## 2 Synthetic Diagnostics and Simulation Data
Fractional abundances are calculated with ionisation, recombination, and thermal charge exchange rate coefficients. The parameter grid and interpolation on the HDG values are rough, so oxygen concentration is employed only to show qualitative sensitivity of the method to the presence of light impurities. Four time moments, corresponding to the limiter, ramp-up, flat-top, and ramp-down stages with \(t=0.26\), 1, 4.48, and 7.52 s are chosen. The mentioned maps are interpolated by using built-in functions, and the 2D profiles on corresponding meshes are shown in Figures 2 and 3. Plasma is modeled as an axysimmetric volume emitter. OpenADAS [25] is used for atomic data. To calculate the bolometer signals, the TotalRadiatedPower model from Cherab is applied. It uses the ADF11 subpackage of ADAS, PLT files for line excitation radiation, and PRB for continuum and line recombination and bremsstrahlung power losses. Moreover, the bolometer, bolometer slit and foils classes from Cherab are employed to describe the system. The horizontal WEST tokamak bolometer system with two cameras, each with eight fan-spanned channels, which was operated in previous campaigns, is used in this article. Each of the two horizontal cameras contains of slits of dimension 9 \(\times\) 3.4 mm positioned at \(R=4.482\) m, \(Z=\pm\) 0.336 m, and toroidal angle \(\phi=84.88^{\circ}\). Ten centimeters behind the slit, eight bolometer foils of dimension 3.8 \(\times\) 1.3 mm are positioned vertically every 5 mm. The LOS are shown in Figure 1. The error, associated with the experimental data are in the range from 1 to a few %, linked to calibration procedures and subtraction of low-frequency integration drift [26]. Figure 2: Time evolution of electron \(T_{e}\) (**a–d**) and ion \(T_{i}\) (**e–h**) temperature isolines on snapshots for \(t=0.26\), 1, 4.48, 7.52 s. Separatrix is shown by the black solid line. The PinholeCamera Raysect class with 512 \(\times\) 512 pixels was used to introduce the availability and performance of the synthetic visible camera. It is positioned at equatorial plane \(R=3.085\) m, \(Z=-0.2\) m, \(\phi=-139.6^{\circ}\), and 20\({}^{\circ}\) from the Y-axis in the clockwise direction. The field of view was set to 45\({}^{\circ}\). For visible camera image generation WI 401.22 nm, deuterium Balmer series recombination and excitation lines, as well as bremsstrahlung are used. Simplified models of the WEST vessel and PPCs were obtained from the ToFu library [27]. As this vessel model lacks port descriptions, the walls were omitted, and only PPCs were taken into account while calculating the bolometer signal. To avoid double counting of the plasma signal for central channels (when a ray can pass through plasma twice due to the absence of the wall) an absorbing proxy cylinder was placed in the center of the scene. At this stage of the work, we assume all of the WEST components to be made of the same material. Where the material is not mentioned, an absorbing surface was used. This approach provides enough accuracy for the initial benchmark and does not require much effort. However, in the dedicated Section 3.2, we compare several methods of PFC description, which include the JET description for bulk tungsten and for PPCs, coated with tungsten [8] and a specular tungsten. These assumptions, probably being not exactly correct, still cover a significant range of possible optical properties and, therefore, they influence the diagnostics. Figure 3: Time evolution of isolines of logarithms of electron \(n_{e}\) (**a–d**), deuterium ions \(n_{D^{*}}\) (**e–h**), deuterium neutrals, \(n_{D^{0}}\) (**i–l**) and total tungsten \(\sum n_{W^{2,*}}\) (**m–p**) densities on snapshots for \(t=0.26\), 1, 4.48, 7.52 s. Separatrix is shown by the black solid line.