HAL Id: jpa-00219349
https://hal.archives-ouvertes.fr/jpa-00219349
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.
AN EXPERIMENTAL INVESTIGATION OF THE CONTINUOUS OPTICAL DISCHARGE
D. Wróblewski, A. Cybulski, Z. Szyma_ski
To cite this version:
D. Wróblewski, A. Cybulski, Z. Szyma_ski. AN EXPERIMENTAL INVESTIGATION OF THE CONTINUOUS OPTICAL DISCHARGE. Journal de Physique Colloques, 1979, 40 (C7), pp.C7-733- C7-734. �10.1051/jphyscol:19797354�. �jpa-00219349�
JOURNAL DE PHYSIQUE Colloque C7, suppliment au n07, Tome 40, J u i l l e t 1979, page C7- 733
AN EXPWMENTAL INVESTIGATION ff THE CONTINUOUS OPTICAL DISCHARGE
D. Wdblewski, A. Cybulski and 2. Szymafiski.
Department of Fluid Dynamics, I n s t i t u t e o f Fundamental TechnoZogicaZ Research, PoZish Academy o f Sciences, 00-049 Warszma, u l . M e t o k r z y s k a 21, Poland.
1. INTRODUCTION i n v e s t i g a t e t h e dynamics of t h e gas flow
A plasma maintained by C.W. l a s e r o s c i l l a t i o n s .
beam i s r e f f e r e d t o a s a continuous o p t i - It was found t h a t t h e l r i n g e s h i f t due c a l d i s c h a r g e /COD/. For t h e plasma main
-
t o t h e e l e c t r o n component of t h e plasma tenance focused r a d i a t i o n of p o w e r f u l l C02 w a s i n t h e range of t h e measurement accu- l a s e r s i s used. The COD was o b t a i n e d i nr a r e g a s e s / I , 2 , 3 , 4 / and i n t h e a i r /5/.
Due t o l a r g e temperature g r a d i e n t s a c o n v e c t i v e flow i s produced i n t h e v i c i n i - t y of t h e p1asma.h i n t e r e s t i n g p r o p e r t y of t h e flow i s i t s r e g u l a r o s c i l l a t i o n w i t h t h e frequency of about 25 Hz /4/.
The aim of t h e s t u d y , t h e p r e l i m i n a r y r e s u l t s of which a r e given here,was t o in- v e s t i g a t e t h e temperature and d e n s i t y d i s - t r i b u t i o n i n t h e COD i n argoii.3pecJ--- l,rosco- py Nas used t o s t u d y t h e h o t plasma c o r e and i n t e r f e r o m e t r y f o r t h e n e u t r a l
as
de- n s i t y i n v e s t i g a t i o n i n t h e o u t e r region.2. EXPERIMEivTAL ARRANGEMENT
The scheme of t h e experimental set-up i s shown on Fig. 1. The plasma was produ-
r a c y
-
a f r a c t i o n of a fririge.Thus, t h e i n t e r f e r o g r a m s were i n t e r p r e t e d i n t h e terms of t h e n e u t r a l d e n s i t y only.The i n t e r f erograms e x h i b i t e d pronoun- ced v e r t i c a l symmetry a x i s and were evalu- a t e d v i a t h e Abel transformation.The re- s u l t of t h e t r a n s f o r m a t i o n i s t h e r e l a t i v e d e n s i t y d i s t r i b u t i o n and i n o r d e r t o ob- t a i n t h e a b s o l u t e v a l u e s t h e d e n s i t y must be known i n some point.The f i t t i n g a t t h e flow boundary r e s u l t s i n poor accuracy a d t h e r e f o r e i n our c a s e i t was made a t t h e plasma boundary,with t h e u s e of t h e d a t a o b t a i n e d from t h e s p e c t r o s c o p i c measure- ment s.
A s an example,the d e n s i t y d i s t r i b u -
ced i n s i d e t h e p r e s s u r e chamber i i ~ t h e f o - c u s of horizon-Lally p r o p a g a t i n g GO2-laser 8 beam.T'fie beam was focused by a s p h e r i c a l u i r r o r , i t s power was i n t h e r a n g e from 100 t o 300 iiiatts.9he p r e s s u r e o f t h e argon @ was 4 t o 6 bars.
