The ionization balance of the atmosphere

Abstract. We report on observations of a diverging ion flow along the geomagnetic field that is often seen at the EISCAT Svalbard radar. The flow is upward above the peak of the electron density in the F-region and downward below the peak. We estimate that in such events mass transport along the field line is important for the ionization balance, and that the shape of the F-layer and its ion composition should be strongly influenced by it. Diverging flow typically occurs when there are signatures of direct entry of sheath plasma to the ionosphere in the form of intense soft particle precipitation, and we suggest that it is caused by the ionization and ionospheric electron heating associated with this precipitation. On average, 30% of all events with ion upflow also show significant ion downflow below. Key words.Ionosphere (polar ionosphere; ionization mechanism; plasma temperature and density)

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What Do We Really Know About the Winds of Massive Stars?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308020371 ◽

2007 ◽

Vol 3 (S250) ◽

pp. 89-96

Author(s):

D. John Hillier

Keyword(s):

Mass Loss ◽

Massive Stars ◽

Standard Theory ◽

Stellar Winds ◽

X Rays ◽

X Ray ◽

Stellar Photosphere ◽

Weak Winds ◽

Ionization Balance ◽

Loss Rates

AbstractThe standard theory of radiation driven winds has provided a useful framework to understand stellar winds arising from massive stars (O stars, Wolf-Rayet stars, and luminous blue variables). However, with new diagnostics, and advances in spectral modeling, deficiencies in our understanding of stellar winds have been thrust to the forefront of our research efforts. Spectroscopic observations and analyses have shown the importance of inhomogeneities in stellar winds, and revealed that there are fundamental discrepancies between predicted and theoretical mass-loss rates. For late O stars, spectroscopic analyses derive mass-loss rates significantly lower than predicted. For all O stars, observed X-ray fluxes are difficult to reproduce using standard shock theory, while observed X-ray profiles indicate lower mass-loss rates, the potential importance of porosity effects, and an origin surprisingly close to the stellar photosphere. In O stars with weak winds, X-rays play a crucial role in determining the ionization balance, and must be taken into account.

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Моделирование плазмы короткодугового ксенонового разряда сверхвысокого давления

Журнал технической физики ◽

10.21883/jtf.2019.10.48171.103-19 ◽

2019 ◽

Vol 89 (10) ◽

pp. 1556

Author(s):

Н.А. Тимофеев ◽

В.С. Сухомлинов ◽

G. Zissis ◽

И.Ю. Мухараева ◽

Д.В. Михайлов ◽

...

Keyword(s):

Experimental Data ◽

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Arc Discharge ◽

Plasma Temperature ◽

Cathode Region ◽

Ultrahigh Pressure ◽

Thoriated Tungsten ◽

Ionization Balance

AbstractWe have studied a high- (ultrahigh-) pressure short-arc discharge in xenon with thoriated tungsten cathodes. A system of equations formulated based on earlier experimental data indicating possible emission of cathode material (thorium) into the discharge gap has made it possible to determine the electric field strength, plasma temperature, and concentration of thorium atoms as well as thorium and xenon ions in the plasma. The problem has been solved for a model discharge between planar electrodes. The results indicate the key role of thorium atoms in the cathode region. Thorium atoms determine the ionization balance and other electrokinetic properties of plasma. Emission of thorium atoms reduces the plasma temperature at the cathode, which turns out to be noticeably lower than the plasma temperature near the anode; this is a new result that agrees with experimental data. Other electrokinetic characteristics of the plasma (in particular, charged particle concentration and electric field strength) are also in good agreement with the experiment.

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Measurements of ionization balance parameters in atomic ions. Final report, May 1, 1982--May 31, 1989

10.2172/10135059 ◽

1991 ◽

Author(s):

J.L. Kohl

Keyword(s):

Final Report ◽

Atomic Ions ◽

Ionization Balance

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Open Issues Regarding Ionization Balance

10.1063/1.1960912 ◽

2005 ◽

Author(s):

J. Martin Laming ◽

Arati Dasgupta ◽

Una Hwang

Keyword(s):

Ionization Balance ◽

Open Issues

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Radiative cooling rates, ion fractions, molecule abundances, and line emissivities including self-shielding and both local and metagalactic radiation fields

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2172 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4857-4883 ◽

Cited By ~ 2

Author(s):

Sylvia Ploeckinger ◽

Joop Schaye

Keyword(s):

