Engineering Design, Installation, and Conditioning of Ferritic Steel Plates/Wall for AMTEX in JFT-2M

The JFT-2M tokamak has been modified three times during the Advanced Material Tokamak EXperiment (AMTEX) program to investigate the compatibility of the low-activation ferritic steel F82H with tokamak plasmas as structural material for future reactors. The ferritic steel plates/wall were installed inside and/or outside of the vacuum vessel to reduce the ripple of the toroidal magnetic field step by step through three modifications. This paper focuses on engineering aspects of these modifications: electromagnetic analysis to find a suitable way to attach these plates, installation procedure to keep small tolerances, and a three-dimensional magnetic field measurement device used to obtain information of the actual shape of the vacuum vessel used as a standard installation surface. To maintain good surface conditions of the ferritic steel plates/wall that rust easily, careful treatment was executed before the installation. To reduce oxygen impurities further, a boronization system with trimethyl boron, which is safe and easy to operate, was developed.