Unprecedented quality factors at accelerating gradients up to 45 MVm ⁻¹ in niobium superconducting resonators via low temperature nitrogen infusion

Journal Article · Mon Aug 14 00:00:00 EDT 2017 · Superconductor Science and Technology

DOI:https://doi.org/10.1088/1361-6668/aa7afe· OSTI ID:1437715

Grassellino, A.; Romanenko, A.; Trenikhina, Y.; Checchin, M.; Martinello, M.; Melnychuk, O. S.; Chandrasekaran, S.; Sergatskov, D. A.; Posen, S.; Crawford, A. C.; Aderhold, S.; Bice, D.

Here, we report the finding of new surface treatments that permit to manipulate the niobium resonator nitrogen content in the first few nanometers in a controlled way, and the resonator fundamental Mattis-Bardeen surface resistance and residual resistance accordingly. In particular, we find surface infusion conditions that systematically a) increase the quality factor of these 1.3 GHz superconducting radio frequency (SRF) bulk niobium resonators, up to very high gradients; b) increase the achievable accelerating gradient of the cavity compared to its own baseline with state-of-the-art surface processing. Cavities subject to the new surface process have larger than two times the state of the art Q at 2K for accelerating fields > 35 MV/m. Moreover, very high accelerating gradients ~ 45 MV/m are repeatedly reached, which correspond to peak magnetic surface fields of 190 mT, among the highest measured for bulk niobium cavities. These findings open the opportunity to tailor the surface impurity content distribution to maximize performance in Q and gradients, and have therefore very important implications on future performance and cost of SRF based accelerators. They also help deepen the understanding of the physics of the RF niobium cavity surface.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: Early Career Award "Impurity D; GARD Program; AC02-07CH11359
• OSTI ID: 1437715
• Alternate ID(s): OSTI ID: 1407126
• Report Number(s): arXiv:1701.06077; FERMILAB-PUB-17-458-TD
• Journal Information: Superconductor Science and Technology, Journal Name: Superconductor Science and Technology Vol. 30 Journal Issue: 9; ISSN 0953-2048
• Publisher: IOP Publishing
• Country of Publication: United Kingdom
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
SRF
nitrogen doping
nitrogen infusion
high Q
high accelerating gradient
radio frequency surface resistance