A diagnostics slim cassette for reflectometry measurements in DEMO: Design and simulation studies

Abstract

The reflectometry diagnostic proposed for DEMO aims to measure the radial edge density profile and to provide data for the feedback control of plasma position and shape. Microwave (MW) reflectometry measurements are foreseen at 16 poloidal locations (gaps) and require plasma-facing antennas and waveguides (WGs) to route the microwaves through the upper port (UP) to the diagnostic hall. The current integration proposal is based on the Diagnostics Slim Cassette (DSC) concept, a full, 25-cm thick poloidal sector dedicated to house the antennas and WGs. This paper translates the main findings from previous studies into an updated, coherent design of the DSC, while discussing integration aspects not considered before. Neutronics simulations, thermo-mechanical analyses and electromagnetic simulations are employed to evaluate the WG deformation under operating conditions and its effect on the reflectometry measurements. Although the estimated deformations are not expected to compromise the performance of the diagnostic, this work shows that the operating conditions must be considered when optimizing the shapes of the WGs to minimize losses.