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TY - CONF AU - Warren, M. AU - Denchfield, A.R. AU - Gai, W. AU - Samuelson, N. AU - Shao, J.H. AU - Spentzouris, L.K. AU - Wisniewski, E.E. AU - Yusof, Z.M. AU - Zasadzinski, J. ED - Schaa, Volker RW ED - He, Yuan ED - Li, Lu ED - Zhao, Ning TI - Development of Hybrid Superconducting Photocathodes on Niobium Using High QE Coatings J2 - Proc. of SRF2017, Lanzhou, China, July 17-21, 2017 C1 - Lanzhou, China T2 - International Conference on RF Superconductivity T3 - 18 LA - english AB - High power, low emittance electron beams require superconducting RF photoinjectors, typically made of pure Nb, and a superconducting photocathode is desired. However, superconductivity and high photocathode quantum efficiency (QE) are not compatible, e.g. QE for pure Nb is only 10⁻⁵ at 260 nm wavelength. Here is presented the current status of the development of hybrid superconducting photocathodes by the deposition of thin films of a high QE metal or semiconductor on Nb. Nb plugs coated with 10-100 nm of Mg have been tested for adhesion and dark current under RF fields as high as 60MV/m. QE measurements show significant enhancements over Nb. In another test, ultra thin films of the high QE material Cs2Te deposited on Nb are reported. Using the standard deposition procedure, QE ~12% is found for films ~ 200Å. As the thickness is reduced QE maintains a high value ~ 6% for films as thin as 2.0 nm. These results are quite promising for future superconducting photocathodes. PB - JACoW CP - Geneva, Switzerland SP - 205 EP - 209 KW - ion KW - cathode KW - electron KW - site KW - SRF DA - 2018/01 PY - 2018 SN - 978-3-95450-191-5 DO - 10.18429/JACoW-SRF2017-MOPB065 UR - http://jacow.org/srf2017/papers/mopb065.pdf ER -