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Merabet, H.; Bailey, Martin J.; Bruch, R.; Hanni, J.; Bliman, S.; Fursa, Dmitry V.; Bray, Igor; Bartschat, Klaus; Tseng, H. C.; Lin, C. D.

doi:10.1103/physreva.64.012712

“…As in table 1, we display only those electron energies, for which there are data obtained using different methods. Such are the theoretical results from [6,21], the experimental data from [21,22,23], and the recommended values (RV) from [24]. One can see from table 3 that our results are closer to those from [10] than to other theoretical data.…”

Section: Excitation Of Helium Atomsupporting

confidence: 72%

Methods, algorithms, and computer codes for calculation of electron-impact excitation parameters

Bogdanovich¹,

Kisielius²,

Stonys³

2014

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We describe the computer codes, developed at Vilnius University, for the calculation of electron-impact excitation cross sections, collision strengths, and excitation rates in the plane-wave Born approximation. These codes utilize the multireference atomic wavefunctions which are also adopted to calculate radiative transition parameters of complex many-electron ions. This leads to consistent data sets suitable in plasma modelling codes. Two versions of electron scattering codes are considered in the present work, both of them employing configuration interaction method for inclusion of correlation effects and Breit-Pauli approximation to account for relativistic effects. These versions difer only by one-electron radial orbitals, where the first one employs the nonrelativistic numerical radial orbitals, while the other version uses the quasirelativistic radial orbitals. The accuracy of produced results is assessed by comparing radiative transition and electron-impact excitation data for neutral hydrogen, helium, and lithium atoms as well as highly charged tungsten ions with theoretical and experimental data available from other sources.

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“…As in Table 1, we display only those electron energies for which there are data obtained using different methods. Such are the theoretical results from [6,21], the experimental data from [21][22][23], and the recommended values (RV) from [24]. One can see from Table 3 that our results are closer to those from [10] than to other theoretical data.…”

Section: Excitation Of Helium Atomsupporting

confidence: 71%

Methods, algorithms, and computer codes for calculation of electron-impact excitation parameters

Bogdanovich¹,

Kisielius²,

Stonys³

2014

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We describe the computer codes, developed at Vilnius University, for the calculation of electron-impact excitation cross sections, collision strengths, and excitation rates in the plane-wave Born approximation. These codes utilize the multireference atomic wavefunctions which are also adopted to calculate radiative transition parameters of complex many-electron ions. This leads to consistent data sets suitable in plasma modelling codes. Two versions of electron scattering codes are considered in the present work, both of them employing configuration interaction method for inclusion of correlation effects and Breit-Pauli approximation to account for relativistic effects. These versions difer only by one-electron radial orbitals, where the first one employs the nonrelativistic numerical radial orbitals, while the other version uses the quasirelativistic radial orbitals. The accuracy of produced results is assessed by comparing radiative transition and electron-impact excitation data for neutral hydrogen, helium, and lithium atoms as well as highly charged tungsten ions with theoretical and experimental data available from other sources.

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“…In this section, HeII (2p) 2 P o polarization measurements and their corresponding sublevel cross sections for e-+ He and H + + He collision systems following ionization-excitation are compared with our recent 23-state R-matrix and/or 1 st and 2 nd Born calculations [22][23] including spatial and temporal electron-electron correlation. In addition, HeI (1s2p) 1 P o cross sections are judged against the convergent close coupling 20,24 (CCC) and the Rmatrix technique with pseudostates 20,24 (RMPS) for electrons, and atomic-orbital close coupling 20,24 (AOCC) procedure together with first-Born 20,24 results for protons.…”

Section: Introductionmentioning

confidence: 99%

Polarization measurements of the extreme ultraviolet (EUV) emission following excitation and ionization-excitation of helium by fast electron, proton, and molecular hydrogen (H 2 + and H 3 +) impact

Merabet¹,

Bruch²,

Fuelling³

et al. 2002

SPIE Proceedings

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We report intensive experimental and theoretical data corresponding to helium extreme ultraviolet (EUV) emission in the 30-60 nm wavelengths range for e -+ He, H + + He, and H n + + He (n=2-3) collisions with impact velocities from 1.4 to 8.5 a.u. Specifically, the degree of linear polarization associated with HeI (1snp) 1 P o levels, n=2-5, (λ=51.7 to 58.4 nm for n=2-5 to n=1 transitions) and HeII (2p) 2 P o states (λ=30.4 nm) have been measured at intermediate-to high-energy range using a compact lightweight molybdenum/silicon multilayer mirror polarimeter (MLM). The combination of these polarization measurements with our previous total EUV cross sections has enabled us to determine experimental magnetic substate scattering angleintegrated cross sections, 0 σ and 1 σ for M L = 0, ±1, following excitation of He (1s 2 ) 1 S to HeI (1s2p) 1 P o levels and ionizationexcitation to He + (2p) 2 P o for electron and proton impact at a wide range velocities. The degree of linear polarization and obtained magnetic sublevel cross sections are compared to earlier theoretical calculations together with our recent 23-state RMatrix, 1 st and 2 nd Born calculations. Such a detailed comparison may shed more light on the collision processes involved in positively and negatively single-charge particle impact in helium. In particular it shows that electron-electron interactions play an important role in the ionization-excitation mechanism. In addition, this comprehensive database will possibly provide a deeper understanding of electron and proton induced jets in solar flare astrophysical investigations.

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Cross sections and collision dynamics of the excitation of(1snp)1P

Cited by 16 publications

References 37 publications

Methods, algorithms, and computer codes for calculation of electron-impact excitation parameters

Methods, algorithms, and computer codes for calculation of electron-impact excitation parameters

Methods, algorithms, and computer codes for calculation of electron-impact excitation parameters

Polarization measurements of the extreme ultraviolet (EUV) emission following excitation and ionization-excitation of helium by fast electron, proton, and molecular hydrogen (H 2 + and H 3 +) impact

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