SATELLITE LINES OF NEON-LIKE RESONANCE LINES, FOR 17<Z<48

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SATELLITE LINES OF NEON-LIKE RESONANCE

LINES, FOR 17

S. Jacquemot, M. Louis-Jacquet, O. Peyrusse, M. Cornille, J. Dubau, P.

Lautard

To cite this version:

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SATELLITE LINES OF NEON-LIKE RESONANCE LINES, FOR 17<2<48

s.

JACQUEMOT,

M.

LOUIS-JACQUET, O. PEYRUSSE, M. CORNILLE*, J. DUBAU* and P. LAUTARD*

*

Commissariat

il

1'Energie Atomique, Centre d'Etudes de Limeil-Valenton.

BP 27, F-94190

Villeneuve-Saint-Georges,

France

*u.A. 812/DAMAp Observatoire de Meudon, F-92915 Meudon, France

* *

_{Observatoire de la C6te d'Azur, F-06003 Nice Cedex, France}

Rksumk

Les raies diklectroniques satellites des raies de resonance des ions nkonoi'des,du type ls22s22p53d

-

ls22s22p6,0nt kt6 observkes dans des spectres produits par irradiation laser

h

Limei1,lors d1exp6riences Laser X,de plasmas collisionnels denses (10~~<ne<1021cm-3,~e=600e~) de Cu,Ge,Se,Mo e t Ag.

Nous presentons ici les calculs thkoriques des coefficients de taux de recombinaison diklectronique des ions nkonoi'des vers les ions sodiumoi'des.Les paramktres atomiques nkcessaires

h

c e t t e etude : knergies, longueurs d10nde,probabilit8s radiatives e t dlautoionisation sont calcul6es

h

llaide de deux codes :

SUPERSTRUCTURE e t AUTOLSJ. Abstract

The dielectronic satellite lines of t h e neon-like resonance lines l s 2 2 ~ ~ 2 ~ ~ 3 d - ls22s22p6 have been observed in the spectra obtained during the Limeil X-ray Laser experiments under collisional dense plasma conditions ( 1 0 2 ~ < n e < 1 0 ~ ~ c m - ~ , ~ e = 6 0 0 e ~ ) for Cu,Ge,Se,Mo and Ag.We present here the theore- -tical calculations of dielectronic recombination r a t e coefficients for neon-like ions t o form sodium- like ions.The atomic parameters required a r e energy levels,wavelengths,radiative and autoionization probabilities-The quantities a r e calculated with two coherent codes SUPERSTRUCTURE and AUTOLSJ.

Introduction

The X-ray spectra in the range of Ne-like resonance lines emitted from a soft X-ray Laser plasma i s used t o make a spectroscopic diagnostic of t h e p1asma.B~ computing intensity ratios of Ne-like resonance and Na-like satellite lines,we a r e able t o obtain plasma parameters (electronic density and temperature). This study implies the knowledge of t h e Z-dependance of different atomic parameters:

*

wavelengths (for the resonance and satellite lines)

*

autoionization and decay rates (of doubly excited states involved in the satellite lines) or

*

corresponding line factors F*,:

P*, = g,/gi

.

AaAr/(Aa+Ar) (see Figure 1).

We used,to determine all these parameters,atomic structure and electron-ion computer codes:

*

SUPERSTRUCTURE

and

*

AUTOLSJ.

The calculations,including relativistic effects in a fine structure scheme,have been done on a large selection of ions,from Ar t o Ag.

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JOURNAL DE PHYSIQUE

1 ~ 2 2 ~ 2 2 ~ 5 3 1 3 1 '

ls22s22p6 (ionization limit)

Figure 1 : Diagram of Ne- and Na-like ions,showing t h e resonance lines and associate satellite transitions.

Theoretical methods

The energy levels,wavelengths and decay rates a r e calculated using t h e SUPERSTRUCTURE computer code /l/.In a first step,this code constructs a s e t of non-relativistic wavefunctions of the 10-electron system by diagonalization of t h e non-relativistic Hamiltonian,using orbitals nl calculated in a scaled Thomas-Fermi-Dirac potentia1,the scaling parameters

A1

being obtained by a self-consistent energy minimization procedure of all the

terms

of t h e configurations ls22s22p6,2p531 (l=s,p,d) (see Figure 2).In a second step,the code diagonalizes on this basis t h e Breit-Pauli Hamiltonian,including relativistic corrections in configuration mixing,to determine all the

levels

of t h e following configuration sets:

The autoionization probabilities and the line factors a r e calculated by using t h e AUTOLSJ code /2/,which needs a s inputs

,

from SUPERSTRUCTURE :

*

the 'term coupling coefficientsf for N and N+l electronic systems (N=10),

*

the radiative de-excitation probabilities (A,).

It determines t h e bound-free transition matrix elements,in a Distorted Waves approximation,

and calculates the recoupling coefficients,and,afterwards,the autoionization probabilities (Aa) and the line factors ( F * ~ ) .

Application of t h e histogram-construction t o the satellites of Ne-like resonance lines

On Figures 4 t o l0,the histograms represent (solid lines) t h e line factors F*, of t h e dielectronic satellites:

normalized t o their maximum (for each element) F*s,reached atX(see Figure 3),and (dashed lines) t h e position of the corresponding resonance lines versus wavelengths:

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Determination of t h e dielectronic recombination r a t e coefficients 1000.

0

l=d

:;;7-i-1

l=p 500

- .

_.

_z 18 22 26 2 9 3 2 3 6 39 42 47

All these calculations allow us

to

determine the dielectronic recombination r a t e coefficient %(j)

*

from the Ne-like ground s t a t e i=ls22s22p6 I s O

*

t o the Na-like ground s t a t e or one of t h e n=3 singly excited s t a t e s j=ls22s22p631 (l=s,p,d)

*

via t h e chosen s e t of doubly excited states s=ls22s22p531311 (l=ll=s,p,d) which can be written,if Te is the electronic temperature of t h e plasma (in eV) :

%(j)=1.65

lo-22

~ * ( j ) ~ ~ - 3 1 2 exP(-~*(j)/Te) (see Figure 13) The partial n=3 total dielectronic r a t e coefficient ddtot = ~ ( j ) is then approximated by :

j=zP631

Figure 2 : Scaling parameters of a 10-electrons Figure 3 : Line factors and wavelengths of the TFD potential versus nuclear charge. strongest dielectronic satellite line

((ls22s22p5)3d2 2 ~ 7 / 2

-

2p3d 2 ~ 5 / 2 ) versus nuclear charge.

f - v

,i

-

, ; ,$'

-K

,.*

.*

--

'.

-

_.--

1

18 22 26 29 3 2 3 4 3 6 39 42 47 Z

d d t o t = ~ e x p ( - 'Z2/Te)(~,/z2)-3/2 (see Figure 14).

20

. 5

References

/1/ W. Eissner,M. Jones,H. Nussbaumer Comput.Phys.Comm.8,270(1974)

/2/ J. Dubau,M. Loulergue J;Phys.B15,1007 (1981)

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Figure 4 : Argon ( 2 4 8 )

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Figure 11 : Germanium (Z=32)

Targgt :

500 A Ge deposited on 500 CH

Laser :

non gaussian pulse 1 ns,2*5 1 0 1 3 ~ / c m 3

"'0

(all the satellite lines are blended)

( F*, is in 1012 unit)

3C

satellite lines

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I

satellite lines

1

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Figure 13 : Total line factors and averaged energies versus nuclear charge.