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TY - CONF AU - Grewe, R. AU - Alff, L. AU - Arnold, M. AU - Conrad, J. AU - Flege, S. AU - Hug, F. AU - Major, M. AU - Pietralla, N. ED - Michel, Peter ED - Arnold, André ED - Schaa, Volker RW TI - Superconducting RF Cavity Materials Research at the S-DALINAC 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 - Current state-of-the-art superconducting rf (srf) accelerators are mostly using cavities made of high RRR bulk niobium (Nb). The maximum field gradients and quality factors (Q₀) of these cavities are basically reached now. To further increase the srf cavity properties for future accelerator facilities, research of new materials for srf cavity applications is necessary. The current research at the S-DALINAC* is focused on the development of bake-out procedures of Nb samples and cavities in nitrogen (N) atmosphere of up to 100 mbar to nucleate the delta-phase (d-phase) of the Nb-N binary system. The d-phase has superconducting properties which exceed the properties of bulk Nb. This makes the d-phase attractive for srf applications. The vertical test cryostat (vt) at the S-DALINAC has been upgraded and recommissioned to allow investigations of the quality factor and accelerating field gradients of cavities before and after bake-out. The vt upgrade includes a newly developed variable input coupling to allow matching of the external q-factor (Qex) to Q₀. The results of the ongoing research of the nitrogen atmosphere bake-out procedures and the upgrade of the vt will be presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 74 EP - 76 KW - cavity KW - niobium KW - linac KW - SRF KW - simulation DA - 2019/08 PY - 2019 SN - "" SN - 978-3-95450-211-0 DO - doi:10.18429/JACoW-SRF2019-MOP022 UR - http://jacow.org/srf2019/papers/mop022.pdf ER -