The SwissFEL C-band Linac will have 26 RF modules, each one consisting of a solid-state modulator and a 50 MW klystron that feeds a pulse compressor and four two meters long accelerating structures. The pulse compressor is of the Barrel Open Cavity type (BOC). A first prototype was successfully produced and high-power tested, reaching for full power klystron operation a peak power of 300 MW. For testing this BOC at maximum RF power, a broadband load was designed and built, based on a ridge waveguide design and high permeability stainless steel. Based on the experience gained at CERN for CLIC X-band high power loads, the RF design of the load was optimized to ensure high losses for a quite large range of magnetic steels. Test pieces were realized in three different magnetic steels to choose the best suited material commercially available.
This paper reports about the RF design, material study, production and impressive high power results of this C-band load.