Electron-impact cross sections for dipole- and spin-allowed excitations of hydrogen, helium, and lithium

Stone, Philip M.; Kim, Yong Sik; Desclaux, J. P.

doi:10.6028/jres.107.026

Cited by 47 publications

(70 citation statements)

References 17 publications

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“…For excitation of hydrogen and neutral helium we use the fitting functions given by Stone, Kim and Desclaux [64]. For kinetic energies well above threshold, the cross sections have the form, σ eH,eHe = 4a 2 0 R E kin + E bin + E exc (A ln(E kin /R) + B + CR/E kin ) .…”

Section: Ionization Excitation and Collisional Heatingmentioning

confidence: 99%

CMB constraints on WIMP annihilation: Energy absorption during the recombination epoch

2009

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We compute in detail the rate at which energy injected by dark matter annihilation heats and ionizes the photon-baryon plasma at z ∼ 1000, and provide accurate fitting functions over the relevant redshift range for a broad array of annihilation channels and DM masses. The resulting perturbations to the ionization history can be constrained by measurements of the CMB temperature and polarization angular power spectra. We show that models which fit recently measured excesses in 10-1000 GeV electron and positron cosmic rays are already close to the 95% confidence limits from WMAP. The recently launched Planck satellite will be capable of ruling out a wide range of DM explanations for these excesses. In models of dark matter with Sommerfeld-enhanced annihilation, where σv rises with decreasing WIMP velocity until some saturation point, the WMAP5 constraints imply that the enhancement must be close to saturation in the neighborhood of the Earth.PACS numbers: 95.35.+d,98.80.Es

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Section: Ionization Excitation and Collisional Heatingmentioning

confidence: 99%

CMB constraints on WIMP annihilation: Energy absorption during the recombination epoch

2009

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“…Electron impact cross sections for He were obtained by Jackman et al (), electron‐H cross sections for electron energies below 3 keV were taken from Olivero et al () and from Stone and Kim () for energies higher than 3 keV. Total ionization cross sections for electron impact with atomic H were fitted to data from Shah et al ().…”

Section: Physical Processes and Model Descriptionmentioning

confidence: 99%

Jovian Auroral Ion Precipitation: Field‐Aligned Currents and Ultraviolet Emissions

et al. 2018

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A model is described for the transport of magnetospheric oxygen ions with low charge state and energies up to several MeV/nucleon (MeV/u) as they precipitate into Jupiter's polar atmosphere. A revised and updated hybrid Monte Carlo model originally developed by Ozak et al. (2010, https://doi.org/10.1029/2010JA015635) is used to model the Jovian X‐ray aurora. The current model uses a wide range of incident oxygen ion energies (10 keV/u to 5 MeV/u) and the most up‐to‐date collision cross sections. In addition, the effects of the secondary electrons generated from the heavy ion precipitation are included using a two‐stream transport model that computes the secondary electron fluxes and their escape from the atmosphere. The model also determines H2 Lyman‐Werner band emission intensities, including a predicted spectrum and the associated color ratio. Implications of the new model results for interpretation of data from National Aeronautics and Space Administration's Juno mission are discussed. In particular, the model predicts that for a 2 MeV/u oxygen ion energy input of 10 mW/m2: (1) escaping electrons are produced with an energy range from 1 eV to 4 keV, which is a smaller range than previous models by Ozak et al. (2013, https://doi.org/10.1002/2013GL50812) predicted, (2) H2 band emission rates of 75 kR are generated, similar to previous estimates, and (3) a newly calculated Lyman and Werner band color ratio of 10 is expected. The color ratios are put into a context of various methane number density distributions.

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“…22 The ratio of the intensities of HeI 667.8 and 587.6 nm spectral lines was found to be 1. During the experiment, the monomer sample was apparently etched, situation that it can be correlated to the weight decrease of the monomer sample as a function of the discharge time.…”

Section: Resultsmentioning

confidence: 93%

N‐isopropylacrylamide decomposition process in helium plasma

Martı́nez

Rodrı́guez-Lazcano

2006

J of Applied Polymer Sci

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Emission spectroscopy was applied to observe decomposed species of N-isopropylacrylamide (NIPAAm) exposed to He plasma, which was generated by AC discharge at the pressure of 400 Pa. As the NIPAAm monomer was exposed to He plasma, light emitted from the NIPAAm and plasma was monitored. In the diagnosis measurement, several emission peaks assigned to the H a and H b atomic lines, CH 3 O, CN(B 2 S-X 2 P), CH(A 2 D-X 2 P), and C 3 H 5 , CN, CHO, CH 2 O, and C 4 H 2 þ transitions were observed and measured at various discharge times. The present results show the presence of C 4 H 2 and C 4 H 2 þ *, which are not manifested in great concentration in the simulation of RF acetylene discharge. The time dependence of the emission intensities was also investigated. When the discharge time of He plasma was increased, the emission intensities of the observed transitions also increased and then gradually decreased.

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Electron-impact cross sections for dipole- and spin-allowed excitations of hydrogen, helium, and lithium

Cited by 47 publications

References 17 publications

CMB constraints on WIMP annihilation: Energy absorption during the recombination epoch

CMB constraints on WIMP annihilation: Energy absorption during the recombination epoch

Jovian Auroral Ion Precipitation: Field‐Aligned Currents and Ultraviolet Emissions

N‐isopropylacrylamide decomposition process in helium plasma

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