Parasitic-modes free, high-performance operation of the European 1 MW, 170 GHz Short-Pulse Prototype Gyrotron for ITER

The short-pulse (SP) prototype tube has been initially manufactured at KIT in 2015 to support the development of the European 1 MW, 170 GHz, CW gyrotron for ITER [1]. The SP gyrotron is in operation and used for testing and experimental validation of new gyrotron subcomponents for further improvements of the gyrotron performance. The very recent experiments were dedicated to the investigations of further enhancement of the gyrotron stability by the suppression of parasitic oscillations, observed during the previous gyrotron experimental campaigns. With recent modifications on the gyrotron setup, encouraging results have been achieved. In particular, for the first time a parasitic-modes free operation, in a very broad range of parameters, stable operation has been observed, leading to a significant improvement of the gyrotron overall performance. Achieved results will be presented in this paper.