Cosmic Rays ◽

Radiation Field ◽

Spectral Synthesis ◽

Cosmic Ray ◽

Cooling Rates ◽

Radiation Fields ◽

Hydrodynamical Simulations ◽

Lower Temperature ◽

X Ray Background ◽

Ionization Balance

ABSTRACT We use the spectral synthesis code cloudy to tabulate the properties of gas for an extensive range in redshift (z = 0–9), temperature (log T[K] = 1–9.5), metallicity (log Z/Z⊙ = −4 – +0.5, Z = 0), and density ($\log n_{\mathrm{H}}[\, \mathrm{cm}^{-3}] = -8$ − +6). This therefore includes gas with properties characteristic of the interstellar, circumgalactic, and intergalactic media. The gas is exposed to a redshift-dependent UV/X-ray background, while for the self-shielded lower-temperature gas (i.e. ISM gas), an interstellar radiation field and cosmic rays are added. The radiation field is attenuated by a density- and temperature-dependent column of gas and dust. Motivated by the observed star formation law, this gas column density also determines the intensity of the interstellar radiation field and the cosmic ray density. The ionization balance, molecule fractions, cooling rates, line emissivities, and equilibrium temperatures are calculated self-consistently. We include dust, cosmic rays, and the interstellar radiation field step-by-step to study their relative impact. These publicly available tables are ideal for hydrodynamical simulations. They can be used stand alone or coupled to a non-equilibrium network for a subset of elements. The release includes a C routine to read in and interpolate the tables, as well as an easy-to-use python graphical user interface to explore the tables.

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Ionization Equilibrium for Ions of Na, Al, P, Cl, A, K, Ca, Cr and Mn

International Astronomical Union Colloquium ◽

10.1017/s0252921100089715 ◽

1972 ◽

Vol 14 ◽

pp. 586-587 ◽

Cited By ~ 2

Author(s):

M. Landini ◽

B.C. Monsignori Fossi

Keyword(s):

Solar Atmosphere ◽

Radiative Recombination ◽

Dielectronic Recombination ◽

Ionization Equilibrium ◽

Collisional Ionization ◽

Ionization Balance ◽

Equilibrium Calculations

Ionization equilibrium calculations, which have a number of astrophysical applications, have been computed by Jordan for the ions of C, N, O, Ne, Mg, Si, S, Fe, and Ni.The aim of this paper is to extend the evaluation to other elements relevant to the investigation of the solar atmosphere. Ions of Na, Al, P, Cl, A, K, Ca, Cr, and Mn have been considered and the ionization balance has been computed for temperature from 104 to 107 K.The computation is performed including collisional ionization, autoionization, radiative recombination and dielectronic recombination.

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Monte Carlo radiative transfer for the nebular phase of Type Ia supernovae

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3412 ◽

2019 ◽

Vol 492 (2) ◽

pp. 2029-2043 ◽

Cited By ~ 2

Author(s):

L J Shingles ◽

S A Sim ◽

M Kromer ◽

K Maguire ◽

M Bulla ◽

...

Keyword(s):

Radiative Transfer ◽

Atomic Data ◽

Type Ia Supernovae ◽

Data Set ◽

High Ionization ◽

Type Ia ◽

Non Local ◽

Ionization Balance ◽

Ia Supernovae ◽

Modest Effect

ABSTRACT We extend the range of validity of the artis 3D radiative transfer code up to hundreds of days after explosion, when Type Ia supernovae (SNe Ia) are in their nebular phase. To achieve this, we add a non-local thermodynamic equilibrium population and ionization solver, a new multifrequency radiation field model, and a new atomic data set with forbidden transitions. We treat collisions with non-thermal leptons resulting from nuclear decays to account for their contribution to excitation, ionization, and heating. We validate our method with a variety of tests including comparing our synthetic nebular spectra for the well-known one-dimensional W7 model with the results of other studies. As an illustrative application of the code, we present synthetic nebular spectra for the detonation of a sub-Chandrasekhar white dwarf (WD) in which the possible effects of gravitational settling of 22Ne prior to explosion have been explored. Specifically, we compare synthetic nebular spectra for a 1.06 M⊙ WD model obtained when 5.5 Gyr of very efficient settling is assumed to a similar model without settling. We find that this degree of 22Ne settling has only a modest effect on the resulting nebular spectra due to increased 58Ni abundance. Due to the high ionization in sub-Chandrasekhar models, the nebular [Ni ii] emission remains negligible, while the [Ni iii] line strengths are increased and the overall ionization balance is slightly lowered in the model with 22Ne settling. In common with previous studies of sub-Chandrasekhar models at nebular epochs, these models overproduce [Fe iii] emission relative to [Fe ii] in comparison to observations of normal SNe Ia.

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