RF surface resistance tuning of superconducting niobium via thermal diffusion of native oxide

Abstract

Recently, Nb superconducting radio frequency cavities vacuum heat treated between 300-400 C for a few hours have exhibited very high quality factors (~5x10^10 at 2.0 K). New secondary ion mass spectrometry measurements of O, N and C show this enhancement in RF surface conductivity is primarily associated with interstitial O alloying via dissolution and diffusion of the native oxide. We use a theory of oxide decomposition and O diffusion to quantify previously unknown parameters crucial in modeling this process. RF measurements of a vacuum heat treated Nb superconducting radio frequency cavity confirm the minimized surface resistance (higher Q0) previously expected only from 800 C diffusive alloying with N.

References in corpus (21)

• The Superconducting TESLA Cavities
• Nitrogen and argon doping of niobium for superconducting radio frequency cavities: a pathway to highly efficient accelerating structures
• Three-dimensional superconducting resonators at $T<20$ mK with the photon lifetime up to $\tau =2$ seconds
• Unprecedented Quality Factors at Accelerating Gradients up to 45 MV/m in Niobium Superconducting Resonators via Low Temperature Nitrogen Infusion
• Ultra-high quality factors in superconducting niobium cavities in ambient magnetic fields up to 190 mG
• Effect of high temperature heat treatments on the quality factor of a large-grain superconducting radio-frequency niobium cavity
• Surface impedance and optimum surface resistance of a superconductor with imperfect surface
• Ultra-Low Surface Resistance via Vacuum Heat Treatment of Superconducting Radiofrequency Cavities
• Effect of vortex hotspots on the radio-frequency surface resistance of superconductors
• Field-dependent nonlinear surface resistance and its optimization by surface nano-structuring in superconductors
• Effect of Impurities on the Superheating field of Type II superconductors
• Sensitivity of Niobium Superconducting Cavities to Trapped Magnetic Flux Dissipation
• Reply to "Comment on the 'Decrease of the surface resistance in superconducting niobium resonator cavities by the microwave field'"
• Effect of Low Temperature Baking in Nitrogen on the Performance of a Niobium Superconducting Radio Frequency Cavity
• Nitrogen-Doped 9-Cell Cavity Performance in a Test Cryomodule for LCLS-II
• The Importance of the Electron Mean Free Path for Superconducting RF Cavities
• Revealing the role of nitrogen on hydride nucleation and stability in pure niobium using first principles calculations
• High-Field Q-slope Mitigation due to Impurity Profile in Superconducting Radio-Frequency Cavities
• Fermilab experience of post-annealing losses in SRF niobium cavities due to furnace contamination and the ways to its mitigation: a pathway to processing simplification and quality factor improvement
• Advances in secondary ion mass spectroscopy
• Effects of Interstitial Oxygen and Carbon on Niobium Superconducting Cavities

Cited by in corpus (4)

• Oxygen Vacancies in Niobium Pentoxide as a Source of Two-Level System Losses in Superconducting Niobium
• Depth-resolved measurements of the Meissner screening profile in surface-treated Nb
• A New High Parallel-Field Spectrometer at TRIUMF's $\beta$-NMR Facility
• Depth-resolved measurement of the Meissner screening profile in a niobium thin film from spin-lattice relaxation of the implanted $\beta$-emitter ${}^8$Li