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In the frame of a R\&D effort conducted by CEA toward the design and thequalification of a 5 GHz LHCD system for the ITER tokamak, two 5 GHz 500 kW/5 swindows have been designed, manufactured and tested at high power incollaboration with the National Fusion Research Institute (NFRI). The windowdesign rely on a symmetrical pill-box concept with a cylindrical berylliumoxide ceramic brazed on an actively water cooled copper skirt. The ceramic RFproperties have been measured on a test sample to get realistic values forguiding the design. Low power measurements of the manufactured windows showreturn losses below-32 dB and insertion losses between-0.01 dB and-0.05 dB,with an optimum frequency shifted toward lower frequencies. High power testsconducted at NFRI show unexpected total power loss for both windows. Theceramic temperature during RF pulses has been found to reach unexpected hightemperature, preventing these windows to be used under CW conditions. Apost-mortem RF analysis of samples taken from one window shows that thedielectric properties of the ceramic were not the ones measured on themanufacturer sample, which partly explain the differences with the referencemodelling.

Design and Tests of 500kW RF Windows for the ITER LHCD System