COMPARISON BETWEEN SOME MACROSCOPIC PROPERTIES OF THE BEAM AND GLOW DISCHARGE PLASMA IN NITROGEN

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COMPARISON BETWEEN SOME MACROSCOPIC PROPERTIES OF THE BEAM AND GLOW

DISCHARGE PLASMA IN NITROGEN

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

To cite this version:

R. Winkler, J. Wilhelm, A. Ivanov, V. Starykh. COMPARISON BETWEEN SOME MACROSCOPIC PROPERTIES OF THE BEAM AND GLOW DISCHARGE PLASMA IN NITROGEN. Journal de Physique Colloques, 1979, 40 (C7), pp.C7-131-C7-132. �10.1051/jphyscol:1979764�. �jpa-00219470�

JOURNAL DE PHYSIQUE CoZZoque ~ 7 , suppZ6ment au n07, Tome 40, JuiZZet 1979, Page C7- 131

COMPARISON BETWEEN1 SOME MACROSCOPIC PROPERTIES OF THE BEAM AND GLOW DISCHARGE PLASMA IN NITROGEN

R. ~inkler', J. wilhelmi, A.A. ~vanov*', V.V. starykhx".

' c e n t r a l I n s t i t u t e o f Electron Physics Part V, Academy o f Science 22 ~ r e i f s w a Z d G.D.R.

*? I.V. Kurchatov I n s t i t u t e of Atomic Energy Moscow, U.S.S.R.

I n f roduct ion:Especially f rom the p o i n t of plasma.In (1) the f i r s t term r e p r e s e n t s view t h a t discharge plasma devices a r e be- the a c t i o n of the turbulent or the direct;

i n g used f o r plasmachemical purposes i t e l e c t r i c f i e l d , t h e f i r s t 4 Berms p ~ o p o r - i s of g r e a t i n t e r e s t t o bave s u f f i c i e n t t i o n a l t o g khe Coulomb i n t e r a c t i o n of the knowledge,based on k i n e t i c theory, about; e l e c t r o n s with one another and the f i f t h the behaviour of plasmas i n s e l e c t e d no- of these Chat between the e l e c t r o n s and 1ecu.la.i- gases .In p a r t i c u l a r i t i s impor- ions.The Oerm with the f a c t o r 6n/Pd r e s u l t s t a n t t o o b t a i n information on the pre- from the e l a s t i c c o l l i s i o n s and the last v a i l i n g energy channels tbrough which the term from the d i f f e r e n t i n e l a s t i c pro- energy,given t o the e l e c t r o n s by d i f f e r e n t cesseseFurthermore,by appropriate a n a l y t i - kinds of e l e c t r i c f i e l d , i s d i s s i p a t e d in- c a l i n t e g r a t i o n we obtained the energy ba- t o the s e v e r a l degrees of ibedom of the l a n c e s p e r one eleobron and per pressure heavy components .In this paper we calcu-

l a t e d t h e eleoiiron d i s t r i b u b i o n f u n c t i o n s f o r the beam and glow discharge plasma i n N2 and compared important macroscopic quantities,determined by this f u n c t i o n s , under the condition of equal power i n p u t s p e r volume unit.

Kinetic equations and e n e r n balances:We s t a r t e d from s u i t a b l e Boltzmann equations with a d d i t i o n a l Fokker-Planck terms f o r the CouLomb interaction.Using the usual development of %he Boltzmann equation we f i n a l l y got the equations /2/

i

^{' U+UPA U}

+ 3 ~ : J uQy:"cir,+JtO)dS = O

PI"

"

⁽¹⁾

(S-b-bem and &=@;-glow dischmge phsma) f o r the i s o t r o p i c p a r t f s ( U ) of the d i s t r i b u t i o n funct;ion wi%h

K .

H,=~U l J L ( ~ a + 2

Q;+

&,/u2),

w-4

^{( 2a)}

H%

=(E/~E)'

o /f

n? (QCL + ,&&.=.

g

I Q:,,".

0'1.

( 2b)

a

^{i s} the t o t a l turbulence energy p e r one eleotpon i n the beam discharge plasma,non- resonant; heated by Langmuir waves, and B t h e e l e c t r i c f i e l d i n the glow discharge

K -2%

8

⁼

( ~ 9 ~ ~ ) ~

⁺

toei/po 1,

⁺

5- c or-

/PO)J ^(3a,b) with

4 N 2

.P,

⁼

U

V J / &

,

^'$%= p?be

(E/~.)).

