ON THE CHARACTERISTICS OF A HIGH VOLTAGE GLOW DISCHARGE

(1)

HAL Id: jpa-00219490

https://hal.archives-ouvertes.fr/jpa-00219490

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 published 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.

ON THE CHARACTERISTICS OF A HIGH VOLTAGE GLOW DISCHARGE

C. Popovici, M. Balaceanu, Nicu Ceausescu, E. Avram

To cite this version:

C. Popovici, M. Balaceanu, Nicu Ceausescu, E. Avram. ON THE CHARACTERISTICS OF A HIGH VOLTAGE GLOW DISCHARGE. Journal de Physique Colloques, 1979, 40 (C7), pp.C7-171-C7-172.

�10.1051/jphyscol:1979784�. �jpa-00219490�

(2)

JOURNAL DE PHYSIQUE CoZZoque C7, supp2Bment au n07, Tome 40, JuiZZet 1979, page c7- 171

ON THE CHARACTERISTICS OF A HIGH VOLTAGE GLOW DISCHARGE C. Popovici, M. Balaceanu, Nicu Ceausescu and E. Avram.

n s t i t u t e o f Physics and TeehnoZogy o f Radiation Devices, Bucharest, P. 0. Box 5206, Romania.

1, I n t r o d u c t i o n

Generation of e n e r g e t i c e l e c t r o n benrns i n h i g h v o l t s g e (1-100 kV) and ave- r s g e p r e s s u r e (10-'-10-'torr)glow d i s c h a r - ges p r e s e n t s a g r e a t il~iportnnce i n non- conventionzl techiiologies used i n many

i n d u s t r i a l applications/+/-/2/.This paper d e a l s w i t h some c h a r a c t e r i s t i c s of high v o l t a g e glow d i s c h a r g e s f o r c e r t a i n para- a e t e r s s p e c i f i c t o p l a s s a e l e c t r o n sources.

2. Experiments

The e l e c t r o d e s system i s shown i n

Fig. 7 - e l e c t r o d e ,stem i n Fig

- e l e c t r o d e ,stem i n F i g

Fig. 4

e l e c t r o d e s y s t e x i n Fig2 -- w i t h c e n t r ~ l e n o d e

-- -

without c e n t r a l enode 1-p=4 .lo-?; 2-p=6 ,lo-?;

3-p=6 .lo-'; 4-p= 10-'torr,

9 1 VIKV'

Fig.1 and Pig.2. 2 . 2 ~ h e r m a l e f f e c t s a t t h e anode.

Fig. 1 Fig. 2

2.1 V - I C h a r a c t e r i s t i c s

Fig. 3 and 4 r e p r e s e n t s V - I cha

-

r a c t e r i s t i c s i n argon.

For d i s c h a r g e s without c e n t r e 1 a- node , i t i s , n o t i c e d a s e v e r e decrease i n t h e burning v o l t a g e and a s t r o n g i n c r e a s e i n t h e discharge c u r r e n t . This d i s c h a r g e characteristic,well-known i n t h e c a s e of of t o r r - o r d e r p r e s s u r e s , i s explained by t h e nechanism of t h e hollow cathode e f f e c t /J/-/4/.V/hen t h e anode i s placed i n t h e n e g a t i v e glow plasma, t h e d i s c h a r g e r e

-

t a i n s t h e c h a r a c t e r i s t i c s of t h e conven- t i o n a l glow discharge.

The thermal e f f e c t s e x h i b i t e d by t h e c a t h o d i c e l e c t r o n s beam i n a h i g h vol- t a g e d i s c h a r g e , p r o v i d i q t h e b a s i s f o r a l a r g e number of p r a c t i c a l a p p l i c a t i o n s o f plasma e l e c t r o n s o u r c e s , depend on d i s - charge parameters.

I n o r d e r t o o b t a i n i n f o r m a t i o n concerning t h e anode h e a t i n g ( t h e system i n Fig. 2) under v a r i o u s o p e r a t i o n c o n d i t i o n s , s e v e r a l temperature d e t e r m i n a t i o n s o f t h e anode have been performed a f t e r t h e same i n t e r v a l (3Osec) *om the d i s c h a r g e i g n i - t i o n .

Table 1.

