• Aucun résultat trouvé

THE RELATIVE CONTRIBUTION OF ASSOCIATIVE IONIZATION AND PHOTOIONIZATION IN XENON PRECURSORS

N/A
N/A
Protected

Academic year: 2021

Partager "THE RELATIVE CONTRIBUTION OF ASSOCIATIVE IONIZATION AND PHOTOIONIZATION IN XENON PRECURSORS"

Copied!
3
0
0

Texte intégral

(1)

HAL Id: jpa-00219456

https://hal.archives-ouvertes.fr/jpa-00219456

Submitted on 1 Jan 1979

HAL

is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire

HAL, est

destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

THE RELATIVE CONTRIBUTION OF ASSOCIATIVE IONIZATION AND

PHOTOIONIZATION IN XENON PRECURSORS

M. Vasil’Ev, T. Zhikhareva, G.K. Tumakaev

To cite this version:

M. Vasil’Ev, T. Zhikhareva, G.K. Tumakaev. THE RELATIVE CONTRIBUTION OF ASSOCIA-

TIVE IONIZATION AND PHOTOIONIZATION IN XENON PRECURSORS. Journal de Physique

Colloques, 1979, 40 (C7), pp.C7-101-C7-102. �10.1051/jphyscol:1979750�. �jpa-00219456�

(2)

JOURNAL DE PHYSIQUE Colloque C7, suppzgment au no?, Tome 40, JuiZZet 1979, page C7- 101

THE RELATIVE CONTRIBUTION OF ASSOCIATIVE IONIZATION AND PHOTOIONIZAflON XENON PRECURSORS

M.G. Vasil'ev, T.V. Zhikhareva and G.K. Tumakaev.

I o f f e Physicotechnical I n s t i t u t e , Academy o f Sciences, Leningrad, U.S.S.R.

A b s t r a c t . The k i n e t i c s of xenon e x c i t a t i o n c o l l i s i o n s w i t h atoms, a l s o tile chances i n and i o n i z a t i o n and of t h e e l e c t r o n gas h e a -

tile electron gas energy involved in the t i n g ahead of t h e shock f r o n t were s t u d i e d

t h e o r e t i c a l l y f a r t h e &Pack number r a n g e 1 4 p i l o t o i o n i z a t i o n , a s s o c i a t i v e i o n l z a t i o n t o 20 and i i l i t i o l p r e s s u r e p = 5 slu~ Hg.The and d i s s o c i a t i v e r e c o n b i n a t i o n p r o c e s s e s . i o n i z a t i o n k i n e t i c s of xenon atoins was

found t o d i f f e r s u b s t a n t i a l l y f r o u t h a t of The r o l e of v a r i o u s Bidberg s t a t e s of argon. I n t h i s c a s e one should t a k e siriiul- &enon atoms p a r t i c i p a t i n g i n tile a s s o c i a - t a n e o u s l y l n t o account b o t h a s s o c i a t i v e

l o l l i z a t i o n a a p h o t o i o n i z a t i o n , t h e l a t t e r t i v e l o n l z a t i o l l r e a c t i o n /4/ h a s a l s o been becouiing predominant i n t h e chkrged p a - t i c - s t u d i e d . S i n c e tile o s c i l l a t ~ r s t r e n g t k ~ s l e p r o d u c t i o n a n xenon w i t h i n c r e a s i n g f o r t h e t r a n s i t i o n s i n t o t h e s e s t a t e s s t r e n g t l i of t h e i n c i d e n t shock. The t h e o r e -

t i c a l p r e d i c t i o n s f o r t h e e l e c t r o n d e n s i t y d i f f e r s u b s t a n t i a l l y r r o u one a n o t i l e r , t h e a r e oompared w i t h e x p e r i m e n t a l v a l u e s . c o n t r i b u t i o n of t h e atoins t o t h e o l ~ a r g e d

A s h a s been e s t a b l i s h e d e a r l i e r //l,;?/, p a r t i c l e p r o d u c t i o n i s n o t t h e same. The p h o t o i o n i z a t i o n i n t h e a r g o n p r e c u r s o r s l a r g e s t and a l m o s t e q u a l c o n t r i b u t i o n s co-

4 C

c a n n o t aocount l o r u r p e r l m e n t a l v a l u e s of me from atoms i n t h e 6d

L1ili

and 5d'

t h e e l e c t r o n d e n s i t y ahead of a shock even

id;];)

s t a t e s , t h e s u l a l l e s t one b e i n g d u e when t h e r e f l e c t i o n of l i n e and continuum t o t h e 7d

[($I:

s t a t e . Tile d i f f e r e n c e r a d i a t i o n from t h c t u b e w a l l s IS I n c l u d e d . i n t h e m o l e c u l a r i o n d e n s i t i e s f o r t h e s e The dominant neckanism of charged p a r t i c l e c a s e s i s a f a c t o r of + lQ3.

