Effective ionization and dissociation rate coefficients of molecular hydrogen in plasma

Sawada, Keiji; Fujimoto, Takashi

doi:10.1063/1.360037

Cited by 166 publications

(93 citation statements)

References 59 publications

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“…For coupling of the population densities only to the hydrogen atom the results of the model are in excellent agreement with the results of the CR models described in [12,13]. In a next step a critical investigation on the cross sections for the excitation channel from the ground state H(1) at low electron temperatures is carried out.…”

Section: Fundamental Characteristics Of the Collisional Radiative Modsupporting

confidence: 63%

“…Otherwise the solution has to be determined by integrating the equations beginning with a specified starting condition. In both cases the solution of equation (3) can be expressed in terms of so-called population coefficients R 0p [12]:…”

Section: Physics Of Collisional Radiative Modelsmentioning

confidence: 99%

“…The first CR model for H was developed by Johnson and Hinnov [11]. Since then other CR models for the hydrogen atom have been presented [12,13], the most prominent one is the ADAS package [13]. The typical application ranges of these models are recombining (T e < 1 eV) or ionizing plasmas (T e > 10 eV) which means that the population densities of exited states are determined mainly by recombination from H + and electron collision excitation from H, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Application of a collisional radiative model to atomic hydrogen for diagnostic purposes

Wünderlich

Dietrich

Fantz

2009

Journal of Quantitative Spectroscopy and Radiative Transfer

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Optical emission spectroscopy is one of the standard diagnostic methods to determine plasma parameters. In hydrogen plasmas often the intensity of the Balmer lines is recorded. To analyze such measurements population models for the hydrogen atom are needed. The flexible package Yacora is used to construct a new collisional radiative model for low pressure, low temperature hydrogen plasmas. This model includes six possible excitation channels: effective excitation of H, recombination of H + , dissociative excitation of H 2 , dissociative recombination of H + 2 , dissociative recombination of H + 3 and mutual neutralization of H − and H + x . The model is applied to an uniform ECR plasma with high dissociation degree and low ionization degree, i.e. electron collision excitation from H is the dominant excitation channel. The cross sections for this channel taken from literature showed a non-physical discontinuity at electron energies close to the threshold energy. This discontinuity has been removed by using a smoothing procedure. For known plasma parameters the deviation between measured and calculated population densities decreases significantly by using the smoothed data. Furthermore the agreement of the electron density deduced from the ratio H β /H γ with results of other diagnostic methods is enhanced dramatically.

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Section: Fundamental Characteristics Of the Collisional Radiative Modsupporting

confidence: 63%

Section: Physics Of Collisional Radiative Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Application of a collisional radiative model to atomic hydrogen for diagnostic purposes

Wünderlich

Dietrich

Fantz

2009

Journal of Quantitative Spectroscopy and Radiative Transfer

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“…This is usually done in the framework of the collisional-radiative model (see e.g. Janev et al 1984;Sawada & Fujimoto 1995), similar to that used for impurities. Secondly, the hydrogen neutral density becomes so high that the divertor volume becomes opaque (see e.g.…”

Section: Recycling Regionmentioning

confidence: 99%

Physics of ultimate detachment of a tokamak divertor plasma

Krasheninnikov¹,

2017

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The basic physics of the processes playing the most important role in divertor plasma detachment is reviewed. The models used in the two-dimensional edge plasma transport codes that are widely used to address different issues of the edge plasma physics and to simulate the experimental data, as well as the numerical schemes and convergence issues, are described. The processes leading to ultimate divertor plasma detachment, the transition to and the stability of the detached regime, as well as the impact of the magnetic configuration and divertor geometry on detachment, are considered. A consistent, integral physical picture of ultimate detachment of a tokamak divertor plasma is developed.

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“…Typical electron density values in divertor region, n e ≈ 10 14 cm −3 , are considerably higher than in technical plasmas and the theoretical model must describe the interplay of different elementary processes, thus considering the different vibrational pumping/de-activation mechanisms of excited electronic states. Attempts in this direction are reported in literature [26], improving the collisional radiative model by Sawada&Fujumoto [27] for hydrogen molecules and atoms. Results [26] clearly indicate that while at low electron densities the pumping mechanism of the excited emitting state is dominated by the forbidden electron-impact induced excitation of the ground state, increasing n e (> 10 12 cm −3 ) the excitation is governed by transitions involving metastable excited states (a 3 Σ + g , c 3 Π u ), with intermediate regimes where both mechanisms are important in populating the emitting state [28].…”

Section: Hollow-cathode Glow Dischargementioning

confidence: 99%

From cold to fusion plasmas: spectroscopy, molecular dynamics and kinetic considerations

Capitelli¹,

Celiberto²,

Colonna³

et al. 2010

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. Non-equilibrium effects in hydrogen plasmas have been investigated in different systems, ranging from RF plasmas to corona discharges. Existing measurements of vibrational and rotational temperatures, obtained by different spectroscopical techniques are reported, rationalized by results calculated by kinetic models. Input data of these models are discussed with particular attention on the dependence of relevant cross sections on the vibrational quantum number. Moreover the influence of vibrational excitation of the H 2 molecules in affecting the translational distribution of atoms in ground and excited levels is shown. Finally a collisional radiative model for atomic hydrogen levels, based on the coupling of the Boltzmann equation for EEDF and the excited state kinetics, is presented, emphasizing the limits of quasi-stationary approximation. In this last case, large deviations of the EEDF and atomic level distributions from the equilibrium are observed.

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Effective ionization and dissociation rate coefficients of molecular hydrogen in plasma

Cited by 166 publications

References 59 publications

Application of a collisional radiative model to atomic hydrogen for diagnostic purposes

Application of a collisional radiative model to atomic hydrogen for diagnostic purposes

Physics of ultimate detachment of a tokamak divertor plasma

From cold to fusion plasmas: spectroscopy, molecular dynamics and kinetic considerations

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