Relativistic atomic structure and electron impact excitation calculations for K-like Kr17+ and Xe35+: A detailed study for fusion plasma relevance

We present a detailed investigation of the atomic structure and electron-impact excitation properties of K-like Kr${}^{17+}$ and Xe${}^{35+}$ ions, focusing on the fine-structure states arising from the configurations $3s^{2}3p^{6}3d$, $3s^{2}3p^{5}3d^2$, $3s3p^{6}3d^2$, and $3s^{2}3p^{4}3d^3$. Calculations are performed using the fully relativistic multiconfiguration Dirac-Hartree–Fock (MCDHF) method, as implemented in the GRASP2018 code, with inclusion of the Breit interaction and quantum electrodynamic corrections. We report energy levels for the lowest 90 states and provide transition data for E1, M1, E2, and M2 transitions among these levels. The impact of virtual orbital choices on the generated wavefunctions is analyzed. To assess the reliability of our results, we estimate uncertainties in line strengths from the MCDHF calculations. Additionally, we perform independent calculations using many-body perturbation theory (MBPT) within the Flexible Atomic Code to validate our findings. The close agreement between MCDHF and MBPT results supports the robustness of our predictions. Furthermore, electron-impact excitation cross sections are calculated using relativistic distorted wave theory for transitions originating from the ground and first excited levels, spanning incident electron energies up to 5 keV for Kr${}^{17+}$ and 10 keV for Xe${}^{35+}$. The corresponding rate coefficients are derived for Maxwellian electron energy distributions over electron temperature ranges of 15–150 eV for Kr${}^{17+}$ and 25–200 eV for Xe${}^{35+}$. We also provide fitting parameters for these rate coefficients to facilitate their use in plasma modeling. The present data set addresses the lack of atomic data for highly charged K-like Kr${}^{17+}$ and Xe${}^{35+}$ and offers reliable benchmarks for theoretical and diagnostic applications in plasma physics.