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The ITER Electron Cyclotron Heating Upper Launcher (ECHUL) will be used to drive current locally inside magnetic islands located at the q = 2 (or smaller) rational surfaces in order to stabilize neoclassical tearing modes (NTMs). Each of the fours antennas consists of eight beam lines, totaling 12.8 m that are designed for the transmission of up to 1.5 MW of mm-wave power at 170 GHz, with at least 90% of the power in the main HE11 mode. Each transmission line consists of a Z shaped set of straight corrugated, aluminum alloy waveguides connected by miter bends with a nominal inner diameter of 50 mm. The FCS system also encompasses intrinsic components such as: closure plate, mm-waveguide taper, isolation valve, diamond window and an EU-US interface waveguide. All FCS components are connected via a dedicated flange coupling, with a bolted connection, comprising of two concentric metallic seals in order to satisfy the SIC-1 requirements. The coupling shall be capable of resisting the applied external loads and displacements, including thermal cycles due to ohmic losses in the transmission line, and also adhere to the matting of different materials (EN AW-6082, CuCrZr, SS 316L) while maintaining ultra-high vacuum tightness (10 −8 mbar). The present study will use a dedicated experimental apparatus for the characterization of the mechanical and vacuum properties of a single metallic seal under compression, with applied heat flow. In order to ensure reproducibility of the components mechanical characteristics, randomly chosen metallic seals of each diameter have been tested from two independent manufactures (A and B).

Condensed moisture from ingressed humid air was responsible for inducing corrosion within the aft radar antenna from an RAAF P-3C Orion maritime surveillance aircraft. Porosity in the silver-plating of a flexible brass waveguide allowed moisture to penetrate to the brass substrate and cause dezincification. The moisture also induced corrosion of some of the AA-6061 aluminium alloy waveguides. An investigation determined that moisture ingress occurred at a waveguide flange, possibly from the failure of a seal.