INVESTIGATION OF ANOMALOUSLY HIGH-SPEED DE-EXCITATION OF Eu+ METASTABLE STATES IN GAS DISCHARGE PLASMA USING MODULATION OF INDUCED RADIATION

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INVESTIGATION OF ANOMALOUSLY HIGH-SPEED DE-EXCITATION OF Eu+ METASTABLE STATES IN GAS DISCHARGE PLASMA USING MODULATION

OF INDUCED RADIATION

P. Bokhan, V. Klimkin, A. Maltsev, V.E., Prokopiev, V. Sokovikov

To cite this version:

P. Bokhan, V. Klimkin, A. Maltsev, V.E., Prokopiev, et al.. INVESTIGATION OF ANOMA- LOUSLY HIGH-SPEED DE-EXCITATION OF Eu+ METASTABLE STATES IN GAS DISCHARGE PLASMA USING MODULATION OF INDUCED RADIATION. Journal de Physique Colloques, 1979, 40 (C7), pp.C7-115-C7-116. �10.1051/jphyscol:1979757�. �jpa-00219463�

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JOURNAL DE PHYSIQUE CoZZoque C7, suppZ6ment a u n07, Tome 40, J u i Z Z e t 1979, page C7- 115

INVESTIGATION OF ANOMALOUSLY HIGH-SPEED DE-EXCITATION OF EU+ METASTABLE STATES I N GAS DISCHARGE PLASMA USING MODULATION OF UUDUCED RADIATION

P.A. Bokhan, V.M. Klimkin, A.N. Maltsev, V.E., Prokopiev, V.G. Sokovikov.

The I n s t i t u t e o f A t m o s p h e r i c O p t i c s , U . S . S . R., Academy o f S c i e n c e s , S i b e r i a n Branch, Tomsk 634055, U.S.S.R.

1. The r e a l i z a t i o n of high-speed de-ex- of 7~1,5 F;U+ s t a t e s using t r a n s p o r t a t i o n c i t a t i o n of metastable s t a t e s i s of deci- of p a r t i c l e s ( ~ 2 % of population) from the s i v e importance f o r e x c i t a t i o n of continu- resonance l e v e l s 7 ~ * . ) ~ , 9p5 by stimulated ous generation o r t h e pulsed one with high, emission, and by observing t h e response frequency of p u l s e r e p e t i t i o n i n t h e l a - of another l e v e l s of Eu atoms and ions.

s e r s on t r a n s i t i o n s from resonance t o me- I n c o n t r a s t t o atomic spectrum t h e inten- t a s t a b l e l e v e l s . The only case when quasi- s i t y modulation with t h e depth about continuous generation on such t r a n s i t i o n s 0.1+2w was observed on a g r e a t number of i n t h e i o n i s observed i s t h e c a s e of ge- Eu i o n l i n e s . A s e r i e s of t h e r e s u l t s of n e r a t i o n i n XU++ He mixture- I n t h i s mix- lGu+ l i n e modulation measurements i s given t u r e t h e l a r g e v a l u e s of power and e f f i c i - i n t h e t a b l e .

ency

[I]

were obtained, t h e r e f o r e t h e in- Table v e s t i g a t i o n of p o s s i b l e mechanisms of high

N Wavelength T r a n s i t i o n

0 B ,%

-speed ( C 4 1 0 - ~ s ) .de-excitation of

A metastable s t a t e s i s of g r e a t i n t e r e s t .

2. D i r e c t experimental study of a l l t h e 6173 +13-6

processes which may determine de-excitati- 2 6049 o f s t a t e s 2 i s d i f f i c u l t .

3 5966 The a n a l y s i s of such processes shows t h a t

4 3721 +11.5

i n r e l a x a t i o n t h e t h r e e paths of p a r t i c l e

motion through e x c i t e d s t a t e s 5 7077 + 1.15

a r e observed. Of obvious i n t e r e s t i s t h e

+ 0.7 experimental determination of t h e p a r t i c l e

motion path, which a c t u a l l y t a k e s place, 10 7301 9, + 0.2

because i n t h i s c a s e a number of r e a c t i - 11 7426 0

ons t o be considered i s much l e s s .