3. IltTBRFEROUBTElrC bBA8UREMENTS Iviach-Zehnder i n t e r f e r o m e t e r w i t h a He -Ne l a s e r a s a l i g h t source was used.The p i c t u r e s 02 t h e i n t e r 2 e r o g ~ ' a m s were t a k e n
fringe image tungsfen ribbao retoruer and di~play
w i t h t h e u s e of a movie-camera.The expo- done
s u r e time was t y p i c a l l y s m a l l e r t h a n 2 ma. Fig. 1. Scheme of t h e e x p e r i m e n t a l arrangement.
The u s e of t h e movie-camera allowed t o
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797354
t i o n s i n t h r e e d i f f e r e n t phases of t h e o- s c i l l a t i o n s , a t t h e p r e s s u r e of 4 b a r s , a r e shown on Pig. 2.
Fig. 2. N e u t r a l d e n s i t y o s c i l l a t i o n s i n t h e COD a t t h e p r e s s u r e of 4 bars.
The frequency of t h e o s c i l l a t i o n s i s 21 Hz. The time i n t e r v a l b e t s e e n t h e frames i s 14.25 m s .
The temperature on t h e 1 x 1 0 ~ ~ cm-3 i s o d e n s e i s 2900 K.
4. SPECTROSCOPIC KEASUREMENTS
The a b s o l u t e i n t e n s i t i e s of A r I 7147a l i n e and t h e continuum a t 7182
a,
7112 1 and 4314 1 were rneasured.For t h e a b s o l u t e c a l l i b r a t i o n a t u n g s t e n r i b b o n lamp w a s used. A s i n d i c a t e d on Fig. 1 a s p h e r i c a l m i r r o r was used t o i n v e s t i g a t e t h e plasma a b s o r p t i o n a t 7147 A.The a b s o r p t i o n was found t o be n e g l i g i b l e . Other d e t a i l s of t h e arrangement a r e shown on Pig. 1.Though t h e plasma was found t o be a- symmetric,with a t a i l i n t h e upward d i r e - c t i o n , t h e Abel i n v e r s i o n was used f o r t h e o b t a i n e d i n t e n s i t i e s and t h e n c o r r e c t i o n f a c t o r s were i n t r o d u c e d t o account f o r t h e
change of t h e shape. The temperature was determined from t h e r e s u l t i n g e m i s s i v i t i e s The r e s u l t s o b t a i n e d from t h e measurement of 7147
1
l i n e and t h e blue and r e d c o n t i - nua d i f f e r e d one from each o t h e r no more t h a n 15 p e r c e n t .A v e r t i c a l s e c t i o n of t h e i s o t h e r m s i n t h e h o t c o r e of t h e plasma, a t t h e pre- s s u r e of 4 b a r s , i s shown on Fig. 3. The d i s p l a y e d v a l u e s r e p r e s e n t t h e average from t h e measurements made a t d i f f e r e n t wavelengt he.
5. COI'?CLUSIo~S
A complex d i a g n o s t i c s of t h e COD was performed and t h e t e m p e r a t u r e / d e n s i t y d i s - t r i b u t i o n was determined i n t h e whole r e - g i o n i n f l u e n c e d by t h e plasma presence.
The i n f l u e n c e of t h e c o n v e c t i v e flow on t h e plasma parameters was shown.The r e s u - l t s can be used a s d a t a f o r hydrodynamic c a l c u l a t i o n s of t h e gas v e l o c i t y f i e l d .
c q h e r Owm direction
-
Fig. 3. Isotherms i n t h e COD plasma a s o b t a i n e d from s p e c t r o s c o p i c measuranent
REFERENCES
1
.
N.A. Generalov e t a l . , J E T P , ~ , 1434/1971/2. D.L.Pranzen,J.Appl.Phys.,fi,1727/1973/
3. C.D.Moody, ~ . ~ ~ ~ l . ~ h y s . ,&,2475/1975/
4. Z.Mucha e t a l . , ~ u l l . ~ c a d . ~ c i . ~ , 3 6 2 /I 977/
5. M.C.Fowler,D.C.Smith,J.Appl.Phys.
46,138/1975/