p r o d u c t i o n i n a r g o n i s a s s o c i a t i v e i o n i z a - The r e s u l t i n g s y s t e u of d i l f e r e n t i a l t i o n of t h o Uolner-type /5/. The p r e s e n t e q u a t i o n s U e s c r i b i n g t h e k i n e t i c s of e l e c t - work d e a l s w i t h a s t u d y O f t h e k i n e t i c s of r o n g a s excitation, i o n i z a t i o n and h e a t i n g fundamental p r o c e s s e s i n t h e xenon y r e c u r - w i t h asymp'totic b o u m a r y c o n d i t i o n s \vas s o r s w i t h t h e p u r p o s e of d e t e r m i n i n g t h e

predominant machanism of i o n i z a t i o n . 'i'he r a d i a t i v e and ; o l l i s i o n a l p r o c e s s e s c o n s i - d e r e d xenon atoms I n r e s o n a n c e and h i g h l y e x c i t e d a t a t e s i n cha p h o t o e x c i t a t i o n of ground s t a t e atoms and t h e i r r a d i a t i v e and oascade t r a n s i t i o n r e l a x a t i o n t h e t h e ground s t a t e ; ( 2 ) P h o t o i o n i z a t i o n of atoms from t h e ground and r e s o n a n c e s t a t e s ) ; (5) E x c i t a t i o n of atoms f r o u t h e ground i n t o r e s o n a n c e s t a t e s and t h e p r o c e s s e s of t h e i r de-exc i t a t i o n and i o n i z a t i o n by e l e - c t r o n i m p a c t ; ( 4 ) A s s o c i a t i v e i o n i z a t i o n i n v o l v i n g an atom i n a h i g h l y e x c i t e d Bid- b e r g s t a t e

XZ;

+ Xe + Xe:+ e and d i - s s o c i a t i v e r e c o m b i n a t i o n ; ( 5 ) l o n i c conver- s i o n %e

+

+ Xe + $2 2 % e l + XQ,

iihen c o n s t r u c t i n g t h e energy b a l a n c e e q u a t i o n f o r t h e e l e c t r o n gas, we i n c l u d e d , a p a r t from e l a s t i c and i n e l a s t i c e l e c t r o n

s o l v e d n u i n e r i c a l l y by t h e ilunye-kutta ule- thod.

The r e s u l t s of elre computations show t h a t w h i l e t h e e x c i t a t i o n k i n e t i c s of t h e i n e r t g a s e s a r e t h e same, t i l e i o n i z a t i o n k i n e t i c s of sellon J i 9 f e r s ruariiedly f r o u t h a t of argon. ittiis i s due p r i r i a r i l y t o t h e h i g h p l i o t o i o n i z a t i o n c r o s s s e c t i o n of e x c i t e 4 xenon u t o u s wirich exceeds by about 20 t i m e s t h a t of argon. The p i ~ o t o i o n i z a t i - on c r o s s s e c t i o n of tire 6 s

[li]; ,

r e s o - nance l e v e l was c a l c u l a t e d b y the ~ietilocl of Uurgess-Seaton /5/, i t s v a l u e a t t h e t h r e s l l o l d b e i n g 3.6 8 lCv'18 c u 2

.

Fig.1 p r e s e n t s i o n i z a t i o n

rates.

v s .dis- t a n c e rrom tile s i ~ o c i i f r o n t i n u n i t s of tu- be r a d i u s ( R 5 cni). Ln c o n t r a s t t o arbon, where t h e p r o d d c t i o n o f charged p a r t i c l e s i s clet ermined p r edoiilinalltly by a s s o c i a t i v e i o n i z a t i o n ~ v i l i l e clle p l ~ o t o i o n i z a t i o n pro-

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979750

(3)

Fig.1. ~ o n i z a t i o n r a t e p r o f i l e s ( ~ m - ~ s ' l ) . S o l i d curve: e x c i t e d s t a t e photoio- n i z a t i o n r a t e ; Dashed curve: asso- c i a t i v e i o n i z a t i o n r a t e .

1: M-14 without r e f l e c t i o n . 2: ~ 5 2 0 w i t h o u t r e f l e c t i o n . 3: Y-20 w i t h r e f l e c t i o n .

~ i g . 2 . E l e c t r o n d e n s i t y p r o f i l e s ( c d 3 )

.

S o l i d curves: t h e o r y f o r t h e c a s e s i n t h e preceding f i g u r e ;

Dashed curves: d a t a obtained by mic- rowave i n t e r f e r o m e t r y /6/.

c e a s e s a r e n e g l i g i b l e , i n xenofi a t f 1 t h e probabilities of p h o t o i o n i z a t i o n ( ~ h ) and a s s o c i a t i v e i o n i l r e t i o n (As) become c o r p a r a b l e a l r e a d y a t M ~ 1 4 , t h e ( ~ h ) r a t e e r . oeeding t h e ( A S ) r a t e i n t h e immediate v i - o i n i f y of t h e shock f r o n t .

