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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 16: Poster

AKBP 16.11: Poster

Thursday, March 23, 2023, 15:45–18:30, HSZ OG3

Investigations of two-dimensional laser polishing of niobium surfaces as a manufacturing process during the production of superconducting cavity resonators — •Florian Brockner and Dirk Lützenkirchen-Hecht — University of Wuppertal, Gauss-Str. 20, 42119 Wuppertal, Germany

Laser polishing (LP) has the potential to increase the electrical field gradients accessible in superconducting RF-cavities made of niobium, by substantially suppressing electron field emission. Thus extensive measurements were performed investigating which effects a planar LP has on the morphology and the microstructure of a niobium surface. Here we will report on a new experimental setup that allows LP under high vacuum conditions, with the capability to in-situ detect effects of the LP by measuring pressure changes, emitted electrical charges and the incident and reflected laser intensities, respectively. The change in surface properties as a result of the LP was subsequently investigated using SEM/EDX, optical profilometry and electron field emission measurements. The results show that moderate laser energies allow a cleaning of the Nb surfaces. Furthermore, local defects can be efficiently removed by LP. In addition, there is no direct relation between surface roughness and the onset fields for parasitic field emission after LP. Moreover, the orientation of individual grains within a large grain Nb sample seem to have a strong influence on the efficiency of the LP processes. This work was supported by the BMBF under grants no. 05H18PXRB1 and 05H21PXRB1.