A Study of the O4+ Emissivity Profiles with Two Separate Photon Emissivity Coefficient Databases and a Comparison of the Impurity Diffusion Coefficients in the Aditya Tokamak

The present study is an analysis between radial emissivity profiles of the 650.024 nm transition of the O4+ ion obtained using two separate Photon Emissivity Coefficient (PEC) databases. Emissivity values of the 650.024 nm O4+ transition in visible-spectral region have been experimentally obtained for the Aditya tokamak. The radial number density distributions of different charge states of oxygen are estimated using a semi-implicit numerical method applied over the radial impurity transport equation. The 650.024 nm emissivity is calculated using the obtained impurity number density and with PECs from two separate databases namely the ADAS (Atomic Data and Analysis Structure) and the NIFS (National Institute for Fusion Science) database. Although impurity diffusivity profiles must not be dependent upon the choice of PEC databases; yet a requirement of separate impurity (oxygen) diffusivity profiles for the two PEC databases is observed, such that their corresponding calculated O4+ emissivities best depict the experimental emissivity data. A difference in the ionization and recombination rate coefficients provided in the ADAS and NIFS databases can lead to discrepancies in the impurity number densities calculated. The effects upon the impurity diffusivity while using ionization and recombination rate coefficients from two separate databases are further studied.