Ud Id t'

( t o r r )

-

(v) _{( A )}

(w> P C )

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979784

(3)

The d a t a i n Table l(whnre Cd

'

I d ' I: d ?.nd T r e p r e s e n t volta~e,currant,disc:-Lsrge pover and anode temperatl;nn,rospectivelg)in6icz- t e t h a t t h e anode h e a t i n g v a r i e s eubatan-

ti all.^ ,

olthavgh t h e d i s c h a r g e power is p r ~ c t i c a l l y c o ; ; ~ t a n t . T k i i s i s exp?.ain ^by t h e f a c t t h e t primary e n e r g e t i c e l e c t r o n s

~ e p r e s s n t 0nl.s- e ?pert o u t of t h e t o t a l dischnry;e ~ u r r e n t ~ d e p e n d i n g on t h e d i a - chzrse parcr.cters .The e l e c t r o n beam i n c r e a - s e s w i t h t h e secondary e ~ i i s s i o n c o e f f i - c i s i ~ t

(T)

of' t h e cathode,v;hich i n i t s t u r n is an i n c r e a s i n g f u a c t i o r ~ of t h e i n c i d e n t i o n enargy.3'or ncr expnri:rentul c o n d i t i c n s , enarcy l o s s e s 02 the p r i r ~ a r y el-ectrons due t o S.nelastic collifiioris mag b o a e g l e s t e d . T h i s could be s e e n i n Tnblc ? .cihick~ provi- d e s -the folloain,r;: deta:Ai-neon 2 r e e i o n i - zing path;n-nc-rcbsr o f i o n i z i n g c o l l i s i o n s i n t h e ccthocle-anode space;AE-enerlyy l o s - s e s by i n e l a s t i c c o l l i s i o n s ;&/>i-relati.ve eiler:;y l o s s censed by i n e l a s t i c c o L l i c i o n s .

T a b l e 2

p E

hi

ⁿ

^ax/?

( t o r r ) ( e V ) (czi)

-

^(ev)^.---.- ^(5')

0 2100 6.25 2.7 81 4

AT- d i f f e r z n c s between f i n a l and i n i t i a l te: . > e r e t u r e ('l'

--xo) ,

t-time necssai-y t o

I

r e a c h Tf.

For our experii;:ental c o n d i t i o n s , PL may be

wliere T

-

nnode t e n p e r ~ t u r e (fn ^OK),E(T) anode e m i s s i v i t y

,

G-StB,ahant a c o n s t a n t

A-

thermcil c o n d u c t i b i l i t y o f t h e anode

-

^sup-

p o r t ~ v i r e ,

3 -

-temperetore i r n d i e n t along d i r e c t i c n of t h e wire,S1

-

anode a r e a and S 2

-

support wire cross-sec.Lion a r e a . The power PL i s a c o m p i i c u ~ e d i u n c t i o n o f temperature ( w i i i c r ~ aepenus on time) and t h e r e f o r e , t h e c ~ l c u l a t i o n from (1) o f t h e time t necessary f o r t h e anode t o r e a c h a c e r t a i n t e a p e r a t w e i s a problem which could be s o l v e d only numerically. If t h e temperature i s not t o o high and t h e ba

-

l a n c e i s f a r *om being reached, t h e time t could be c a l c u l a t e d approximatelly,by s ~ p e r e c t i l r ~ z t i n g t h e power l o s s e s and consi- d e r a t i n g them corresponding t o t h e f i n a l t e ~ p e r e t u r e ,For example, l e t us assume +he h e a t i n g (from 20°c t o 1 3 0 0 ~ ~ ) o f a t a n t a l u m disk anode (diameter=4cm.Width=0.7cn) sds-

2580 5 . 5 2 1.6 54

,.

_-

- --

6 3230 14.57 1 . 2 36 1

. -

4,10-' 4480 28.1'7 0.6 18 1

-

3. Thermal balance of tfie3sode b e a t i @ Thermal balance of t h e anode hea- ting i s :

m c A T

U e c l e c

-

^PL⁼^J

-

_t ⁽¹⁾

where Uec-cathodic f a l l , I e c - p r i n a r y e l e c - t r o n s current,PL-anode power l o s t by r a d i - ation,coPlduction,etc, J-conversion con- stant,rn-anode 'mass,c-specific anode h e a t ,

pended by a wolfram w i r e (diam.=O.lcm) i n a h i g h v o l t a g e discharge(5kV,0,5A).Assu

-

mingf=0.35 ana dT-lOOOO~/cm, r e o b t a i n

t = 2 7 s e c e

T-

References

/I/ RbA.Dwdale,Nature,249,440,(1974) /2/ R.A,Dugdale,J.of M a t e r i a l s Science,lO,

896, (1975)

/3/ E.BZidlreu,C.Popovici,Ann,der Physik 7, Bde153313 (1965)

/4/ C.Popovici,M.Some~an,G.Pavelescu,Int.

JeElectronics,34,259,(1973).