The physical modeling of diagnostic systems is essential for the development of synthetic diagnostics in magnetic confinement fusion research, particularly in guiding the design of diagnostics and performing error analysis. A polarimeter–interferometer (POINT) model based on a ray-tracing approach has recently been developed for the experimental advanced superconducting tokamak, enabling the calculation of both line-integrated electron density and Faraday rotation angle. The model demonstrates excellent agreement with experimental measurements and has been successfully benchmarked against the ITER toroidal interferometry and polarimetry model using the same input data. To address the challenges posed by future burning plasma devices, characterized by higher density, temperature, and magnetic field, the POINT model has been enhanced to incorporate finite-temperature (FT) and Cotton–Mouton effects. This upgraded model offers a reliable platform for diagnostic system design, including optimization of the probing wavelength and arrangement of lines of sight. As an application, preliminary design studies for China’s next-generation burning plasma device, burning experimental superconducting tokamak, have been carried out, supporting the selection of an optimal wavelength and the configuration of the POINT systems.
Diagnostics: Chapter 8 of the special issue: on the path to tokamak burning plasma operation