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arXiv · 2603.02612

Relativistic calculations of electron impact excitation cross-sections of neutral tungsten

Ritu Dey·Ayushi Agarwal·Reetesh Kumar Gangwar·Deepti Sharma·M. B. Chowdhuri·Rajesh Srivastava·Joydeep Ghosh
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Abstract

Reliable tungsten spectroscopy is essential for modelling and diagnosing tungsten-containing plasmas, particularly in edge/divertor conditions where neutral tungsten (WI) is produced by sputtering and contributes to visible/near-UV emission. In this work, we present fine-structure-resolved EIE cross sections for W I computed using the relativistic distorted-wave (RDW) method. Target states are described by multi-configurational Dirac-Fock (MCDF)wave functions with an extensive configuration-interaction (CI) expansion including valence-valence and core-valence correlation through hole and deeper-core configurations. The resulting energies are bench marked against available theoretical results and the recommended values from the NIST database. Fine-structure-resolved cross sections are reported for excitations from the ground level 5d4 6s2 (5 D0) and six metastable levels 5d4 6s2 (5D1 , 5D2 , 5D3, 5D4 , 3P0) and 5d5 (6S)6s (7S3 ) into excited levels belonging primarily to the 5d4 6s(6 D)6p and 5d5 (6S)6p configurations, over incident electron energies from threshold to 500 eV. With the exception of a limited set of previously studied transitions, most of the reported fine-structure-resolved cross sections are presented here for the first time. The results show a strong dependence on the initial level and indicate that excitation from the metastable state yields the largest cross sections among the states considered, highlighting the importance of metastable populations in W I modelling. In addition, radiative transition probabilities for selected prominent transitions are calculated and compared with existing data. The present dataset is expected to be valuable for collisional-radiative modelling and spectroscopic diagnostics of tungsten plasmas in the 1-50 eV range.

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Ritu Dey, Ayushi Agarwal, Reetesh Kumar Gangwar, Deepti Sharma, M. B. Chowdhuri, Rajesh Srivastava, Joydeep Ghosh. 2026-03-03. Relativistic calculations of electron impact excitation cross-sections of neutral tungsten. https://arxiv.org/abs/2603.02612

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