The ECRH-Power Upgrade at the Wendelstein 7-X Stellarator

¹ Max-Planck-Institute for Plasma Physics, Greifswald, D-17491, Germany
² IHM, Karlsruhe Institute of Technology (KIT), Karlsruhe, D-76131, Germany
³ IGVP, Stuttgart University, D-70569 Stuttgart, Germany
⁴ Microwave & Imaging Sub-Systems, THALES, Vélizy-Villacoublay, F-78141, France
⁵ Department of Physics National and Kapodistrian University, Athens, GR-15784, Greece

⁶ The W7-X team is the list of authors in Thomas Sunn Pedersen et al 2022 Nucl. Fusion 62 042022

Published online: 23 February 2023

Abstract

The existing ECRH system at W7-X consists of 10 gyrotrons, with output power levels ranging from 0.6 MW up to 1.0 MW each at a frequency of 140 GHz, quasi-optical transmission lines and microwave launchers at the plasma vessel. Compared to other large fusion experiments, W7-X has a relatively low power-to-volume ratio. However high heating power is particularly necessary for achieving high plasma beta values, where the improved confinement of fast ions, one of the optimization criteria of W7-X, can be examined. It is therefore necessary to expand the ECRH systems in several consecutive steps. It is planned to increase the number of gyrotron positions from 10 to 12 and at the same time to evolve the gyrotron output power in several development steps from 1 MW to nominal 1.5 MW and, finally, up to 2 MW. At the same time, the transmission lines will also be upgraded for 2 MW operation. A special effort is also made to improve the reliability of the system by the fast control system.