FEM analyses and prototype tests of the UPP structure for the ECRH in ITER

The ITER electron cyclotron upper port launching system has to provide local current drive in order to stabilize neoclassical tearing modes (NTMs) and the sawtooth instability. The mm-wave system is embedded in a rigid upper port plug structure optimized for the rough operating conditions. During regular operation the structure is heated by neutrons and photons which are simulated by the Monte-Carlo method. The structural system has to provide sufficient cooling especially in the front part where high heat loads occur. If the active plasma stabilization fails the worst case scenario for the upper port plugs is the upward vertical displacement event (VDE) followed by a fast current quench. The fast plasma disruption occurs close to the plugs; eddy currents are induced and interact with the strong static magnetic field. The resulting mechanical forces and torque moments stress the structural system to its physical limits; a detailed numerical analysis, prototype crosschecks and design optimization is required to obtain a working system for ITER. Numerical structural, thermal and fluid dynamic analyses are presented as well as prototype tests and finally the effect of plasma disruptions on the structural design is discussed.