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High field Q slope and the baking effect: Review of recent experimental results and new data on Nb heat treatments

Journal Article · · Physical Review Special Topics. Accelerators and Beams
 [1];  [2];  [2];  [2]
  1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  2. North Carolina State Univ., Raleigh, NC (United States)
+ Show Author Affiliations
Here, the performance of superconducting radio-frequency (SRF) cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing rf losses (high-field Q-slope), in the absence of field emission, which are often mitigated by low temperature (100-140 °C, 12-48 h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated in a vacuum furnace at high temperature without subsequent chemical etching. These studies are aimed at understanding the role of hydrogen on the high-field Q-slope and at the passivation of the Nb surface during heat treatment. Improvement of the cavity performances, particularly of the cavities’ quality factor, have been obtained following the high temperature heat-treatments, while SIMS surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.
Research Organization:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
Grant/Contract Number:
AC05-06OR23177
OSTI ID:
1021722
Alternate ID(s):
OSTI ID: 979572
Report Number(s):
DOE/OR/23177--1255; JLAB-ACC--10-1204
Journal Information:
Physical Review Special Topics. Accelerators and Beams, Journal Name: Physical Review Special Topics. Accelerators and Beams Journal Issue: 02 Vol. 13; ISSN 1098-4402
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Cited By (16)

Influence of material parameters on the performance of niobium-based superconducting radiofrequency cavities journal July 2019
Vacancy-Hydrogen Interaction in Niobium during Low-Temperature Baking journal May 2020
Modeling the nanoscale linear response of superconducting thin films measured by a scanning probe microwave microscope journal May 2014
Near-field microwave magnetic nanoscopy of superconducting radio frequency cavity materials journal June 2014
Efficient expulsion of magnetic flux in superconducting radiofrequency cavities for high Q 0 applications journal June 2016
Electrostatic tuning of mechanical and microwave resonances in 3D superconducting radio frequency cavities journal November 2018
Flux pinning characteristics in cylindrical niobium samples used for superconducting radio frequency cavity fabrication journal April 2012
Theory of RF superconductivity for resonant cavities journal January 2017
Surface processing for bulk niobium superconducting radio frequency cavities journal February 2017
Unprecedented quality factors at accelerating gradients up to 45 MVm −1 in niobium superconducting resonators via low temperature nitrogen infusion journal August 2017
Effect of low temperature baking in nitrogen on the performance of a niobium superconducting radio frequency cavity journal March 2018
Nanoscale nonlinear radio frequency properties of bulk Nb: Origins of extrinsic nonlinear effects journal October 2015
Vacancy-Hydrogen Interaction in Niobium during Low-Temperature Baking text January 2020
Near-Field Microwave Magnetic Nanoscopy of Superconducting Radio Frequency Cavity Materials text January 2013
Modeling the nanoscale linear response of superconducting thin films measured by a scanning probe microwave microscope text January 2014
Nanoscale Nonlinear Radio Frequency Properties of Bulk Nb : Origins of Extrinsic Nonlinear Effects text January 2015

Figures / Tables (34)

FIG. 1(p. 2)figure FIG. 1
FIG. 2(p. 3)figure FIG. 2
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FIG. 12(p. 11)figure FIG. 12
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TABLE III(p. 14)table TABLE III
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FIG. 22(p. 18)figure FIG. 22
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Related Subjects

08 HYDROGEN
36 MATERIALS SCIENCE
BAKING
CAVITIES
ETCHING
FIELD EMISSION
HEAT TREATMENTS
HYDROGEN
MAGNETIC FIELDS
PASSIVATION
PERFORMANCE
QUALITY FACTOR
VACUUM FURNACES