• G. Devanz, D. Braud, P. Carbonnier, J.-P. Charrier, S. Chel, M. Desmons, A. Hamdi, H. Jenhani, D. Roudier, P. Sahuquet
  CEA, Gif-sur-Yvette

Coaxial power couplers capable of handling 1MW peak power have been developped for high intensity superconducting proton linacs. They have been conditioned in travelling wave up to the maximum power available on the Saclay test bench, 1.2 MW forward peak power, up to 10% duty cycle. One coupler has been assembled on a 5-cell medium beta cavity in the class 10 area of the clean room, and installed in our horizontal test cryostat CryHoLab. This paper focusses on the RF operation of the coupler in this cryogenic environment and thermal aspects.