds of tool.
1) A replica technique that allows to reproduce the internal surface of cavities (non destructive testing).
2) A morphological analysis tool. Classical roughness measurements are not adapted to determine local curvature radius.
This paper describes a new topological approach aiming at a better characterization of the surface morphology. This technique has been applied to niobium samples treated with different surface treatments. We also present the first results applied to replica taken from cavities at the quench site.
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