Krier L, Avramidis KA, Braune H, Gantenbein G, Illy S, Ioannidis Z, Jelonnek J, Laqua HP, Marsen S, Moseev D, et al. Frequency Stabilization of Megawatt-Class 140 GHz Gyrotrons at W7-X Using an Off-the-Shelf PLL System. In: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. Vol. 2021-August. ; 2021.