Validation and verification of helium collisional radiative codes on the Resonant Antenna Ion Device (RAID)

Optical emission spectroscopy (OES) is a non-invasive plasma diagnostic technique that relies on the plasma’s self-emission to determine key parameters such as electron density (ne) and electron temperature (Te). Collisional radiative (CR) codes are crucial for interpreting data from OES, they provide a detailed understanding of the complex interactions within plasma. This work focuses on verification of the CoRa-He CR model, developed at the Swiss Plasma Center for helium plasmas, and its validation with measurements obtained at the Resonant Antenna Ion Device (RAID). The model has been compared with the established Goto and CraC models across a broad range of plasma conditions, showing a relative difference in state populations below 50% for states with n <4. Additionally, experimental validation was achieved by performing OES measurements on RAID, and using ne and Te profiles obtained from Thomson scattering. The results show that CoRa-He can closely replicate observed emission line intensity ratios, especially when opacity effects are modeled with a single fitting parameter, achieving a relative difference below 60% in the central plasma region. While there is potential for further refinement, particularly in opacity modelling, the current implementation of CoRa-He demonstrates a significant step forward in developing flexible and reliable CR models for precise plasma diagnostics on the RAID device.