Mechanical analyses of the ITER electron cyclotron upper launcher first confinement system

Abstract

The Electron Cyclotron Upper Launcher is an eight beamline ITER antenna whose main goal is to drive current locally, inside magnetic islands that may form on the q=3/2 or 2 rational magnetic flux surfaces, in order to stabilize neoclassical tearing modes (NTMs). The primary vacuum boundary at the port plug extends into the port cell region through the ex-vessel mm-wave waveguide components, defining the so-called First Confinement System (FCS). Thermal expansion, seismic events and plasma disruption events result in displacements of the vacuum vessel, relative to the tokamak building, that are transferred to the FCS at its interfaces with the port plug. In absence of suitable inline waveguide bellows, the adaptation to such imposed displacements is provided by bending compliance of the straight waveguide sections. An analysis methodology for the ex-vessel components was developed which covers a preliminary set of applicable load combinations throughout the system life-cycle. This methodology describes the FCS numerical model developed to assess the system against independent events as well as the load combination strategy followed to combine the results. Some simplifications like the simulation of the Vertical Displacement Events (VDEs) by a static approach are considered in order to develop this methodology. The analysis of the results shows that the miter bends and the pieces of waveguides rigidly attached to the port cell ceiling are the most demanded components for most of the considered load combinations.