Open AccessNitrogen infusion R&D at DESY a case study on cavity cut-outs
Author(s) -
Marc Wenskat,
Christopher Bate,
Arti Dangwal Pandey,
Arno Jeromin,
Thomas F. Keller,
Jens Knobloch,
Julia Köszegi,
Felix Krämer,
Oliver Kugeler,
S. Kulkarni,
D. Reschke,
J. Schaffran,
Guilherme Dalla Lana Semione,
Sven Sievers,
Lea Steder,
Andreas Stierle,
Nicholas Walker
Publication year - 2020
Publication title -
superconductor science and technology/superconductor science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.033
H-Index - 105
eISSN - 1361-6668
pISSN - 0953-2048
DOI - 10.1088/1361-6668/abb58c
Subject(s) - desy , materials science , niobium , carbide , nitrogen , analytical chemistry (journal) , nitride , niobium carbide , thermal conductivity , composite material , metallurgy , optics , chemistry , physics , organic chemistry , chromatography , layer (electronics)
A first series of nitrogen infusion runs of 1.3 GHz single-cell cavities at DESY resulted in an unexpected and severe deterioration observed during the vertical cold test. To investigate the origin of the deterioration, one of the cavities underwent extensive radio-frequency measurements and a temperature- and magnetic field-mapping was performed in collaboration with the Helmholtz-Zentrum Berlin. After combining all results, regions of interests were identified and cut-out of the cavity. Subsequent surface analysis techniques (EBSD, PALS, PIXE, SEM/EDX, SIMS, XPS) were applied in order to identify the microscopic origin of the deterioration and especially the differences between hot and cold spots as well as quench spots. An excess of niobium carbides, reducing the thermal conductivity, was identified as the probable cause for the deterioration, and the size- and density-distributions were observed to be crucial for the resulting performance reduction. The origin for the local differences in the niobium carbide formation between hot and cold spots is an effect of preexisting variations of the crystal structure.