KINETICS OF THE ELECTRONS IN THE STATIONARY BEAM DISCHARGE PLASMA IN DIATOMIC GASES

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KINETICS OF THE ELECTRONS IN THE STATIONARY BEAM DISCHARGE PLASMA IN

DIATOMIC GASES

R. Winkler, J. Wilhelm, A. Ivanov, V.V. Starykh

To cite this version:

R. Winkler, J. Wilhelm, A. Ivanov, V.V. Starykh. KINETICS OF THE ELECTRONS IN THE STA-

TIONARY BEAM DISCHARGE PLASMA IN DIATOMIC GASES. Journal de Physique Colloques,

1979, 40 (C7), pp.C7-261-C7-262. �10.1051/jphyscol:19797128�. �jpa-00219100�

JOURNAL DE PHYSIQUE CoZZoque 67, suppZgment n07, ~ o m e 40, juitZet 1979, page C7- 261

KINETICS OF THE ELECTRONS IN M E STATIONARY BEAM DISCHARGE PLASMA IN DIATOMIC GASES

R. Winkler, J. Wilhelm, A.A. ~vanov* and V.V. 5tarykhX.

.&entraZ I n s t i t u t e of Electron Physics Part V , Academy of Science 22 GreifswaZd G.D.R.

I . V . Kurehatov I n s t i t u t e of Atomic Energy, Moscow

S. S. R.

1ntroduEtion:In r e c e n t y e a r s i n c r e a s i n g a t t e n t i o n has been p a i d t o the investiga- t i o n s of the s t a t i o n a r y turbulent beam discharge plasma, nonresbnant heated by h n & u i r waves, e s p e c i a l l y under tihe as- pect of a p p l i c a t i o n i n plasma chemistry /'?/. Thus i t i s important t o i n v e s t i g a t e

the k i n e t i c s of the e l e c t r o n component of such type of disoharge plasma because the energy input by the turbulenli e l e c t r i c f i e l d oocurs v i a the e l e c t r o n ensemble i n t o the degrees of freedom of the heavy components of the plasma by binary c o l l i - s i o n s and Coulomb interaction,Within cer- t a i n limits the dominance of s p e c i a l eaer- g y t r a n s f e r channels can be optimized by v a r i a t i o n of the dischaPge parame tiers.

Theot.etioa1 back~roundtwe starlied from the Boltzmann equation including turbulent h e a t i n g , e l a s t i o and s e v e r a l d i r e c t i n e l a - s t i c c o l l i s i o n s between e l e c t r o n s and mo- l e c u l e s as well as Qhe i n t e r a c t i o n of elec- Orons with e l e c t r o n s and with the i o n s i n t h e form of Pokker-Planok tierms.The equa- t i o n obQained f o r the i s o t r o p i c p a r t of the v e l o c i t y d i s t r i b u * i o n f u n c t i o n was nu- merically solved f o r Botal turbulenoe e n e r g i e s p e r one e l e o t r o n $ and degrees of i o n i z a t i o n (nefiIb i n a l a r g e range of v a l u e s i n whioh such beam dissharge p l a s - mas e x i s t , The me*hod necessary t o solve the complex integro-differentiial equabion was developed i n /2/,/3/.This treatmenO h a s proved s u i t a b l e f o r calculaliing Ohe q u a n t i t a t i v e behaviour of t h e electiron component and the energy t r a n s f e r s i t u a - t i o n i n beam plasmas With molecular gases.

I n t h i s paper we r e p o r t about new r e s u l t s i n nit;rogen.For c a l c u l a t i o n we used the c r o s s s e c t i o n s f o r impulse t r a n s f e r , f o r v i b s a t i c n a l and e l e o t r o n i c e x c i t a t i o n and

direct; d i s s o c i a t i o n and i o n i z a t i o n from /4/.This i n v e s t i g a t i o n i n n i t r o g e n and the comparison with the former r e s u l t s i n hy- drogen /3/ allow conclusions about the s p e c i f i c influence of the molecular pro- per t i e s on the maoroscobio behaviour .

