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TY - CONF AU - Dhakal, P. ED - Michel, Peter ED - Arnold, André ED - Schaa, Volker RW TI - Recent Development on Nitrogen Infusion Work Towards High Q and High Gradient J2 - Proc. of SRF2019, Dresden, Germany, 30 June-05 July 2019 CY - Dresden, Germany T2 - International Conference on RF Superconductivity T3 - 19 LA - english AB - A quality factor as high as 2 × 10¹⁰ at 1.5 GHz was achieved at a gradient of 35 MV/m by 800 °C annealing and N-infusion at 140 °C. A comparison of the field dependence of the surface resistance after N-infusion with a recent theoretical model that extends the calculation of the BCS surface resistance to high rf fields suggests an increase in the quasiparticles’ relaxation time with increasing infusion temperature, which could be due to a decreasing density of subgap states. Nb coupons treated similarly showed the formation of thicker oxynitride layer on the surface beneath thin dielectric Nb₂O₅ layer. A plausible explanation for the improved Q₀ is that the oxynitride layer on the Nb surface adds additional electron scattering within RF penetration depth. PB - JACoW Publishing CP - Geneva, Switzerland SP - 355 EP - 359 KW - cavity KW - SRF KW - niobium KW - injection KW - radio-frequency DA - 2019/08 PY - 2019 SN - 978-3-95450-211-0 DO - doi:10.18429/JACoW-SRF2019-TUFUA5 UR - http://jacow.org/srf2019/papers/tufua5.pdf ER -