2014/10/29 by A. Romanenko, A. Grassellino, A. C. Crawford +2 · 3 citations
Engineering · Physics and Astronomy · #Electromagnetic shielding #Magnetic field #Magnetic flux #Niobium #Niobium-tin #Particle Accelerators and Free-Electron Lasers #Particle accelerators and beam dynamics #Penetration depth #Quality (philosophy) #Superconducting Materials and Applications #Superconducting magnet #Superconducting magnetic energy storage #Superconductivity #physics.acc-ph
paper · pdf · doi:10.1063/1.4903808
arxiv created 2014/10/29 · openalex publication_date 2014/12/08 · arxiv updated 2015/06/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Ambient magnetic field, if trapped in the penetration depth, leads to the residual resistance and therefore sets the limit for the achievable quality factors in superconducting niobium resonators for particle accelerators. Here, we show that a complete expulsion of the magnetic flux can be performed and leads to: (1) record quality factors Q > 2 × 1011 up to accelerating gradient of 22 MV/m; (2) Q ∼ 3 × 1010 at 2 K and 16 MV/m in up to 190 mG magnetic fields. This is achieved by large thermal gradients at the normal/superconducting phase front during the cooldown. Our findings open up a way to ultra-high quality factors at low temperatures and show an alternative to the sophisticated magnetic shielding implemented in modern superconducting accelerators.