INVESTIGATION OF EXCITATION MECHANISMS IN NEON WITH THE AID OF THE RADIAL DISTRIBUTION OF EXCITED ATOMS

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INVESTIGATION OF EXCITATION MECHANISMS IN NEON WITH THE AID OF THE RADIAL

DISTRIBUTION OF EXCITED ATOMS

S. Valignat, J. Leveau, F. Deigat

To cite this version:

S. Valignat, J. Leveau, F. Deigat. INVESTIGATION OF EXCITATION MECHANISMS IN NEON WITH THE AID OF THE RADIAL DISTRIBUTION OF EXCITED ATOMS. Journal de Physique Colloques, 1979, 40 (C7), pp.C7-7-C7-8. �10.1051/jphyscol:1979703�. �jpa-00219062�

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JOURNAL DE PHYSIQUE CoZZoque C7, suppzdment m n07, Tome 40, JuiZZet 1979, pape C7- 7

INVESTIGATION OF EXCITATION MECHANISMS IN NEON W I T H ME AID ff THE RADIAL DISTRIBUTIMU OF EXCITED ATOMS

S. Valignat, J. Leveau, F. Deigat.

E.R.A., C.N.R.S. n o 302 Laboratoire de Spectroscopic e t de L d n e s c e n c e , Universite' CZaude Bernard Lyon I, 43, Bd du 11 Novembre 1918 69621 ViZZembanne, France.

The r a d i a l distribution of excited neon atoms i n with other experimental r e s u l t s /2/.

5 5

the 2p 3p and 2p 3s configurations a r e investigated 2- The variation of t h e a v e r a g e e l e c t r o n energy under the following experimental conditions : g a s with p r e s s u r e is plotted i n Fig. 2 . These r e s u l t s p r e s s u r e 0.4 t o 3.1 T o r r , radius of the d i s c h a r g e c o r r e s p o n d satisfactorily with calculated data /3/.

tube R=O. 5 c m , discharge c u r r e n t 1=2 t o 40 mA. 3- The electronic density on the a x i s of the d i s - The absolute concentrations of excited a t o m s on c h a r g e is well r e p r e s e n t e d by the following equa- the axis of the discharge and the e l e c t r i c a l p a r a - tion 9

ne= (2.6 + 0.4) 10 I P m e t e r s a r e a l s o determined. All these r e s u l t s per- with ne i n cm-3, P i n T o r r and I in mA.

m i t us t o obtain the excitation c r o s s sections of the 4- The r a d i a l distribution N ( r ) of excited a t o m s 2p 3p levels f r o m the ground s t a t e and f r o m the 5 shows the s a m e behaviour f o r a l l the 2p53p s t a t e s 2p 3s configuration. I n the l a t t e r p r o c e s s we can, 5 (Fig. 3 ) . In c o n t r a s t the r a d i a l metastable and r e - with the a i d of r a d i a l distributions, differenciate sonant profiles M ( r ) a r e d i f f e r e n t a t low p r e s s u r e s the r o l e s played by metastable and resonant states. and become s i m i l a r when the p r e s s u r e i s i n c r e a - Experimental methods. The e l e c t r i c a l p a r a m e t e r s s e d (Fig. 4).

a r e obtained with cylindrical probes. F o r the elec- 5- The t o t a l density of a l l the 2p 3 p ( Z ni) and a l l 5 t r o n energy distribution funci .on we use the m e - 5

the 2p 3 s (t m . ) s t a t e s on the a x i s of the dischakge J

thod of probe c u r r e n t modulation. We deduce the tube a r e shown i n Fig. 5 a s a function of p r e s s u r e intensity of the e l e c t r i c field f r o m the difference a t different c u r r e n t intensities.

between the floating potentials of two probes. The 6- At steady s t a t e we have f o r the i t h level of the electronic mobility is calculated f r o m the m e a s u - 2p 3p configuration 5 :

r e d distribution functions. These r e s u l t s allow us ( 1 ) ni T i ⁼^{ne(n Zoi}⁺

f

Zji m j )

t o determine the electronic density. where n i s the ground s t a t e atomic concentration, The investigation of the s p e c t r a l lines intensities g. the relaxation frequency and Z Z .. a r e the

O i ' ^ji

a r e c a r r i e d out a c r o s s the a x i s of the d i s c h a r g e d i r e c t and stepwise excitation coefficients. Know- tube. The r a d i a l distribution of 2p 3p a t o m s i s de- 5 ing the e l e c t r o n velocity distribution functionf(v) t e r m i n e d a f t e r Abel inversion and a cw tunable dve - - we mav w r i t e the l a t t e r a s

5 - ^a0

l a s e r i s used t o find the r a d i a l distribution of 2p 3 s - ^j*vf(v)dv ^; Z . . . . vf(v)dv a t o m s / l / . Putting a m i r r o r behind the discharge z ~ i i Q ~ i vi 31 ~1 v j i

-

where Q and Q.. a r e the m e a n c r o s s sections tube we m e a s u r e the autoabsorption and thus the O i J1

corresponding t o the two excitation p r o c e s s e s . density of metastable s t a t e s . With the help of a c a -

Calling j = l and j=2 the metastable and resonant librated l a m p we obtain the absolute intensity of

s t a t e s and assuming a z e r o o r d e r B e s s e l function the radiating atoms.

r a d i a l profile of the i th level : with electronic deficit i n the energy region above

the f i r s t excitation potential (Fig. I ) i n a g r e e m e n t

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979703

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Z.i m.(O) ni(r)

with b.. =

' '

^IVi(r)⁼^-

31 ZOi n ni(o)

The c r o s s sections QOi, Qli, QZi a r e computed

f r o m equations (1) and (2) and experimental data. A 1 3 _dV&(p. v")

'

^{' J a}

The r e s u l t s a r e given i n Table 1. They a r e ingood Rrst ( e v ) -

a g r e e m e n t with those found i n /4/ (values of Qoi 4.. , exciliiKon m e a s u r e d by the e l e c t r o n b e a m method) /5/ (theo-

-

r e t i c a l values of Q.. calculated with the B o r n ap-

J1 -

proximation) and /6/ (experimental values of Qli found by optical pumping).

References.

C R / l / v a l i g n a t S . , Leveau J., Deigat F. e t Falgon R.

400 Rev. Phys. Appl. 12 (1977) 1007

/ 2 / ~ u t s c h e r A. e t P f a u 5. Fig 3 Fig &

B e i t r . Plasmaphys. 7 (1967) 43 / 3 / ~ a r a m o o n A. A. e t I s m a i l I. A.

J. Phys. D :Appl. Phys. 10 (1977) 991 / 4 / ~ r i s h S. E. e t Revald V. F.

Opt. and Spectrosc. 15 (1963) 395 / 5 / ~ e t e r o v I. M. e t Chebotaev V. P.

Opt. and Spectrosc. 23 (1967) 467 / b / ~ a m s o n A . V.

Opt. and Spectrosc. 42 (1977) 321

Torr 3.4 Torr

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Table 1