Critical Fields of Nb${}_3$Sn Prepared for Superconducting Cavities

Abstract

Nb${}_3$Sn is currently the most promising material other than niobium for future superconducting radiofrequency cavities. Critical fields above 120 mT in pulsed operation and about 80 mT in CW have been achieved in cavity tests. This is large compared to the lower critical field as derived from the London penetration depth, extracted from low field surface impedance measurements. In this paper direct measurements of the London penetration depth from which the lower critical field and the superheating field are derived are presented. The field of first vortex penetration is measured under DC and RF fields. The combined results confirm that Nb${}_3$Sn cavities are indeed operated in a metastable state above the lower critical field but are currently limited to a critical field well below the superheating field.

References in corpus (6)

• musrfit: A free platform-independent framework for muSR data analysis
• Superheating field of superconductors within Ginzburg-Landau theory
• Observation of non-exponential magnetic penetration profiles in the Meissner state - A manifestation of non-local effects in superconductors
• Performance-defining properties of Nb${}_3$Sn coating in SRF cavities
• Field of first flux entry and pinning strength of superconductors for RF application measured with muon spin rotation
• Extension of the Measurement Capabilities of the Quadrupole Resonator

Cited by in corpus (11)

• Advances in Nb3Sn superconducting radiofrequency cavities towards first practical accelerator applications
• Superfluid flow in disordered superconductors with Dynes pair-breaking scattering: depairing current, kinetic inductance, and superheating field
• Superheating fields of semi-infinite superconductors and layered superconductors in the diffusive limit: structural optimization based on the microscopic theory
• Effects of nonmagnetic impurities and subgap states on the kinetic inductance, complex conductivity, quality factor and depairing current density
• Microwave measurements of the high magnetic field vortex motion pinning parameters in Nb${}_3$Sn
• Tuning microwave losses in superconducting resonators
• Evidence for current suppression in superconductor-superconductor bilayers
• Measurements of the first-flux-penetration field in surface-treated and coated Nb: Distinguishing between surface pinning and an interface energy barrier
• A Field-Enhanced Conduction-Cooled Superconducting Cavity for High-Repetition-Rate Ultrafast Electron Bunch Generation
• Niobium's intrinsic coherence length and penetration depth revisited using low-energy muon spin spectroscopy and secondary-ion mass spectrometry
• Significant improvement of the lower critical field in Y doped Nb: potential replacement of basic material for the radio-frequency superconducting cavity