Results and d i s c u s s i o n r %cause of t h e chosen broad i n t e r v a l s f o r and ne/B great; changes i n the dominant proaesses determining $he d i s t r i b u t i o n Tunc t i o n fb(U) a r e t o be expe6tied.fhis i s r e f leo- t e d i n the behaviour of fb(U) - ^{U momen-}

t a r y e l e c t r o n energy i n V - which a r e shown f o r n i t r o g e n and hydrogen i n Fig. 1 +or 4&=low2 and U~..16V,o.o16V,o,oo16

V and i n Fig. 2 f o r

U.0 .ol6 V and

lo'2, 1 0 - ~ . ~ r o r n t B i s we obtained Ohe mean bnergy cb shown i n Fig. 3 a s f u n c t i o n of f o t ne/R=lo-', 'loo2 and 'log3. It can be e a s i l y seen t h a t the qualit;ative depen- hence on Bhe parametels % and ne/R. 5 s the same i n n i t r o g e n and hydrogen, which sug- kesbs t h a t the q u a l i b a t i r e behaviour of Phe e l e c t r o n mean energy with ? and ne/N shows no s e n s i t i v e dependence on the natu- be of molecular gases i n the beam d i s - charge plasma. More d e t a i l e d , uN

smaller. than i n a broad medi&sized range of $ f o r she same values of ne/A due t o Dbe dominant; r o l e of ihe binary o o l l i - 9ions of e l e c t r o n s with the molecules, e s p e o i a l l y i n n i t r o g e n with i t s more com- p l i c a t e d strucsture concerning t h e vibra- t i o n a l l e v e l s . A t v e w small 5 we f i n d

bN > EH , ^{which i s} p ~ i m a r i l y due t o tihe big eneiigy l o s s e s i n bhe e l e c b r o n ~ i o n in- t e r a c t i o n POE H2.

A

-

The power i n p u t s Pb=U Veff/p0 per one electiron and p e r one Torr (with ve,/po as

the normalized e f f e c t i v e frequency f o r t u r b u l e n t h e a t i n g /2/, /3/) ake shown i n

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797128

Fig.4.The big d i f f e r e n c e of the ?-values

f o r very smail i s n e a r l y pPoportiona1 t o

neJM due t o the s t r o n g electron-ion i n t e r -

a c t i o n i n H i n comparison with N2, With

n12

increased U both v a l u e s of P a r e n e a r l y

hl

the -same i n a broad range of TJ and neD.

The small d i f f e r e n o e s a r e connected with

!he d i f f e r e n t s t r u c t u r e s of the moleculaP gases and thus with the behaviour of the corresponding diatiribution f u n c t i o n s (Figs. 1,2) ,

I n Figs. 5,6 the energy l a s s e s ze1, eei, _{Pig. 1}

TP, ifEE, ~ ~ 01 1 f o r e l a s t i c ana electron- , Pig, 2

IO*L

i o n i n t e r a c t i o n , v i b r a t i o n a l and e l e o t r o - n i c e x c i t a t i o n a s w e l l as d i s s o c i a t i o n and ,, i o n i z a t i o n r e l a t e d t o the t o t a l energy

l o s s E~ a r e represented f o r ne/N=lo-3,1 Comparing the l o s s e s i n H2 and N2 we ob-

serve g r e a t d i f f e r e n c e s with regard t o the ^{' -} e s s e n t i a l energy channels by which the

g r e a t e s t amount of enerm,introduced f r

the turbulent f i e l d , i s d i s s i p a t e d t o the Fig. 3 Fig. 4 molecules. I n H2 the energy l o s s by eleo-

rrt

tron-ion i n t e r a c t i o n p r e v a i l s a t low U s

-_

: -,/%\

Chen i n some range of 5 %he l o s s by vibra-

tjional e x c i t a t i o n and f i n a l l y at high ?f _{I '.}

tihe l o s s due t o d i s s o c i a t i o n p l a y s the do- minant r o l e . On t h e o t h e r hand i n N2 tihe v i b r a t i o n a l energy l o s s i s dominang n e a r l y i n khe whole range of 5 and only a t h i g h v

the e x c i t a t i o n of e l e c t r o n i o s t a t e s pre-

10-4

-

v a i l s . F i n a l l y , with increasing ne/N a re- -

markable s h i f t of the d i f f e r e n b l o s s pro- -

^-

oesses i n H2 as t o t h e i r dominant r o l e oc-

c u r s but i n If, t h e r e is only a change of Pi@;* 5

the range of d i n which energy 1 0 ~ S e s due

--- t o v i b r a t i b n a l and e l e o t r o n i c e x c i t a t i o n

p r e v a i l . Bef erences :

1(1975)147.

/I/ A.A. Ub.cuc& , + u ; y c ~ n j u r ; y u ~ -

/2/ R.Winkler ,J.Wilhelm,V.V .St8,rykh,XIII.

ICPIE4977,Contr.Pap.Part I1,p. 739.

/3/ ?. &.+~,ILR+ U. %AS/UJLIJL

3- 3- C m y

~

C b y p - N I Y ( 1979) i n p r i n t . /4/ S.Pf au, R.Winkler , Bei6r .piasmaphys.

l 8 (1978) 113; (1973) 273.

-

Fig. 6