The influence of opacity on hydrogen excited-state population and applications to low-temperature plasmas

Behringer, K.; Fantz, U.

doi:10.1088/1367-2630/2/1/323

Cited by 69 publications

(68 citation statements)

References 16 publications

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“…the calculated ratio of the emission of two Balmer lines is adjusted to the measured ratio. This method was described in [6,18,40] for the determination of the dissociation degree, in [41] for the electron density and in [24] for the density of the negative hydrogen ion. For further verification of the smoothing procedure the line ratio H β /H γ was used to determine the electron density for all pressures.…”

Section: Resultsmentioning

confidence: 99%

“…X qp and X pq are the rate coefficients for excitation or de-excitation by electron collisions. α and β are the rate coefficients for recombination of an ion with density n + and S p is the rate coefficient for ionization of the state p. Equation (3) must be extended when heavy particle collisions (for example Penning ionization and quenching), selfabsorption due to optical thickness of emission lines [18] or other additional processes have to be considered.…”

Section: Physics Of Collisional Radiative Modelsmentioning

confidence: 99%

“…ence of self-absorption due to the optical thickness of the Lyman lines on the population densities of excited states is taken into account by multiplying the transition probabilities for spontaneous emission with the appropriate population escape factors as suggested in [18].…”

Section: Fundamental Characteristics Of the Collisional Radiative Modmentioning

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: Resultsmentioning

confidence: 99%

Section: Physics Of Collisional Radiative Modelsmentioning

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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“…In low temperature plasmas (Te on the order of 10 eV) the rate for atomic excitation is typically greater by more than an order of magnitude. 6 However, the exact ratio of the two excitation channels depends on the vibrational distribution of the molecules. The Fulcher-band emission around 600 nm corresponds to the molecular triplet transition d −8 s, respectively.…”

Section: Discussionmentioning

confidence: 99%

Ultra-fast intensified frame images from an electron cyclotron resonance hydrogen plasma at 2.45 GHz: Some space distributions of visible and monochromatic emissions

Cortázar

Megía-Macías

Vizcaíno-de-Julián

et al. 2013

Review of Scientific Instruments

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First results from an ultra-fast frame image acquisition diagnostic coupled to a 2.45 GHz microwave hydrogen discharge are presented. The plasma reactor has been modified to include a transparent doubled shielded quartz window allowing to viewing the full plasma volume. Pictures describing the breakdown process at 1 μs exposure time have been obtained for integrated visible light signal, Balmer-alpha, Balmer-beta lines, and Fulcher-band. Several different plasma emission distributions are reported. The distribution depends on the magnetic field configuration, incident microwave power, and neutral gas pressure.

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“…Due to low caesium ground state densities (lower as 10 16 m -3 , [24]) resulting in a high mean free path of photons and additionally a low intensity of the photon field, processes like self-absorption due to optical thickness of emission lines [16] or photo ionization can be neglected.…”

mentioning

confidence: 99%

A collisional radiative model for caesium and its application to an RF source for negative hydrogen ions

Wünderlich

Wimmer²,

Friedl³

2015

AIP Conference Proceedings

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The influence of opacity on hydrogen excited-state population and applications to low-temperature plasmas

Cited by 69 publications

References 16 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

Ultra-fast intensified frame images from an electron cyclotron resonance hydrogen plasma at 2.45 GHz: Some space distributions of visible and monochromatic emissions

A collisional radiative model for caesium and its application to an RF source for negative hydrogen ions

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