Mechanical design aspects of a "Long-Waveguide" version of the remote steering ECRH upper port launcher for ITER

The current status of the mechanical design of the remote steering electron cyclotron resonance heating upper port launching system for ITER is presented. Although an alternative front steering launcher has now been selected as the reference design for ITER, the development of a remote steering launcher continues so that it can be used as a backup solution and as a candidate for DEMO. Since earlier proposals of a remote steering launcher could not fulfill the design criteria with respect to physics performance and because a number of engineering issues remained that have proven to be very difficult to solve, a change was applied to its layout. By increasing the length of the square waveguides that form the heart of the remote steering design, the layout of the optics could be further optimized so that the performance could be improved, while a number of engineering issues could be solved. This paper provides a brief description of the previous design followed by the modifications taken in the optical design to improve the physics performance by reducing the beam size at the resonance location. A first indication is given that the expected reduction of beam size at the resonance location is more than 30%, relative to earlier designs.