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Title: SRF niobium characterization using SIMS and FIB-TEM

Our understanding of superconducting radio frequency (SRF) accelerator cavities has been improved by elemental analysis at high depth resolution and by high magnification microscopy. This paper summarizes the technique development and the results obtained on poly-crystalline, large grain, and single crystal SRF niobium. Focused ion beam made possible sample preparation using transmission electron microscopy and the images obtained showed a very uniform oxide layer for all samples analyzed. Secondary ion mass spectrometry indicated the presence of a high concentration of hydrogen and the hydrogen content exhibited a relationship with improvement in performance. Depth profiles of carbon, nitrogen, and oxygen did not show major differences with heat treatment. Niobium oxide less than 10 nm thick was shown to be an effective hydrogen barrier. Niobium with titanium contamination showed unexpected performance improvement.
Authors:
 [1]
  1. Analytical Instrumentation Facility, North Carolina State University, 2410 Campus Shore Dr., Raleigh, NC 27695, US (United States)
Publication Date:
OSTI Identifier:
22492688
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1687; Journal Issue: 1; Conference: Ingot niobium summary workshop, Newport News, VA (United States), 4 Dec 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACCELERATORS; CARBON; CAVITIES; CONCENTRATION RATIO; HEAT TREATMENTS; HYDROGEN; IMAGES; ION BEAMS; ION MICROPROBE ANALYSIS; MASS SPECTROSCOPY; MONOCRYSTALS; NIOBIUM; NIOBIUM OXIDES; NITROGEN; OXYGEN; RADIOWAVE RADIATION; SAMPLE PREPARATION; SUPERCONDUCTING CAVITY RESONATORS; TITANIUM; TRANSMISSION ELECTRON MICROSCOPY