The c o m p e t i t i v e r o l e of t h e photoionisa- Bfon of e x c i t e d s t a t e s eompared w i t h t h e

@ e ~ e s t 3 of a s s o c i a t i v e i o n i z a t i o n i n a r e a s -

e s subs t a n t i a l l y with i n c r e a s i n g Mach num- b e r anci when t a k i n g i n t o account t h e r e f - l e c t i o n of r a d i a t i o n from t h e w a l l s . Ande- ed, even without t h e i n c l u s i o n of r e f l e c t i - on, (ph) exceeds (AS) by an o r d e r of magni- t u d e near t h e b l f r o n t a t k320, These ~ ~ ~ ~ p r o c e s s e s become comparable h e r e a t a much l a r g e r d i s t a n c e from t h e f r o n t ( #&lo) t h a n i s t h e c a s e a t ~ ~ 1 4 , Taking t h e r e f - l e c t i o n i n t o account i n c r e a s e s s u b s t a n t i - a l l y t h e r o l e of t h e e x c i t e d s t a t e photo- i o n i z a t i o n . As a r e s u l t , t h e p h o t o i o n i z a t i - on p r o c e s s becoues predominant throu&lout t h e range of f~ considered.

Note t h a t a s t d e p h o t o i o n i z a t i o n e f f i c i - ency i n c r e a s e s , t h e e f f i c i e n c y of t h e ato- mic-to-molecular i o n conversion a s w e l l a s of t h e d i s s o c i a t i v e recombination p r o c e s s w i l l l i k e w i s e i n c r e a s e accordingly. Indeed, a t ~ " 2 0 t h e i o n conversion r a t e throughout t h e range of

9

considered exceeds t h e as- s o c i a t i v e i o n i z a t i o n r a t e i f t h e r a d i a t i o n r e f l e c t i o n i s c o n s i d e r e d , so t h a t under t h e s e c o n d i t i o n s t h e molecular i o n s s i ~ o u l d f oru p r i n a r i l y by way of conversion of ato- mic i o n s r a t h e r t h a n i n the course of t h e

a s s o c i a t i v e i o n i z a t i o n process a s was t h e c a s e f o r 61514.

Fig.2 shows the t h e o r e t i c a l and experi- mental p r o f i l e s of e l e c t r o n u e n s i t y . A con- p a r i s o n of t h e r e s u l t s i n d i c a t e s a s a t i s - f a c t o r y agreement between t h e experimental and t h e o r e t i c a l d a t a and a q u a l i t a t i v e l y good f i t of t h e c a l c u l a t e d e l e c t r o n d e n s i - t i e s f o r bile c a s e of r a d i a t i o n - r e f l e c t i n g w a l l s t o t h e experimental dependence on

8 -

References.

1. T .V.ZhikhBrevB, ~ . ~ . ~ a s i l ' y e v

,

12 I n t

Conf .Phen.Ion.Gas, S n d h o v e n , The Nether- l a n d s , 1975.

2rT .V .Zhikhareva, -.G'.Vasi 1' ev, J~*G.iforo- zov, Zhur.Tekhn.Fiz.

&,

N 3 , 568 (1975).

3 r A .g.Bulyshev, N.G.Preobrazhenskii, A.&.

Suvor ov, V ,N .Yakovlev, i n ttPhysical Gas Dynamicsit ( l n ~ u s s i a n ) , N 6, AETM, No- v o s i b i r s k , p .19 (1976) r

4. P.I.Huffmsn, U.H.Katayama, J.Chem.Phys.

&,

138 (1966).

5. A .BurgesB, Mbi7.Seabon, Mn.Not .Boy.Ast- ron.Soc.

a,

1 2

-

1 2 1 (1960).

'6. b . ~ & a v a r i n , V .V.Bozhdeetvenskii, G.K.

Tumakaev, Proc .I All-Union Saminar on Plasme Conductometry, Yoscow, 1977.

Références

Documents relatifs

To test whether the vesicular pool of Atat1 promotes the acetyl- ation of -tubulin in MTs, we isolated subcellular fractions from newborn mouse cortices and then assessed

Néanmoins, la dualité des acides (Lewis et Bronsted) est un système dispendieux, dont le recyclage est une opération complexe et par conséquent difficilement applicable à

Cette mutation familiale du gène MME est une substitution d’une base guanine par une base adenine sur le chromosome 3q25.2, ce qui induit un remplacement d’un acide aminé cystéine

En ouvrant cette page avec Netscape composer, vous verrez que le cadre prévu pour accueillir le panoramique a une taille déterminée, choisie par les concepteurs des hyperpaysages

Chaque séance durera deux heures, mais dans la seconde, seule la première heure sera consacrée à l'expérimentation décrite ici ; durant la seconde, les élèves travailleront sur

A time-varying respiratory elastance model is developed with a negative elastic component (E demand ), to describe the driving pressure generated during a patient initiated

The aim of this study was to assess, in three experimental fields representative of the various topoclimatological zones of Luxembourg, the impact of timing of fungicide

Attention to a relation ontology [...] refocuses security discourses to better reflect and appreciate three forms of interconnection that are not sufficiently attended to