Mechanical design and analysis of JT-60U ICRF launcher

An upgrading of the ICRF (ion cyclotron range of frequencies) heating system for JT-60 (JAERI Tokamak-60) was performed during the modification of the JT-60 tokamak, which, after the upgrade, allowed 6 MA of plasma current and 100 m/sup 3/ of plasma volume. In the upgrade, the old ICRF launcher was replaced by two new ones in order to inject more power ( approximately 4.5 MW). The new launcher has severe design conditions of high heat flux from the plasma (max. 0.4 MW/m/sup 2/) and large electromagnetic force induced by plasma disruption (6 MA/5 ms). The total torque acting on the launcher by the electromagnetic force is about 35 t-m. Structural analysis was carried out to evaluate the integrity of the launcher, particularly of the feedthrough and the Faraday shield, under these severe conditions. The launchers are now being installed on the horizontal ports of the JT-60U vacuum vessel, which are movable by 40 mm in a radial direction. >