12 4205

' 9

_s40

-

0.9

I n this paper t h e p a r t i c l e p a t h was

determined by t h e population p e r t u r b a t i o n These r e s u l t s were obtained a t He

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979757

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p r e s s u r e of 450 t o r r and c u r r e n t d e n s i t y -10 A/cm2. The modulation c o e f f i c i e n t B=( J-J' ) / J where J, J' a r e t h e l i n e inten- s i t i e s without generation a t A =I .0019~u m and with generation of mean power 0.25 W.

The s i m p l i f i e d scheme of EU+ t r a n s i t i o n s , explaining t h e t a b l e , i s given i n Fig.?.

l a s e r operating t r a n s i t i o n

3. The r e s u l t s of t h e experiments were analyzed both q u a l i t a t i v e l y , taking i n t o account t h e reabsorption e f f e c t on t h e in- t e n s i t i e s of spontaneous l i n e s and l i f e - times of excited s t a t e s , and q u a n t i t a t i v e - l y , using a computer, according t o t h e c a l c u l a t i o n .procedure given i n [ 3

] .

^This

a n a l y s i s has shown:

a ) I n t h i s case t h e e x c i t a t i o n t r a n s f e r be-

9 7

tween P and P2,4 s t a t e s occurs. The 5

most probable t r a n s f e r mechanism i s t h e c o l l i s i o n s of e x c i t e d E'u i o n s with He.

b)l'!he o r i g i n of generation causes t h e 15- -20% decrease of population of t h e upper operating l e v e l 7 ~ 4 (and a l l the associa- t i o n of 9 ~ 5 , 7 ~ 2 1 4 l e v e l s ) and 2% and 5%

i n c r e a s e of population of 9 ~ j , 4 and 9 DIG5 l e v e l s , r e s p e c t i v e l y .

c)The reason of t h e 9 ~ 3 , 4 populations inc- r e a s e i s t h e growth of ~ u + ground s t a t e population with a c t i v a t i o n of generation.

d)Absolute values of resonance s t a t e s po- p u l a t i o n s a r e ( 3 ~ 8 ) . 1 0 ~ ~ c m - ~ , and those of 9~ s t a t e a r e (417)

.lo

13 cm3. E f f e c t i v e

5

temperature of populations d i s t r i b u t i o n i n s i d e t h e 9 D m u l t i p l e t i s llOO°K.

These r e s u l t s %ogether with t h e f a c t of absence of modulation of s p e c t r a l l i n e s belonging t o t h e atomic spectrum, allowed t o draw a conclusion on conservation of a number of p a r t i c l e s i n considered associat- i o n of l e v e l s ( 7 9 9 ~ , 7 r 9 ~ , 7 9 9 ~ ) i n t h e cour- s e of r e l a x a t i o n . It i s impossible t o de-

termine t h e type of t h e p a t h , ( l ) o r (2),on t h e b a s i s of t h e a n a l y s i s c a r r i e d out.

4. A p o s s i b l e mechanism of de-excitation of metastable s t a t e s i s , i n our opinion,recombination i n t h e displaced atomic spectrum with He w i t h subsequent r e l a x a t i o n among displaced spectrum l e v e l s and with auto-io- n i z a t i o n i n t o t h e i o n ground s t a t e . A t pre- s e n t this process i s n o t s t u d i e d p r a c t i c a l - l y , b u t it i s of i n t e r e s t not only f o r s o l - ving t h e problem of continuous generation regime on s e l f - l i m i t i n g t r a n s i t i o n s of o t - h e r i o n s , b u t a l s o f o r i n v e s t i g a t i n g proce- s s e s of e l e c t r o n capture, recombination, a n a l y s i s of p a r t i c l e s and energy balances i n ionized gases, e t c .

References

1 .P. A.Bokhan,V .M .Klimkin,V .E .Prokopiev

,

S .S .Monastyrev, JETP L e t t e r s ,2,4?0,?977.

2.P.A.Bokhan,V.D.Burlakov,V.M.K1~mk~n,

V.E.Prokopiev, The papers of 3-rd I n t e r n . Confer. on Lasers and Applications,Dresden,

GDR, 1977.

3.PeA.Bokhan,A.N.Maltsev,In:Effective l a s - e r s on metal vapors,IOA SO AN SSSR,l978,p.46.