Electromagnetic energy and plasmas: super power klystrons for fusion plasma heating

AbstractFor fusion plasma heating, two types of 2 GHz 1 MW klystrons were developed. They were 6-cavity, frequency-tunable klystrons which could deliver 1 MW continuous output power for 10 s duration. Each klystron has a similar electron gun with a modulation anode, and an evaporation-cooled collector.A prototype klystron was tested for 1 MW performance successfully and a two-window version was also manufactured in order to reduce the thermal stress of the window material. A high-power magic tee was used in order to combine the two power outputs and to produce more than the 1 MW power output. The window temperature was observed to rise, with light emission. The measured temperature rise was about 16°C at the end of 10 s duration, when the klystron was operated at the power level of 500 kW per window.An external digital computer was used to control the high-speed tuning mechanism several times during every one pulse operation.