Yamamoto, Y. Irikura, M. Ishibashi, M. Kako, E. Matsumoto, T. Michizono, S. Yamamoto, A. Yasutake, H. JACoW Geneva, Switzerland 978-3-95450-191-5 10.18429/JACoW-SRF2017-MOPB063 English 194-198 MOPB063 ion vacuum FEL cavity SRF Contribution to a conference proceedings 2018 2018-01 https://doi.org/10.18429/JACoW-SRF2017-MOPB063 http://jacow.org/srf2017/papers/mopb063.pdf From the view point of mass-production for the power coupler in ILC, the fundamental studies for the STF-type power coupler are under progress by the collaboration between KEK and TETD. At present, there are various rinsing procedures for power coupler in the world-wide laboratories. In this R&D, the main topic is to investigate the various rinsing effects in the copper plating and the ceramic through the high power test. In this paper, the first results will be presented.