Die Emissionskontinua thermischer Edelgasplasmen

Schlüter, D.

doi:10.1007/bf01379872

Cited by 90 publications

(12 citation statements)

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“…It employs in Equation (6) a Thomas-Fermi (TF) potential V(r) modified in such a way, that the experimental energy values e,,~ are reproduced, Stewart and Rotenberg [8]. For an atom or ion with N electrons and nuclear charge Z, this potential is given by -V(r)=/2Z (6) [7-.q x_->x0…”

Section: The Scaled-thomas-fermi Potentialmentioning

confidence: 99%

“…The quantum defects can be extrapolated into the region of positive energies. This Quantum-Defect-Method (QDM) has been applied by Burgess and Seaton [4J, Peach [5], Schliiter [6] and Hofsaess [7] for a large number of elements. Many calculated photoionization cross sections agree satisfactorily with the few experimental results.…”

Section: D2p(r) [ /-(/+ 1)] P(r)=o (4) Dr~-t-v(r)+e R2mentioning

confidence: 99%

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Photoabsorption of alkali and alkaline earth elements calculated by the Scaled Thomas Fermi method

Hofsaess

1977

Z Physik A

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Photoionization cross sections have been calculated by means of the Scaled-ThomasFermi method for the alkali metals and the alkaline earths. Using these results the absorption coefficients for bound-free transitions have been obtained for thermal plasmas of 6000 to 20,000 K and wavelengths from 500 to 10,000•. In addition the oscillator strengths are given for the principal series of the alkali metals.

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Section: The Scaled-thomas-fermi Potentialmentioning

confidence: 99%

Section: D2p(r) [ /-(/+ 1)] P(r)=o (4) Dr~-t-v(r)+e R2mentioning

confidence: 99%

Photoabsorption of alkali and alkaline earth elements calculated by the Scaled Thomas Fermi method

Hofsaess

1977

Z Physik A

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“…Thus, at large distances from the shock front, we recover the inverse square law geometric attenuation for the spectral intensity of the subordinate continuum, which is not strongly absorbed in either the hot or cold gas. The atomic absorption coefficient, K X , is given by the following equation, 23 In Eq. (22) we have approximated the ratio of the statistical weights of the ion and atom as 6.0, and the factor %(v,T) represents the quantum mechanical correction factor for departure from hydrogenic behavior.…”

Section: Photoionization Of Excited Argonmentioning

confidence: 99%

“…In our calculations, we use Schltiter's 23 values of the %(v,T) function which do not involve the concept of a cutoff frequency. Some values of £(V,T f )23 appropriate to the v^ frequency range are quoted, along with values of 0/2(j>),24 in…”

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confidence: 99%

Precursor photoexcitation and photoionization of argon in shock tubes

Dobbins

1970

AIAA Journal

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A chemical kinetic model describing photochemical reactions that are likely to be important in "cold" argon ahead of a strong shock wave in a shock tube is examined on a quantitative basis. The model includes the propagation of resonance radiation far from the shock front in the wings of the resonance absorption line, imprisonment of the absorbed resonance radiation, subsequent photoionization of excited atoms, photoionization of ground state argon, and certain recombination and de-excitation processes. Specific consideration is given to shock tube geometry, the finite extent of the equilibrium region and the (experimentally) known shock tube wall reflectivity. Theoretical predictions of excited atom and argon ion concentrations in the precursor region are presented for typical shock tube operating conditions. The regimes favorable to the production of argon ions by photoionization of ground state argon and by photoionization of photoexcited argon, respectively, are delineated. NomenclatureA 21 = spontaneous emission probability B(i>i2,T ({) ) = Planck function evaluated at temperature Tĉ = speed of light e r i,c r 2 = first and second reflectivity constants e -charge on an electron / = oscillator strength QI = statistical weight of ground state #2 = statistical weight of excited state <7/2(*0 = Gaunt factor for photoionization cross section of excited state g t i = escape probability from radiation imprisonment theory h = Planck's constant 3 = impurity concentration in parts per million I v -specific spectral intensity J v = average spectral intensity KO = absorption coefficient at center frequency of a spectral line k = Boltzmann constant K V W = spectral absorption coefficient L = distance between shock wave pressure discontinuity and contact surface Li = distance between the pressure discontinuity and the equilibrium front L% = distance between equilibrium front and the contact surface M = Mach number of shock wave m e = mass of an electron n a i = number of ground state atoms per unit volume n a z -number of excited state atoms per unit volume n a + = number of argon ions per unit volume Presented as Paper 68-666 at the AIAA Fluid and Plasma effective principal quantum number Qiz = photoexcitation rate from state 1 to state 2 Qzi = photoionization rate from state 2 to state i p (1) = pressure upstream of shock wave R = shock tube radius R y = Rydberg constant /S (i) = line strength TW = temperature in region i TAO = frozen flow temperature behind the shock wave u (l)= velocity of gas approaching shock wave as measured in coordinates fixed in the wave x = distance from shock front x' = distance from the equilibrium region a (2) = degree of ionization in the equilibrium region (XL = semi-half width due to Lorentz broadening A = frequency interval f = distance measured in ratio x'/R y] = distance measured in ratio x/R 6 = arctangent of R/x f K X = atomic absorption coefficient X = wavelength \2i= wavelength corresponding to frequency vzi v = frequency vzi = frequency of radiation accompanying de-excitation from...

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“…Die vorliegende Arbeit befaßt sich mit der Messung der Rekombinationskontinua von Krypton und Xenon im Wellenlängenbereich zwischen 2300 Ä und 3600 Ä. Diese Kontinua sind einmal für Experimente am Stoßrohr von Interesse, da die Edelgase häufig als Trägergase Verwendung finden; zum anderen liegen seit einiger Zeit quantenmechanische Rechnungen zu den Absorptionsquerschnitten vor 1 …”

Section: Introductionunclassified

Messung der Kontinuumstrahlung von Krypton und Xenon in einem durch Stoßwellen aufgeheizten Plasma

Carls

1974

Zeitschrift Für Naturforschung A

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Measurement of the Continuous Radiation of Shock Heated Krypton and XenonWe report on the measurement of the Recombination Continuum of Krypton in the wavelength region between 2300 Ä and 3600 Ä. The plasma behind a reflected shock has been used as a light source. Good agreement was found between measured absorption coefficients and theoretical ones if the electron density was measured from the broadening of the Balmer line H^, while the measurements show departures by a factor 5 to 9 from Rankine-Hugoniot predicted values. Possible deviations from ideal shock behaviour are discussed.

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Die Emissionskontinua thermischer Edelgasplasmen

Cited by 90 publications

References 0 publications

Photoabsorption of alkali and alkaline earth elements calculated by the Scaled Thomas Fermi method

Photoabsorption of alkali and alkaline earth elements calculated by the Scaled Thomas Fermi method

Precursor photoexcitation and photoionization of argon in shock tubes

Messung der Kontinuumstrahlung von Krypton und Xenon in einem durch Stoßwellen aufgeheizten Plasma

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