Characterization of open resonator for 42 GHz, 200 kW gyrotron

A open resonator for a 42GHz, 200kW gyrotron for an Indian TOKAMAK system has been designed. The RF characterization of open ended tapered cylindrical resonator for a gyrotron is considered to see the performance of the resonator before the final assembly of the device. The experimental results for cold testing of first Indian gyrotron open resonator are present in this paper. The experiments were accomplished to measure resonant frequency and their particular quality factor for TE mode at the frequency 42GHz. The resonance frequency was deterined by trasmission technique and the loaded quality factor was comuted by half power bandwidth method at -3 dB point. TE modes were exited by means of an electric probe injecting power through a 1 -mm diametre hole located in the middil of the uniform section of the resonator. A pyramidal horn antenna which was connected to the vector network analyzer, was used as a reciving device to collect the RF power reradiated by the resonator. The resonance curve was directly collect from VNA display. On the behalf of the experiments, good agreement between experimental and theoretical results was found. The results were quite good and suitable for suppression the undesired modes in the specific gyrotron cavity.