Calculation of Population Densities of Helium Atoms in Non-L.T.E. Plasmas

Particle densities of helium atoms in the ground and excited states have been calculated for non-L.T.E. plasmas on the basis of a collisional-radiative model in which singlet and triplet states have separately been taken into account. Distinction is made between two physical situations: 1- a homogeneous stationary state, 2- a transient and/or inhomogeneous plasma state. In both cases, the particle densities have been calculated for an optically thin, a slightly optically thick and strongly absorbing plasmas. Only the results for the homogeneous stationary state are presented in this paper. Those for the transient and/or inhomogeneous states have been summarized in numerical tables which will be sent on request. (Title: "Tables of reduced population coefficients for the levels of atomic helium", Report EUR-CEA-FC-697.) The tables are sufficiently complete to permit a wide application in the field of spectroscopic diagnostics of different types of non-L.T.E. plasmas. - Comparison of our results with the values measured by Boersch et al. 10 shows good agreement with our calculations when one assumes that the observed plasma is strongly inhomogeneous and dominated by diffusion.

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The band systems ending on the 1 s σ2 s σ 1 Ʃ g ( 1 X g ) state of H 2 —Part I

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1937.0122 ◽

1937 ◽

Vol 160 (903) ◽

pp. 487-507 ◽

Cited By ~ 4

Keyword(s):

Ground State ◽

Principal Quantum Number ◽

Electronic States ◽

Ground Level ◽

Triplet States ◽

Private Communication ◽

Singlet States ◽

Singlet And Triplet States ◽

State 1 ◽

Atomic Helium

It is now well established that the electronic states of the band systems of H 2 have a close analogy to those of atomic helium and consist of a set of singlet states and a set of triplet states. There are no known combinations between singlet and triplet states. The ground level of H 2 is the v = 0, K = 0 level of the even state 1 s σ 1 s σ 1 Ʃ g . The possible states with one electron excited to principal quantum number 2 are 1 s σ 2 s σ 1 Ʃ g , 1 s σ 2 p σ 1 Ʃ u , 1 s σ 2 pπ 1 II u , 1 s σ 2 s σ 3 Ʃ g , 1 s σ 2 p σ 3 Ʃ g and 1 s σ 2 pπ 3 II u Of these the only ones which can go down to the ground state are 1 s σ 2 p σ 1 Ʃ u and 1 s σ 2 pπ σ 1 Ʃ u on account of the triplet ↔ singlet and odd ↔ odd and even ↔ even prohibitions. The bands with these transitions are well known and understood both in emission and absorption. A large number of emission band systems which go down to the states 1 s σ 2 p σ 1 Ʃ u and 1 s σ2 pπ σ 1 II u from higher even states have been found and analysed so that we now have quite discovered, and most of those involving the v = 1 level, which he has greatly extended, I am indebted to a private communication from Professor Dieke. Incidentally the success of this method of locating the position of 1 s σ3 pπ 1 II u is to some extent also a confirmation of my identification of 3 1 O as 1 s σ 3 s σ 1 Ʃ g .

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Diagnostics of Gold Laser Plasmas

International Astronomical Union Colloquium ◽

10.1017/s0252921100108085 ◽

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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