Hydrogenic species transport model for ceramic alumina used in ITER ICRH H&CD & Diagnostics Systems

A transport model for deuterium and tritium in Al2O3 under Ion Cyclotron Radiation Heating (ICRH) Vacuum Window (VW) operational conditions is presented. The aim is to provide a broad evaluation of permeation fluxes and soluted/trapped inventories in this material. A phenomenological release-rate transport model is formulated. The operational physical scenarios of the alumina VW in the ICRH line, in particular ionising doses and local electric fields, are analysed with special attention paid to the system design assumptions defining neutrals and implanted H-isotopes source terms in the VW. Available transport data for alumina is discussed and taken as a reference base for a parametric exercise. Results show significantly high values of D/T concentrations, both trapped and mobile, in the VW material. For the VW lifetimes, the fluxes across the VW, are seen to be clearly below established ITER Design Requirement Guidelines.