Design and validation of a 700 kW/CW water load for 3.7 GHz klystrons

To develop Continuous Wave (CW) high power klystrons for fusion experiments, calorimetric matched loads absorbing the RF power are necessary. To test and adjust the parameters of the new klystrons TH2103C [1] able to produce 700 kW/CW at a frequency of 3.7 GHz for upgrading the RF power available in Tore Supra LHCD transmitter, SPINNER GmbH has successfully developed, in collaboration with the CEA, and manufactured a water load capable to absorb the RF power with a Voltage Standing Wave Ratio (VSWR) < 1.05. Crucial part of the water load is the ceramic window cooled with demineralised water to absorb the RF power. Klystrons working at different frequencies like 4.6 GHz and 5 GHz are being developed for CW experiments. The water load could be adapted for these frequencies. The paper describes the specifications, the development and the high RF power tests to validate the dummy load.