In this work, we describe validation efforts conducted for the stellarator Monte-Carlo neutral beam and fast ion code BEAMS3D. This code is used at Wendelstein 7-X to analyze fast ion physics and has numerous integrated interfaces facilitating a wide range of applications. We use experimental fast-ion Dα data from the ASDEX Upgrade tokamak, covering on- and off-axis neutral beam heating phases. We obtained synthetic Dα spectra using the FIDASIM code, leveraging a newly developed interface that allows a distribution function from BEAMS3D to be used. Comparing the simulated distributions from BEAMS3D and the well-established NUBEAM codes to the data shows that both codes reproduce the experiment equally well given the same initial conditions. The experimental FIDA spectra are quantitatively matched. The slowing down model of BEAMS3D is thus validated and can be applied to quantitative stellarator investigations in future studies.
This paper validates the BEAMS3D code, used to analyze fast-ion physics at Wendelstein 7-X, by comparing its simulations to experimental fast-ion D-alpha data from ASDEX Upgrade. The study shows that BEAMS3D and the well-established NUBEAM code both reproduce the experimental data equally well, validating the BEAMS3D slowing-down model for future stellarator investigations.