Gyrotron development at Thomson-CSF†

Abstract Experience in the field of gyrotron tubes was acquired in our laboratory through the development of a very short pulse 250 kW 35 GHz tube. The development of a 200kW 100 GHz tube is now in progress with a first objective of 100 ms pulse duration, later extendible to CW operation. The diameters of the cathode and beam cannot be reduced proportionally to wavelength. The high cavity losses impose operation with higher order modes and pose a severe mode seperation problem, which we attempt to solve with a ‘complex’ cavity. We describe the preliminary study of thermal and mechanical problems in the output window, the collector and the cavity, on the basis of a plausible design with an efficiency of 30%.