This study presents a spectroscopic investigation of Kr^24+ ion, generated via a krypton impurity seeding experiment in the Large Helical Device, aimed at supporting Extreme Ultraviolet (EUV) diagnostics of high-temperature fusion plasma. EUV spectral lines corresponding to fine-structure transitions among the 2p^6 3s^2, \, 2p^6 3s3p, \, 2p^6 3s3d, and 2p^6 3p^2 configurations were observed in the 12–25 nm wavelength range. To systematically analyze the measured emission lines, extensive relativistic atomic structure calculations were carried out over a broad configuration space, spanning more than 40 configurations, including core-excited and correlation-dominated states up to n 7 and 4. Bound-state wave functions were obtained using the relativistic many-body perturbation theory and configuration interaction method, implemented via the Flexible Atomic Code. Parallel calculations based on the relativistic multiconfiguration Dirac-Hartree-Fock method with configuration interaction were performed using the GRASP-2018 code to ensure numerical consistency. This article presents fine-structure-resolved excitation energies and transition parameters, including oscillator strengths and transition probabilities, for the relevant spectroscopic configurations up to 3. Moreover, electron impact excitation and ionization cross-sections from the ground state (2p^6 3s^2 \, ^1 S₀) as well as from selected excited states to higher-lying levels were calculated using the relativistic distorted wave method from the respective thresholds over a wide energy range. The corresponding Maxwellian averaged rate coefficients for excitation, de-excitation, ionization, and three-body recombination were evaluated over fusion-relevant electron temperatures. The results are presented for the prominent spectroscopic transitions up to 3. These complete atomic and electron-collision datasets were incorporated into a suitable collisional-radiative model, accounting for the dominant population and depopulation processes, including electron impact excitation, de-excitation, ionization, radiative decay, and three-body recombination. The theoretically modeled EUV spectrum, calculated at n_ e =5. 5 10^ 19 \, m^ -3 and T_ e =578 \, eV, shows good agreement with experimental observations, validating the accuracy of the calculated atomic structure, and electron-collision parameters. The resulting atomic dataset and modeling framework enable detailed spectral analysis of highly charged Kr^24+ ion under magnetically confined fusion plasma conditions.
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