TY  - CONF
AU  - Reece, C.E.
AU  - Angle, J.W.
AU  - Kelley, M.J.
AU  - Lechner, E.M.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - SIMS Characterization of Nitrogen Doping of LCLS-II-HE Production Cavities
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - The thermal diffusion of nitrogen into the surface of niobium has been shown to yield superior low-loss SRF performance. An effective solution was identified and promptly employed in the production of cryomodules for LCLS-II. With added experience and R&D, a modified process was chosen for use in the upgrade for LCLS-II-HE. Largely motivated by this circumstance, supporting research has significantly refined the technique for making calibrated secondary ion mass spectrometry (SIMS) measurements of the N concentration depth profiles produced by production processes. Standardized reference samples were included with four HE production cavities in their N-doping furnace runs. We report the calibrated dynamic SIMS depth profiles of N, C, and O for these samples, together with the cryogenic acceptance test performance of the associated cavities. Interpretation and comparison with similar samples acquired in other furnaces highlights the importance of intentional process quality control of furnace conditions.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 67
EP  - 69
KW  - cavity
KW  - SRF
KW  - niobium
KW  - vacuum
KW  - controls
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB006
UR  - https://jacow.org/srf2023/papers/mopmb006.pdf
ER  - 

TY  - CONF
AU  - Lechner, E.M.
AU  - Angle, J.W.
AU  - Baxley, C.G.
AU  - Kelley, M.J.
AU  - Reece, C.E.
ED  - Saito, Kenji
ED  - Xu, Ting
ED  - Sakamoto, Naruhiko
ED  - Schaa, Volker R.W.
ED  - Thomas, Paul W.
TI  - Topographic Evolution of Nitrogen Doped Nb Subjected to Electropolishing
J2  - Proc. of SRF2023, Grand Rapids, MI, USA, 25-30 June 2023
CY  - Grand Rapids, MI, USA
T2  - International Conference on RF Superconductivity
T3  - 21
LA  - english
AB  - Surface quality is paramount in facilitating high perfor-mance SRF cavity operation. Here, we investigate the topographic evolution of samples subjected to N-doping and 600 °C vacuum anneal. We show that in N-doped Nb, niobium nitrides may grow continuously along grain boundaries. Upon electropolishing high slope angle grooves are revealed which sets up a condition that may facilitate a supression of the superheating field.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 207
EP  - 210
KW  - SRF
KW  - cavity
KW  - niobium
KW  - vacuum
KW  - ECR
DA  - 2023/09
PY  - 2023
SN  - 2673-5504
SN  - 978-3-95450-234-9
DO  - doi:10.18429/JACoW-SRF2023-MOPMB044
UR  - https://jacow.org/srf2023/papers/mopmb044.pdf
ER  -