Prototype design of the ITER ICRF vacuum transmission line dielectric window

The dielectric window is an essential and critical component of the ICRF VTL, as it provides primary vacuum and Tritium containment. Although several models of dielectric window have been developed and are currently in use, the severe ITER reliability requirements call for special design and prototyping also to allow a realistic evaluation of the failure modes and rates. An earlier design of the (double) dielectric window of the ITER ICRF transmission line has indicated a best strength and compatibility for the alumina (97.5%) (for weak radiation) and beryllia (<10-3 dpa) ceramics together with both titanium and niobium conductors. Vacuum brazing has been chosen for joining the ceramics to the conductor. In the present work, the material and dielectric shape definition with respect to nuclear, mechanical, and thermal properties in due consideration of material availability, fabrication issues and response to cyclic loads is completed and summarized. Solutions for the cooling and remote handling arrangements are presented. (author)