Electron-impact single ionisation of W${}^{q+}$ ions: Experiment and theory for $11\le \mathbf{q}\le 18$

Abstract

Absolute cross sections for electron-impact single ionisation (EISI) of multiply charged tungsten ions (W${}^{q+}$) with charge states in the range $11\le q\le 18$ in the electron-ion collision energy ranges from below the respective ionisation thresholds up to 1000~eV were measured employing the electron-ion crossed-beams method. In order to extend the results to higher energies, cross section calculations were performed using the subconfiguration-averaged distorted-wave (SCADW) method for electron-ion collision energies up to 150~keV. From the combined experimental and scaled theoretical cross sections rate coefficients were derived which are compared with the ones contained in the ADAS database and which are based on the configuration-averaged distorted wave (CADW) calculations of Loch et al. [Phys. Rev. A 72, 052716 (2005)]. Significant discrepancies were found at the temperatures where the ions investigated here are expected to form in collisionally ionised plasmas. These discrepancies are attributed to the limitations of the CADW approach and also the more detailed SCADW treatment which do not allow for a sufficiently accurate description of the EISI cross sections particularly at the ionisation thresholds.

arXiv comment14 pages, 4 figures, 4 tabels

References in corpus (7)

• Dielectronic recombination of xenonlike tungsten ions
• Recombination of W18+ ions with electrons: Absolute rate coefficients from a storage-ring experiment and from theoretical calculations
• Dielectronic recombination of lanthanide and low ionization state tungsten ions: W${}^{13+}$ - W${}^{1+}$
• Recombination of open-f-shell tungsten ions
• Photoionization of the valence shells of the neutral tungsten atom
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Cited by in corpus (3)

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• Hybrid subconfiguration-average and level-to-level distorted-wave treatment of electron-impact single ionisation of W${}^{15+}$ and W${}^{16+}$
• Commissioning of a fast fine-step electron-energy-scan system for electron-ion crossed-beams experiments