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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 12: AKBP Poster Session

AKBP 12.5: Poster

Thursday, March 21, 2024, 11:00–14:00, Poster A

Investigation of laser macro- and micropolishing on fine-grained niobium for use in Superconducting radio frequency cavities — •Florian Brockner¹, Laura Kreinest², Patrick Schwoche¹, and Dirk Lützenkirchen-Hecht¹ — ¹Bergische Universität Wuppertal — ²Fraunhofer-Institut für Lasertechnik ILT

We carried out a feasibility study on laser macro and micro polishing of polycrystalline fine-grained planar niobium sheets, which fulfil the specification for a use in SRF cavities. Due to the high initial roughness of the untreated, non-polished sheets, macropolishing was first carried out under an inert Ar-gas atmosphere using a diode-pumped fiber laser, and the laser polishing parameters (laser power, feed rate, beam diameter, number of cycles) were systematically varied. The optimal parameters are adjusted and selected after analysing the surface using white light interferometry. The test areas prepared in this way (approx. (5x5)mm²) were then subjected to micropolishing by varying the average laser power and pulse duration of the ns laser used. The prepared surfaces were characterised using optical profilometry, electron microscopy, energy dispersive X-ray spectroscopy and measurements of the parasitic field emission.

Keywords: laser polishing; niobium; surface structure; field emission