Design and construction of a 1-MW, 352-MHz RF test load

A 1-MW, 352-MHz RF load was built at Argonne National Laboratory for performance testing the klystrons used as final amplifiers at the Advanced Photon Source (APS). The load utilizes four CERN-type 300-kilowatt coaxial water loads which are fed from a single WR2300 waveguide using a four-way power splitter consisting of a WR2300 hybrid-T junction and two WR2300 waveguide-to-dual-6-1/8" coaxial transitions. The load system is cooled using deionized water at a nominal flow rate of 160 GPM. The entire load system is mounted on a wheeled carriage which allows for rapid relocation to specific areas of the APS klystron gallery. The metering and interlock system will be described. The load has logged approximately 250 hours of use and has demonstrated accuracy in flow and temperature measurement sufficient to allow calorimetric RF power measurement