Testing the high power gyrotrons for fusion ECRH at KIT FULGOR – recent activities

KIT FULGOR test facility (Fusion Long Pulse Gyrotron Laboratory) is dedicated to the operation and test of high power Continuous Wave (CW) gyrotrons for Electron Cyclotron Resonance Heating and Current Drive (ECRH&CD) of future nuclear fusion power plants applications. In the first experiments, the commissioning of the FULGOR laboratory has been successfully performed using the 140 GHz 1.5 MW CW W-7X gyrotron and the first microwave at FULGOR was confirmed. Recently, the 105 GHz 1MW CEA WEST gyrotron is installed in FULGOR and stable gyrotron operation in the MW range has been demonstrated. During these tests the microwave power up to 1.2 MW has been measured in short pulse operation regime, up to 3 ms, with efficiencies close to 35 % and above 45 %, respectively during non-depressed and depressed collector operation. In addition, the characterization of the RF beam free-space fundamental Gaussian beam content in short pulse operation has been realized. Preparations of the FULGOR test stand for first long-pulse operation, including the installation of components such as arc detectors, absorbers, mirrors and cooling elements, as well as the implementation of the long pulse relevant sub-systems: magnetic field sweeping systems in the collector sector and the mode-loss fast interlock, are in the final stage. ... mehrA description of the measurements installed and the results performed demonstrating the long pulse operation test capability in FULGOR will be detailed.
As a next activity in FULGOR laboratory the first tests of the gyrotron with a Multi-stage-Depressed-Collector (MDC) at KIT are planned and this experimental campaign will be briefly presented. Furthermore, a 10.5 T superconducting cryogen-free magnet with a bore hole of 400 mm, which has been specified to satisfy the requirements for testing of future fusion gyrotrons at FULGOR, is already ordered and will be delivered to KIT in 2024.