Investigation of Excited States of Helium Atoms in a Stationary PIG-Discharge

1971 ◽  
Vol 26 (2) ◽  
pp. 186-197 ◽  
Author(s):  
H. W. Drawin ◽  
F. Klan ◽  
H. Ringler
Keyword(s):  
Excited States ◽  
Theoretical Calculations ◽  
Principal Quantum Number ◽  
Population Densities ◽  
Boltzmann Plot ◽  
Line Intensities ◽  
Quantum Numbers ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Large Experimental Error

AbstractSpectral line intensities emitted by a quiescent PIG-discharge have been measured and the population densities up to a principal quantum number n = 24 have been derived from them. The experimentally determined population densities have been compared with theoretical ones calculated on the basis of a collisional-radiative model in which one accounts for electron and atom collisions. I t is shown that even in the case of different electron and atom temperatures, Te and Ta, an evaluation of the Boltzmann plot at medium and moderately high quantum numbers always leads to the electron temperature, whereas the Saha-Eggert equation for the same states may yield incorrect electron densities. The theoretical calculations predict an inflection of the slope of the Boltzmann plot from Te to Ta for very highly excited states. For the plasma para­ meters under which the PIG-discharge was operated (ne ≅ 2.5 × 1012 cm-3, Te ≅ 1200°K, n0 ≅ 1.5 × 1015 cm-3, 300°K) the change of the slope should become visible for states having principal quantum numbers n > 18. Due to the large experimental error bars it was not possible to check this behaviour.

Collisional radiative model for the evaluation of the Thermal Helium Beam diagnostic at ASDEX Upgrade

2022 ◽  
Author(s):  
Daniel Wendler ◽  
Ralph Dux ◽  
Rainer Fischer ◽  
Michael Griener ◽  
Elisabeth Wolfrum ◽  
...  
Keyword(s):  
Excited States ◽  
Ultra Violet ◽  
Plasma Edge ◽  
Excitation Mechanism ◽  
Computationally Efficient ◽  
Injection Point ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Measured Line ◽  
Vacuum Ultra Violet

Abstract The thermal helium beam diagnostic at ASDEX Upgrade is used to infer the electron density ne and temperature Te in the scrape-off layer and the pedestal region from the emission of visible lines of the locally injected helium. The link between ne and Te and the emission is provided by a collisional radiative model, which delivers the evolution of the populations of the relevant excited states as the He atoms travel through the plasma. A computationally efficient method with just three effective states is shown to provide a good approximation of the population dynamics. It removes an artificial rise of Te at the plasma edge when using a simple static model. Furthermore, the re-absorption of the vacuum ultra-violet resonance lines has been introduced as additional excitation mechanism being mainly important in the region close to the injection point. This extra excitation leads to a much better fit of the measured line ratios in this region for larger puff rates.

scholarly journals The Cu I And Zn I-Like Spectra of Pr, Eu, Gd, Dy And Yb Emitted by a Tokamak Plasma in the 50–200 Å Range

1988 ◽  
Vol 102 ◽  
pp. 75-77
Author(s):  
W.L. Hodge ◽  
M. Finkenthal ◽  
H.W. Moos ◽  
S. Lippmann ◽  
L.K. Huang ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Grazing Incidence ◽  
Spectral Lines ◽  
Tokamak Plasma ◽  
Low Density ◽  
Line Intensities ◽  
Time Histories ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractSpectra of rare earth elements, praseodymium, europium, gadolinium, dysprosium and ytterbium (Z=59 to Z=70) have been recorded from a high temperature (Te=1–1.4 keV) - low density (ne=1013cm−3) tokamak plasma, in the 50–200 Å range. The absolute brightnesses of the lines originating in 4–4 transitions of Cu I and Zn I-like ions of the above mentioned elements have been measured by means of a photometrically calibrated grazing incidence spectrometer. Newly identified Cu I-like, 4s2S1/2-4p2P1/2transitions in Pr30+, Eu34+, Gd35+, Dy37+and Yb41, and intercombination transitions 4s21S0-4s4p3P1, in the Zn I-like ions of the mentioned elements are presented. The identifications are based on interpolation of previous experimental results, ab initio energy level computations using the RELAC code and are substantiated by the time histories of individual spectral lines. The experimental line intensities of the Cu I and Zn I-like ions are compared with those predicted by a collisional-radiative model under the conditions of the tokamak plasma.

Non L.T.E. Properties of Quasistationary Oxygen Plasmas

1976 ◽  
Vol 31 (3-4) ◽  
pp. 362-368 ◽  
Author(s):  
M. Cacciatore ◽  
M. Capitelli
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Ground State ◽  
Radiative Recombination ◽  
Local Thermodynamic Equilibrium ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Ionization Coefficients ◽  
Selection Of ◽  
The Continuum

The non L.T.E. (local thermodynamic equilibrium) properties of optically thin and thick quasistationary oxygen plasmas have been calculated for the temperature range k T = 0.5 - 1.5 eV and for the electron density interval 108 - 1016 cm-3 , by using the collisional-radiative model of Bates, Kingston and McWhirther. The results include1 the coefficients r0(i) and r1(i), which represent the contribution to the population density of the ith quantum level from the continuum and from the ground state, respectively2 the values of α and S, which are the collisional-radiative recombination and ionization coefficients, respectively. The accuracy of the present results is discussed in connection with the adopted plasma model and with the selection of the collisional cross sections for forbidden and allowed transitions. A discussion is also presented of the influence of the two low lying excited states of oxygen atoms (i.e. the states 2p41D, 2p41S) on the non L.T.E. properties of these plasmas. A satisfactory agreement is found with the calculations of Julienne et al. and with the experimental results of Jones.

Precise energies of highly excited hydrogen and deuterium

2002 ◽  
Vol 80 (11) ◽  
pp. 1373-1382 ◽  
Author(s):  
S Kotochigova ◽  
P J Mohr ◽  
B N Taylor
Keyword(s):  
Least Squares ◽  
Quantum Number ◽  
Excited States ◽  
Quantum Electrodynamics ◽  
Theoretical Calculations ◽  
Principal Quantum Number ◽  
Energy Levels ◽  
Fundamental Constants ◽  
Relativistic Corrections ◽  
Least Squares Adjustment

The energy levels of hydrogen and deuterium atoms are calculated to provide frequencies for transitions between highly excited states with principal quantum number n up to 200. All known quantum electrodynamics and relativistic corrections have been included in the calculation. In some cases, contributions originally calculated for a few states have been extrapolated to highly excited states. The fundamental constants necessary for the calculation are taken from the 1998 CODATA least-squares adjustment. Evaluated uncertainties take into account uncertainties in the theoretical calculations, uncertainties in the fundamental constants, and covariances between the various contributions and input parameters. PACS Nos.: 31.15Pf, 31.30Jv, 32.10Hq

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

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