Recommended Cross Section Data for Carbon Ions and Atoms: Electron-impact Excitation, Ionization and Charge Exchange

Suno, Hiroya; Katō, Takako

doi:10.1088/1742-6596/72/1/012018

Cited by 3 publications

(3 citation statements)

References 19 publications

(14 reference statements)

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“…In contrast to protons, which may originate in both SW and PW, the C II ion is only of planetary origin (the stellar wind carbon is too highly ionized) 32,97 , and connects directly with the bulk composition of the exoplanet. In contrast to H I, H II and OI that are very sensitive to charge-exchange between them and with other species, C II is not sensitive to charge exchange with other species 98,99 . In addition, electron-impact ionization and recombination are very slow in the energy regime of a few electron-volts of the low energy population considered in the magnetotail region 99 , thus keeping the average global C II abundance unaffected by the magnetospheric processes, unless the particles are picked up by the stellar wind (for example, outside the cusps regions).…”

Section: Exploration Of Modelling Resultsmentioning

confidence: 82%

“…In contrast to H I, H II and OI that are very sensitive to charge-exchange between them and with other species, C II is not sensitive to charge exchange with other species 98,99 . In addition, electron-impact ionization and recombination are very slow in the energy regime of a few electron-volts of the low energy population considered in the magnetotail region 99 , thus keeping the average global C II abundance unaffected by the magnetospheric processes, unless the particles are picked up by the stellar wind (for example, outside the cusps regions). Note that C II dominates the C population because C I is quickly photo-ionized.…”

Section: Exploration Of Modelling Resultsmentioning

confidence: 82%

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Signatures of strong magnetization and a metal-poor atmosphere for a Neptune-sized exoplanet

et al. 2021

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Section: Exploration Of Modelling Resultsmentioning

confidence: 82%

Section: Exploration Of Modelling Resultsmentioning

confidence: 82%

Signatures of strong magnetization and a metal-poor atmosphere for a Neptune-sized exoplanet

et al. 2021

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“…Calculations of ionisation cross-sections were made with FAC, whilst bearing in mind the known shortcomings of the DW approximation for near-neutral charge-states. The main experiment used for comparison has been Brook et al (1978), which Bell et al (1983) and Suno & Kato (2007) use for their recommended data.…”

Section: Direct Ionisationmentioning

confidence: 99%

Modelling ion populations in astrophysical plasmas: carbon in the solar transition region

Dufresne

Zanna

2019

A&A

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The aim of this work is to improve the modelling of ion populations in higher density, lower temperature astrophysical plasmas, of the type commonly found in lower solar and stellar atmospheres. Ion population models for these regions frequently employ the coronal approximation, which assumes conditions more suitable to the upper solar atmosphere, where high temperatures and lower densities prevail. These assumptions include all ion charge-states being in the ground state, and steady-state equilibrium where there is sufficient time for ionisation and recombination to take place. Using the coronal approximation for modelling the solar transition region gives theoretical lines intensities for the Li-like and Na-like isoelectronic sequences which can be factors of 2-5 times lower than observed. The works of Burgess & Summers (1969) and Nussbaumer & Storey (1975) showed the important part ions in excited levels play when included in the modelling. As density increases metastable levels become populated and ionisation rates increase, whereas dielectronic recombination through the highly-excited levels becomes suppressed. Photo-ionisation was also shown by Nussbaumer & Storey to have an effect on the charge-state distribution of carbon in these regions. Their models, however, used approximations for the atomic rates to determine the ion balance. Presented here is the first stage in updating these earlier models of carbon by using rates from up-to-date atomic calculations and more recent photo-ionising radiances for the quiet Sun. Where such atomic rates are not readily available, in the case of electron-impact direct ionisation and excitation-auto-ionisation, new calculations have been made using the Flexible Atomic Code and Autostructure, and compared to theoretical and experimental studies. The effects each atomic process has on the ion populations as density changes is demonstrated, and final results from the modelling are compared to the earlier works. Lastly, the new results for ion populations are used to predict line intensities for the solar transition region in the quiet Sun, and these are compared with predictions from coronal-approximation modelling and with observations. Significant improvements in the predicted line intensities are seen in comparison to those obtained from zero-density modelling of carbon.

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Effect of helium incorporation on plasma parameters and characteristic properties of hydrogen free carbon films deposited using DC magnetron sputtering

Sahu

Kim

Lee

et al. 2020

Journal of Applied Physics

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The present work investigates the effects of helium (He) gas mixing with Ar on plasma parameters and examines its effect on film properties of C films. We used a closed-field unbalanced magnetron sputtering system for the deposition of C thin films at a direct current power density of 30 W/cm2 and an operating pressure of ≈3 mTorr. On the basis of systematic analysis, we present an attempt to enhance the electron temperature and investigate the high-energy electron tail, which is required for the efficient ionization in the plasmas, by incorporating He gas in the Ar background. This approach also promotes the plasma density to become high, which is more than two times at a mixing ratio of 80%. Moreover, the present study utilizes these plasma conditions to prepare hydrogen-free highly conductive nanostructured carbon films. Systematic plasma diagnostic and film analysis reveal that a high content of He incorporation is accountable for the fabrication of a highly conductive nanocrystalline carbon film in a high-density plasma environment.

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Recommended Cross Section Data for Carbon Ions and Atoms: Electron-impact Excitation, Ionization and Charge Exchange

Cited by 3 publications

References 19 publications

Signatures of strong magnetization and a metal-poor atmosphere for a Neptune-sized exoplanet

Signatures of strong magnetization and a metal-poor atmosphere for a Neptune-sized exoplanet

Modelling ion populations in astrophysical plasmas: carbon in the solar transition region

Effect of helium incorporation on plasma parameters and characteristic properties of hydrogen free carbon films deposited using DC magnetron sputtering

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