Conceptual design of cooling systems for the launcher and receiver mirrors of the ITER LFS-CTS diagnostic

A conceptual design of a cooling system for the launcher and receiver mirrors of ITER Low Field Side (LFS) Collective Thomson Scattering (CTS) diagnostic is presented. It is motivated by the fact that these mirrors are subjected to high thermal loads, e.g., neutron fluxes, that lead to maximum temperatures above the required maximum operational temperature of 450 °C for the material (SS 316L(N)-IG). Thus, it is necessary to develop a cooling system capable of maintaining the maximum temperatures of the mirrors below 450 °C, while complying with the CTS and nuclear fusion requirements. Computer Aided Design (CAD) and Finite Element (FE) models of the mirrors with different cooling channel geometries are developed. Steady state and transient thermal Finite Element Analyses (FEA) considering different mass flow rates are conducted for the assessment of the feasible solutions. The results obtained are conclusive, i.e., the cooling requirements are verified and with one of the proposed configurations it is possible to decrease the maximum temperatures of the SS 316L(N)-IG launcher and receiver mirrors from 2307 °C and 1064 °C to 381 °C and 147 °C, respectively, which, corresponds to a maximum temperature decrease of 83% and 86%, respectively. In future works, fatigue and creep analyses shall be implemented for stress and deformation assessment of the mirrors and respective reflective surfaces.