^(4a,b)

The terms i n (4) r e p r e s e n t s the energy input p e r one e l e c t r o n and pressure unit;

by the turbulent OP %he d i r e c t e l e o t r i e f i e l d , t h e 3 terms on the e.h.s.of (3a,b)

the energy l o s s e s i n e l a s t i c c o l l i s i o n s , by Coulomb i n t e r a c t i o n between e l e c t r o n s and i o n s and f i n a l l y by tihe d i f f e r e n t i n e l a s t i c c o l l i s i o n procssses.We chose tihe same cross s e c t i o n s f o r the descrip- t i o n as i n /?/.The comparision was per- formed undes the condition

2 "'Q 3 4 ^{2 4}

T,SP,, 3" zno(pt)

(F)blb I?3zeOnO(P:)($)7k ( 5 ) so t h a t the energy input p e r unit volume, was the same i n boeh plasmas.Using (5)

o a l y 5 of the parameters

3,

(ne/ll) b,po, b E/~:, (ne/log,pz a r e f r e e .We chose E / ~ : a s determined by t h e o t h e r parametePs.The s o l u t i o n was found by a threefold i t e r a - t i v e prooess /2/.Espaoially i t i s neces- s a r y t o selecb such values f o r the para- meters w h i ~ h permit a cornparision beeween boeh p l a s m 8 under t y p i a a l conditions of t h e i r existence such a s po=lo-2,p~=l_grr b and the i o n i e a t i o n degree (n,/ll) -10

g-

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979764

Resulfia and Discussion :Fig .'l shows t h e

. . . I

energy input P& =P a s funotion of U b g

with (ne/Pl) as parame 2er.The r e s u l t i n g energy i n p u t s f o r the chosen (ne/IJIb a r e d i f f e r e n t from one another by about one order oP magnieude f o r each given value of

J U and vary i n the range from 5 loo2 t o ~ 3 0 w/om3.The oorresponding E/~: a r e presented i n Fig.2 and change from ?: 1 t o "-160 V/( cm Torr) .In Fig, 3 anexample ( 6 1 . 6 ~ 'Ioo2v) i s given f OP the obtained d i s t r i b u -

t i o n f u n c t i o n s fb(U) and fg(U) which a r e adequate t o one another according t o (5)

.

While the two corresponding dis1;ribuf i o n f u n c t i o n s f o r (ne/N) b=10-2 and t h e r e f ore

A 4

with P =P a r e olose t o one a n o t h e r s t h e r e b €3

a r e very great d i f f e r e n c e s i n the o t h e r cases.Bwcthermore ,we see a l s o d i s t i n c t d i f f e r e n c e s i n the structure.Especially from the strong v i b r a t i o n a l e x c i t a t i o n of the N2 molecules i n the range of' 2-4 V a sbeplike decrease follows f o r f =(U) .In oontrast t o t h i s fb(U) i s n e a r l y PlrIaxwel- l i a n f o r equal ^a energy i n p u t s .Finally the energy i n p u t s

i;6

and t h e d i f f e r e n t energy l o s s e s (ae1/Po)&,(aei/Po)a(~8m/~O)d

,

(@E/po)g , ( ~ * ~ / p , & - and (U /pO)h fop ela- s t i c and electron-ion c o l l i s i o n s , v i b r a t i o - n a l and e l e c t r o n i c e x c i t a t i o n as well a s d i s s o c i a t i o n and i o n i z a t i o n a r e presented i n Figs.& and 5 f o r ( n e / N ) b = ~ ~ - 3 and lo-'.

We observe 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 energy input from the turbulent and the d i ~ e c t e l e c t r i c f i e l d i s d i s s i p a t e d t o the molecules and i o n s i n the two plasma types.The obtained r e s u l e s show t h a t equal energy input p e r

A A

one e l e c t r o n and pressure u n i t Pb=Pg can be considered t o some extent as a simila- r i t y l a w f o r the e l e c t r o n k i n e t i c s in va- r i o u s collision dominat;ed discharge plas- mas,i .e. the i s o t r o p i c disfiribution f unc- t i o n s of d i f f e r e n t discharge plasmas w i l l be nearly equal i n the same gas ( s e e a l s o Fig. 3)

Ref erences :

/I/ S .Pf au,R.Winkler , B e i t r .Plasmaphys

.%

(1978)113;

3

(1973)273*

/2/ 'P. % u ~ l c ~ q ~

,

^U

.

^%*LL., A. A. UE-be, 3 . % . G m y , c b y a nnw (e1333) i n p r i n t .

I I