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Kepple, P.; Griem, Hans R.

doi:10.1103/physrev.173.317

Cited by 351 publications

(126 citation statements)

References 25 publications

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“…Hydrogen lines profile is well described by Kepple and Griem [54,67]. The Stark broadening is mainly due to the ions, its form is linear and the resulting shape is more complex than a Lorentzian profile when the dynamics of the ions is considered.…”

Section: -Stark Broadeningmentioning

confidence: 75%

Net emission of Ar–H₂–He thermal plasmas at atmospheric pressure

Cressault¹,

Rouffet²,

Gleizes³

et al. 2010

J. Phys. D: Appl. Phys.

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The Net Emission Coefficient (NEC) has been calculated for Ar-H 2 -He thermal plasmas and for a temperature range from 5000K to 30000K. The plasma is supposed to be in Local Thermodynamic Equilibrium (LTE) at atmospheric pressure. This study takes into account the radiation resulting from the atomic continuum, the molecular continuum, and the atomic lines. A particular attention has been paid to the treatment of helium lines broadenings. The results of net emission coefficients are presented for pure gases and Ar-H 2 -He mixtures. Radiation is weak in pure helium at low temperatures because of the high ionization energy of this species. On the opposite, at very high temperature, the influence of hydrogen tends to decrease because ionic lines do not exist for this last species. Finally, a small proportion of helium in Ar-H 2 mixtures does not change the net emission coefficient because of the weak intensity of the helium lines.

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Section: -Stark Broadeningmentioning

confidence: 75%

Net emission of Ar–H₂–He thermal plasmas at atmospheric pressure

Cressault¹,

Rouffet²,

Gleizes³

et al. 2010

J. Phys. D: Appl. Phys.

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“…That the orbital angular momentum states of hydrogen labeled by the quantum number, l, are not degenerate in the presence of an electric field perturbation is described by the well-known Stark effect (e.g., Kepple & Griem 1968;Vidal et al 1971;Seaton 1990). In stellar atmospheres, this perturbation is due to a net electric microfield from fluctuations Temperature as a function of column mass for loop models generated using the XEUV backwarming method described here (black), using the XEUV technique of A05 (green), and without XEUV backwarming (red).…”

Section: Line Broadeningmentioning

confidence: 99%

A Unified Computational Model for Solar and Stellar Flares

Allred

Kowalski

Carlsson

2015

ApJ

243

282

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We present a unified computational framework that can be used to describe impulsive flares on the Sun and on dMe stars. The models assume that the flare impulsive phase is caused by a beam of charged particles that is accelerated in the corona and propagates downward depositing energy and momentum along the way. This rapidly heats the lower stellar atmosphere causing it to explosively expand and dramatically brighten. Our models consist of flux tubes that extend from the sub-photosphere into the corona. We simulate how flare-accelerated charged particles propagate down one-dimensional flux tubes and heat the stellar atmosphere using the Fokker-Planck kinetic theory. Detailed radiative transfer is included so that model predictions can be directly compared with observations. The flux of flare-accelerated particles drives return currents which additionally heat the stellar atmosphere. These effects are also included in our models. We examine the impact of the flare-accelerated particle beams on model solar and dMe stellar atmospheres and perform parameter studies varying the injected particle energy spectra. We find the atmospheric response is strongly dependent on the accelerated particle cutoff energy and spectral index.

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“…In addition, it differs slightly between calculations. The halfwidth α 1/2 of the H β line (approximately 0.085) is plotted as a function of temperature (density) for several representative densities (temperatures) in figures 4(a) and (b) according to the Gigosos-Cardeñoso (GC) theory [20] and according to the Kepple-Griem (KG) theory [19], showing a slight discrepancy between the two theories. The uncertainty in α 1/2 introduces an error <20% in density estimation for our hydrogen plasma jets.…”

Section: Uncertainty In Stark Parametermentioning

confidence: 99%

“…The half-width α 1/2 has been tabulated for many hydrogen lines based on both theoretical calculations and experimental data for the temperature range 0.5-4 eV and density range 10 20-24 m −3 [19,20,22]. The half-width α 1/2 has a weak dependence on density and on temperature.…”

Section: Uncertainty In Stark Parametermentioning

confidence: 99%

Large density amplification measured on jets ejected from a magnetized plasma gun

Yun¹,

You²,

Bellan³

2007

Nucl. Fusion

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Observation of a large density amplification in the collimating plasma jet ejected from a coplanar coaxial plasma gun is reported. The jet velocity is ∼30 km s −1 and the electron density increases from ∼10 20 to 10 22-23 m −3 . In previous spheromak experiments, electron density of the order 10 19-21 m −3 had been measured in the flux conserver region, but no density measurement had been reported for the source gun region. The coplanar geometry of our electrodes permits direct observation of the entire plasma dynamics including the source region. Analysis of Stark broadened spectral lines shows that the electron density increases by a factor of 100 as the jet collimates, with a peak density of up to 10 22-23 m −3 . The observed density amplification is interpreted according to an MHD theory that explains collimation of current-carrying plasma-filled magnetic flux tubes. Issues affecting interpretation of Stark broadened line profiles and the possibility of using the high-density plasma jet for tokamak fuel injection are discussed.

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Improved Stark Profile Calculations for the Hydrogen LinesHα,Hβ,Hγ, and

Cited by 351 publications

References 25 publications

Net emission of Ar–H₂–He thermal plasmas at atmospheric pressure

Net emission of Ar–H₂–He thermal plasmas at atmospheric pressure

A Unified Computational Model for Solar and Stellar Flares

Large density amplification measured on jets ejected from a magnetized plasma gun

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Improved Stark Profile Calculations for the Hydrogen LinesHα,Hβ,Hγ, and

Cited by 351 publications

References 25 publications

Net emission of Ar–H2–He thermal plasmas at atmospheric pressure

Net emission of Ar–H2–He thermal plasmas at atmospheric pressure

A Unified Computational Model for Solar and Stellar Flares

Large density amplification measured on jets ejected from a magnetized plasma gun

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Product

Resources

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Net emission of Ar–H₂–He thermal plasmas at atmospheric pressure

Net emission of Ar–H₂–He thermal plasmas at atmospheric pressure