Physics and material science of ultra-high quality factor superconducting resonator

Thesis/Dissertation · Sat Aug 01 00:00:00 EDT 2015

DOI:https://doi.org/10.2172/1221362· OSTI ID:1221362

Vostrikov, Alexander ^[1]

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1. Univ. of Chicago, IL (United States)

The nitrogen doping into niobium superconducting radio frequency cavity walls aiming to improve the fundamental mode quality factor is the subject of the research in the given work. Quantitative nitrogen diffusion into niobium model calculating the concentration profile was developed. The model estimations were confirmed with secondary ion mass spectrometry technique measurements. The model made controlled nitrogen doping recipe optimization possible. As a result the robust reproducible recipe for SRF cavity walls treatment with nitrogen doping was developed. The cavities produced with optimized recipe met LCLS–II requirements on quality factor of 2.7 ∙ 10¹⁰ at acceleration field of 16 MV/m. The microscopic effects of nitrogen doping on superconducting niobium properties were studied with low energy muon spin rotation technique and magnetometer measurements. No significant effect of nitrogen on the following features was found: electron mean free path, magnetic field penetration depth, and upper and surface critical magnetic fields. It was detected that for nitrogen doped niobium samples magnetic flux starts to penetrate inside the superconductor at lower external magnetic field value compared to the low temperature baked niobium ones. This explains lower quench field of SRF cavities treated with nitrogen. Quality factor improvement of fundamental mode forced to analyze the high order mode (HOM) impact on the particle beam dynamics. Both resonant and cumulative effects caused by monopole and dipole HOMs respectively are found to be negligible within the requirements for LCLS–II.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 1221362
• Report Number(s): FERMILAB-THESIS-2015-19; TRN: US1601314
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
NIOBIUM
NITROGEN
QUALITY FACTOR
CRITICAL FIELD
SUPERCONDUCTING CAVITY RESONATORS
MASS SPECTROSCOPY
RF SYSTEMS
ION MICROPROBE ANALYSIS
TEMPERATURE RANGE 0273-0400 K
ELECTRONS
MUON SPIN RELAXATION
COMPARATIVE EVALUATIONS
CONCENTRATION RATIO
DOPED MATERIALS
PARTICLE BEAMS
BEAM DYNAMICS
DIPOLES
MAGNETOMETERS
WALLS
MEAN FREE PATH
MAGNETIC FLUX
PENETRATION DEPTH
ABUNDANCE
DIFFUSION
OPTIMIZATION
SURFACES
MAGNETIC FIELDS
STANFORD LINEAR ACCELERATOR CENTER
LIGHT SOURCES