Advanced Experimental Investigations on Cooling Concepts of Cavities for Megawatt-Class CW Gyrotrons

• Published in: 2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) pp. 1 - 2
• Main Authors: Stanculovic, S., Avramidis, K., Difonzo, R., Gajetti, E., Gantenbein, G., Illy, S., Jelonnek, J., Leggieri, A., Ruess, T., Rzesnicki, T., Savoldi, L.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 17-09-2023
• Subjects: cavity cooling; Cooling; gyrotron; Gyrotrons; mini-channel cooling; Nickel; nuclear fusion; Numerical models; Raschig-ring cooling; Thermocouples; Three-dimensional printing; Uncertainty
• ISSN: 2162-2035
• DOI: 10.1109/IRMMW-THz57677.2023.10299069

The ongoing research and development of high-power fusion gyrotrons demands for an effective cavity cooling system for optimum gyrotron operation. Since the last decade, fundamental experimental research of advanced cooling techniques using mini-channels for high-power gyrotron cavities is carried out at KIT. In this work, the latest improvements in the test set-up for the thermal-hydraulic investigation of a cavity cooling is described. In order to increase the overall accuracy in the experiments and to eliminate potential uncertainties a set of improvements of the test set-up are considered: a new flowmeter with flow rates that range up to 12 l/min and with improved measurements accuracy; faster thermocouples, with reaction times \lt 0.1\mathrm{s}. Additionally, following modifications are introduced: a coating of the inner surface of the copper cavity with a Nickel layer of 100 \mu \mathrm{m} thickness in order to increase the heat load using induction heating; 3D printing Additive Manufacturing (AM) of the mock-up in order to directly compare the cooling performances and to validate the 3D printing AM technique for this application; (3) installation and test of a new mock-up with mini-channels and with Raschig rings for a direct comparison between the two cooling techniques. The obtained experimental results provide input to validate numerical models used for the cavity cooling optimization.